Antimicrobial therapy for patients with severe sepsis and septic shock: An evidence-based review Pierre-Yves Bochud, MD; Marc Bonten, MD; Oscar Marchetti, MD; Thierry Calandra, MD, PhD Objective: In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for antimicrobial therapy for patients with severe sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis. Design: The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. Methods:The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation I n 2001, the International Sepsis Forum published guidelines on the management of patients with severe sepsis and septic shock, including an evidence-based review on antibiotic therapy (1). The recommendations on antibiotic therapy for sepsis comprised sections on the epidemiology of sepsis and the impact of appropriate antimicrobial therapy on outcome of Gram-negative, Gram-positive, and fungal sepsis and an evidence-based review of monotherapy vs. combination therapy for From The Institute for Systems Biology, Seattle, WA (PYB); the Department of Internal Medicine, Division of Acute Internal Medicine and Infectious Diseases, University Medical Center Utrecht, Utrecht, The Netherlands (MB); Infectious Diseases Service, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (OM, TC). Supported by grants from the Swiss Foundation for Medical and Biological Grants to PYB (1121), from the Swiss National Science Foundation to PYB (81LA65462) and to TC (3100 – 066972), the Bristol-Myers Squibb Foundation, the Santos-Suarez Foundation for Medical Research, and the Leenaards Foundation. TC is a recipient of a career award from the Leenaards Foundation. Copyright © 2004 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins DOI: 10.1097/01.CCM.0000143118.41100.14 Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591. Conclusion: Since the prompt institution of therapy that is active against the causative pathogen is one of the most important predictors of outcome, clinicians must establish a system for rapid administration of a rationally chosen drug or combination of drugs when sepsis or septic shock is suspected. The expanding number of antibacterial, antifungal, and antiviral agents available provides opportunities for effective empiric and specific therapy. However, to minimize the promotion of antimicrobial resistance and cost and to maximize efficacy, detailed knowledge of the likely pathogens and the properties of the available drugs is necessary for the intensivist. (Crit Care Med 2004; 32[Suppl.]:S495–S512) the empirical management of patients with severe sepsis or septic shock. Under the auspices of the Surviving Sepsis Campaign, a joint venture of the International Sepsis Forum, the Society of Critical Care Medicine, and the European Society of Intensive Care Medicine, the International Sepsis Forum guidelines have been updated and extended. The revised guidelines extend, but do not entirely replace, the previously published article (1), as several parts of the initial document are still up-to-date. As for the original publication, the revised guidelines were developed using an evidencebased review of the literature. The processes used by the panel of experts to select and review the relevant literature are outlined in the Material and Methods section. The panel elected to focus on the following topics: 1) impact of appropriate antibiotic therapy on the outcome of sepsis; 2) impact of pharmacokinetic and pharmacodynamic principles on treatment outcome; 3) need for prompt initiation of antimicrobial therapy in patients with severe sepsis and septic shock; 4) analyses of the efficacy and toxicity of monotherapy vs. combination therapy as empirical therapy; 5) indications for empirical use of anti-Gram-positive antibiot- ics; 6) need for empirical antifungal therapy in patients with severe sepsis; 7) analyses of the efficacy and safety of conventional vs. lipid formulations of amphotericin B and of azoles and echinocandins vs. amphotericin B for the treatment of fungal sepsis; and 8) impact of antibiotic cycling on morbidity and mortality of sepsis. Materials and Methods Selection of Panel, Topics of Interest, and Review Process. The panel was composed of three board-certified infectious diseases specialists, with expertise in the fields of antimicrobial therapy, sepsis, intensive care medicine, and infection control, who have been selected by the cochairs of the “Diagnosis and Management of Infection in the Severe Sepsis” track of Surviving Sepsis Campaign. The panelists, chairpersons, and directors of the Surviving Sepsis Campaign discussed the specific scopes of the guidelines during a 2-day meeting (June 27–28, 2003). Identified topics of interest were distributed among the panelists based on individual expertise. Each panelist either alone or in collaboration with colleagues wrote several sections of the guidelines, which S495 were assembled by the panel chair and reviewed and critiqued by the panelists and track co-chairs. Data Source. Medline was used to search articles published between 1966 and July 1, 2003. Medline searches and selections of articles were performed by each of the authors. Medical Subject Heading (MeSH; http://www.nlm.nih.gov/ mesh/meshhome.html) terms used in the Medline search were sepsis (comprising the terms septicemia, sepsis syndrome, septic shock, bacteremia, fungemia, parasitemia, and viremia), pneumonia (comprising the terms bronchopneumonia, pleuropneumonia, aspiration pneumonia, bacterial pneumonia, viral pneumonia, and Pneumocystis carinii pneumonia). Since no ad hoc MeSH term exists for intraabdominal infections, we used the words and MeSH terms intraabdominal, abdomen, abdominal infection, peritonitis, appendicitis, abdominal abscess to search for articles on intraabdominal infections. The Medline search was then narrowed by using the MeSH terms antiinfective agents (comprising the term antibiotics, which was exploded to include all classes of antibiotics and all antibiotic names), clinical trials, or randomized controlled trials, further limiting the search to human studies and English literature. The MeSH keywords agranulocytosis, antibiotic prophylaxis, and ambulatory care were used to exclude studies on neutropenic patients, antibiotic prophylaxis, and outpatient therapy. Additional articles were retrieved from references of articles identified by the Medline search and of guidelines and review articles on the following topics: sepsis, community-acquired pneumonia, ventilatorassociated pneumonia, and intraabdominal infections. Epidemiologic data were extracted from articles identified by a Medline search using the keywords epidemiology and sepsis and by a systematic review of 27 clinical trials of antiinflammatory or mediator-targeted therapies in patients with severe sepsis and septic shock (2– 6). For the section on empirical therapy for Gram-positive severe sepsis or septic shock, a Medline search was performed using the terms empirical combined with either vancomycin or teicoplanin, which revealed one and 33 hits, respectively. Extension of the search to the terms empirical, glycopeptide, and clinical trials yielded 20 hits. However, none of these articles included nonneutropenic paS496 tients with Gram-positive infections and severe sepsis. A Medline search using the terms clinical trial and either linezolid or quinupristin/dalfopristin and Synercid yielded 100 and 41 hits, respectively. Selection of Articles. Abstracts of all articles satisfying the selection criteria were reviewed to exclude irrelevant studies. Review articles and articles on topics such as antibiotic prophylaxis, pharmacology, microbiology, oncology, hematology, immunology, mediators of inflammation, allergy, catheter management, animal studies, chronic infections, or specific infections (acquired immunodeficiency syndrome, endocarditis, chronic salmonellosis, viral infections in organ transplant patients, hemorrhagic fever, viral hepatitis, parasitic infections, and malaria) were excluded if they did not fulfill the inclusion criteria. For the comparison of monotherapy vs. combination therapy, articles on each of the three clinical entities reviewed (i.e., sepsis, pneumonia, and intraabdominal infections) were selected only if there was unequivocal evidence that patients had either clinically or microbiologically documented infections and if the study met at least one of the following criteria: 1) a definition of sepsis or severe sepsis consistent with the definition of the Consensus Conference of the American College of Chest Physicians and the Society of Critical Care Medicine (7); 2) sepsis with at least one organ dysfunction or sign of hypoperfusion present in ⬎50% of the patients; or 3) an overall mortality ⬎10%. This cutoff for mortality was chosen to ensure that articles included a substantial proportion of patients with severe sepsis and not simply sepsis. To ensure that articles on antimicrobial therapy had been properly selected by one of the authors (PYB), a random sample of 20% of the articles identified by the Medline search were examined by the panel chair (TC). Overall agreement between the two reviewers was 94% for articles on intraabdominal infections ( statistic of 0.71) and 96% for articles on community-acquired pneumonia and ventilatorassociated pneumonia ( statistic of 0.81) corresponding to “substantial” and “almost perfect” agreements, respectively, according to the criteria proposed by Sackett et al. (8). Consensus was reached between the two authors on the articles for which there was disagreement regarding the inclusion criteria. Epidemiological Features of Severe Sepsis and Septic Shock Data on secular epidemiologic trends of the etiological agents and most frequent sites of sepsis have not changed since the 2001 review and will, therefore, not be reviewed in detail again (1). Microorganisms and Sites of Infection. By the mid-1980s, the frequency of Gram-positive sepsis (mainly caused by Staphylococcus aureus, coagulase-negative staphylococci, enterococci, and streptococci) has equaled that of Gramnegative sepsis (mainly caused by Enterobacteriaceae, especially Escherichia coli and Klebsiella pneumoniae, and by Pseudomonas aeruginosa). Recent epidemiologic data in the United States and in Europe indicated that Gram-positive bacteria have now surpassed Gram-negative bacteria as etiological agents of sepsis (9, 10), confirming a trend observed in many recent sepsis studies (4, 5, 11–17). Fungi account for about 5% of all cases of sepsis, severe sepsis, and septic shock (1). Most cases of fungal sepsis are caused by Candida species, which are the fourth most common bloodstream pathogens in all recent U.S. studies of nosocomial bloodstream infections and are associated with the highest mortality (40%) of all bloodstream pathogens (18, 19). The incidence of fungal sepsis has increased three-fold between 1979 and 2000 (10). However, due to the paucity of published data on national surveys of fungal infections, it is unclear whether the incidence of fungal sepsis has increased in a similar fashion in other parts of the world. Dutch investigators reported a two-fold increase in the incidence of candidemia in the early 1990s (20). In contrast, a Norwegian survey also conducted in the early 1990s reported stable incidence of candidemia and Candida species distribution (21). Likewise, a recent survey of the incidence of candidemia in Switzerland has shown that the incidence of candidemia remained stable between 1991 and 2000 (median, 0.5 episodes/10,000 patientdays) (22). By decreasing order of frequency, the predominant sites of infections in patients with severe sepsis and septic shock are the lungs, the bloodstream (i.e., without another identifiable source of infection), the abdomen, the urinary tract, and the skin and soft tissues. Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) Need for Prompt Initiation of Antimicrobial Therapy in Patients with Severe Sepsis and Septic Shock Rationale: Establishing vascular access and initiating aggressive fluid resuscitation is the first priority when managing patients with severe sepsis or septic shock. However, prompt infusion of antimicrobial agents is also a logical strategy and may require additional vascular access ports. Establishing a supply of premixed antibiotics in an emergency department or critical care unit for such urgent situations is an appropriate strategy for enhancing the likelihood that antimicrobial agents will be infused promptly. Staff should be cognizant that some agents require more lengthy infusion time, whereas others can be rapidly infused or even administered as a bolus. Impact of Appropriate Antibiotic Therapy on Outcome of Sepsis Recommendations: Initial empirical antiinfective therapy should include one or more drugs that have activity against the likely pathogens (bacterial or fungal) and that penetrate into the presumed source of the sepsis. The choice of drugs should be guided by the susceptibility patterns of microorganisms in the community and in the hospital. Grade D Rationale: Early administration of appropriate antibiotics reduces mortality in patients with Gram-positive and Gramnegative bacteremias. Retrospective studies conducted in the 1960s and in the 1970s have shown that appropriate antimicrobial therapy, defined as the use of at least one antibiotic active in vitro against the causative bacteria, reduced the mortality of Gram-negative bacteremia when compared with patients receiving inappropriate therapy (23–26). In a landmark study of 173 patients with Gram-negative bacteremia, who were classified in three categories based on the severity of the underlying disease categories (i.e., rapidly fatal, ultimately fatal, and nonfatal), McCabe et al. (23) observed that appropriate antibiotic therapy reduced mortality from 48% to 22%. Four subsequent studies that included larger numbers of patients yielded similar results (24 –27). In a recent prospective study of 2,124 patients with Gram-negative bacteremia, mortality was 34% in 670 patients who received inappropriate antibiotics and Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) 18% in 1,454 patients who received appropriate antibiotics (p ⬍ .0001) (28). Smaller recent studies showed that the appropriateness of the antibiotic regimen favorably influenced the outcome of patients infected with specific Gram-negative bacteria, such as Enterobacter species (29), P. aeruginosa (30), and ceftazidime-resistant K. pneumoniae or E. coli (31). Fewer data have been published on the impact of appropriate antibiotic therapy in patients with Gram-positive sepsis (32). Several studies evaluated the impact of appropriate antimicrobials in patients with severe infections due to Gramnegative and Gram-positive bacteria (33– 44). In all but one study (42), appropriate antibiotic therapy was associated with a better outcome. Empirical Antimicrobial Therapy for Patients with Severe Sepsis and Septic Shock The evidence-based review of the literature on empirical antimicrobial therapy for patients with severe sepsis and septic shock has focused on three clinical entities: sepsis (i.e., primary or secondary bloodstream infections), pneumonia (both community-acquired and hospitalacquired), and intraabdominal infections. Management guidelines and review articles have been published recently on these topics (45–53), which should be used as a supplement to the present article, which focuses on clinical trials of antimicrobial agents for patients with severe sepsis or septic shock. A total of 2,065 articles (sepsis, 988; community-acquired pneumonia and ventilator-associated pneumonia, 509; intraabdominal infections, 393; Grampositive infections, 175) were identified using the Medline search strategy described in Material and Methods, of which 1,464 did not meet our inclusion criteria based on the content of the abstract (Fig. 1). A full text review was performed on the remaining 614 articles, of which 79 (13%) (sepsis, 37; community-acquired pneumonia and ventilator-associated pneumonia, 35; and intraabdominal infections, 7) met the inclusion criteria of severe sepsis or septic shock. Thus, only a small proportion of the screened clinical trials of antibiotic therapy have included critically ill septic patients with high mortality. The overall mortality of the patients in the selected studies was 18%. Most studies performed before 1990 comprised a limited number of patients (usu- ally ⬍100 per trial), a majority of these patients with Gram-negative sepsis, and did not include intent-to-treat analyses. Studies performed in the 1990s were larger, included patients with both Grampositive and Gram-negative sepsis, and in most instances, included an intent-to-treat analysis. Given the relatively small number of studies available and the fact that the sepsis subset of studies included patients with various types of infections, including community-acquired and ventilator-associated pneumonias and intraabdominal infections, all studies were pooled. Among the 79 studies identified, 67 met the inclusion criteria for severe sepsis and/or septic shock due to bacterial infections and were grouped in four main categories: 1) studies comparing different combination therapies, usually a -lactam antibiotic or a fluoroquinolone plus an aminoglycoside (n ⫽ 9; sepsis, 4; pneumonia, 5) (54 – 62); 2) studies comparing a monotherapy with a combination therapy with an aminoglycoside (n ⫽ 24; sepsis, 11; pneumonia, 7; intraabdominal infections, 6) (63– 86); 3) studies comparing single-agent therapies (n ⫽ 26; sepsis, 14; pneumonia, 11; intraabdominal infections, 1) (56, 87–111); and 4) miscellaneous studies (n ⫽ 8; pneumonia, 7; sepsis, 1) (112–119). Monotherapy Vs. Combination Antibiotic Therapy Recommendation: Monotherapy is as efficacious as combination therapy with a -lactam and an aminoglycoside as empirical therapy of patients with severe sepsis or septic shock. Carbapenem: Grade B. Third- or fourth-generation cephalosporins: Grade B. Extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors: Grade E Rationale. The use of antibiotic combinations for the treatment of severe infections relies on the following rationale: 1) a combination of two antibiotics broadens the antibacterial spectrum, which may be important as treatment is usually initiated empirically in critically ill septic patient; 2) combination of antibiotics may exert additive or synergistic effects against the infecting pathogen, resulting in enhanced antibacterial activity and possibly better clinical response (120 – 122); 3) the use of a combination of antibiotics may reduce the emergence of resistant bacteria (123) or of superinfections (124). S497 Figure 1. Study flow. Studies were searched in Medline as indicated in Material and Methods. Abstracts were reviewed, and studies that satisfied the inclusion criteria were selected for a full text review. MRGP, multiple-resistant Gram-positive bacteria. In the late 1960s and early 1970s, a series of retrospectives studies examined the potential benefits of combination therapy (27, 125). Overall, combination therapy was not found to be superior to single-agent therapy, but some benefits of antibiotic combinations were noted in subsets of patients, such as those with rapidly or ultimately fatal diseases. However, the impact of these results for today’s practice is limited given the retrospective nature of these studies and the facts that it utilized antibiotics that would no longer be considered appropriate today and that it did not include multivariate analyses. Subsequent studies evaluated the efficacy of different antibiotic combinations, usually a -lactam and an aminoglycoside, for the treatment of Gram-negative infections (54 –59, 61, 62, 126). By and large, there were no differences between the various antibiotic regimens in terms of clinical success, microbiological eradication, and mortality rates. However, in one study of 204 patients with ventilator-associated pneumonia, the clinical cure rate of piperacillin/ tazobactam plus amikacin was superior to that of ceftazidime plus amikacin (26/ 51, 51%, vs. 23/64, 36%; p ⫽ .009), but mortality was similar in the two treatment groups (8/51, 16%, vs. 13/64, 20%; p ⫽ .4) (60). Since the 1980s, the advent of broadspectrum and highly bactericidal antibiS498 otics, such as the extended-spectrum penicillins, third-generation or fourthgeneration cephalosporins, or the carbapenems, has substantially reduced the need for aminoglycoside-containing antibiotic combinations. During the last two decades, most antibiotic studies have, therefore, compared the efficacy and toxicity of single-agent antibiotic therapies (i.e., monotherapies) with that of -lactams paired with aminoglycosides (i.e., combination therapies). Twenty-four studies of empirical monotherapy vs. combination therapy were identified by the Medline search. The results obtained with carbapenems, third-generation or fourth-generation cephalosporins, and extended-spectrum penicillins with activity against Pseudomonas species are shown in Table 1. Carbapenems. In five prospective, randomized, controlled studies, monotherapy with imipenem-cilastatin or meropenem was shown to be as effective as a combination of a -lactam (cefuroxime, ceftazidime, or imipenem) and an aminoglycoside (gentamicin, amikacin, or netilmicin) (Table 1) (64 – 66, 74, 75). It is worth mentioning that the same -lactam antibiotic (imipenem) was used in both treatment arms in only one of these studies, in which the success rates, the occurrence of superinfections, and of P. aeruginosa resistant to the carbapenem were similar in the imipenem and in the imipenem plus netilmicin treatment groups (65). However, nephrotoxicity was significantly more frequent in the aminoglycoside-containing treatment arm. In three studies of severe sepsis or intraabdominal sepsis, imipenem was found to be at least as efficacious as and less nephrotoxic (one study) than a combination of gentamicin or tobramycin and clindamycin or metronidazole (63, 81, 82). Third-Generation and Fourth-Generation Cephalosporins. In ten prospective, randomized, controlled studies, monotherapy with a third- or fourth-generation cephalosporin (cefotaxime, moxalactam, cefoperazone, or ceftazidime) was as effective as combination therapy with a -lactam (usually an extended-spectrum penicillin or a cephalosporin) and an aminoglycoside (67–71, 77, 78) or clindamycin and an aminoglycoside (76, 83, 84). In four of the ten studies, clinical success rates were significantly higher in the monotherapy treatment groups (69, 76 – 78). However, it is difficult to draw firm conclusions from these observations as different -lactams were used in the monotherapy and combination therapy treatment groups in all but one study. Mortality rates were similar in the monotherapy and combination therapy treatment groups in nine of the ten studies. A trend toward a lower mortality in the monotherapy treatment arm was observed in one trial (77). As expected, nephrotoxicity was higher in the aminoglycoside-containing regimen in seven of the ten studies, reaching statistical significance in five. Extended-Spectrum Penicillins with Anti-Pseudomonas Activity. In four prospective, randomized, controlled studies, extended-spectrum carboxypenicillins (ticarcillin) or ureidopenicillins (piperacillin) used either alone or in combination with a -lactamase inhibitor (clavulanic acid or tazobactam) were found to be as effective as amoxicillin-clavulanate, piperacillin, piperacillin-tazobactam, or clindamycin combined with an aminoglycoside (gentamicin, amikacin, or netilmicin) as empirical antibiotic therapy for patients with intraabdominal infections, pneumonia, or neonatal sepsis (72, 79, 85, 86) (Table 1). However, as noted for the carbapenem or cephalosporin studies, in three of these four studies, different -lactam antibiotics were used in the monotherapy and combination therapy treatment groups. In a study of 206 patients with intraabdominal sepsis, Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) clinical success, and mortality and nephrotoxicity rates were similar in patients treated with piperacillin-tazobactam or with piperacillin-tazobactam plus amikacin (86). Fluoroquinolones. One study showed that monotherapy with ciprofloxacin was as effective as therapy with a -lactam and/or an aminoglycoside for the treatment of patients with documented Gramnegative sepsis (80). However, given that first-generation fluoroquinolones exhibit suboptimal activities against Grampositive bacteria, this class of antibiotics should not be used as empirical singleagent therapy in patients with severe sepsis. Comments. The evidence-based review of the literature tends to suggest that monotherapy with a broad-spectrum -lactam antibiotic is as efficacious and less nephrotoxic than a combination of a -lactam and an aminoglycoside as empirical therapy for critically ill patients presenting with severe sepsis or septic shock. However, monotherapy should not be regarded as a universal remedy to be used indiscriminately for several reasons. Compared with the abundant literature on empirical therapy for febrile neutropenia, few studies have been conducted in patients with severe sepsis or septic shock. Moreover, many of the clinical trials reviewed here included ⬍200 patients, and the statistical power was, therefore, limited. Furthermore, rarely was the same -lactam antibiotic used in the control and experimental treatment groups, thus limiting the conclusions that could be drawn about the apparent equivalent efficacy of the two regimens. There is clearly a need for large, prospective, randomized trials to assess the efficacy and toxicity of new antibiotics in critically ill septic patients. One should keep in mind that the choice of empirical antibiotic therapy depends on several factors related to the patient’s history (including drug intolerance), underlying diseases, and susceptibility patterns of microorganisms of the hospital environment and patient’s community. The initial selection of an empirical antimicrobial regimen should be broad enough to cover all likely pathogens. Despite a lack of clearcut advantage, clinicians may still prefer to rely initially on a -lactam and aminoglycoside combination, especially in the context of high level of antibiotic resistance or when treating patients with suspected Pseudomonas infection, Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) even though the benefit of combination therapy for the latter indication remains controversial. Yet, the benefit from additive or synergistic effects of antibiotic combination and the possible prevention of emerging resistant bacteria must be weighed against the risk of increased toxicity. Indeed, aminoglycoside-containing regimens have been shown repeatedly to increase the risk of nephrotoxicity or ototoxicity. Single-Agent Antibiotic Therapies Recommendation: Third-generation and fourth-generation cephalosporins, carbapenems, and extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors are equally effective as empirical antibiotic therapy in patients with severe sepsis. Third- or fourth-generation cephalosporins: Grade A. Carbapenem: Grade B. Extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors: Grade C. Carbapenems, Third-Generation, or Fourth-Generation Cephalosporins. Six prospective, randomized, clinical trials (of which five included between 150 and 400 patients) were identified that investigated the efficacy and safety of a carbapenem (imipenem or meropenem), a third-generation cephalosporin (ceftazidime or cefotaxime combined with metronidazole), a ureidopenicillin with a -lactamase inhibitor (piperacillin-tazobactam), or another carbapenem (Table 2) (92, 95–97, 99, 107, 111). In all but one study, virtually identical clinical response rates and overall mortality were observed in patients treated with either imipenem or meropenem or control -lactam antibiotics. In a smaller clinical trial of 94 patients with intraabdominal sepsis, the clinical response rate of patients treated with meropenem was superior to that of those treated with cefotaxime plus metronidazole (111). In summary, as one might have anticipated given the fairly comparable antimicrobial spectrum of activity of most third-generation and fourth-generation cephalosporins, the studies conducted with these agents for the treatment of patients with severe sepsis and community-acquired or nosocomial (including ventilator-associated) pneumonia or miscellaneous types of infections have yielded very comparable results (Table 2) (91,93,94,98,101–104,108). Response rates for the various cephalosporins were in the range of 65% to 85% in most studies, except for slightly lower response rates for ceftriaxone and cefotaxime in two smaller studies (101, 104). Aminoglycosides, Monobactams, or Fluoroquinolones. In the late 1970s and early 1980s, three studies compared the efficacy and safety of different aminoglycosides (gentamicin vs. tobramycin, gentamicin vs. amikacin, and netilmicin vs. amikacin) as single-agent therapy for Gram-negative sepsis (87– 89). Clinical responses rates, overall mortality, and nephrotoxicity were similar among the various aminoglycosides compared in these studies. A high incidence of aminoglycoside-induced nephrotoxicity and ototoxicity were noted in these studies, which is a major concern in critically ill septic patients already at high risk of developing organ failures due to the circulatory collapse associated with severe sepsis or septic shock. In two small studies, aztreonam was found to be as effective and less toxic than aminoglycosides as empirical monotherapy of patients with severe Gram-negative sepsis (90, 100). However, today, aminoglycosides or a monobactam antibiotic such as aztreonam should not be used as single-agent empirical therapy of severe sepsis because of their narrow antibacterial activity and risk of toxicity (aminoglycosides). More recently, five studies, of which four enrolled only patients with severe community-acquired or nosocomial pneumonias, showed that fluoroquinolones (ciprofloxacin, four studies; levofloxacin, one study) were as efficacious as -lactam antibiotics (imipenem in four studies; various -lactams with or without an aminoglycoside in one study) for the treatment of patients with severe sepsis caused predominantly by Gramnegative bacteria (Table 2) (56, 105, 106, 109, 110). Of note, a large number of patients (ranging between 250 and 400) were randomized in three of the four pneumonia studies. However, given the limited activity of first-generation fluoroquinolones (i.e., norfloxacin and ciprofloxacin) against Gram-positive bacteria and the possibility of resistance among Gram-negative bacteria, these antibiotics cannot be recommended as empirical monotherapy for patients with severe sepsis or septic shock of unknown etiology, including patients with communityacquired or healthcare-associated pneumonia. The most recent, so-called respiratory fluoroquinolones (i.e., levoS499 Table 1. Monotherapy versus combination antibiotic therapy as empirical treatment of severe sepsis and septic shock Authors and Yr of Publication Type of Infection Experimental Therapy Control Therapy Success (%) (Exp. vs. Control) Carbapenems vs. -lactams or antianaerobes combined with an aminoglycoside Solomkin et al. 1985 (63) SEPSIS Imipenem Poenaru et al. 1990 (81) ABDOM Imipenem Gentamicin ⫹ clindamycin 28/37 (76) vs. 27/37 (73) Tobramycin ⫹ clindamycin — or metronidazole Solomkin et al. 1990 (82) ABDOM Imipenem Tobramycin ⫹ clindamycin 67/81 (83) vs. 57/81 (70) Mouton et al. 1990 (64) SEPSIS Imipenem Cefotaxime ⫹ amikacin 58/70 (83) vs. 54/70 (77) a SEPSIS Imipenem Imipenem ⫹ netilmycin 113/142 (80) vs. 119/138 (86) Cometta et al. 1994 (65) Sieger et al. 1997 (74) HAP Meropenem Ceftazidime ⫹ amikacin 76/106 (72) vs. 62/105 (59) Jaspers et al. 1998 (66) SEPSIS Meropenem Cefuroxime ⫹ gentamicin 27/39 (69) vs. 25/40 (63) ⫹/⫺ metronidazole Alvarez-Lerma et al. 2001 (75) HAP Meropenem Ceftazidime ⫹ amikacin 47/69 (68) vs. 39/71 (55) Third- or fourth-generation cephalosporins vs. -lactams or antianaerobes combined with an aminoglycoside Arich et al. 1987 (67) SEPSIS Cefotaxime Cefazolin ⫹ tobramycin 22/25 (88) vs. 17/22 (77) Schentag et al. 1983 (83) ABDOM Moxalactam Tobramycin ⫹ clindamycin 37/49 (76) vs. 36/49 (73) a Oblinger et al. 1982 (68) SEPSIS Moxalactam 33/38 (87) vs. 32/40 (80) Conventional therapy Mangi et al. 1988 (76) HAP Cefoperazone Clindamycin or cefazolin 41/46 (89) vs. 44/61 (72) and gentamicin Greenberg et al. 1994 (84) ABDOM CefoperazoneClindamycin ⫹ gentamicin 33/47 (70) vs. 15/29 (52) sulbactam b Fernandez-Guerrero et al. 1991 (77) HAP Cefotaxime 217/275 (79) vs. 193/273 (71) Combination therapy Croce et al. 1993 (78) HAP Ceftazidime or Ceftazidime or cefoperazone 22/39 (56) vs. 22/70 (31) cephoperazone ⫹ gentamicin Rubinstein et al. 1995 (69) SEPSIS Ceftazidime Ceftriaxone ⫹ tobramycin 227/306 (74) vs. 179/274 (65) d Extermann et al. 1995 (70) SEPSIS Ceftazidime 38/41 (93) vs. 28/30 (93) “Best guess” combination McCormick et al. 1997 (71) SEPSIS Ceftazidime Mezlocilin ⫹ netilmicin 50/65 (77) vs. 48/63 (76) Antipseudomonas penicillins vs. -lactams or anti-anaerobes combined with an aminoglycoside Fink 1991 (85) ABDOM Ticarcillin-clavulanate Gentamicin ⫹ clindamycin 15/20 (75) vs. 16/25 (64) Hammerberg et al. 1989 (72) SEPSIS Piperacillin Ampicillin ⫹ amikacin — Speich et al. 1998 (79) CAP ⫹ HAP PiperacillinAmoxiclav ⫹ netilmicin or 37/41 (90) vs. 36/43 (84) tazobactam gentamicin Dupont et al. 2000 (86) ABDOM PiperacillinPiperacillin-tazobactam ⫹ 44/99 (44) vs. 55/105 (52) tazobactam amikacin Miscellaneous monotherapies versus -lactams combined with an aminoglycoside f Korvick et al. 1992 (73) SEPSIS -lactam ⫹ aminoglycoside — -lactam or aminoglycoside alone Manhold et al. 1998 (80) HAP Ciprofloxacin Ceftazidime ⫹ gentamicin — p 1.000 — .094 .527 .155 .061 .637 .121 .446 1.000 .547 .052 .143 .030 .015 .023 1.000 1.000 .525 — .521 .266 — — p, two-tailed Fisher’s exact test; ABDOM, intraabdominal infections; CAP, community-acquired pneumonia; HAP, hospital-acquired pneumonia (ventilator-associated or not). a Conventional therapy included a -lactam (i.e., penicillin, ampicillin, ticarcillin, nafcillin, cefamandole, cefoxitin) given either alone or in combination with an aminoglycoside (tobramycin or amikacin); bcombination therapy comprised a -lactam (a cephalosporin or a “broad-spectrum” penicillin) with an aminoglycoside (gentamicin, tobramycin, or amikacin); cinfection-related mortality; dbest guess combination usually include a -lactam with an aminoglycoside (not specified); f-lactam included a cephalosporin, imipenem, or an extended-spectrum penicillin; aminoglycosides included gentamicin, tobramycin, amikacin, or kanamycin. floxacin, gatifloxacin, moxifloxacin, or gemifloxacin) exhibit enhanced in vitro activities against Gram-positive bacteria. Numerous studies have shown that these agents are highly efficacious as singleagent therapy of community-acquired pneumonia in the outpatient or inpatient setting (48, 50, 127). When used for the treatment of severe community-acquired or nosocomial infections in intensive care unit (ICU) patients in whom Pseudomonas infection is a concern, ciprofloxacin or the respiratory fluoroquinolones should preferentially be combined with an anti-Pseudomonas antibiotic (i.e., a carbapenem, a third- or fourth-generation cephalosporin, or an extendedS500 spectrum penicillin) with or without an aminoglycoside. Empirical Use of Anti-GramPositive Antibiotics in Patients with Severe Sepsis Recommendation: Empirical use of glycopeptide antibiotics (vancomycin, teicoplanin), oxazolidinones (linezolid), or streptogramins (quinupristin/dalfopristin) in patients with severe sepsis or septic shock is justified in patients with hypersensitivity to -lactams or in institutions with resistant Gram-positive bacteria (i.e., methicillin-resistant staphylococci, penicillin-resistant pneumo- cocci, or ampicillin-resistant enterococci) in the community or in the hospital. Grade E Rationale: Antimicrobial coverage of both Gram-positive and Gram-negative bacteria is mandatory in the empirical treatment of critically ill patients with severe sepsis. Naturally, many broad-spectrum antibiotics reliably cover both pathogens and, therefore, can be used for empirical therapy. The choice of empirical treatment, however, should depend on the local epidemiology of pathogens associated with infections and their antimicrobial Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) Table 1. Continued. Mortality (%) (Exp. vs. Control) 6/37 (16) vs. 4/37 (11) 4/52 (8) vs. 9/52 (17) 11/81 (14) vs. 14/81 (17) 7/70 (10) vs. 7/70 (10) 18/142 (13) vs. 13/138 (9) 13/104 (13) vs. 23/107 (21) 3/39 (8) vs. 4/40 (10) p Nephrotoxicity (%) (Exp. vs. Control) p .736 .235 1/37 (3) vs. 10/27 (27) — .007 — .664 1.000 .448 .100 1.000 — 1/105 (1) vs. 4/102 (4) 0/158 (0) vs. 6/149 (4) 0/104 (0) vs. 2/105 (2) 2/39 (5) vs. 5/35 (13) — .369 .014 .498 .432 0/69 (0) vs. 2/69 (3) .497 16/69 (23) vs. 20/71 (28) .564 8/25 (32) vs. 5/22 (23) 7/49 (14) vs. 6/49 (12) 8/33 (24) vs. 9/32 (28) 9/61 (15) vs. 13/71 (18) .530 1.000 .783 .645 0/25 (0) vs. 3/19 (14) 6/49 (12) vs. 14/35 (29) 3/41 (7) vs. 11/36 (23) 6/61 (10) vs. 12/66 (15) .095 .078 .046 .447 6/47 (13) vs. 3/29 (10) 1.000 0/47 (0) vs. 1/28 (3) .382 36/275 (13) vs. 52/273 (19) c 2/39 (5) vs. 7/70 (10) .063 .485 0/275 (0) vs. 7/266 (3) 5/39 (13) vs. 25/45 (36) .007 .013 31/306 (10) vs. 33/274 (12) 6/41 (15) vs. 4/30 (13) 13/65 (20) vs. 9/63 (14) .508 1.000 .484 0/306 (0) vs. 9/265 (3) — 2/65 (3) vs. 8/55 (13) .001 — .053 3/20 (15) vs. 5/25 (20) 17/200 (9) vs. 27/196 (14) 1/41 (2) vs. 6/43 (14) .716 .110 .110 19/99 (19) vs. 22/105 (21) .862 24/118 (20) vs. 20/112 (18) .738 — — 13/28 (46) vs. 6/23 (26) .158 — — susceptibility. It is, therefore, essential to get frequent feedbacks from the microbiology laboratory on antibiotic susceptibilities trends. Major changes in the relative importance of Gram-positive and Gramnegative infections among critically ill patients have occurred during the last 10 yrs. While Gram-negative bacteria predominated until the middle 1980s, Grampositive bacteria now account for at least one-half of the infections occurring in patients with severe sepsis (128, 129). Moreover, methicillin-resistant S. aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis are responsible for a majority of staphylococcal infections in some institutions. The frequency of penCrit Care Med 2004 Vol. 32, No. 11 (Suppl.) 1/20 (5) vs. 0/25 (0) 50/200 (25) vs. 43/153 (22) 0/44 (0) vs. 2/43 (4) 3/99 (3) vs. 3/102 (3) icillin-resistant S. pneumoniae is also increasing in many areas of the world. Yet, the relevance of reduced susceptibility of Streptococcus pneumoniae to penicillin on clinical outcome of patients treated with -lactam antibiotics is uncertain, especially for respiratory tract infections (130). Clinical failures, however, have been reported in patients with bacterial meningitis caused by a penicillin-resistant S. pneumoniae treated with ceftriaxone (131). Does this epidemiologic context justify the empirical use of glycopeptides (vancomycin or teicoplanin), oxazolidinones (linezolid), or streptrogramins (quinupristin/dalfopris- .444 .480 .494 1.000 tin) on a routine basis in all patients with severe sepsis and septic shock? Glycopeptides. To the best of our knowledge, randomized trials comparing empirical treatment with or without Gram-positive coverage (including glycopeptides) have never been performed in adult nonneutropenic patients and such an approach would probably be judged as unethical. None of the articles retrieved by the Medline search included a comparison of empirical treatment with or without Gram-positive patients in nonneutropenic adults with severe sepsis. Although the indiscriminate use of glycopeptides for presumed Gram-positive infections in patients with severe sepsis or septic shock S501 Table 2. Comparison of monotherapies as empirical treatment of severe sepsis and septic shock Authors and Yr of Publication Type of Infection Experimental Therapy Control Therapy Carbapenems versus third-generation cephalosporins or carbapenems Norrby et al. 1993 (92) SEPSIS Imipenem Ceftazidime Kempf et al. 1996 (111) ABDOM Meropenem Cefotaxime ⫹ metronidazole Colardyn and Faulkner 1996 (95) SEPSIS Meropenem Imipenem Mehtar et al. 1997 (96) SEPSIS Meropenem Ceftazidime ⫹ metronidazole Garau et al. 1997 (97) SEPSIS Meropenem Imipenem a HAP Imipenem Piperacillin-tazobactam Jaccard et al. 1998 (107) Verwaest 2000 (99) SEPSIS Meropenem Imipenem Third- or fourth-generation cephalosporins vs. a third-generation cephalosporin Mangi et al. 1988 (91) SEPSIS Cefoperazone Ceftazidime Reeves et al. 1989 (101) HAP Ceftriaxone Cefotaxime Mangi et al. 1992 (102) HAP Ceftriaxone Cefoperazone Thomas et al. 1992 (103) HAP Cefotaxime Ceftriaxone Norrby and Geddes 1993 (93) SEPSIS Cefpirome Ceftazidime Barckow et al. 1993 (104) CAP ⫹ HAP Cefepime Cefotaxime Schrank et al. 1995 (94) SEPSIS Cefepime Ceftazidime Norrby et al. 1998 (98) SEPSIS Cefpirome Ceftazidime Grossman et al. 1999 (108) CAP Cefepime Ceftriaxone Fluoroquinolones vs. -lactams b CAP ⫹ HAP Ciprofloxacin Imipenem Fink et al. 1994 (105) Siami et al. 1995 (106) CAP ⫹ HAP Ciprofloxacin Imipenem Krumpe et al. 1999 (56) SEPSIS Ciprofloxacin Several -lactams Torres et al. 2000 (109) HAP Ciprofloxacin Imipenem West et al. 2003 (110) HAP Levofloxacin Imipenem followed by (IV then oral) oral ciprofloxacin Success (%) (Exp. vs. Control) p Mortality (%) (Exp. vs. Control) p 27 /197 (64) vs. 124/196 (63) 41 /43 (95) vs. 30/40 (75) .834 .012 20/197 (10) vs. 31/196 (16) 3/43 (7) vs. 5/40 (13) .101 .473 68 /90 (76) vs. 67/87 (77) 46 /48 (96) vs. 40/43 (93) .861 .664 24/106 (23) vs. 17/98 (17) 10/68 (15) vs. 11/63 (17) .385 .812 55 /66 (83) vs. 49/67 (73) 56 /79 (71) vs. 62/75 (83) 67 /87 (77) vs. 62/91 (68) .208 .091 .240 22/76 (29) vs. 26/75 (35) 6/79 (8) vs. 7/75 (9) 22/107 (21) vs. 14/105 (13) .488 .777 .201 48 /62 (77) vs. 54/63 (86) .256 12 /25 (48) vs. 19/26 (73) .089 35 /50 (70) vs. 48/60 (80) .269 8 /12 (67) vs. 10/15 (67) 1.000 131 /176 (74) vs. 34/50 (68) .372 27 /37 (73) vs. 10/18 (56) .231 11 /13 (85) vs. 12/15 (80) 1.000 123 /188 (65) vs. 132/188 (70) .377 53 /67 (79) vs. 46/61 (75) .676 23/62 (37) vs. 24/63 (38) 2/25 (8) vs. 4/26 (15) 12/50 (24) vs. 10/60 (17) 1/12 (8) vs. 5/15 (33) 28/282 (10) vs. 10/80 (13) 13/37 (35) vs. 4/18 (22) 1/13 (8) vs. 2/15 (13) 15/188 (8) vs. 23/188 (12) 7/76 (9) vs. 7/75 (9) 1.000 .668 .351 .182 .536 .372 1.000 .231 1.000 92 /202 (46) vs. 90/200 (45) .921 17 /24 (71) vs. 14 /21 (67) 1.000 138 /166 (83) vs. 74/87 (85) .858 40 /57 (70) vs. 34/52 (65) .683 135 /204 (66) vs. 143/206 (69) .526 43/202 (21) vs. 38/200 (19) 2/24 (8) vs. 3/21 (14) 26/207 (13) vs. 13/99 (13) 8/41 (20) vs. 4/34 (12) 38/220 (17) vs. 32/218 (15) .620 .652 .857 .529 .515 p, two-tailed Fisher’s exact test; CAP, community-acquired pneumonia; HAP, hospital-acquired pneumonia (ventilator-associated or not). a Infection-related mortality; bsame study as Snydam et al. 1994. should be avoided, their use is appropriate in severely ill patients in the following circumstances: 1) endemic levels of MRSA; 2) documented hypersensitivity to -lactam antibiotics; and 3) treatment of bacterial meningitis in areas with high levels of penicillin-resistance of S. pneumoniae. Naturally, “endemic” and “high” levels of resistance are subjective, and no studies have been performed to determine the level of resistance above which the empirical use of antibiotics active against these resistant pathogens is warranted. There probably is an inverse relationship between the severity of sepsis and the willingness to accept a risk not to cover an antibiotic-resistant pathogen empirically. However, the possible clinical benefit associated with the empirical use of glycopeptides should be weighed against the risks of selecting resistant microorganisms and of increased toxicity, especially when vancomycin is used in combination with an aminoglycoside or other nephrotoxic agents. To further reduce the risk of emergence of vancomycin-resistant staphylococci, empirical vancomycin therapy should be rapidly discontinued in patients in whom Grampositive infections have been ruled out. Finally, it is rarely, if ever, appropriate to use vancomycin alone as empirical therapy since most cases require additional S502 Gram-negative coverage, at least until microbiological results are available. Empirical use of either vancomycin or teicoplanin has been common practice in the management of neutropenic patients with fever, in whom coagulase-negative staphylococci and viridans streptococci are predominant pathogens. Although some studies have suggested that the use of glycopeptides at the initiation of empirical therapy might be beneficial, a recent prospective, randomized, doubleblind trial failed to demonstrate clinical benefits (132). Prolonged courses of vancomycin therapy have been associated with the development of vancomycinresistance S. aureus, either through reduced cell wall permeability (133) or through acquisition of the vanA gene from vancomycin-resistant enterococci (VRE) (134). Linezolid and Quinupristin/Dalfopristin. Linezolid and quinupristin/dalfopristin are recently introduced antibiotics for the treatment of Gram-positive infections. Linezolid is a new oxazolidinone antibiotic with activity against staphylococci (including MRSA), and Enterococcus faecium and Enterococcus faecalis (including strains resistant to vancomycin) (135). Indications for the empirical use of linezolid are similar to that of glycopeptides plus two other indications, namely the need for empirical coverage of VRE and documented hypersensitivity to glycopeptides. The use of linezolid is approved for infections with VRE (including bacteremia), community-acquired and nosocomial pneumonia caused by S. pneumoniae or S. aureus (including MRSA), and skin and soft tissue infections caused by Gram-positive bacteria. Four randomized trials comparing the efficacy of linezolid with alternative treatment in adult nonneutropenic patients have been identified (Table 3). In an open-labeled randomized trial, San Pedro and coworkers (136) compared linezolid (sequential intravenous-to-oral therapy) with ceftriaxone IV followed by oral cefpodoxime for patients hospitalized with community-acquired pneumonia. Episodes of community-acquired pneumonia were primarily caused by S. pneumoniae, and overall clinical cure rates were higher for linezolid-treated patients, especially for patients with S. pneumoniae bacteremia (93.1% vs. 68.2%; p ⫽ .021). In two double-blind, randomized trials, a combination of linezolid and aztreonam was compared with vancomycin and aztreonam for the treatment of patients with hospital-acquired pneumonia (119, 137). Although equivalence of activity was found in both trials, a subsequent retrospective analysis of the combined Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) Table 3. Clinical studies of linezolid in patients with Gram-positive infections Authors and Yr of Publication Rubinstein et al. 2001 (119) Stevens et al. 2002 (139) San Pedro et al. 2002 (136) Wunderink et al. 2003 (137) Wunderink et al. 2003 (138) Type of Infection Experimental Therapy Control Therapy Success (%) (Exp. vs. Control) p Linezolid ⫹ Vancomycin ⫹ 71/107 (66.4)a vs. 62/91 (68.1)a aztreonam aztreonam 86/161 (53)b vs. 74/142 (52)b Known/suspected MRSA Linezolid Vancomcyin 109/192 (57)b vs. 93/169 (55)b infections Documented MRSA 41/56 (73) vs. 38/52 (73) infections CAP due to S. Linezolid Ceftriaxon/ 316/381 (83) vs. 280/366 (76) pneumoniae cefpodoxim HAP Linezolid ⫹ Vancomycin ⫹ 135/256 (53)b vs. 128/245 (52)b aztreonam aztreonam 114 /168 (68)a vs. 111/171 (65)a Documented SA HAP Linezolid ⫹ Linezolid ⫹ 70/136 (51.5)a vs. 59/136 (43.4)a (n ⫽ 339) aztreonam aztreonam Documented MRSA HAP 36/61 (59.0)a vs. 22/62 (35.5)a (n ⫽ 160) SA HAP diagnosed by 47/92 (51)a vs. 39/90 (43)a invasive procedure (n ⫽ 223) MRSA HAP diagnosed by 19/33 (58)a vs. 13/39 (33)a invasive procedure (n ⫽ 95) HAP NS .908 NS Survival (%) (Exp. vs. Control) p 36/203 (18)b vs. 49/193 (25) b 40/240 (17) vs. 30/220 (14) .067 b NS NS .04 NS NS 366/381 (4) vs. 347/366 (5) NS 257/321 (80)b vs. 241/302 (80)b 145/157 (92)a vs. 150 /166 (90)a 131/168 (78) vs. 121/171 (71) NS NS ⬍.01 60/75 (80) vs. 54/85 (64) .025 NS 86/109 (79) vs. 82/114 (72) NS 34/40 (85) vs. 37/55 (67) .05 .04 HAP, hospital-acquired pneumonia (ventilator-associated or not); MRSA, methicillin-resistant Staphylococcus aureus; SA, Staphylococcus aureus. a In the clinically evaluable population; bIntention-to-treat analysis. dataset revealed that initial therapy with linezolid was associated with significantly better survival and clinical cure rates in patients with nosocomial pneumonia due to MRSA (138). Finally, in an openlabeled randomized trial, Stevens and coworkers (139) compared the efficacy of linezolid with that of vancomycin for the treatment of patients with suspected MRSA. Linezolid and vancomycin had similar efficacy, both in an intention-totreat analysis and in a subgroup of patients with documented MRSA infections. Most patients, however, had skin or soft tissue infections and probably did not fulfill the criteria of severe sepsis. No clinical data are available on the use of linezolid for bacterial meningitis in areas of high levels of penicillin-resistant S. pneumoniae. Resistance to linezolid is based on specific point mutations in the 23S ribosomal RNA of the 50S subunit of the ribosome preventing binding of linezolid (135). Resistance development of VRE and S. aureus during therapy was associated with the presence of indwelling prosthetic devices and prolonged courses of antimicrobial therapy (140, 141). Moreover, nosocomial spread of linezolidresistant VRE has been reported as well (142). Therefore, empirical linezolid therapy should be rapidly discontinued in patients in whom Gram-positive infections have been ruled out. Quinupristin/dalfopristin is an injectable streptogramin available for the treatment of Gram-positive infections caused by S. aureus (including MRSA) and E. faecium (including VRE), but it has no activity against E. faecalis. Two Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) randomized clinical trials of quinupristin/dalfopristin have been identified (Table 4). Fagon and coworkers (118) compared quinupristin/dalfopristin with vancomycin (aztreonam was allowed in both treatment arms) in patients with Gram-positive nosocomial pneumonia. The second study was a combined report of two nearly identical open-label randomized trials in which patients with Gram-positive skin and skin structure infections were treated with quinupristin/dalfopristin or with one of three comparator antibiotics (cefazolin, vancomycin, or oxacillin) (143). In both studies, clinical cure rates of quinupristin/dalfopristin and of control antibiotics were similar. However, only a few patients fulfilled the criteria of severe sepsis in the latter study (143). A formal head-to-head comparison of linezolid and quinupristin/dalfopristin has not been performed. Therefore, empirical therapy with quinupristin/dalfopristin should be limited to severely ill patients with a high likelihood of infection caused by vancomycin-resistant E. faecium or MRSA and to patients with documented or presumed hypersensitivity to linezolid. The indiscriminate use of linezolid or of quinupristin/ dalfopristin for presumed Gram-positive infections in patients with severe sepsis or septic shock should be avoided. The possible clinical benefit associated with the empirical use of these agents should be weighed against the risks of selection of resistant microorganisms, toxicity, and increased treatment costs. Finally, it is rarely, if ever, appropriate to use linezolid or quinupristin/dalfopristin alone as empirical therapy of severe sepsis or septic shock, since Gram-negative coverage is needed, at least until microbiological results become available. Modification of Empirical Antimicrobial Therapy Based on Culture Results Recommendation: Modification of empirical antimicrobial therapy with the aim to restrict the number of antibiotics and narrow the spectrum of antimicrobial therapy is an important and responsible strategy for minimizing the development of resistant pathogens and for containing of costs. Grade E To the best of our knowledge no studies have been performed in which patients were randomized either to continue to receive empirical broadspectrum antibiotic therapy or to be switched to a narrow-spectrum antibiotic regimen selected on the basis of susceptibility data of the causative pathogen. In a before-after study design, Ibrahim and coworkers (144) assessed the effects of a clinical guideline on the appropriateness of empirical therapy in patients with ventilator-associated pneumonia. The clinical guideline consisted of empirical therapy with imipenem, ciprofloxacin, and vancomycin, followed by narrowing of antibiotic therapy when a microbiological cause of infection was identified and discontinuation of antibiotic therapy after 7 days when the clinical condition allowed. Implementation of the clinical guideline S503 Table 4. Clinical studies of quinupristin/dalfopristin in patients with Gram-positive infections Authors and Yr of Publication Fagon et al. 2000 (118) Nichols et al. 1999 (143) Type of Infection HAP Complicated Grampositive skin and structure infections Experimental Therapy Control Therapy Success (%) (Exp. vs. Control) Quinup/Dalfop ⫹ Vancomycin ⫹ aztreonam aztreonam 49/87 (56)a vs. 49/84 (58)a Quinup/Dalfop 65/150 (43) vs. 67/148 (45) 68.2%a vs. 70.7% Cefazolin or vancomycin or oxacillin b p Survival (%) (Exp. vs. Control) p NS b NS NS NS b b 38/150 (25) vs. 116/148 (22) HAP, hospital-acquired pneumonia (ventilator-associated or not). a In the clinically evaluable population. was associated with higher appropriateness of empirical therapy and a reduction in the mean duration of therapy. However, the number of patients in whom antibiotics were narrowed was not reported. In fact, there are arguments both in favor and against such an approach. On the one hand, narrowing of the antimicrobial spectrum may reduce the risk of selecting resistant microorganisms and treatment costs. On the other hand, microbiological documentation of the etiology of sepsis is lacking in a significant proportion of sepsis cases, making it difficult, if at all possible, to narrow the antibiotic coverage based on clinical criteria only. Recommendations: The antimicrobial regimen should always be reassessed after 48 –72 hrs on the basis of microbiological and clinical data with the aim of using a narrow-spectrum antibiotic to recant the development of resistance, to reduce toxicity, and to reduce costs. Once a causative pathogen is identified, there is no evidence that combination therapy is more effective monotherapy. The duration of therapy should typically be 7–10 days and guided by clinical response. Grade E Recommendations: If the presenting clinical syndrome is determined to be due to a noninfectious cause, antimicrobial therapy should be stopped promptly to minimize the development of resistant pathogens and superinfection with other pathogenic organisms. Grade E Antibiotic Cycling Recommendations: At the present time, there is insufficient evidence to recommend the use of antibiotic cycling as a strategy to reduce the development of antibiotic resistance. S504 Grade C Rationale: Antibiotic cycling has been proposed as a strategy to minimize the development of antibiotic resistance and thus to improve the patient’s outcome. The rationale is that the cyclic exposure to different classes of antibiotics should prevent emergence of resistance by exposing the microbial flora to homogeneous selective antibiotic pressure during a limited period of time. This concept is based on several assumptions. First, it is assumed that antibiotic-resistant microorganisms have a growth disadvantage when the selective antibiotic pressure is withdrawn. Therefore, development of resistance during exposure to a given antibiotic will be counterbalanced during periods of nonexposure. Second, should resistance develop during one period, exposure to another class of antibiotics in the following cycle will eliminate the resistant microorganisms. For this to occur, it presupposes the absence of crossresistance (i.e., that the mechanism of resistance be different among different classes of antibiotics). However, besides these theoretical considerations, antibiotics are just one of many factors that have an impact on the development of resistance. For example, changes in the numbers of patients introducing resistant microorganisms into the unit or changes in compliance with hygienic measures will also affect the emergence of antibiotic resistance. The effectiveness of infection control programs can be influenced by changes in the workload of healthcare workers or understaffing, which both will lead to more contacts between patients and healthcare workers and less adherence to hand hygiene and thus to more transmission of pathogens (145–147). Whether the theoretical benefits of antibiotic cycling hold true in daily practice can only be tested in studies in which there is careful control of confounding variables. The “real-life” experience with antibiotic cycling is sparse, and interpretation of findings is seriously hampered by numerous methodologic problems in study design. These included a nonstructured antibiotic cycling scheme (148), evaluation of changes in empirical therapy in a before-after design (149), use of multiple antibiotics for cycling and different cycling intervals (148, 150), presence of important confounding factors, such as reduction in the antibiotic use (151), or changes in infection control strategies (152). Clinical Data. The impact of antibiotic cycling on a patient’s outcome has been analyzed in three studies. Kollef and coworkers (149) compared the effects of replacing ceftazidime by ciprofloxacin in the empirical treatment of suspected Gram-negative infections in two 6-month periods. The incidence of ventilatorassociated pneumonia (VAP) decreased from 11.6% to 6.7% (p ⫽ .028), as did the incidences of VAP and bacteremia due to antibiotic-resistant Gram-negative bacteria (4% to 0.9%, p ⫽ .013, and 1.7% to 0.3%, p ⫽ .12, respectively). However, outcome parameters such as survival and length of stay remained unaffected. In another trial, Raymond and coworkers (152) compared a 1-yr period of nonprotocol-driven antibiotic use with a subsequent 1-yr period of rotating empirical antibiotic assignment. Different classes of antibiotics were used for different indications (pneumonia vs. peritonitis or sepsis of unknown origin) with rotation of antibiotic combinations after 4 months. Infection rates with resistant Gram-positive and Gram-negative bacteria significantly decreased, survival in the ICU increased, and antibiotic rotation was identified as an independent predictor for survival in logistic regression analysis. Yet, other confounding factors were changed as well. An antibiotic surveillance team was instituted in the second half of the first study period, and alcohol hand dispensers Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) were distributed at the start of the second period. In the third study, Gruson and coworkers (151) investigated whether a new program of antibiotic use had an impact on the incidence of VAP caused by antibiotic-resistant bacteria in a beforeafter study. In the second part of the study, ceftazidime and ciprofloxacin use were restricted, antibiotics were rotated without favoring any one antibiotic, and each antibiotic prescription was determined by one of the two investigators. In addition to these measures, a policy of shorter duration of aminoglycoside therapy was implemented and compliance with protocol was stimulated by daily meetings between of one of the two investigators with critical care physicians, weekly meetings with nurses to identify nosocomial problems, monthly evaluation of antibiotic consumption, and three-monthly evaluation of changes in resistance patterns. The rotation protocol included the variable use of a -lactam antibiotic (cefepime or piperacillintazobactam or imipenem or ticarcillin during periods of at least 1 month) and an aminoglycoside (amikacin or tobramycin, netilmicin or isepamicin) for lateonset VAP. For early-onset VAP, prescription was rotated on a monthly basis using either amoxicillin-clavulanic acid, cefotaxime, ceftriaxone, or cefpirome in combination with an aminoglycoside or fosfomycin. Importantly, implementation of all these measures reduced overall antibiotic use by ⬎50%. In addition, antibiotic resistance levels of isolated pathogens decreased, both for antibiotic use that had been reduced (i.e., ciprofloxacin and ceftazidime) and for antibiotics use that had been increased (i.e., cefepime and piperacillin-tazobactam). Incidences of microbiologically confirmed VAP decreased from 22.1% to 15.7% (p ⬍ .01) among patients requiring mechanical ventilation for ⬎48 hrs, but ICU mortality did not change (40.6% to 37.2%; p ⫽ NS). In summary, none of these studies have taken into account the most important factors contributing to the development of dynamics of antibiotic resistance in the hospital settings (i.e., relative importance of introduction, cross-transmission, and endogenous acquisition by selective antibiotic pressure), precluding a reliable assessment of the role played by antibiotic cycling. Furthermore, the optimal choice of antibiotics and cycle intervals remain to be determined (153, 154). Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) Empirical Use of Anti-Fungal Agents in Patients with Severe Sepsis or Septic Shock Recommendation: Empirical antifungal therapy should not be used on a routine basis in patients with severe sepsis or septic shock, but it may be justified in selected subsets of septic patients at high risk for invasive candidiasis (155). Grade E Rationale: Since the 1980s, fungi have emerged worldwide as an increasingly frequent cause of nosocomial infections in critically ill patients and are associated with significant morbidity and mortality (156 –159). Candida was the fourth most frequent cause of bloodstream infections in U.S. hospitals in the 1990s (18). About one third of all episodes of candidemia occur in medical, surgical, or pediatric ICUs (22, 160). Fungi were isolated from 17% of the patients with ICU-acquired infections in a 1-day point prevalence study conducted in 1,417 ICUs in western European countries (129). However, it is unclear whether all these fungal isolates were the etiological agent of infections or simply colonizing microorganisms. Clinical manifestations of candidiasis are usually not specific, and standard culture techniques lack sensitivity. Detection of Candida antigens (mannan and -glucan), metabolites (arabinitol and enolase), or antibodies (anti-mannan) and amplification of fungal DNA by polymerase chain reaction have been or are currently under investigation. The facts that Candida infections are difficult to diagnose and associated with severe morbidity and high mortality are arguments in favor of the empirical or preemptive use of antifungal agents in critically ill ICU patients at high risk of candidiasis. The likelihood of fungal sepsis is increased in patients who have been treated with several broad-spectrum antibiotics, who are colonized with Candida at multiple sites, who have damaged physiologic barriers (i.e., recurrent gastrointestinal perforations or anastomotic leakages, acute necrotizing pancreatitis, chemotherapyinduced mucositis, vascular access devices, and total parenteral nutrition), or who are immunosuppressed (i.e., cancer patients with neutropenia, or hematopoietic stem cells or solid organ transplant recipients) (155, 161). However, recent epidemiologic studies and multicenter trials have shown that fungi account for only 5% of all cases of severe sepsis or septic shock, which does not justify the use of antifungal therapy on a routine basis, but only in selected subsets of septic patients at high risk for invasive candidiasis. Treatment of Candidemia Recommendation: Azoles (fluconazole) and echinocandins (caspofungin) are as efficacious as and less toxic than amphotericin B deoxycholate for the treatment of patients with candidemia. Albeit better tolerated, there is no evidence that lipid formulations of amphotericin B are superior to amphotericin B deoxycholate for the treatment of candidemia. Azoles: Grade A; Echinocandins: Grade B; Lipid formulations of amphotericin B: Grade E Rationale: Candidemia is associated with significant morbidity, prolonged hospital stay, long-term sequelae, and high crude mortality rates (40% to 60%) (162, 163). Moreover, the presence of disseminated infection is an independent prognostic factor of fatal outcome in patients with candidiasis (164), and antifungal therapy has been shown to reduce mortality (165, 166). Therefore, recent management guidelines have recommended that all patients with candidemia be treated with antifungal agents (155, 167). For decades, amphotericin B deoxycholate, a fungicidal compound targeting ergosterol in the cell membrane of a broad spectrum of fungi, has been the agent of choice for the empirical therapy of invasive fungal infections. However, nephrotoxicity and infusion-related adverse events, especially fever and rigors, are frequent adverse events of conventional amphotericin B therapy that have limited its use. In the late 1980s, the advent of azoles constituted a major progress in the management of invasive mycoses. This class of drugs inhibits the synthesis of ergosterol. Fluconazole and itraconazole became available in the early 1990s. Different clinical studies compared the efficacy of fluconazole and amphotericin B deoxycholate for the treatment of candidemia. Azoles. In a multicenter study of 206 nonneutropenic patients with candidemia, fluconazole (400 mg/day) was shown to be as efficacious (success rates were 72% and 79%, respectively) as and better tolerated than amphotericin B deoxycholate (0.5– 0.6 mg/kg/day) (168). Similar findings were made in a prospecS505 tive observational candidemia study in which 227 patients were treated with amphotericin B deoxycholate (median daily dose, 0.5– 0.7 mg/kg) and 67 patients with fluconazole (median daily dose, 200 mg) (165) and in several other smaller comparative studies (169 –171). Noncomparative studies yielded similar success rates for fluconazole (172–178). In summary, fluconazole (400 mg/day) was found to be as effective as and better tolerated than amphotericin B deoxycholate (used at a dose of 0.3–1.2 mg/kg/ day) for the treatment of candidemia or invasive candidiasis. Whether higher doses of fluconazole would be associated with better response rates is unknown. In a study of 65 patients with Candida albicans bloodstream infections, clinical response rates were 60% and 83% for patients treated with 5 or 10 mg/kg/day of fluconazole (179). The favorable efficacytoxicity profile of fluconazole led to a rapidly increasing use of this azole for prophylaxis and treatment of invasive candidiasis. As anticipated, in the late 1990s an increasing incidence of infections due to non-C. albicans species with reduced dose-dependent susceptibility (Candida glabrata) or intrinsic resistance (Candida krusei) to azoles was observed in some U.S. centers (18, 180). The use of high doses (800 –1200 mg) of fluconazole has been advocated for the empirical treatment of candidemia when infections with azole-resistant Candida species are suspected, but efficacy data from comparative trials are lacking. However, for most experts, amphotericin B remained clearly the first choice for empirical therapy of invasive candidiasis in the preechinocandin area (155, 167). This may have changed since the advent of the echinocandins. Itraconazole, an azole with improved in vitro activity against fluconazoleresistant Candida species, has been available since the early 1990s. However, a poor bioavailability of the oral formulation of itraconazole has been a major limitation for its use in critically ill patients. Recently, an intravenous form of itraconazole has been developed, but there are very few data on the efficacy of IV itraconazole for the treatment of candidemia. Voriconazole, a member of the newest generation of antifungal triazoles, has been shown to exhibit excellent in vitro and in vivo activities against Candida species (181). In patients with oropharyngeal and/or esophageal candidiasis, voriconS506 azole was found to be at least as effective as fluconazole (182). Moreover, voriconazole salvage therapy showed an overall treatment success rate of 55% and 61% in patients with refractory systemic or esophageal candidiasis, respectively (183). A large multicenter study comparing voriconazole with sequential use of amphotericin B deoxycholate followed by fluconazole in nonneutropenic patients with candidemia has recently been completed, and the first results of that trial indicate that voriconazole is as effective as and was better tolerated than amphotericin B/fluconazole. Posaconazole and ravuconazole are two other triazoles in clinical development. Echinocandins. Echinocandins are a new class of antifungal agents that act by inhibiting the synthesis of -(1, 3)-Dglucan, a component of the fungal cell wall (184). Caspofungin, the first representative of this new family of antifungal agents, is active against Candida (C. albicans and non-C. albicans) and Aspergillus species. In immunosuppressed, mostly human immunodeficiency viruspositive patients with oropharyngeal and esophageal candidiasis, caspofungin was observed to be as effective as and better tolerated than amphotericin B deoxycholate (185, 186). In a large multicenter trial that included 239 patients (of whom 24 were neutropenic) with invasive candidiasis (80% of the patients had candidemia), caspofungin (70-mg loading dose, followed by 50 mg daily) was at least as efficacious as and less toxic than amphotericin B deoxycholate (0.6 –1.0 mg/ kg/day) (success rates, 73% vs. 62%; discontinuation for adverse events, 3% vs. 23%) (187). Of note, the success rates of caspofungin against C. glabrata and C. krusei were comparable with those obtained in azole-susceptible Candida species. Micafungin and anidulafungin are two other echinocandins that are currently in clinical development. In summary, azoles (fluconazole) and echinocandins (caspofungin) have been shown to be as efficacious as and better tolerated than amphotericin B deoxycholate for the treatment of patients with candidemia and invasive candidiasis. Limited information is available on the efficacy of these agents in neutropenic patients. Amphotericin B and caspofungin are the antifungal agents of choice for the treatment of infections caused by fluconazole-resistant non-C. albicans species. The place of the newest triazole voriconazole with improved in vitro activity against resistant strains awaits the results of a recently completed large multicenter study in patients with candidemia. Given the poor prognosis of fungal sepsis, clinicians have shown great interest for the use of combinations of antifungal agents of different classes for the treatment of critically ill patients with invasive mycoses. However, up to now, there have been relatively few in vitro or in vivo studies of combinations of antifungal agents. While awaiting the results of prospective, randomized clinical trials demonstrating that combinations of antifungals are superior to and reasonably not more toxic than treatment with single agents, the undiscriminating use of these costly treatment regimens should be discouraged. Lipid Formulations of Amphotericin B. Nephrotoxicity and infusion-related reactions are frequent adverse events of treatment with amphotericin B deoxycholate, and treatment interruptions because of toxicity may have a negative impact on efficacy. In noncomparative studies, continuous infusion of amphotericin B deoxycholate over 24 hrs has been shown to limit infusion-related reactions and nephrotoxicity and did not seem to affect efficacy (188, 189). Yet, the influence of this mode of administration of amphotericin B on treatment efficacy remains to be demonstrated, as it results in a marked alteration of drug pharmacokinetics. Lipid formulations have been developed to improve the toxicity and possibly also the efficacy profile of amphotericin B. Three lipid formulations with different pharmacologic properties are available: liposomal amphotericin B, amphotericin B lipid complex, and amphotericin B colloidal dispersion. They have been primarily used for the treatment of cancer patients with neutropenia and persistent fever or with invasive aspergillosis. In large, multicenter clinical trials, the lipid formulations were shown to be as efficacious as and usually better tolerated than amphotericin B deoxycholate (190 –197). Yet, there were differences between the lipid preparations in terms of adverse events. Infusion-related reactions were significantly less frequent with liposomal amphotericin B (5% to 20%) than with amphotericin B lipid complex (40% to 80%) or colloidal dispersion of amphotericin B (50% to 80%). Therefore, liposomal amphotericin B has been used as the control treatment regimen in most recent studies of empirical antifungal therapy for persistent fever in Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) neutropenic cancer patients (193, 198). Lipid formulations are considerably more expensive than conventional amphotericin B, which has had a negative impact on their use. There are few data on the direct comparison of the efficacy and toxicity of amphotericin B deoxycholate and the lipid formulations for the treatment of patients with invasive candidiasis. Small noncomparative studies suggest that lipid formulations of amphotericin B are as efficacious as but better tolerated than conventional amphotericin B (199 –202). Their high costs, the paucity of clinical data, and the existence of alternative antifungal therapies (azoles and echinocandins) explain why the use of lipid formulations has been limited in patients with invasive candidiasis (155). Recommendation: Third- or fourthgeneration cephalosporins: Grade A. Carbapenem: Grade B. Extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors: Grade C 5. Empirical use of glycopeptide antibiotics (vancomycin, teicoplanin), oxazolidinones (linezolid), or streptogramins (quinupristin/dalfopristin) in patients with severe sepsis or septic shock is justified in patients with hypersensitivity to -lactams or in institutions with resistant Gram-positive bacteria (i.e., methicillin-resistant staphylococci, penicillin-resistant pneumococci, or ampicillin-resistant enterococci) in the community or in the hospital. Recommendation: Grade E Summary Recommendations 1. Antibiotic therapy should be started within the first hour of recognition of severe sepsis, after appropriate cultures have been obtained. Recommendation: Grade E 2. Initial empirical antiinfective therapy should include one or more drugs that have activity against the likely pathogens (bacterial or fungal) and that penetrate into the presumed source of sepsis. The choice of drugs should be guided by the susceptibility patterns of microorganisms in the community and in the hospital. Recommendation: Grade D 3. Monotherapy is as efficacious as combination therapy with a -lactam and an aminoglycoside as empirical therapy of patients with severe sepsis or septic shock. Recommendation: Carbapenem: Grade B. Third- or fourth-generation cephalosporins: Grade B. Extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors: Grade E. 4. Third-generation and fourth-generation cephalosporins, carbapenems, and extended-spectrum carboxypenicillins or ureidopenicillins combined with -lactamase inhibitors are equally effective as empirical antibiotic therapy in patients with severe sepsis. Crit Care Med 2004 Vol. 32, No. 11 (Suppl.) 6. Modification of empirical antimicrobial therapy with the aim to restrict the number of antibiotics and narrow the spectrum of antimicrobial therapy is an important and responsible strategy for minimizing the development of resistant pathogens and for containing costs. Recommendation: Grade E 7. The antimicrobial regimen should always be reassessed after 48 –72 hrs on the basis of microbiological and clinical data with the aim to use a narrowspectrum antibiotic to prevent the development of resistance, to reduce toxicity, and to reduce costs. Once a causative pathogen is identified, there is no evidence that combination therapy is more effective monotherapy. The duration of therapy should typically be 7–10 days and guided by clinical response. Recommendation: Grade E 8. If the presenting clinical syndrome is determined to be due to a noninfectious cause, antimicrobial therapy should be stopped promptly to minimize the development of resistant pathogens and superinfection with other pathogenic organisms. Recommendation: Grade E 9. At the present time, there is insufficient evidence to recommend the use of antibiotic cycling as a strategy to reduce the development of antibiotic resistance. Recommendation: Grade C 10. Empirical antifungal therapy should not be used on a routine basis in patients with severe sepsis or septic shock, but it may be justified in selected subsets of septic patients at high risk for invasive candidiasis (155). Recommendation: Grade E 11. Azoles (fluconazole) and echinocandins (caspofungin) are as efficacious as and less toxic than amphotericin B deoxycholate for the treatment of patients with candidemia. Albeit better tolerated, there is no evidence that lipid formulations of amphotericin B are superior to amphotericin B deoxycholate for the treatment of candidemia. Recommendation: Azoles: Grade A. Echinocandins: Grade B. Lipid formulations of amphotericin B: Grade E. REFERENCES 1. Bochud PY, Glauser M, Calandra T: Antibiotics in sepsis. Intensive Care Med 2001; 27(14 Suppl):S33–S48 2. Zeni F, Freeman B, Natanson C: Antiinflammatory therapies to treat sepsis and septic shock: A reassessment. Crit Care Med 1997; 25:1095–1100 3. 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