Case Study Pathogenic Bacteriology 2009 Case 51 Anthony Obisesan Tania Guevara Edmund yeo Case Summary A 53 year-old man with non-insulin-dependent diabetes and hypertension presents symptoms of fever, chills, and a cough with green sputum. Gram stain, blood culture, biochemical test, chest x-ray were performed to identify the causative agent. Streptococcus Pneumoniae was isolated and identified. This organism is by far the most common cause of bacterial pneumonia, particularly in the elderly. Key Information Pointing to Diagnosis Degree of resistance to host: Age: 53 year old Gender: Male Physical Health: Mellitus diabetes and Hypertension, 2 packs of cigarettes daily for 40 years. Symptoms: fatigue, fever, chills, dyspnea, left-sided pleuritic chest pain, and cough with green sputum. Gram Staining and blood culture to role out other organism The Diagnosis for Case 51 •Based on the patient’s symptoms (green sputum) and findings from physical examination (crackles in lung fields) Pneumonia is suspected. •Chest X-ray: •Chest X-ray is typically used for diagnosis in hospitals •Right lower lobe, left lingular, and left lower lobe infiltrates One week into admission, there is segmental infiltrate within right upper lobe. After 4 weeks in hospital, multiple cavities with air-fluid level are seen in right lung Computed tomography of chest (lung window) shows two large cavities with air fluid level. Diagnosis • • Blood Culture: Significant in ruling out other gram (+) organism that cause pneumonia such as staph. aureus, and strep. agalactiae an important cause of pneumonia (especially in new borns). Gram stain: Strep Pneumoniae present & Normal Respiratory Flora • High white blood cell count indicates the presence of an • • • • infection or inflammation. staining: Gram (+) Catalase (+) Coagulase (-) Staph Epidermidis Present, NF in upper respiratory tract. Classification,Gram Stain Results, and Microscopic Appearance of Streptococcus Pneumoniae • Classification: Streptococcus – a major cause of human infections. They are untypable in the Lancefield classification which is based on the antigenicity of a carbohydrate which is soluble in dilute acid and called the C carbohydrate. They can, however, be subdivided into more than 80 serological types on the basis of antigenic differences in their capsular polysaccharide. For pneumococcal pneumonia, 23 types are the cause of 90% of the case Morphology and General Characteristics: a gram (+), aphahemolytic diplococcus, aerotolerant anaerobe. Gram Stain Results: Gram positive diplococcus Streptococcus pneumoniae Gram-stain of blood broth culture. CDC Diseases and Pathogenesis of Disease Caused by Streptococcus Pneumoniae Diseases: Lobar Pneumonia, meningitis, Otitis media, Septicemia, endocarditis and so on. In the elderly or in other individuals whose ciliary activity or respiratory drainage is likely to be impaired the organism can reach its pathogenic site in the lung and cause serious disease. Those most susceptible would be the bedridden, heavy smokers, alcoholics, or individuals who had suffered a recent respiratory viral infection or toxic damage to the mucociliary escalator.. Transmission: Person to person by direct inoculation from shared respiratory equipment has been documented, other medical equipment might be cause to infection, and transmission via HCW Pathogenesis Virulence Factors: The capsule of the pneumococci is its most potent virulence factor. •The antiphagocytic properties of the capsule allow the pneumococci to grow in the lung. This results in an inflammatory response in which fluid accumulates in the lung. Other virulence factors include: the cell wall; cholinebinding proteins; pneumococcal surface proteins A and C (PspA and PspC); the LPXTG-anchored neuraminidase proteins; hyaluronate lyase (Hyl); pneumococcal adhesion and virulence A (PavA); enolase (Eno); pneumolysin; autolysin A (LytA); and the metal-binding proteins pneumococcal surface antigen A (PsaA), pneumococcal iron acquisition A (PiaA) and pneumococcal iron uptake A (PiuA). Common Disease & Symptoms caused by Streptococcus Pneumoniae Septicemia Fever Hypotension Acute confusion Chills Dyspnea Tachypnea Headache Tachycardia Bacteremia Pneumonia Fever Dyspnea Lung consolidation Hemoptysis chills Chest pain Cyanosis malaise Rust colored sputum Diagnosis/Isolation/Identification/ of Streptococcus Pneumoniae •Isolation: Isolation can be done on Columbia Blood Agar (CBA) •Identification: Gram staining; Pneumococci are differentiated in the laboratory from other alpha hemolytic streptococci by virtue of their sensitivity to optichin. This is usually tested by means of an impregnated disc, the P disk, placed on a lawn of the bacteria on a blood agar plate, and sensitivity demonstrated by a zone of no growth around the disc. Test for Bile solubility also Therapy, Prevention and Prognosis of Patient Infected with Streptococcus Pneumoniae •Prevention: Vaccination is recommended for individuals over 10 years of age who are at risk; i.e., those with sickle cell disease, splenic malfunction, congestive heart failure, alcoholism, diabetes, confinement in a nursing home. •Sterilized hospital equipment and the use of personal safety equipment (gloves, gowns etc) by healthcare worker will reduce transmission. A recent disturbing finding is that about 25% of isolates of S. pneumoniae are now resistant to one or more antibiotics. The penicillin resistance in this organism is usually not due to beta lactamase, but rather to mutations in penicillin binding proteins. Sensitivity testing is necessary Between 5 and 10 million people get pneumonia in the United States each year, and more than 1 million people are hospitalized due to the condition. As a result, pneumonia is the third most frequent cause of hospitalizations (births are first, and heart disease is second). About 500,000 children are hospitalized for respiratory infections each year, and a third of them have pneumonia. Although the majority of pneumonias respond well to treatment, the infection kills 40,000 - 70,000 people each year. Primary Research Article Contributing to the Understanding of the Disease caused by Streptococcus Pneumoniae Kwan, S.K. et al, 2009, “Changes of serotype and genotype in Streptococcus pneumoniae isolates from a Korean hospital in 2007”, Diagnostic Microbiology and Infectious Disease, vol 63: 271 - 278. Experimental set up: Capsular quellung method: To determine serotypes of Strep. pneumoniae (154 isolates) from sputum, blood, tracheal aspirate, nasal swab, and pus. 104 were invasive In vitro susceptibility testing was performed by broth microdilution (MIC). 8 antimicrobial agents were tested: penicillin, erythromycin, amoxixillin-clavulanate, levofloxacin, ciprofloxacin, clarithromycin, clindamycin and trimethoprimsulfamethoxazole. Multilocus sequence typing was performed to determine the genotypes of all isolates. Erythromycin-resistant genes in isolates were determined by duplex PCR method. Findings New serotypes found Antimicrobial Resistance in isolates between 1998-2000 and 2007 Conclusion Conclusion: Helpful information on local vaccine serotype expansion or replacement in Korea Emergence of new serotypes with time Resistance to antimicrobials Changes in serotype and genotype in Streptococcus pneumoniae is unfavorable to preventing pneumoniae especially in hospital patients. With these changes, resistant serotypes emerge and are a major threat to human lives. Take Home Message Pneumonia is a common illness which occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically and terminally ill Typical symptoms are fatigue, fever, chills, dyspnea, left-sided pleuritic chest pain, and cough with green sputum. Pathogen is Streptococus pneumoniae, a gram (+), apha-hemolytic diplococcus, aerotolerant anaerobe Diagnostics include test gram staining, optochin susceptibility & bile solubilty, blood culture, and X-ray Therapy is based on vaccination, vaccination to prevent certain strains are available Prognosis: with treatment, pneumonia can be cleared within two to four weeks. The eventual outcome of an episode depends on how ill the person is when he or she is first diagnosed • Prevention is via vaccination for individuals over 10 years of age who are at risk; i.e., those with sickle cell disease, splenic malfunction, congestive heart failure, alcoholism, diabetes, confinement in a nursing home.Sterilized hospital equipment and the use of personal safety equipment (gloves, gowns etc) by healthcare worker will reduce transmission Transmission is via Person to person by direct inoculation from shared respiratory equipment has been documented, other medical equipment might be cause to infection, and transmission via HCW Threat is Changes in serotype and genotype in Streptococcus pneumoniae is unfavorable to preventing pneumoniae especially in hospital patients. With these changes, resistant serotypes emerge and are a major threat to human lives References Kwan, S.K. et al, 2009, “Changes of serotype and genotype in Streptococcus pneumoniae isolates from a Korean hospital in 2007”, Diagnostic Microbiology and Infectious Disease, vol 63: 271 - 278. http://www.cdc.gov/ncidod/biotech/strep/strepindex. htm accessed on March 11, 2008 Point Spread Case summary 5 Key Information pointing to Diagnosis 10 Diagnosis 5 Microbiology of Pathogen 10 Pathogenesis of the disease 10 Diagnostic tests 5 Therapy and Prognosis 5 Prevention 5 Epidemiology and threats 5 Primary research article (last 5 years) 20 Take home message 5 Are all questions addressed? 5 Appearance 5 Presentation skills (individual) 5 Total 100