Chlamydial Infection In Pregnancy Professor David Taylor-Robinson MD MRCP FRCPath Until retirement in 1996, he was Head of the MRC's Sexually Transmitted Diseases(STD) Research Group at St. Mary's Hospital Medical School, and Professor of Genitourinary, Microbiology and Medicine. His extensive research interests include aetiology of acute and chronic non-gonococcal urethritis, epidydimitis, chronic prostatitis and pelvic inflammatory disease (PID); improved methods of detection for Chlamydia trachomatis infection; seroepidemiology and prevention of STDs; Bacterial vaginosis; and pathogenesis of Mycoplasma infections. Introduction The genus Chlamydia comprises at least four species. Chlamydia trachomatis contains 15 serovars of which serovars A-C cause trachoma and, rarely, sexually related infection, whereas serovars D-K seem not to be associated with trachoma but cause paratrachoma and a variety of genital-tract diseases. Serovars L1L3 are responsible for lymphogranuloma venereum (LGV). C. pecorum causes pneumonia and diarrhoea in cattle and sheep and C. psittaci causes disease in birds and animals and respiratory disease (psittacosis) in humans. C. pneumoniae is the binomial designation for strains which originally were termed TWAR. It also causes human respiratory disease and, in addition, has been associated with atherosclerosis. Chlamydiae are recognised as bacteria because they possess peptidoglycan cell wall material, contain RNA and DNA and are sensitive to a wide variety of broad-spectrum antibiotics. However, the size of the infectious particles (elementary bodies: EBs) is about that of large viruses (300 nm) and, like viruses, they have an obligate intracellular existence. During the intracellular reproductive cycle EBs are converted into metabolically active reticulate bodies, which increase in number by binary fission, reorganise themselves in inclusions into new EBs that are released from the cell after 36-48 hours. Recognition of inclusions by staining techniques forms the basis of chlamydial detection in cell culture. Detection of EBs by the use of fluorescent monoclonal antibodies is another approach to diagnosis Prevalence of C. trachomatis infection in pregnancy Prevalence rates for C. trachomatis genital tract infection, varying from 2% to 37%, have been reported for asymptomatic woman in the United States1,2. A similar range has been recorded for pregnant women, but overall it has been estimated that the prevalence rate in the United States is about 5% 3, 4. The chlamydial prevalence rate for pregnant women in the UK, based on the results of several studies5-8 in the past 15 years, varies from 7% to 15%. In fact, as expected, the range is in keeping with that for asymptomatic non-pregnant women attending general practice clinics for routine cervical cytology, gynaecology clinics and colposcopy units. It has to be recognised, however, that chlamydial prevalance rates for both pregnant and non-pregnant women are based largely on the use of relatively insensitive tests, such as culture and enzyme immunoassays. It is to be expected that the rates will be higher when populations are examined by means of the more sensitive molecular techniques (PCR or LCR). The main demographic risk factors for chlamydial cervical infection occurring in pregnant women are similar to those for non-pregnant women9 and include age less than 20 years, single marital status, the presence of mucopurulent cervicitis, abacteriuric pyuria and late antenatal booking4. It is not clear, however, whether oral contraceptive usage prior to pregnancy affects the rate of infection with C. trachomatis in pregnancy. Clinical aspects of complications in pregnancy Infection with C. trachomatis can occur at any time during pregnancy and in the postpartum period, the consequence depending on the trimester in which it occurs. Infection by C. trachomatis in the first trimester of pregnancy Approximately 20% of patients with C. trachomatis infection prior to surgical termination have developed salpingitis10,11 and screening for C. trachomatis to avoid this iatrogenically induced pathology has been advocated (see below). In contrast to induced abortion, it is not known whether infection with C. trachomatis predisposes to spontaneous abortion, since the high background rate of both C. trachomatis and spontaneous abortion make an aetiological association difficult to prove. Infection by C. trachomatis in the second and third trimesters of pregnancy C. trachomatis has rarely been isolated from amniotic fluid and infrequently from the placenta or membranes. In various prospective studies of pregnant women, most of whom were enrolled in the third trimester, no association of chlamydial infection with prematurity was demonstrated12-14. However, in a study in which women were enrolled at 19 weeks of gestation, a highly significant association was found between infection with C. trachomatis and stillbirth, premature birth and prenatal death from prematurity15. In another study16, no association overall was shown between C. trachomatis infection and any of the poor outcomes of pregnancy, but in a subgroup of women in whom infection was detected by culture and by having serum IgM chlamydial antibody (24% of those infected with C. trachomatis), the infection was associated with low-birth-weight infants and with premature rupture of the membranes. Thus, although opinions about the effect of a chlamydial infection have varied, the impression is that the infection in the second rather than the third trimester may lead to poor outcome. Effect of previous or chronic C. trachomatis on future pregnancies Chlamydial infection may cause tubal infertillity through damage to the fallopian tubes and increase the chance of ectopic pregnancy in those women who become pregnant,. While attempts to isolate C. trachomatis from the fallopian tubes of women with ectopic pregnancy have produced conflicting results, reflecting possibly differences between acute and chronic salpingitis, the association has been seen best serologically. Thus, significantly greater titres of chlamydial IgG antibody occur in patients with ectopic pregnancy than in those without17,18. Postpartum C. trachomatis infection Chlamydial endometritis may be asymptomatic or patients may present with secondary postpartum haemorrhage, fever, Rila Publications Ltd • CME BULLETIN Sexually Transmitted Infections & HIV • Volume1 No.2 November/December 1997 37 Chlamydial Infection In Pregnancy lower abdominal pain and/or vaginal discharge. Postpartum endometritis may be subdivided into early (within the first 48 hours after birth) and late (3 days to 6 weeks after birth), chlamydial postpartum endometritis tending to fall into the late category with an onset usually 2 to 6 weeks after birth. Chlamydial postpartum endometritis tends to be associated with vaginal delivery. In one study of women with late postpartum endometritis after vaginal delivery, 23% had C. trachomatis detected in the endometrium and a further 37% had C. trachomatis detectable in the cervix, and the majority of those with endometritis were afebrile and not seriously ill19. The effect of C. psittaci and C. pneumoniae on pregnancy C. pneumoniae is known to escape from the respiratory tract and to lodge in the atheromatous plaques of major arteries20. However, so far there is no evidence that such dissemination has had any effect on pregnancy. In contrast, it is known that in the UK and France, pregnant women have aborted after exposure to C. psittaci-infected sheep during the lambing season21-25. Chlamydiae have been isolated from placental samples of women, usually sheep farmers’ wives, who had been in contact with aborting ewes, and the women also exhibited antibody responses. Showing that strains isolated from human fetuses and placentae were of bovine origin has been helpful in clinching the diagnosis26. The pathological features of human disease are those of severe acute placentitis27. Although the exact mechanism of placental involvement and abortion is unknown, the pathological features suggest the likely course of events. C. psittaci organisms acquired presumably through the respiratory rather than the genital route, escape into the maternal circulation and invade the placenta because of a predilection for the human trophoblast. There they multiply rapidly, and are released into the intervillous spaces and spread to other chorionic villi, including an intense acute inflammatory response, the considerable tissue damage causing placental insufficiency and fetal anoxic death. The maternal disseminated intravascular coagulation/shock syndrome is probably due to the destruction of trophoblastic tissue releasing large amounts of thromboplastic material and/or chlamydial endotoxin into the maternal circulation. While the events described above are dramatic, it is important to get the situation in perspective. It is noteworthy that the prevalance of C psittaci antibodies in sera collected from workers on farms in northern England, where chlamydial ovine abortion occurred, was low and that antibody was detected no more frequently in farmers and their wives than in the non-farming adult community28. Indeed, as indicated above, only a few cases of human abortion arising in the way described have been recorded. Nevertheless, it is clearly prudent to advise pregnant women to avoid contact with sheep, especially in the lambing season. C. trachomatis infection in the newborn Intrauterine infection with C. psittaci, as described, or with C. trachomatis is a rare event. The major risk to the infant of acquiring a C. trachomatis infection and developing disease, as described below, is from passing through an infected cervix. Clearly, the frequency with which this occurs depends entirely on 38 the prevalence rate of cervical infection which as indicated previously, varies widely. Conjunctivitis The results of various studies indicate that between one-fifth and one-half of infants exposed to C. trachomatis infecting the cervix develop conjunctivitis29. The disease is seen usually from 1 to 3 weeks after birth and is characterised by a mucopurulent discharge and occasionally by pseudomembrane formation. Although it may be quite severe, corneal ulceration and follicle formation are rare and the disease is usually self-limiting, resolution occurring without visual impairment. If complications should arise, however, they tend to do so in untreated infants. Respiratory tract infection Overall, about 10-20% of exposed infants develop pneumonia30, that is about half of those who develop conjunctivitis. However, pneumonia is not always preceded by conjunctivitis. A history of recent conjunctivitis and bulging eardrums is found in about half the cases. Chlamydial pneumonia occurs usually between the fourth and eleventh weeks of life, preceded by upper respiratory symptoms, and is characterised by an afebrile protracted course in which there is tachypnoea and a prominent stacatto-type cough. Generalised hyperinflation with bilateral, diffuse and symmetrical interstitial infiltration with scattered areas of atelectasis are the radiographic findings. The occurrence of C. trachomatis IgM antibody in the infant’s serum is a useful diagnostic marker. The exact way in which pneumonia develops is unknown, although a relative eosinophilia in some cases has suggested the possibility of a hypersensitivity mechanism. However, whatever the mechanism, the disease is not to be dismissed lightly because there is evidence that it can lead to permanent lung damage. Thus, children who have experienced a chlamydial infection during infancy are more likely to develop obstructive lung disease and asthma than are those who have had pneumonia due to other causes or healthy controls31-33. Infection at other sites Apart from the eyes and respiratory tract, the vagina and rectum may be colonised by C. trachomatis at birth3, although colonisation has apparently not been associated with clinical disease. The possibility of chlamydiae causing gastroenteritis in infants has been considered32, but it amounts to no more than speculation. Management of C. trachomatis in pregnancy Screening Effective screening requires the availability of a sensitive and specific test which is acceptable to patients, the existence of effective treatment in the event of a positive result, and that it be costeffective. Although not all investigators agree, the number of organisms shed by asymptomatic women, whether pregnant or not, is probably no fewer than by symptomatic ones34, which suggests that asymptomatic chlamydial infection should be no more difficult to diagnose. However, small numbers of chlamydia are shed by Rila Publications Ltd • CME BULLETIN Sexually Transmitted Infections & HIV • Volume1 No.2 November/December 1997 Chlamydial Infection In Pregnancy about 40% of infected women, irrespective of symptoms35 and most of these will be detected only by use of the most sensitive methods. The problem is compounded in a low prevalence population in which the positive predictive value of a test, even one with a relatively high specificity, is unacceptably low. Thus, in one study36 in which an enzyme immunoassay was used to test asymptomatic women in whom the prevalence of chlamydial infection was 6.7%, the positive predictive value was 57%. This means that in a low risk population there may be more false-positive than true-positive results, a situation that can be rectified only by using tests of the greatest sensitivity and specificity. It would seem reasonable, although not widely practiced, to screen patients who have had a previous spontaneous pre-term rupture of the membranes at less than 37 weeks of gestation for infection, including that by C. trachomatis. Whether to screen for C. trachomatis in pregnancy routinely should be based on local prevalence rates, with the knowledge that insensitive tests which constitute the majority, will provide false-negative results and reduce the cost-effectiveness of screening. Certainly, with prevalence rates of 5-7% in the United States and Sweden, antenatal screening programmes have been regarded as cost-effective3,37,38 and in view of the high morbidity associated with chlamydial infection in pregnant women, particularly infection of the newborn, the prevalence rate at which screening becomes cost-effective is almost certainly lower than for non-pregnant women. Nevertheless, in the UK, a routine screening programme in pregnancy has never been instituted, either because of apathy or because evidence that C. trachomatis causes damage to the fetus during pregnancy is not strong. Furthermore, in high-risk population early screening would provide the opportunity for maternal infection to occur between screening and delivery. On the other hand, screening and treating later in pregnancy, for example in the thirty-sixth week, to prevent infection of the newborn is, as indicated above, worthwhile in a high-risk population. In addition, screening of women who are to have a termination of pregnancy would seem entirely justified in view of the greater risk to chlamydia-positive women. This becomes even more rational now that highly sensitive tests are available. Treatment of the mother Tetracylines are generally considered to be the drugs of first choice for treating chlamydia-infected, non-pregnant women. Other choices are the 4-fluoroquinolones (such as ofloxacin and ciprofloxacin), co-trimoxaole and broad-spectrum penicillins such as pivampicillin. The choice is more restricted in pregnant women, who are found to be infected with chlamydiae as a result of a screening programme or otherwise. The use of tetracylines is precluded since they cross the placenta and may cause skeletal growth retardation and permanent discolouration of the teeth. The 4 fluoroquinolones are not advocated because they have caused arthropathy in immature animals and, furthermore, they are excreted in breast milk. Co-trimoxazole, in animal studies, has caused the typical teratogenic effect of a folate antagonist and its safety for pregnant women has not been demonstrated. Furthermore, sulphonamide-containing products should not be prescribed in the third trimester because of the risk of kernicterus. Although co-trimoxazole is found in breast milk, it prob- ably represents negligible risk to the suckling infant. By elimination, the antibiotic of choice in pregnancy is erythromycin, which should be given in a dose of 250 mg, four times daily for 7 days39. Providing there has been compliance, an insensitive microbiological test of cure, for example, an enzyme immunoassay, is almost certain to be negative and a sensitive molecular technique, despite full compliance, may provide positive results for several weeks. Needless to say, neither is likely to be cost-effective. Single 1g dose Azithromycin, a highly effective azalide antibiotic against uncomplicated chlamydial infection in the non-pregnant population was found to have comparable efficacy to Erythromycin and better tolerated by pregnant women in one study of cervical chlamydia 40. However, Azithromycin is not currently licensed for use in pregnancy. Women pregnant, or otherwise, whose partners have chlamydial infections, should have a full screen for sexually transmitted diseases and epidemiological treatment for C. trachomatis, using the regimen indicated above, as is advised irrespective of the results. Conversely, partners of women with chlamydial infections should be investigated and treated appropriately. If a diagnosis of chlamydial infection is made in the newborn, both parents should be investigated and treated, irrespective of the diagnosis. Doxycycline 100mg, taken twice daily for 7 days, is preferred for mothers who are not breast feeding. The father should be referred to a genitourinary physician for investigation and treatment. Breast-feeding mothers should be treated with erythromycin as mentioned above. Prevention of chlamydial infection in the newborn Prophylaxis may involve treatment of the mother, or of the infant after birth, usually for conjunctivitis. Treatment of the mother, in the manner mentioned previously, is preferred since it prevents neonatal infection at all sites, as well as postpartum endometritis. The use of antibiotic in the third trimester is more than 90% effective in preventing neonatal infection and with less than a 5% rate of side effects41. Logically, treatment would be based on a late pregnancy screening programme (see above). However, if screening were not possible in an area of high chlamydial prevalence, an option would be to administer antibiotics to women in high risk categories, using the criteria outlined above. In a population where the prevalence of chlamydial infection is low, the policy would not be to screen mothers but to maintain vigilance and treat infection in the neonate when it occurred. The results of relatively recent studies have not confirmed the efficacy of topical prophylaxis for conjunctivitis42. Moreover, it has no effect on nasopharyngeal colonisation and does not prevent pneumonia. Not surprisingly, oral rather than topical erythromycin is superior for the treatment and prevention of pneumonia43. Treatment of the chlamydia-positive newborn Once infection with C. trachomatis has been diagnosed, treatment of the newborn depends on the site affected. Conjunctivitis is best treated with a combination of tetracyline eye ointment and erythromycin systemically. Topical chloramphenicol is ineffective Rila Publications Ltd • CME BULLETIN Sexually Transmitted Infections & HIV • Volume1 No.2 November/December 1997 39 Chlamydial Infection In Pregnancy and topical tetracycline alone inadequate. Pharyngitis, pneumonia, vaginal and rectal infection are best treated with erythromycin given systemically in a dose of 40 mg/kg per day for 14 days30. psittaci in a sheep farmer’s wife. Brit J Med 1985; 290: 592-4 25. McKinlay AW, White N, Buxton D et al. Severe Chlamydia psittaci sepsis in pregnancy. Quart J Med 1985; 57 : 222; 689-96 26. Herring AJ, Anderson IE, McClenaghan M et al. Restriction endonuclease analysis of DNA from two isolates of Chlamydia psittaci obtained from human abortions. Brit Med J 1987; References 1. 295: 1239 Hammersclag MR, Anderka M, Semine DZ et al. 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Sexually transmitted diseases, New York 1990, 14. Mårdh P-A, Helin I, Bobeck S et al. Colonisation of pregnant and puerperal women and neonates with Chlamydia trachomatis. Brit J Vener Dis 1980; 56: 96-100 15. Martin DH, Koutsky L, Eschenbach DA et al. Prematurity and perinatal mortality in pregnancies complicated by maternal Chlamydia trachomatis infections. J Amer Med Assoc 1982; 247: 1585-8 McGraw-Hill, pp 771-801 39. Stamm WE, Holmes KK. Chlamydia trachomatis infections of the adult. Holmes KK, Mårdh P-A, Sparling PF el al, editors. Sexually Transmitted Diseases, New York 1990, McGraw Hill, pp 181-94 40. Bush R. M, Rosa C. Azithromycin and Erythromycin in the treatment of cervical chlamydial 16. Harrison HR, Boyce WT, Haffner WH et al. The prevalence of genital Chlamydia trachomatis and mycoplasmal infections during pregnancy in an American Indian population. Sex Transm Dis 1983; 10: 184-6 infection during pregnancy. Obstet Gynaecol 1994; 84: 61-3 41. Schachter J, Sweet RL, Grossman M et al. Experience with the routine use of erythromycin for chlamydial infections in pregnancy. New Engl J Med 1986; 314: 276-9 17. Sherman KY, Daling JR, Steryachis A et al. Sexually transmitted diseases and tubal pregnancy. Sex Transm Dis 1990; 17: 115-21 42. Hammerschlag MR, Cummings C, Roblin PM et al. Efficacy of neonatal occular prophylaxis for the prevention of chlamydial and gonococcal conjunctivitis. New Engl J Med 1989; 320: 18. Gates WJC, Wasserheit JN. Genital chlamydia infections: epidemiology and reproductive sequelae. Amer J Obstet Gynecol 1991;164: 1771-81 19. Hoyme UB, Kiviat N, Eschenbach DA. Microbiology and treatment of late post partum 769-72 43. Patamasucon P, Rettig PJ, Faust KL et al. Oral versus topical erythromycin therapies for chlamydial conjunctivitis. Amer J Dis Child 1982; 136: 817-21 endometritis. Obstet Gynecol 1986; 68: 226-32 20. Ong, G, Thomas BJ, Mansfield AO et al. Detection and widespread distribution of Chlamydia pneumoniae in the vascular system and its possible implications. J Clin Pathol 1996; 49: 102-6 21. Giroud P, Roger F, Dumes N. Certains avortements chez la femme peuvent etre dus a des agents situés a coté du groupe de la psittacose. Comptes Rendus Hebdomadaire des Séances de L’Académie des Sciences 1956; 242:697-9 22. Roberts W, Grist NE, Giroud P, Human abortion associated with infection by ovine abortion agent. Brit Med J 1967; 222: 37 23. Beer RJS, Bradford WP, Hart RJC. Pregnancy complicated by psittacosis acquired from sheep. Brit Med J 1982; 284: 1156-7 24. Johnson FWA, Matheson BA, Williams H et al. Abortion due to infection with Chlamydia 40 Rila Publications Ltd • CME BULLETIN Sexually Transmitted Infections & HIV • Volume1 No.2 November/December 1997
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