Failure of serology in diagnosing chlamydial infections of the female genital tract

Performance of the multitarget Mikrogen Chlamydia trachomatis IgG ELISA in the prediction of tubal factor infertility (TFI) in subfertile women: comparison with the Medac MOMP IgG ELISA plus

There is a need for more accurate Chlamydia trachomatis (CT) IgG antibody tests for tubal factor infertility (TFI) diagnostics. We evaluated the predictive value for TFI of Medac ELISA plus (MOMP) and multitarget Mikrogen ELISA (MOMP-CPAF-TARP). Based on Medac ELISA plus results, 183 subfertile women underwent either hysterosalpingography or laparoscopy to diagnose TFI. TFI was defined as extensive adhesions and/or distal occlusion of at least one tube. Women not fulfilling the definition of TFI served as controls. Serum was subsequently tested with Mikrogen ELISA and results were compared. 48 patients had TFI, 135 were controls. Mikrogen ELISA tested 125 patients positive/borderline of which 32% had TFI. Medac ELISA plus tested 77 patients positive/borderline of which 29.9% had TFI. Mikrogen tested 40 out of 48 TFI patients positive/borderline, Medac 23 out of 48. Kappa value was 0.34. PPV of Mikrogen ELISA and Medac ELISA plus were respectively 32% (95% CI 26%-39%) and 30% (95% CI 24%-37%), and NPV 86% (95% CI 81%-91%) and 76% (95% CI 70%-82%). Both tests were comparable in the prediction of TFI. However, Mikrogen ELISA had a higher NPV and might be more reliable in identifying patients without TFI. Kappa-value showed limited concordance between both tests.

The role of serology, antibiotic susceptibility testing and serovar determination in genital chlamydial infections

Systemic and local antibodies regularly develop in genital infections caused by Chlamydia trachomatis. Such antibodies cannot be used as a sign of current infection as they often persist for years after the infection has resolved. Chlamydial antibodies have, however, been extremely useful for demonstrating associations between C. trachomatis and clinical conditions such as ectopic pregnancy and tubal factor infertility. In particular, antibodies to the chlamydial heat shock protein 60 predict the presence of tubal scarring.C. trachomatis has been divided into 15 (or 18) serovars, with many genotypes within each serovar. Differences in pathogenicity between serovars have been reported but no general pattern has emerged. Genotyping is a powerful epidemiological tool but is not yet ready for routine clinical use.C. trachomatis infections can be successfully treated by tetracycline or macrolides. Some resistant strains have been reported, causing treatment failures, and the problem of emerging antibiotic resistance cannot be neglected.

Tubal pelvic damage: prediction and prognosis

Tubal pelvic damage is a common cause of infertility, and laparoscopy is the accepted gold standard for its diagnosis. However, laparoscopy is both costly and invasive. Chlamydia is now recognized as the most common cause of tubal pelvic damage. In contrast to laparoscopy, evidence of past chlamydial infection using serology is readily available, and the test is simple and quick to perform. As such, serology can be used as a screening test in infertile women. It is accepted that screening tests may have higher margins of error and may be less accurate than diagnostic tests. Screening is most valuable when detecting a disease for which the treatment is more effective when undertaken at the earliest opportunity. Because there are justified constraints to the indiscriminate use of laparoscopy, there is a need to minimize the number of patients who do not have disease (false positives) who are subjected to this diagnostic investigation. An appropriate Chlamydia antibody titre that would distinguish women at risk of tubal pelvic damage should be determined using diagnostic test analysis and clinical judgement. Identification by serology of women who are likely to have damage would enable these women to undergo a diagnostic test such as laparoscopy sooner, allowing treatment to be provided earlier. However, the severity of tubal pelvic damage varies, and the need to distinguish women with a favourable or unfavourable prognosis after treatment using a simple classification system is discussed.

Cross-reaction between the genus-specific lipopolysaccharide antigen of Chlamydia spp. and the lipopolysaccharides of Porphyromonas gingivalis, Escherichia coli O119 and Salmonella newington: implications for diagnosis

Seven hybridoma clones, secreting monoclonal antibodies (MAbs) against the genus-specific chlamydial lipopolysaccharide (LPS) antigen were obtained after immunization of BALB/c mice with formalin killed Chlamydia psittaci. The antigen-binding properties of the MAbs were characterized in different immunologic reactions with purified chlamydial elementary bodies and LPS antigens from S- and R-forms of Gram-negative bacteria. Four MAbs reacted with the heterologous LPS antigens of Salmonella R-mutants, Escherichia coli Re chemotype and Acinetobacter calcoaceticus. Two MAbs demonstrated in addition a significant reactivity with Porphyromonas gingivalis, E. coli O119 and Salmonella newington LPS in ELISA, dot-ELISA and passive hemolysis assay (for clone 204G9). One MAb cross-reacted only with Salmonella minnesota Re LPS in ELISA. In indirect immunofluorescent assay six MAbs produced bright green fluorescence with all tested chlamydial strains and five of them reacted with the Re and Rb2 chemotypes of S. minnesota. The results demonstrate a wide cross-reactivity of the produced MAbs with LPS antigens of various Gram-negative bacteria, posing the question for careful consideration and interpretation of serology results for Chlamydia spp.

Evaluation of two nonculture antigen tests and three serotests for detection of anti-chlamydial antibodies in the diagnosis of ocular chlamydial infections

BACKGROUND

Diagnosis of chlamydial conjuctivitis is difficult in chronic diseases because chlamydial elementary bodies are mostly undetectable in conjunctival scrapings by cell culture. We therefore compared two nonculture antigen tests and three different serotests for anti-chlamydial antibodies with McCoy cell culture, the "gold standard" of chlamydial diagnosis. Conjunctival scrapings and serum samples of 93 patients attending the outpatient eye clinic in Graz because of chronic follicular conjunctivitis were tested.

METHODS

A total of 558 conjunctival scrapings and 93 serum samples were investigated. Chlamydial antigen detection was done by McCoy cell culture, polymerase chain reaction (PCR; Amplicor, Roche), and direct immunofluorescence assay (DFA; Microtrak, Syva). Antichlamydial IgA and IgG antibodies in the sera were detected by an immunoperoxidase assay (IPAzyme, Savyon) and two different enzyme-linked immunosorbent assays (SeroELISA, Savyon and rELISA, medac).

RESULTS

Cell culture and PCR yielded identical results. The positivity rate for chlamydial conjunctivitis was 8.6% (8 of 93 patients). PCR proved most sensitive and most specific. IPAzyme was 75% sensitive for IgA and 100% for IgG; SeroELISA and rELISA were less sensitive. IPAzyme was 81% specific for IgA and 47.3% for IgG. SeroELISA and rELISA were less specific for IgA, but more specific for IgG. Post-test likelihood of disease was greatest in IPAzyme.

CONCLUSIONS

PCR proved to be a good alternative to cell culture; DFA is useful for quick diagnosis. Genus-specific serotests cannot compete with chlamydial antigen detection. They differ in sensitivity and specificity because of the antigen type they present. They are still of only supportive value in cases where chlamydial antigen detection is not possible. Recently introduced species-specific antibody tests should be of greater value.

Diagnostic efficacy of chlamydial antibodies in cervical secretions from pregnant women and adolescent girls

OBJECTIVE

To assess the prevalence of cervical antibodies to Chlamydia trachomatis in two different populations and to correlate the findings to culture, direct fluorescent antibody test (DFA) and serum antibodies.

SETTING

Antenatal clinics and clinic for teenage counselling in Gävle.

PATIENTS

1078 pregnant women attending for routine follow up in the third trimester of pregnancy and 256 teenage girls.

OUTCOME MEASURES

Cervical IgG and IgA antibodies to Chlamydia trachomatis. Cervical cultures for chlamydia. Serum IgG antibodies. DFA tests were used only in the teenage group.

RESULTS

The prevalence of positive culture was 2.0% in pregnant women and 8.6% in teenage girls. In pregnant women cervical IgG > or = 8 and IgA > or = 8 were found in 7.2% and 5.8% respectively and in teenage girls in 6.6% and 2.0% respectively. The agreement between cervical IgG > or = 8 and humoral IgG > or = 32 was 0.76 in the pregnant group and 0.95 in the teenage group. The sensitivity, specificity and positive predictive value (PPV) for cervix IgG > or = 8 to predict a positive culture was 0.64, 0.94 and 0.18 respectively in pregnant women and 0.41, 0.97, 0.53 respectively in teenage girls. Of 31 teenage girls with either positive culture or positive DFA 12 had cervical IgG > or = 8 while five of 225 with negative chlamydia tests had cervical IgG > or = 8 (sensitivity 0.40 and PPV of 0.71). Cervical IgG > or = 16 was found in eight of 31 with positive chlamydia tests and in one of 225 with negative tests (sensitivity 0.26 and PPV 0.89).

CONCLUSIONS

The finding of cervical IgG > or = 16 predicts current chlamydia (culture or DFA) in nearly 90% in a teenage population. It might indicate current infection in spite of negative culture in some cases. For low titres and in a low prevalence pregnant population cervical IgG are not useful for the diagnosis of chlamydia. As the sensitivity is low cervical antibodies cannot be used for screening purposes.

Enzyme immunoassay with enhanced specificity for detection of antibodies to Chlamydia trachomatis

Two different methods for preventing the binding of cross-reacting antibodies to the genus-reactive chlamydial lipopolysaccharide (LPS) were used to improve the specificity of an enzyme immunoassay for the determination of antibodies to Chlamydia trachomatis. Coated elementary bodies were treated with either sodium periodate, to oxidize the antigenic sites of the LPS, or Triton X-100, to extract the LPS. By using these new enzyme immunoassays, the standard enzyme immunoassay, and the whole inclusion fluorescence (WIF) assay, antibodies to C. trachomatis were determined in sera from different groups of patients and controls. Paired serum samples from patients with culture-proven urogenital C. trachomatis infections showed similar responses in all three assays. Paired serum samples from patients with Chlamydia psittaci infections showed similar responses in the WIF assay and the standard enzyme immunoassay, whereas significantly reduced titers were obtained in the enzyme immunoassays with treated antigen, especially in the convalescent-phase serum samples. Serum samples from patients with symptoms suggestive of infection with C. trachomatis, pregnant women, and blood donors were evaluated by all three types of assays. Eighty percent of the significant reductions in immunoglobulin G (IgG), IgA, and IgM titers were observed in sera with WIF assay titers in the lower classes (IgG, 1: < or = 256; IgA, 1: < or = 32; IgM, 1: < or = 16). From these results we conclude that oxidation of the antigen by sodium periodate is a simple and effective method of producing an enzyme immunoassay with enhanced specificity that could be useful for diagnostic purposes and seroepidemiological studies.

Chlamydia trachomatis species specific serology: ImmunoComb Chlamydia bivalent versus microimmunofluorescence (MIF)

The ImmunoComb Chlamydia Bivalent IgG/IgA (Orgenics, Israel) is a new quantitative serologic test that employs LPS extracted Chlamydia trachomatis L2 and LPS extracted Chlamydia pneumoniae elementary bodies on two separate antigenic spots. The Bivalent C. trachomatis specific test results were compared with microimmunofluorescence (MIF), the gold standard of chlamydial species specific serology. For C. trachomatis IgG the Bivalent was highly concordant with the MIF: the rate of positive titres (IgG > or = 1:8) was 10% vs. 11% in 100 blood donors, 18% vs. 16% in 111 obstetric patients (6% antigen prevalence), 26% vs. 22% in sterile women with open (n = 54) and 86% vs. 84% with occluded (n = 51) tubes, and 88% vs. 85% in 103 women with C. trachomatis positive cervical smears. Surprisingly, the Bivalent differed considerably from the MIF in IgA prevalence: in obstetric patients (8% vs. 4%), sterile women with open (13% vs. 6%) and occluded (71% vs. 20%) tubes, and women with positive cervical smears (78% vs. 24%). Bivalent IgA appeared to be more sensitive than MIF IgA and showed a stronger correlation with positive cervical smears in obstetric patients (sensitivity 67% vs. 0%, specificity 95% vs. 96%, positive prediction 44% vs. 0%, negative prediction 98% vs. 94%) and with tubal occlusion in sterile women (sensitivity 71% vs. 20%, specificity 87% vs. 94%, positive prediction 84% vs. 77%, negative prediction 76% vs. 55%). MIF IgM was of little diagnostic help. Supplemental to the often difficult C. trachomatis antigen detection, the easily performed Bivalent IgG/IgA appears to be of great value in routine diagnosis of genital chlamydial infections.

Chlamydial serology in genital infections: ImmunoComb versus Ipazyme

The ImmunoComb Chlamydia trachomatis IgG/IgA (Orgenics, Israel) is a new serologic test using C. trachomatis L2 elementary bodies (Washington Research Foundation, Seattle) as antigen. The Ipazyme IgG/IgA test (Savyon, Israel) employs whole cells with C. trachomatis L2 inclusions, i.e. elementary and reticulate bodies. Theoretically, the ImmunoComb is expected to be less cross-reactive (LPS) with Chlamydia pneumoniae than the Ipazyme (LPS and reticulate body group specific antigens). Compared with the Ipazyme, the ImmunoComb IgA showed both a higher positive predictive value (36% versus 25%) and sensitivity (67% versus 33%) for antigen detection in a control group of 100 post partum women with a 6% prevalence of C. trachomatis positive cervical smears. In sterility patients (45 cases with occluded and 53 with open fallopian tubes) the tube status was predicted by the ImmunoComb (Ipazyme) with 74% (72%) positive predictive value, 87% (80%) sensitivity, and 87% (81%) negative predictive value. IgG/IgA prevalence in 118 patients with C. trachomatis positive cervical smears was 85%/55% for the ImmunoComb and 84%/49% for the Ipazyme. The ImmunoComb is considerably faster and easier in handling and less subjective in reading than the Ipazyme.

Detection of IgG, IgM and IgA antibodies in patients with uncomplicated Chlamydia trachomatis infection: a comparison between enzyme linked immunofluorescent assay and isolation in cell culture

The diagnostic value of serum IgG, IgM and IgA in patients with uncomplicated urogenital Chlamydia trachomatis infection was compared with isolation in cell culture. C. trachomatis specific antibodies were determined with an enzyme linked immunofluorescent assay using elementary bodies from C. trachomatis serotypes E,F,H,I,J and LGV2 as antigens. At least two sera from each patient were tested and cultures were also established on the same day. Excluding the IgM titres in men, significantly more IgG, IgA and IgM and combinations of these antibodies were observed in culture positive patients. The sensitivity with which IgG titres in men or IgG and/or IgM titres in men and women could be determined, was significantly lower using C. trachomatis LGV2 as the only antigen than when all 6 antigens were used. The presence of 10 or more leucocytes in the urine sediment of men correlated positively with an IgG or an IgG and/or IgM titre.

Prevalence of Chlamydia trachomatis infection in women having cervical smear tests

OBJECTIVE

To determine the prevalence of sexually transmitted diseases in patients with normal and abnormal cervical smears.

DESIGN

A prospective study of asymptomatic women with normal cervical smears attending their general practitioner and newly referred patients with abnormal smears attending a colposcopy clinic.

SETTING

A hospital based colposcopy clinic and an urban general practice (list size 5500) in north west Glasgow.

SUBJECTS

197 asymptomatic women attending their general practitioner for cervical smear tests and 101 randomly selected patients attending the colposcopy clinic for investigation of abnormal smears.

MAIN OUTCOME MEASURES

Presence of various sexually transmitted infections as determined by culture and serological tests.

RESULTS

Of the 101 women with cytological abnormalities, six had current chlamydial infection proved by culture and none had gonococcal infection; of the 197 women with normal smears, 24 (12%) had a chlamydial infection and two had gonorrhoea. Serological studies for Chlamydia trachomatis specific antibody also indicated that a large proportion of patients had been exposed to this agent in both groups. There was no significant difference between the groups in the prevalence of any sexually transmitted disease studied.

CONCLUSION

A high prevalence of chlamydial infection is present in women in north west Glasgow irrespective of their cervical cytological state.

Chlamydial infections

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Antibodies to Chlamydia trachomatis in women with infertility, pelvic inflammatory disease and ectopic pregnancy

Sixty-three women admitted to the gynecological ward at the University Hospital, Linköping, were studied for the presence of antibodies to Chlamydia trachomatis. 48% of infertile women, 78% of women with ectopic pregnancy and 44% of women with pelvic inflammatory disease had higher titer (greater than or equal to 1:128) IgG/IgA/IgM antibodies to C. trachomatis. Among 55 healthy pregnant women, used as controls, 13% had this high antibody titer. Among 30 women with a titer of greater than or equal to 1:128, 33% of previous conceptions resulted in ectopic pregnancy and 31% resulted in child birth. The corresponding figures among women with no antibodies to C. trachomatis were 12% and 60%, respectively. The prevalence of IgA antibodies varied from 22% to 38% in women with pelvic inflammatory disease, ectopic pregnancy or infertility. The results indicate the importance for C. trachomatis in development of sequelae to lower genital tract infections in women.

Detection of specific IgG and IgA antibodies to Chlamydia trachomatis in women with salpingitis confirmed by laparoscopy

The sera from 12 consecutive symptomatic women with laparoscopy-confirmed salpingitis were screened for the presence of specific IgG and IgA antibodies to Chlamydia trachomatis by a single antigen (L-2) immunoperoxidase assay. All women were found to have IgG and IgA antibodies to C trachomatis. Six women had positive endocervical cultures for C trachomatis, and one of these had positive cultures from the conjunctiva and fallopian tubes. Serum chlamydial IgA antibodies may serve as markers for active infection with C trachomatis regardless of whether organisms can be identified by culture or direct fluorescent antibody techniques from endocervical or fallopian tube samples.

Laboratory diagnosis of human chlamydial infections

Chlamydia trachomatis is a human pathogen that causes ocular disease (trachoma and inclusion conjunctivitis), genital disease (cervicitis, urethritis, salpingitis, and lymphogranuloma venereum), and respiratory disease (infant pneumonitis). Respiratory chlamydioses also occur with infection by avian strains of C. psittaci or infection by the newly described TWAR agent. Diagnosis of most acute C. trachomatis infections relies on detection of the infecting agent by cell culture, fluorescent antibody, immunoassay, cytopathologic, or nucleic acid hybridization methods. Individual non-culture tests for C. trachomatis are less sensitive and specific than the best chlamydial cell culture system but offer the advantages of reduced technology and simple transport of clinical specimens. Currently available nonculture tests for C. trachomatis perform adequately as screening tests in populations in which the prevalence of infection is greater than 10%. A negative culture or nonculture test for C. trachomatis does not, however, exclude infection. The predictive value of a positive nonculture test may be unsatisfactory when populations of low infection prevalence are tested. Tests that detect antibody responses to chlamydial infection have limited utility in diagnosis of acute chlamydial infection because of the high prevalence of persistent antibody in healthy adults and the cross-reactivity due to infection by the highly prevalent C. trachomatis and TWAR agents. Assays for changes in antibody titer to the chlamydial genus antigen are used for the diagnosis of respiratory chlamydioses. A single serum sample that is negative for chlamydial antibody excludes the diagnosis of lymphogranuloma venereum.

The seroepidemiology of Chlamydiae in Finland over the period 1971 to 1987

The seroepidemiology of chlamydial infections in the Finnish population was studied by analysing the prevalence of chlamydial complement fixing (CF) antibodies in patients sera sent for virus serological screening tests over 17 years from 1971 to 1987. The total number of sera studied was over 160,000. In the early 1970s, the prevalence of chlamydial CF antibodies (CF titres greater than or equal to 8) was low (less than 2%), but later the proportion of seropositive cases rose, and in 1976, 18% of sera contained antibodies. In 1984, the seropositivity rate was over 31%. The prevalence of high chlamydial CF titres (titres greater than or equal to 64) also showed annual variation. In general, under 1% of sera contained chlamydial CF antibodies in high titre, but in 1979 and 1984, distinct peaks occurred when 1.3% and 1.4% of sera, respectively, had titres greater than or equal to 64. The age-related antibody positivity rate showed a decline during early infancy, an increase in childhood and adolescence, and a stable level in adulthood when approximately 20% of the sera contained antibodies. The chlamydial antigen used in this survey was genus-specific, i.e. it detects antibodies against all chlamydial species. Epidemiological data support the hypothesis that infections due to a novel chlamydial species, TWAR chlamydia, are the most likely explanation for the relatively frequent occurrence of chlamydial CF antibodies and for the variation in CF antibody prevalence.

Chlamydia trachomatis infections in infants

In recent years considerable progress has been made in understanding chlamydial infections. The spectrum of pediatric Chlamydia trachomatis infection includes neonatal inclusion conjunctivitis, infantile pneumonia, occasional respiratory or genital tract infections in older children and sexually transmitted diseases in adolescents. The role of maternal chlamydial infection in prematurity and in perinatal death is currently an area of active study. We outline the current knowledge of the biologic characteristics of C. trachomatis, the epidemiologic features of chlamydial infection, and the clinical aspects, diagnosis and treatment of neonatal chlamydial infections.

Screening for Chlamydia trachomatis infection in a pregnancy counseling clinic

Five hundred twenty asymptomatic women attending a pregnancy counseling clinic were interviewed and screened for cervical Chlamydia trachomatis infection before therapeutic abortion. Overall, 56 (10.8%) women were culture positive for C. trachomatis. Restricting testing to women with risk factors for infection or who had cervical leukocytosis on Gram staining of cervical mucus, or who were seropositive for C. trachomatis antibodies proved impractical because of insensitivity or nonspecificity. We evaluated three chlamydia diagnostic tests to determine which test had the best performance characteristics. In comparison with culture, the direct fluorescent antigen test had a sensitivity of 89% and a positive predictive value of 78%, whereas the enzyme immunoassay had 96% and 69%, respectively. When analysis was redone with any two positive laboratory tests to define true infection status, the performance parameters of enzyme immunoassay were sensitivity 98%, specificity 98%, and positive predictive value 87%. We conclude that all women undergoing therapeutic abortion require testing for C. trachomatis infection and that enzyme immunoassay is the most effective and practical test in this group of women.

Diagnosis of Chlamydia trachomatis infection--culture versus serology

The diagnostic value of different laboratory methods in detecting Chlamydia trachomatis infections in high risk groups was analysed. The efficiency of a direct specimen test was compared with serology (IgG and IgM ELISA) and culture in L929 cells, stained either with fluorescein conjugated monoclonal antibodies or with iodine. Patients (no. = 1041) with localized genital infections attending a STD clinic, sexual contacts and patients with ascending infections from urological and gynecological clinics were examined. Chlamydia trachomatis was detected in 225 patients: 210 (93.3%) were reactive in the direct test (smears stained with monoclonal antibodies), whereas culture missed only 5 (sensitivity 97.8%) when stained by the same method. Cultures stained with iodine produced the lowest recovery rate (73.8%), but this rate increased to 80.9% when a second passage was performed. In addition the prevalence of Neisseria gonorrhoeae, Mycoplasma hominis, Ureaplasma urealyticum, Candida albicans and Trichomonas vaginalis was investigated. In patients with non-gonococcal urethritis (no. = 331) and cervicitis (no. = 353), Chlamydia trachomatis was isolated in 32.3% and 12.8% respectively. However, this pathogen could be isolated in only 3 (15.8%) out of 19 patients with epididymitis and 15 (14%) out of 107 patients with adnexitis, although 66.7% and 93.3% respectively had specific IgG antibodies. Specific IgM could by detected with a sandwich ELISA in patients with adnexitis (46.7%), epididymitis (33.3%), cervicitis (22.2%), non-gonococcal urethritis (14%) and in the sexual partners of patients with genital infections (35.7%). The direct specimen test with monoclonal antibodies is the method of choice for the diagnosis of a C. trachomatis infection in patients with urethritis and cervicitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between cell culture and serology for detecting Chlamydia trachomatis in women seeking abortion

The efficiency of an immunoperoxidase serological assay and culture of Chlamydia trachomatis were compared in 127 women seeking first trimester abortion. Serum IgG and IgA antibodies specific for C trachomatis were detected by a single serovar (L2) inclusion immunoperoxidase assay (IPA). Eighty (63%) women were seropositive for chlamydial IgG and 31 (24%) for IgA antibodies. C trachomatis was isolated from 21 of 127 (17%) women. Twenty of the 80 women (25%) seropositive for specific IgG antibodies and one of 47 (2%) patients without these antibodies were culture positive (p less than 0.001). Compared with isolation, chlamydial antibodies at a titre of greater than or equal to 16 showed high sensitivity and negative predictive value (95% and 98%, respectively), but low specificity and efficiency (43% and 52%, respectively). Chlamydial IgA antibodies at a titre of greater than or equal to 8 showed low sensitivity (52%), but a higher specificity, negative predictive value, and efficiency of 81%, 90%, and 76%, respectively. C trachomatis IgG antibodies at a titre of 16 as determined by IPA can be used as an efficient negative exclusion marker for active chlamydial infection in screening women seeking abortion.

Evaluation of single whole inclusion serum test for IgG antibody to Chlamydia trachomatis in asymptomatic women

IgG antibody titres against Chlamydia trachomatis were measured using a whole inclusion assay (Electro-Nucleonics Laboratories, Bethesda, Maryland, USA) in single serum samples of patients who presented for termination of pregnancy with evidence of infection with this organism (case group) and of 30 women with no evidence of infection (control group). Case and control patients were matched for age, race, marital status, history of sexually transmitted diseases, number of lifetime sexual partners, and whether they had had a new sexual partner in the preceding month. Fifty eight of 60 (97%) serum samples tested had chlamydial antibodies present at a titre of 1/8 or more. There was no significant difference between the geometric mean titres of the 30 case patients and the 28 controls with chlamydial antibodies (1/161.3 and 1/77.4 respectively). Significantly more case patients than controls, however, had a titre of 1/128 or more (p less than 0.01). The sensitivity, specificity, and positive and negative predictive values of a single serum antibody titre of 1/128 or more as an indicator of recent infection compared with isolation of the organism in cycloheximide treated McCoy cells or antigen detection by Chlamydiazyme (Abbot Laboratories; North Chicago, Illinois, USA), or both, were each 67%. The value of the antibody assay seems to be questionable as high levels of antibodies failed to correlate with isolation or antigen detection results, or both, in our population.

Chlamydia trachomatis: a practical obstetric/gynecologic management approach

Chlamydia trachomatis has assumed a critically important role in the pathogenesis of gynecologic/perinata/neonatal infectious morbidity. C. trachomatis is responsible for several infectious syndromes in the non-pregnant woman, the mother and her offspring. Detection and treatment of chlamydia infections are as important as that of other sexually transmitted diseases (STDs) such as GC, syphilis, trichomoniasis, etc. An appreciation of the seriousness of the resulting disorders and a high index of suspicion are absolute prerequisites for successful management.

Accuracy of immunoglobulin M immunoassay for diagnosis of chlamydial infections in infants and adults

An improved solid-phase enzyme immunoassay (EIA) with Chlamydia trachomatis L2 434/Bu elementary bodies was developed for the measurement of immunoglobulin M (IgM) antibody to C. trachomatis in serum. Comparison of EIA and microimmunofluorescence IgM antibody titers of 156 serum samples revealed an EIA sensitivity and specificity of 100% for infants, but reduced sensitivity (85%) and specificity (76%) for sera from adults. Sera containing IgM class rheumatoid factor produced false-positive IgM results which could easily be eliminated by pretreatment of the sera with anti-human IgG. Analysis of sera from infants with chlamydial infections revealed that 17 of 17 infants with C. trachomatis pneumonia had high IgM antibody titers (geometric mean titer, 1:64,812), whereas two infants with conjunctivitis only lacked detectable IgM antibody. EIA detected IgM antibody to several serovar groups in serum, including serovars B, BDE, FG, and J. IgM antibody to C. trachomatis in serum was detected as early as 5 days after the infection that was acquired at delivery and persisted for 3 months. The availability of an EIA possessing good sensitivity and specificity for the detection of IgM antibody to C. trachomatis may permit more laboratories to diagnose perinatal chlamydial infections.

Persistence of chlamydial antibodies after pelvic inflammatory disease

The persistence of chlamydial immunoglobulin G (IgG) antibodies and long-term sequelae of pelvic inflammatory disease (PID) were studied in 70 women who had been treated for PID 3 to 6 years previously. Fifty-one women had had PID associated with Chlamydia trachomatis infection (Chlamydia group), and 19 women had had PID not associated with C. trachomatis (non-Chlamydia group). Chlamydial IgG antibodies, as determined by the indirect immunofluorescence test with inclusions of C. trachomatis L2 as antigens, persisted at stable levels in 43% of the women for up to 6 years; 43% of the women showed a decrease in IgG titer, and 13% showed an increase. IgA antibody levels in serum correlated with IgG antibody levels in serum and with the presence of cervical IgA antibodies. Both serum antibodies and cervical IgA antibodies were more often found in the Chlamydia group. Forty-two percent of the women were infertile. Every fifth subsequent pregnancy was ectopic. The presence of cervical IgA antibodies might protect the women from tubal damage.

Chronic respiratory disease in premature infants caused by Chlamydia trachomatis

The relation between chronic respiratory disease and infection with Chlamydia trachomatis in premature infants was investigated to ascertain the aetiological importance of intrauterine C trachomatis infection and chronic respiratory disease in premature infants. Serum IgM antibodies against C trachomatis were determined by enzyme linked fluorescence assay. Sections of lung tissues obtained by biopsy and at necropsy were also tested for the presence of antigens using fluorescein conjugated monoclonal antibodies to C trachomatis. Of 16 sera from premature infants with chronic respiratory diseases clinically diagnosed as bronchopulmonary dysplasia or the Wilson-Mikity syndrome, five had IgM antibodies to C trachomatis L2 strain by enzyme linked fluorescence assay (titre greater than or equal to 1/500). Of 37 sera from premature infants with extremely low birth weights, two had IgM antibodies to C trachomatis. No specific IgM antibody was detected in 31 neonates who showed raised serum IgM concentrations but who did not have respiratory tract symptoms. C trachomatis was identified from two specimens of lung tissue obtained at necropsy from premature infants with chronic respiratory disease positive for IgM antibody. These findings indicate the aetiological importance of intrauterine C trachomatis infection in chronic respiratory disease in premature infants.

Detection of IgM antibodies against Chlamydia trachomatis by enzyme linked fluorescence immunoassay

A simple, sensitive enzyme linked fluorescence immunoassay has been developed to detect IgM antibodies against Chlamydia trachomatis. Reticulate bodies and elementary bodies from C trachomatis L2/434 Bu strain were isolated and used as antigens in the assay. Of 113 serum samples obtained from infants with pneumonia, 27 (23.9%) had IgM antibodies to C trachomatis L2 reticulate bodies and nine (8.0%) had IgM antibodies to C trachomatis L2 elementary bodies (titre greater than or equal to 1/500). Specific IgM antibodies were not detected in 20 control serum samples obtained from healthy adults and children. The possible use of enzyme linked fluorescence assay to determine IgM antibodies in the serodiagnosis of C trachomatis infection is discussed.

Comparison of enzyme linked immunosorbent assay and enzyme linked fluorescence immunoassay for detection of antibodies against Chlamydia trachomatis

An enzyme linked fluorescence immunoassay (ELFA) has been evaluated for the detection of antibodies against Chlamydia trachomatis. Reticulate bodies and elementary bodies from C trachomatis L2/434 strain were used as antigens. An enzyme linked immunosorbent assay (ELISA) has also been evaluated using the same antigens. Results obtained by ELISA and ELFA for human sera with these two antigens were compared with each other and with the results obtained by a micro-immunofluorescence (micro-IF) test. Serum IgG antibodies against C trachomatis L2 reticulate bodies and elementary bodies were found in 32 (20.0%) and 11 (6.9%), respectively, of 160 serum samples from pregnant women by the micro-IF test (titre greater than or equal to 1/32). All of these 32 pregnant women had IgG antibodies to C trachomatis reticulate bodies (titre greater than or equal to 1/100), whereas 20 (12.5%) had IgG antibodies to elementary bodies in the ELISA. On the other hand, 25 (15.6%) and 19 (11.9%) of them had IgG antibodies to C trachomatis L2 reticulate bodies and elementary bodies, respectively, by the ELFA (titre greater than or equal to 1/500).

Risk, health promotion, disease intervention and sexually transmitted disease

Sexually transmitted diseases (STDs) are a major public health problem, causing enormous human suffering and heavy health care expenditures. With the list of STDs having expanded fourfold in recent years and the incidence of several of these diseases increasing annually, an urgent need exists for investigators, clinicians and public health practitioners to collaborate in developing the most cost-effective STD prevention and intervention strategies (Table 7). Achievement of this goal will require that key risk factors associated with current STD trends be closely scrutinized and appropriate health promotion messages better emphasized.

Immune response in mice infected in the genital tract with mouse pneumonitis agent (Chlamydia trachomatis biovar)

Female Swiss-Webster mice were inoculated intravaginally with mouse pneumonitis agent (MoPn), a Chlamydia trachomatis biovar. Inoculation with 3.5 X 10(5) egg lethal doses per mouse resulted in shedding of the agent from the genital tract for as long as 21 days. Immunoglobulin M antibodies to MoPn were detected in plasma by day 7 post-inoculation, and immunoglobulin G antibodies were detected by day 14. Antibodies were detected in genital secretions by day 20, and titers in plasma and secretions were still considerable on day 56. Delayed-type hypersensitivity tests, determined by footpad swelling, were not positive in appreciable numbers of animals until after day 25. Delayed-type hypersensitivity reactions were maximal 24 h after testing and were preceded by an Arthus-like reaction, which appeared within 3 h and declined by 12 h. Convalescent animals were rechallenged by intravaginal inoculation and were found to be solidly immune.

Detection of Chlamydia trachomatis inclusions in Mccoy cell cultures with fluorescein-conjugated monoclonal antibodies

We compared two methods for identification of Chlamydia trachomatis inclusions in McCoy cell monolayers: conventional iodine staining and immunofluorescence staining with monoclonal antibodies against the species-specific major outer membrane protein antigen of C. trachomatis. Among 878 urethral and cervical specimens tested in parallel, the immunofluorescence method detected eightfold more inclusions per monolayer, identified a higher proportion of positive specimens on first passage (98 versus 62% by iodine staining; P less than 0.01), and improved overall sensitivity (98% of total positive specimens detected versus 84% by iodine staining; P less than 0.01). Improved sensitivity was most evident in specimens with low numbers of inclusions. Compared with conventional iodine staining, immunofluorescence staining with monoclonal antibodies improves sensitivity and offers more rapid detection of chlamydial inclusions in cell culture.

Screening for chlamydial infections in women attending family planning clinics

Chlamydia trachomatis was recovered from the cervices of 9.8 percent (268/2,729) of women attending seven family planning clinics. The infection rate varied from 5.5 percent to 22.5 percent in different clinics. Chlamydial infection could be associated with younger age, nulliparity, being black and use of oral contraceptives. Most (70 percent) of the chlamydial infections were inapparent and presumptive indicators for antichlamydial therapy that are useful for symptomatic women will not make a major impact on this reservoir. It is concluded that chlamydial cultures are needed to deal with the high prevalence of these infections.

Comparison of reticulate and elementary body antigens in detection of antibodies against Chlamydia trachomatis by an enzyme-linked immunosorbent assay

Reticulate bodies from a type C and elementary bodies from a type L2 strain of Chlamydia trachomatis were isolated and used as antigens in an enzyme-linked immunosorbent assay (ELISA). Results obtained for human sera with these two antigens used in the ELISA were compared with each other and with results obtained for the same sera by the micro-immunofluorescence test. Negative control populations included cloistered nuns and children with respiratory infections. Populations at risk for chlamydial infection consisted of 42 men with nongonococcal urethritis attending a sexually transmitted diseases clinic and 42 college women who had contact with men with nongonococcal urethritis. ELISAs done with the two antigens were equivalent to each other and to the micro-immunofluorescence test in the ability to predict the presence or absence of infection. None of the tests had high predictive values for the men with urethritis. However, the negative predictive value of both the micro-immunofluorescence test and the elementary body ELISA was 0.92 for the college women. Such serological tests may be of value in screening selected populations for subclinical infections with C. trachomatis.

Solid-phase enzyme immunoassay for Chlamydial antibodies

An enzyme immunoassay (EIA) for chlamydial immunoglobulin G antibodies was developed by using microtiter wells coated with partially purified reticulate bodies of Chlamydia trachomatis serotype L2, grown in McCoy cells, and uninfected McCoy cells as a control. Duplicate testing of a single serum dilution, 1:500, was found to be sufficient. A good correlation between positive reactions was observed in a comparative study of 421 patient sera with the EIA and an inclusion immunofluorescence test. A good correlation between positive reactions was also observed in a comparative study of 140 patient sera with EIA and microimmunofluorescence tests in which chlamydial elementary or reticulate bodies were used as antigens. Sera of 77 healthy control individuals with low titers in inclusion immunofluorescence or complement fixation tests gave negative results in the EIA. Immunoblotting experiments showed that the major antigenic component in the EIA antigen was a protein with an Mr of 39,000.

Chlamydia trachomatis: serological diagnosis

Satisfactory methods for the serodiagnosis of Chlamydia trachomatis have been widely discussed in recent years. Until a decade ago, the complement-fixation test measuring group-specific antibody was the most widely applied technique. However, despite showing relatively high diagnostic sensitivity in systemic chlamydial infections, it is of little value in the serodiagnosis of localized chlamydial oculo-genital infections or of trachoma. The more recently developed microimmunofluorescence (micro-IF) test is not only a very sensitive technique, but can also reach a high degree of serodiagnostic specificity in certain chlamydial infections. Unlike the complement-fixation test, it measures type-specific antibody which may be directed against one or more C trachomatis serotypes. By nature, chlamydia infections often lead to high background rates of antibody in affected populations. Interpretation of serological results may therefore be difficult, particularly when only single-serum samples are available. However, in seroepidemiological work, in the study of transmission patterns and in the detection of predominant serotypes in a community, the micro-IF test is especially valuable, and if results are interpreted with care, the test may also serve as an indicator of chlamydial infection. The predictability, sensitivity and specificity of serological tests for C. trachomatis will be discussed.

Chlamydial antigens stabilized with formalin for use in the micro-immunofluorescence test

Formalinized antigen suspensions prepared by differential centrifugation from crude infected yolk sacs and stored at 4 degrees C were satisfactory antigens during at least 36 weeks when used in chlamydial micro-immunofluorescence procedures.