Diagnosis of Chlamydia trachomatis genital infections by cell culture and two enzyme immunoassays detecting different chlamydial antigens

Diagnosis of Chlamydia trachomatis genital infections in the era of genomic medicine

PURPOSE

Chlamydial genital infections constitute significant sexually transmitted infections worldwide. The often asymptomatic status of C. trachomatis (CT) infections leads to an increased burden on human reproductive health, especially in middle- and low-income settings. Early detection and management of these infections could play a decisive role in controlling this public health burden. The objective of this review is to provide an insight into the evolution of diagnostic methods for CT infections through the development of new molecular technologies, emphasizing on -omics' technologies and their significance as diagnostic tools both for effective patient management and control of disease transmission.

METHODS

Narrative review of the diagnostic methodologies of CT infections and the impact of the introduction of -omics' technologies on their diagnosis by review of the literature.

RESULTS

Various methodologies are discussed with respect to working principles, required specifications, advantages, and disadvantages. Implementing the most accurate methods in diagnosis is highlighted as the cornerstone in managing CT infections.

CONCLUSION

Diagnostics based on -omics' technologies are considered to be the most pertinent modalities in CT testing when compared to other available methods. There is a need to modify these effective and accurate diagnostic tools in order to render them more available and feasible in all settings, especially aiming on turning them to rapid point-of-care tests for effective patient management and disease control.

Diagnosis and assessment of trachoma

Trachoma is caused by Chlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in communities where trachoma is present. New rapid assessment protocols incorporating techniques for obtaining representative population samples (without census preparation) may give better estimates of the prevalence of clinical trachoma. Clinical findings do not necessarily indicate the presence or absence of C. trachomatis infection, particularly as disease prevalence falls. The prevalence of ocular C. trachomatis infection (at the community level) is important because it is infection that is targeted when antibiotics are distributed in trachoma control campaigns. Methods to estimate infection prevalence are required. While culture is a sensitive test for the presence of viable organisms and nucleic acid amplification tests are sensitive and specific tools for the presence of chlamydial nucleic acids, the commercial assays presently available are all too expensive, too complex, or too unreliable for use in national programs. There is an urgent need for a rapid, reliable test for C. trachomatis to assist in measuring progress towards the elimination of trachoma.

Male infertility and genital chlamydial infection: victim or perpetrator?

The role of Chlamydia trachomatis in the cause of male infertility is under discussion. This paper attempts to summarize data from the literature, which support the role of C. trachomatis in male infertility or oppose this suggestion. The following observations are based on a survey of the literature: 1) Chlamydia trachomatis is a frequent pathogen in male genital inflammation, the micro-organisms are rarely present in healthy men. 2) Without doubt, C. trachomatis causes inflammations of the male urethra and the epididymis. Prostatitis and glandulitis vesicalis are discussed controversially. 3) Chlamydia trachomatis antigen or DNA is not demonstrable in secretions of the male accessory glands including the semen with sufficient reproducibility. However, it is easily demonstrable in urethral swabs and the urine. 4) Determination of chlamydial antibodies in serum or semen does not conclusively indicate a current infection with C. trachomatis. 5) There are no conclusive studies showing that men infected with C. trachomatis are less fertile than uninfected men. 6) The male genital chlamydial infection is a threat to the female genital organs, because C. trachomatis infection of the female genital organs may be deleterious to female fertility.

Comparison of a polymer conjugate-enhanced enzyme immunoassay to ligase chain reaction for diagnosis of Chlamydia trachomatis in endocervical swabs

Two endocervical swabs from each of 1,123 women were collected into manufacturer-supplied transport tubes and tested for Chlamydia trachomatis by a polymer conjugate-enhanced (PCE) enzyme immunoassay (EIA) (IDEIA PCE Chlamydia; DAKO) and a ligase chain reaction assay (LCx Chlamydia; Abbott). After confirmation by the EIA blocking test, the sensitivity of the IDEIA PCE remained at 91.8% and the specificity increased from 98.2 to 99.8% compared to LCx.

TO STUDY INCIDENCE OF CHLAMYDIAL GENITAL TRACT INFECTIONS USING ENZYME IMMUNO ASSAY-ANTIGEN DETECTION AND CELL CULTURE METHODS

Endocervical swabs from 315 patients were screened for chlamydial infection by using Enzyme Immuno Assay technique for antigen detection. Of these, 190 patients were of infertility and 125 patients were with history suggestive of pelvic inflammatory disease (PID). 100 age matched controls were also screened for the detection of chlamydial antigen by using EIA. The overall incidence of chlamydial infection in this study group was 15.2%. 21 (11.05%) of the infertility patients and 27 (21.6%) of the pelvic inflammatory disease cases were found to be positive for chlamydial antigen. The prevalence rate was found to be high in the age group of 31-40 years in both study groups i.e. infertility group (14.7%) and PID group (50%). All the ELISA positive cases (48) and randomly selected (10) age matched controls were screened by tissue culture using McCoy cell line. In the tissue culture, 44 of the 48 samples were found to be positive and none of the controls groups were found positive. 4 samples showed discordant results possibly due to the presence of non-viable organism or inhibitory material present at the sample site. The sensitivity and specificity of ELISA with respect to tissue culture are 100% and 71% respectively. The positive predictive value and the negative predictive value of the ELISA are 91.6% and 100% respectively. The efficiency of the test was found to be 93.1%.

Confirmation of the Syva MicroTrak enzyme immunoassay for chlamydia trachomatis by Syva Direct Fluorescent Antibody Test

BACKGROUND AND OBJECTIVES

The Syva Micro Trak enzyme immunoassay (EIA) is used widely for screening women infected with Chlamydia trachomatis. Confirmatory tests used in conjunction with EIA screening have shown that false-positive results are common.

GOALS

To evaluate the specificity of the Syva MicroTrak EIA by confirmation of positive specimens with the Syva Direct Fluorescent Specimen Test.

STUDY DESIGN

Of 6,039 endocervical specimens collected from women attending Colorado family planning clinics, 328 positive EIA results (5.4%) were obtained by Syva MicroTrak EIA. A random subset of 136 positive specimens was tested by Syva Direct Specimen Test. Twenty of 136 specimens (14.7%) negative by Syva Direct Specimen testing were also tested by Syva blocking antibody tests (9 of 20 positive, 45%) and Roche Amplicor polymerase chain reaction (PCR; 6 of 20 positive, 30%). Of 20 specimens positive by Syva MicroTrak EIA and negative by Syva Direct Specimen Test, 11 (55%) were also negative by blocking antibody and PCR, including three specimens with initial EIA sample-to-cutoff ratios greater than 2.

CONCLUSIONS

Confirmatory testing of Syva MicroTrak EIA positive specimens with Syva Direct Specimen Test showed that 14.7% were false positive. Coupling the Syva Direct Specimen test with either blocking antibody or PCR reduces the rate of false-positive results to 8%.

Detection of Chlamydia trachomatis in genitourinary tract specimens using an automated enzyme-linked fluorescent immunoassay

BACKGROUND AND GOAL

The VIDAS Enzyme Linked Fluorescent Assay is a fully automated assay for the detection of Chlamydia trachomatis in clinical specimens. Because there is an increasing demand for automated assays for large volume laboratories and there is little performance data available, the authors evaluated the performance of the VIDAS enzyme linked fluorescent assay by comparing it with Chlamydiazyme and polymerase chain reaction.

STUDY DESIGN

Endocervical swabs from 330 women attending a hospital based obstetrics/gynecology clinic and 100 first void urine specimens from males attending a sexually transmitted disease clinic were tested by enzyme linked fluorescent assay, Chlamydiazyme, and polymerase chain reaction.

RESULTS

Fourteen of 330 endocervical specimens and 14 of 100 first void urine specimens were positive by Chlamydiazyme. Enzyme linked fluorescent assay detected 12 of 14 endocervical and 11 of 14 first void urine specimens. Compared with Chlamydiazyme, enzyme linked fluorescent assay had a sensitivity of 85.7% (12 of 14) for endocervical swabs and 76.9% (11 of 14) for first void urine specimens. Polymerase chain reaction detected an additional five endocervical and two first void urine specimens that had negative results by both enzyme linked fluorescent assay and Chlamydiazyme. All 7 were confirmed positive by polymerase chain reaction using a second primer set. Using an expanded gold standard of blocked Chlamydiazyme and confirmed polymerase chain reaction, enzyme linked fluorescent assay had a sensitivity of 63.2% (12 of 19) for endocervical swabs and 68.8% (11 of 16) for first void urine specimens compared with 73.7% (14 of 19) and 87.5% (14 of 16) for Chlamydiazyme. Polymerase chain reaction had a sensitivity of 100% (19 of 19) and 93.8% (15 of 16) for endocervical swabs and first void urine specimens, respectively. The specificity of enzyme linked fluorescent assay and Chlamydiazyme was 100%.

CONCLUSIONS

The VIDAS enzyme linked fluorescent assay for the detection of Chlamydia trachomatis in genitourinary specimens is highly specific but is not sufficiently sensitive for use as a routine diagnostic test.

Sensitivities of PCR, MicroTrak, ChlamydiaEIA, IDEIA, and PACE 2 for purified Chlamydia trachomatis elementary bodies in urine, peripheral blood, peripheral blood leukocytes, and synovial fluid

Routine microbiological diagnosis of Chlamydia-induced reactive arthritis is based mainly on the detection of Chlamydia trachomatis with urogenital swabs or in urine. Because chlamydial antigen, rRNA, and DNA are present in low quantities in the inflamed joint, highly sensitive assays are needed to detect C. trachomatis not only at the primary site of infection but also in peripheral blood and peripheral blood leukocytes, which are suspected carriers for dissemination, and in synovial fluid. To evaluate possible tools for this purpose, the sensitivities of PCR, MicroTrak, Chlamydia EIA, IDEIA, and PACE 2 for the detection of defined numbers of purified C. trachomatis elementary bodies (EB) in urine, peripheral blood, peripheral blood leukocytes, and synovial fluid were determined. In urine, PCR detected 2, MicroTrak and ChlamydiaEIA detected 2 x 10(3), and PACE 2 and IDEIA detected 2 x 10(4) EB per ml. In peripheral blood, only PCR and MicroTrak detected C. trachomatis, with detection limits of 100 and 2 x 10(7) EB per ml, respectively. For peripheral blood leukocytes, the detection limits were 2 EB per ml for PCR and 2 x 10(4) EB per ml for MicroTrak, ChlamydiaEIA, IDEIA, and PACE 2. In synovial fluid, PCR detected 200, MicroTrak and IDEIA detected 2 x 10(5), and PACE 2 detected 10(6) EB per ml. ChlamydiaEIA was unable to detect 2 x 10(6) EB per ml in synovial fluid. In summary, PCR was found to be the most sensitive method. The sensitivities of the other methods tested were at least 1,000 times lower than that of PCR. PCR should therefore be considered a most promising tool for routine diagnosis of Chlamydia-induced arthritis.

Comparison of plasmid- and chromosome-based polymerase chain reaction assays for detecting Chlamydia trachomatis nucleic acids

Several laboratories have demonstrated that the polymerase chain reaction (PCR) is more sensitive than culture or enzyme immunoassay (EIA) for detecting Chlamydia trachomatis in genitourinary tract specimens when various DNA targets are used for amplification, including the cryptic plasmid, major outer membrane protein (MOMP), or rRNA genes. We compared the performances of five different PCR assays, including assays with two plasmid, two MOMP, and one rRNA targets, by amplifying serial dilutions of C. trachomatis DNA and testing genitourinary tract specimens. By using published procedures, two different plasmid primers had sensitivities of 0.1 fg for C. trachomatis plasmid DNA and 10 fg for total cellular DNA. The sensitivities of the assays with the two MOMP primers were 0.1 and 10 pg, and the sensitivity for the assay with the rRNA primers was 1 pg for cellular DNA. Both plasmid-based assays detected 38 of 38 confirmed Chlamydiazyme-positive specimens, whereas the assays with the MOMP and rRNA primers detected 36 of 38 and 29 of 38 confirmed Chlamydiazyme-positive specimens, respectively. Six of 18 Chlamydiazyme-negative specimens collected from individuals whose specimens were positive by culture or immunofluorescence were positive by both plasmid-based PCRs; 4 of these were positive by PCR with the MOMP primers and 3 were positive by PCR with the rRNA primers. The results obtained with both purified DNA and genitourinary tract specimens indicated that the plasmid-based PCRs are more sensitive than bacterial chromosome-based PCRs for detecting C. trachomatis.

Noninvasive detection of Chlamydia trachomatis in men: a comparison of two immunoassay tests

This investigation compared a rapid enzyme immunoassay test and an enzyme-amplified immunoassay test with culture for the noninvasive detection of Chlamydia trachomatis urethritis in men. Urine specimens from 108 male subjects were evaluated for the presence of C trachomatis antigen, using the Kodak Surecell Chlamydia rapid enzyme immunoassay test and IDEIA Chlamydia enzyme-amplified immunoassay test. The test results were then compared with urethral C trachomatis culture and urethral Gram's stain analyses. Performance characteristics of the two tests were similar. The rapid chlamydial enzyme immunoassay test demonstrated several clinical advantages. Appropriate use of these tests may decrease patient morbidity and clarify organism etiology for enhanced specific medical care of urethritis in men.

Urine and the laboratory diagnosis of Chlamydia trachomatis in males

OBJECTIVE

To determine whether the use of urine samples from male patients can replace urethral swabs for the rapid detection of Chlamydia trachomatis by the Pharmacia EIA.

SETTING

The STD clinic, Adelaide, South Australia.

PATIENTS

There were two separate groups of male patients. Group A (398) patients provided urethral specimens for the EIA and culture tests. The patients in Group B (356) provided an urethral swab and a urine sample for the EIA test.

METHODS

The urine samples and urethral swabs were tested for the presence of C trachomatis by the Pharmacia Chlamydia EIA. In addition, the urethral swabs from Group A patients were cultured for the organism by standard cell cultures. The infected cell cultures were identified by an immunofluorescence test using a FITC-monoclonal antibody to C trachomatis (Kallestad).

RESULTS

When the EIA was validated against culture, it showed a sensitivity of 100% and a specificity of 95% with the urethral swabs from Group A patients. The urine specimens were positive in 24% of those patients who yielded a positive EIA result in the urethral swabs.

CONCLUSIONS

Although the EIA test on urethral swabs showed high sensitivity and specificity when validated against culture, our results showed that the use of urine samples cannot replace urethral swabs for the laboratory diagnosis of this sexually transmitted disease.

[Prevalence of cervical Chlamydia trachomatis infection in a female population seeking contraception counseling]

OBJECTIVES

To determine the prevalence and risk indicators of cervical infection due to Chlamydia trachomatis among female patients consulting for contraception and to evaluate an enzyme immunoassay for the detection of C. trachomatis in this setting.

DESIGN

Prevalence study. Endocervical specimens were analysed by means of culture and enzyme immunoassay. C. trachomatis infection was diagnosed through culture.

SETTING

A hospital family planning clinic in Trois-Rivières, Que.

SUBJECTS

All 533 female patients who consulted for contraception between November 1986 and March 1988. Results of culture were available for 495 patients.

MAIN OUTCOME MEASURE

Demographic, epidemiologic and clinical information was collected by means of a standard questionnaire and a gynecologic examination.

MAIN RESULTS

The prevalence rate of chlamydial infection was 9% (45/495). Enzyme immunoassay detected 37 (82%) of the infections. The mean age of the patients was 19.8 years, and 98% of the infections were diagnosed in those aged 25 years or less. The variables significantly associated with C. trachomatis infection were having more than one sexual partner in the preceding year (odds ratio [OR] 2.9; 95% confidence limits [CL] 1.7 and 5.0) and having more than one partner in the preceding 3 months (OR 2.3; 95% CL 1.2 and 4.3). These two indicators would have detected 58% and 22% of the infections respectively.

CONCLUSIONS

Screening for C. trachomatis infection by means of enzyme immunoassay should be proposed to all female patients aged 25 years or less consulting for contraception in our clinic. Such screening may prove to be an effective preventive measure in other similar clinical settings.

Evaluation of the polymerase chain reaction (PCR) for detection of Chlamydia psittaci in abortion material from ewes

The polymerase chain reaction (PCR) was evaluated as a diagnostic tool for detection of Chlamydia (C.) psittaci in abortion material from 40 ewes. For this purpose, PCR results of 87 samples were compared with direct microscopic identification after chemical staining, cell culture isolation and a commercially available enzyme-linked immunosorbent assay (ELISA). The value for sensitivity as compared to cell culture was 97.7% whereas the specificity-value was calculated to be 84.1%.

Chlamydia trachomatis confirmatory testing of PCR-positive genitourinary specimens using a second set of plasmid primers

A plasmid-based PCR for the detection of Chlamydia trachomatis was evaluated with a confirmatory PCR employing a second set of plasmid primers. A total of 258 genitourinary specimens including 134 female endocervical and urethral specimens and 124 male urethral specimens were tested by culture, blocked EIA and PCR. Fifty-four specimens were positive by culture, 50 were positive by EIA and 71 were positive by PCR. Fourteen specimens that were PCR-positive but culture- and EIA-negative were confirmed positive by the confirmatory PCR. Two of the 187 specimens which were negative by culture and EIA were positive by PCR but failed to confirm with the second set of primers. Using an expanded gold standard of culture, blocked EIA and confirmed PCR, the overall sensitivities for culture, blocked EIA and confirmed PCR were 76.0% (54/71), 70.4% (50/71) and 100% (71/71) and the specificities were 100% (187/187), 100% (187/187), respectively. These results demonstrated that a confirmatory PCR was useful for sorting out discordant specimens and establishing the true specificity of PCR. Furthermore, these results demonstrate that PCR is more sensitive than culture and EIA and suggest that a confirmed PCR test should be included in the gold standard for the evaluation of new tests for diagnosing Chlamydia trachomatis infections.

Confirmatory polymerase chain reaction testing for Chlamydia trachomatis in first-void urine from asymptomatic and symptomatic men

First-void urine specimens from 683 men (592 without symptoms) were tested for Chlamydia trachomatis by a polymerase chain reaction (PCR) with KL1 and KL2 plasmid primers and by a Chlamydiazyme enzyme immunoassay (EIA). Thirty-seven specimens were confirmed to be positive by using the EIA blocking reagent and a second set of plasmid primers (T1 and T2). By comparing unconfirmed PCR results (KL1 and KL2 primers only) with the blocked Chlamydiazyme EIA results, the sensitivity and specificity of PCR were 100% (37 of 37 specimens) and 99.5% (643 of 646 specimens), respectively. Three additional specimens were negative by EIA but positive by PCR and were confirmed to be positive with primers T1 and T2. Two of the three specimens were from men with symptoms. The confirmatory PCR assay performed equally well in detecting positive specimens from symptomatic (31 of 31) and asymptomatic (9 of 9) men. Comparison of confirmatory testing of first-void urine specimens by PCR and EIA showed that PCR was 100% sensitive (40 of 40 specimens) and that the EIA was 92.5% sensitive (37 of 40 specimens) but that the assays were equally specific (100%).

Chlamydia trachomatis antigen detection by Chlamydiazyme combined with Chlamydia Blocking Reagent verification

Several options exist for the detection of chlamydial infection in a routine laboratory setting. Enzyme immuno assay (EIA) technology offers rapid turn around of results and is less technically demanding than chlamydial cell culture. In addition, recently introduced EIA confirmatory reagents have the potential to improve the accuracy of EIA detection. We have evaluated one such confirmatory reagent (Chlamydia Blocking Reagent, Abbott Laboratories) to determine the accuracy of the Chlamydiazyme EIA with special regard to interpretation of low absorbance values. An initial series of 192 male urethral specimens showed that use of a lowered cut off level (absorbance value 0.05) compared with that recommended by the manufacturer increased sensitivity of the EIA from 0.73 to 0.83, thus motivating studies on this interpretative modification. Of 1101 EIA reactive specimens, 65% were determined to be chlamydia positive by the Chlamydia Blocking Reagent. The proportion of female cervical specimens that did not confirm positive was elevated compared with male urethral specimens, 43% vs. 5.7% respectively. In samples yielding absorbance from the recommended cut off level to 0.05 (approximately 50% below), the corresponding figures were 78% and 14% respectively. In 85 selected EIA reactive samples, examination by a direct immunofluorescence staining assay (DFA) (MicroTrak, Syva Inc.) revealed elementary bodies in 85% of 67 blocking test positive and in 24% of 18 blocking test negative samples. The possibility that Gram-negative bacteria were responsible for unconfirmed EIA reactive specimens was investigated using bacterial suspensions. While EIA reactivity was noted with several strains for Gram-negative bacteria, both the blocking reagent and DFA correctly verified the absence of chlamydial antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the Clearview Chlamydia test, Chlamydiazyme, and cell culture for detection of Chlamydia trachomatis in women with a low prevalence of infection

Two antigen detection systems, Clearview Chlamydia (Unipath Ltd., Bedford, United Kingdom) and Chlamydiazyme (Abbott Laboratories, North Chicago, Ill.), were compared with culture for the diagnosis of chlamydia infection in women attending gynecological clinics. Chlamydia trachomatis was isolated from 43 (4.5%) of the 965 women tested. In comparison with tissue culture, the Clearview Chlamydia and Chlamydiazyme tests had sensitivities of 79.0 and 74.4%, respectively, and both had a specificity of 99.6%. The results show that the Clearview Chlamydia test is comparable to Chlamydiazyme for the detection of C. trachomatis from endocervical specimens in a population with a low prevalence of infection.

Preliminary evaluation of "Clearview Chlamydia" for the rapid detection of chlamydial antigen in cervical secretions

Clearview Chlamydia (Unipath) is a rapid monoclonal antibody based latex immunodiffusion test for detecting chlamydial antigen in endocervical specimens. The assay does not require specialised equipment or extensive training and takes less than 30 minutes from sample to results. The clinical performance of Clearview Chlamydia was evaluated with 478 paired endocervical swabs from patients attending a genitourinary medicine clinic. In the first part of the study, 221 non-randomised specimens were tested by cell culture (1st swab) and Clearview (2nd swab) whereas in the second part of the study 257 randomised swabs were examined by Clearview, cell culture and immunofluorescence. The overall prevalence of chlamydial infection was 8.8% and the sensitivity, specificity, positive and negative predictive values for Clearview were 85.7%, 99.1%, 90% and 98.6%. The test requires further evaluation to establish its role in the management and control of chlamydial infection.

Comparison of the Kallested Pathfinder EIA, cytocentrifuged direct fluorescent antibody, and cell culture for the detection of Chlamydia trachomatis

A total of 203 duplicate endocervical samples collected from patients at an adolescent health care center were tested for the presence of Chlamydia trachomatis by cell culture, Pathfinder enzyme immunoassay (EIA) (Kallestad) and cytocentrifuged direct fluorescent antibody (DFA). Compared to cell culture, the Pathfinder assay demonstrated a sensitivity and specificity of 85.2% and 100%, whereas the DFA procedure demonstrated to be 92.6% sensitive and 99.4% specific.

Comparison of two enzyme immunoassays to culture for the diagnosis of chlamydial conjunctivitis and respiratory infections in infants

Data are limited for the performance of enzyme immunoassays for the detection of Chlamydia trachomatis in conjunctival and nasopharyngeal specimens from infants. The only available data are for one assay, Chlamydiazyme (Abbott Diagnostics). The purpose of this study was to compare a new enzyme immunoassay, Pathfinder (Kallestad Diagnostics), with Chlamydiazyme and culture for the diagnosis of chlamydial conjunctivitis and pneumonia in infants. Pathfinder differs from Chlamydiazyme in that it uses a monoclonal antibody directed against the chlamydial lipopolysaccharide in addition to a polyclonal antichlamydial antibody. Triplicate conjunctival and nasopharyngeal specimens were obtained from 97 infants with conjunctivitis, and additional nasopharyngeal specimens were obtained from 14 infants with suspected chlamydial pneumonia (total, 111 nasopharyngeal specimens). Twenty-nine (30%) of the conjunctival specimens from infants with conjunctivitis and four (28.6%) of the nasopharyngeal specimens from the infants with pneumonia were positive for C. trachomatis by cell culture. The sensitivities, specificities, and positive and negative predictive values for Pathfinder for conjunctival specimens were 96.6, 98.5, 96.6, and 98.5%, respectively. The results for Chlamydiazyme were 96.6, 100, 100, and 98.6%, respectively. For nasopharyngeal specimens, the results for Pathfinder were 77.8, 94.6, 73.7, and 95.7%, respectively. The results for Chlamydiazyme were 66.7, 95.7, 75, and 93%, respectively. Pathfinder and Chlamydiazyme appeared to perform equivalently for the detection of C. trachomatis in both eye and nasopharyngeal specimens from infants with chlamydial conjunctivitis and pneumonia.

Effect of endocervical specimen quality on detection of Chlamydia trachomatis and on the incidence of false-positive results with the Chlamydiazyme method

Duplicate endocervical swabs were collected from 1,675 patients to assess the effects of variations in specimen quality on Chlamydiazyme (Abbott Laboratories) detection of Chlamydia trachomatis and the incidence of false-positive results. One swab (at random) from each patient was tested for C. trachomatis antigen by using the standard Chlamydiazyme procedure. A 200-microliter volume of 0.9% saline was added to the other swab from each patient. After vortexing, 20 microliters was smeared on a slide for Papanicolaou (Pap) staining and the remaining specimen was then tested with the Chlamydiazyme assay. The Chlamydiazyme result was positive for 170 (10.1%) and 165 (9.8%) of the stained and unstained duplicate specimens, respectively (no significant difference). Pap stains on smears from 1,536 (91.7%) of the patients were analyzed, and endocervical and/or metaplastic (E-M) cells were detected in 789 (51.4%) smears. Of these 1,536 stained and analyzed specimens, 150 (9.8%) were Chlamydiazyme positive but only 132 (88.0%) of the positive results were confirmed by repeating the test and using a monoclonal blocking antibody (Abbott). Confirmed Chlamydiazyme-positive results were obtained from only 34 (4.6%) of 747 specimens lacking E-M cells but from 98 (12.4%) of 789 specimens containing the cells (P less than 0.001). Of the 150 initially Chlamydiazyme-positive results obtained with Pap-stained, analyzed specimens, 12 (26.1%) of 46 were falsely positive from specimens lacking E-M cells but only 6 (5.8%) of 104 were falsely positive from specimens containing E-M cells (P less than 0.01). C. trachomatis antigen was detected significantly more frequently and false-positive results were significantly less common from specimens in which E-M cells were detected.

Comparison of IDEIA III and cell culture for the detection of Chlamydia trachomatis in endocervical specimens

A total of 803 endocervical samples were obtained from females with clinical or epidemiological histories suggesting chlamydia infection. These specimens were tested by IDEIA III and cell culture for the presence of Chlamydia trachomatis. After resolution of discrepant results by direct fluorescent-antibody staining of pelleted cell culture transport materials, IDEIA III demonstrated sensitivity, specificity, and positive and negative predictive values of 93.8, 99, 92.9, and 99.1%, respectively.