Detection of Chlamydia trachomatis: comparison of agar-gel precipitin test and enzyme immunoassay

The agar-gel precipitation test (AGPT) was compared with Enzyme Immunoassay (EIA) for the detection of Chlamydia trachomatis, 164 women being screened for chlamydial antibodies and antigens in their sera and in endocervical specimens, respectively. The AGPT showed good correlation with EIA in the 164 paired sera and endocervical specimens, resulting in 27 (16.5%) and 22 (13.4%) positive results, respectively (P greater than 0.05). The overall sensitivity of the AGPT compared to EIA was 86.4% (19 of 22), and the specificity was 94.4% (134 of 142).     

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.     

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.     

Evaluation of two ELISA's for detecting Chlamydia trachomatis from endocervical swabs.

Two enzyme immunoassays (EIAs) detecting Chlamydia trachomatis from endocervical swabs, Syva MicroTrak (MT) and Abbott Chlamydiazyme (CZ), were compared with a tissue culture (TC) standard. Initially, 8% (100 of 1250) of specimens were TC positive, yielding sensitivities of 94% (94 of 100) for MT and 79% (79 of 100) for CZ with identical 98% specificities (1129 of 1150 for MT and 1130 of 1150 for CZ). Discrepant specimens were retested by both EIAs and assayed for elementary bodies (EBs) by a fluorescent antibody test. After discrepancy analysis, 9.5% (118) of 1240 patients were either TC or EB positive, yielding sensitivities of 94.1% for MT (111 of 118) and 79.7% for CZ (94 of 118) with identical specificities of 100% (1122 of 1122). These results indicate that the MT is significantly more sensitive (p less than 0.05, McNemar test) than CZ in detecting C. trachomatis from endocervical swabs.     

Use of the polymerase chain reaction for the detection of Chlamydia trachomatis from endocervical and urine specimens in an asymptomatic low-prevalence population of women

The Amplicor Chlamydia trachomatis test is a polymerase chain reaction (PCR)-based methodology used for the detection of a cryptic plasmid found in C. trachomatis. It was evaluated in comparison with cell culture and the Microtrak II Chlamydia enzyme immunoassay (EIA) for the detection of C. trachomatis in urogenital specimens from women. Endocervical swabs were collected from 993 women attending the women's unit at the Mount Sinai Hospital in Toronto. In addition, concomitant first void urine specimens were collected from 394 of these women for PCR testing only. As compared with culture of the endocervical specimens, PCR and EIA had a sensitivity, specificity, positive predictive value and negative predictive value of 84.6%, 99.2%, 57.9%, and 99.8% and 61.5%, 99.7%, 72.7%, and 99.5%, respectively. As compared with the secondary gold standard of a positive culture and/or a positive PCR using a primer to the major outer membrane protein the sensitivity, specificity, positive, and negative predictive values for culture were 72.2%, 100%, 100%, and 99.5%, respectively. For the Amplicor PCR and EIA the results were 88.9%, 99.7%, 84.2%, and 99.9% and 61.1%, 99.9%, 91.7%, and 99.6%, respectively. When the urine PCR was compared with the same standard, the test had a sensitivity of 91.7% and a specificity of 99.5%. Based on this study the Amplicor C. trachomatis test was found to be sensitive and specific for the detection of C. trachomatis in both endocervical and urine specimens.     

Diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae. Genitourinary infections in males by the Amplicor PCR assay of urine

The Amplicor CT/NG polymerase chain reaction (PCR) test on urine specimens from males was prospectively evaluated against established specimens and laboratory methods for diagnosing Chlamydia trachomatis and Neisseria gonorrhoeae genitourinary infections, in patients from a remote region of Western Australia. Seventy-three males who were tested for both C. trachomatis and N. gonorrhoeae by both conventional methodology and Amplicor PCR on urine were enrolled in the study. Established testing comprised enzyme immunoassay/immunofluorescence antigen testing (EIA/IF) for C. trachomatis and microscopy and/or culture for N. gonorrhoeae on urethral swabs. Positive test results were confirmed using a set of criteria that included supplemental PCR testing and clinical history. Overall, 13.7% of patients were resolved as positive for C. trachomatis and 52.1% as positive for N. gonorrhoeae. The sensitivity and specificity of the Amplicor CT/NG PCR on male urine specimens for C. trachomatis were 80.0% (8/10) and 95.2% (60/63), compared with 60.0% (6/10) and 100.0% (63/63) for EIA/IF on urethral swabs. For N. gonorrhoeae, the sensitivity and specificity of the Amplicor CT/NG PCR on male urine specimens were both 100% (38/38 and 35/35, respectively) compared with 86.8% (33/38) and 100% (35/35) for microscopy and/or culture on urethral swabs. The results of this study indicate that the Amplicor CT/NG multiplex PCR test for C. trachomatis and N. gonorrhoeae performed on urine in males provides a highly sensitive, specific, and robust method for the diagnosis of both C. trachomatis and N. gonorrhoeae, for the early detection of both symptomatic and asymptomatic infected individuals.     

Enzyme-linked immunoabsorbent assays in the detection of Chlamydia trachomatis: how valid are they?

Two enzyme-linked immunoabsorbent assays (Chlamydiazyme, Abbott Laboratories, North Chicago, IL, and IDEIA, Boots-CellTech Diagnostics Inc., East Hanover, NJ) specific for the detection of Chlamydia trachomatis antigen were used to assess 451 cervical specimens. All specimens obtained from the subjects were also simultaneously cultured for Chlamydia. Both assays identified 90.9% (20/22) of the culture positive cases. Chlamydiazyme identified two and IDEIA three additional specimens as positive. Of these additional positive tests, one of two Chlamydiazyme and three of three IDEIA specimens were confirmed as positive by the direct fluorescent antibody technique (MicroTrak, Syva Co., Palo Alto, CA). Given the inexpense, availability, ease of performance, high sensitivity (91%), and specificity (99%) of these tests, both should become valuable tools to objectively assess women at risk for this common sexually transmitted disease.     

Evaluation of a DNA probe of plasmid origin for the detection of Chlamydia trachomatis in cultures and clinical specimens

This study evaluates five cryptic plasmid-derived DNA probes in a 4-h slot-blot hybridization assay for the detection of Chlamydia trachomatis in cultures and clinical specimens. The probes, consisting of either the entire cloned 7.5 kbp cryptic plasmid pSE8 or one of four Hin dIII/Eco RI fragments measuring 710, 1055, 710, and 500 bp, respectively, were labelled with Photoprobe biotin. The probe was detected using a streptavidin-alkaline phosphatase conjugate followed by addition of BCIP and NBT. The sensitivity of the assay, using 25 ng of probe DNA, ranged from 50 pg (with the entire plasmid as probe) to 5 ng (with the 500 bp fragment as probe). A total of 103 reference strains of Chlamydia trachomatis and other bacteria were tested for reactivity with the probes. All 18 reference strains of C. trachomatis hybridized with the probes. None of the DNA from the heterologous organisms tested was found to hybridize with any of the probes. A total of 174 samples taken from patients visiting the STD clinic at the University Hospital, University of Seville were used in the study. The overall sensitivity of the assay, using the 710 bp biotinylated probe was 94.5% compared to culture while the specificity was 97.5%. Positive and negative predictive values were 96.5% and 97.5%, respectively. It appears that the plasmid-derived probes used in this study could serve as useful tools for the rapid and specific detection of Chlamydia trachomatis in cell cultures and clinical specimens.     

An algorithm to detect Chlamydia trachomatis by polymerase chain reaction on specimens extracted for enzyme immunoassay

Amplification assays for detecting Chlamydia trachomatis have been shown to be more sensitive than enzyme immunoassay (EIA) by many investigators. In this study, we have developed an algorithm for performing PCR (COBAS AMPLICOR™) on selected specimens extracted for EIA (ACCESS®) with sample-to-cutoff (s/co) values between 0.25 and 0.99. Furthermore, we have shown that these specimens can be utilized for PCR without encountering any inhibition problems. In our investigation, 230 out of 6,558 urethral and cervical swabs submitted for C. trachomatis screening by EIA over a period of 9 months, had s/co values ranging between of 0.25 and 0.99. Ninety (39.1%) of these specimens tested positive by PCR. These specimens were stable and gave reproducible PCR results before and after storage for a period of 9 months. This testing algorithm offers an effective way of detecting C. trachomatis with selective use of PCR while increasing the sensitivity of the EIA screening system.     

Evaluation of the Cellmatics and direct monoclonal fluorescence antibody staining for detection of genital chlamydial infections

Three methods for Chlamydia trachomatis detection were compared: the Cellmatics (Difco Laboratories, Detroit, MI), a commercially available tissue culture system which contains a rat cell line; a direct fluorescent Chlamydia antibody (DFA) (Microtrak, Syva Corp., Palo Alto, California) stain; and a standard tissue culture isolation method employing McCoy cells. Of the 121 specimens in the study, 20 were positive by the standard cell culture. All 20 of these specimens were also positive by the Cellmatics but only 10 were positive by DFA.     

Rapid determination of MICs of 15 antichlamydial agents by using an enzyme immunoassay (Chlamydiazyme).

An enzyme immunoassay (EIA), Chlamydiazyme (Abbott Laboratories), was evaluated for its determination of MICs of 15 antimicrobial agents against Chlamydia trachomatis (MRC-1, LB, TRIC/GB/MRC-1 Gf [ATCC VR-1]). The inoculum size, incubation time, and enhancers were defined for the assessment of chlamydial antigen synthesis in HeLa 229 cells seeded as monolayers in 96-well plates. MICs were determined and defined as the lowest antibiotic concentrations required to inhibit, after 24 or 48 h of incubation, antigen production as determined by the EIA. The MICs (after 48 h) were similar to those determined by the peroxidase-antiperoxidase staining of inclusions. MIC determinations after 24 h were suitable for screening the activities of quinolones, but less so for measuring the susceptibility of C. trachomatis to macrolides and tetracyclines. MIC determination by EIA was rapid, appropriate for standardization, and less cumbersome than determination by quantification of inclusions.     

不育男性生殖道沙眼衣原体感染对精子核DNA碎片化指数的影响

目的探讨不育男性生殖道沙眼衣原体感染对精子核DNA碎片化指数的影响。方法选择2017年1月至2017年5月在成都市锦江区妇幼保健院生殖医学中心(成都西囡妇科医院)门诊初诊的117例生殖道沙眼衣原体感染的不育男性(感染组)和92例体检正常的男性(对照组),对两组的精液常规参数及精子核DNA完整性(以精子核DNA碎片化指数DFI表示)检测结果进行回顾性分析。结果⑴感染组的精子浓度低于对照组,但差异无统计学意义(P>0.50);感染组的前向运动精子百分比低于对照组,但差异无统计学意义(P>0.20);⑵与对照组相比,感染组的精子DFI值显著升高,差异有统计学意义(P<0.05)。结论生殖道感染沙眼衣原体的男性不育患者的精子核DNA损伤程度明显高于未感染者。精子核DNA碎片化指数可能是评估男性精液质量的独立指标。     

Performance of microtrak direct test for Chlamydia trachomatis in a prevalence study

Three hundred thirty-two women, aged 18-30 yr. attending two clinics in Burlington Vermont were screened for infection with Chlamydia trachomatis by two methods. Microtrak Direct Test (SYVA) and cell culture. The overall sensitivity for Microtrak compared with culture was 75% (18 of 24), the specificity was 99.7% (307 of 308), the positive predictive value was 94.7% (18 of 19), and the negative predictive value was 98.1% (307 of 313). Prevalence of Chlamydia trachomatis in this population was estimated to be 7.2% (95% confidence intervals 4.4-10.0). The results from this study suggest that Microtrak is less sensitive when used in unselected patient groups from populations of lower prevalence, in contrast to higher sensitivities previously reported.     

Pneumonia due to Chlamydia trachomatis in Japanese infants

Sera from 109 Japanese infants with pneumonia were tested for antibody to Chlamydia trachomatis (C. trachomatis) L2 strain by an indirect immunofluorescence (IF) technique. Nasopharyngeal swabs were also collected to isolate C. trachomatis. Clinical specimens were inoculated onto cycloheximide-treated McCoy cells and DEAE-dextran-treated HeLa 229 cells. Of 109 patients, 32 (29%) were positive for IgM antibodies (titer, greater than or equal to 1:16) to C. trachomatis. C. trachomatis was isolated from 21 (66%) of 32 IgM antibody-positive infants as compared with 5 (7%) of 77 IgM antibody-negative infants. Detectable levels of IgM antibody were common in infants during the first four months of life. Clinical characteristics of pneumonia of these IgM antibody-positive patients were also described. This is the first report of serology and clinical characteristics of C. trachomatis pneumonitis from Asian countries including Japan.     

Critical issues relating standards for technology to patient safety

The Committee members are: Jerry M. Calkins, PhD MD (Chairman), Dept Anesthesiology, University of Arizona, Maricopa Medical Center, Phoenix, AZ; David W. Arnett, PhD, Puritan Bennett Corporation, Carlsbad, CA; Peter Carstensen, Food and Drug Administration, Rockville, MD; Joseph A. Condurso, North American Drager, Telford, PA; Patrick A. Foster, FFA, Hershey Medical Center, Hershey, PA; Alex Gerwer, San Diego, CA; Michael Good, MD, University of Florida, Gainesville, FL; Ervin Moss, MD, NJSSA, Verona, NJ; Allen K. Ream, MD, PE (Secretary), Stanford University, Woodside, CA; Terry E. Spraker, PhD, Ohmeda, Madison, WI. Address correspondence to Dr Calkins, Department of Anesthesiology, Maricopa Medical Center, 2601 East Roosevelt, PO Box 5099, Phoenix, AZ 85010.     

Validation of the Roche COBAS Amplicor system for Chlamydia trachomatis.

OBJECTIVE: Validation of the Roche Amplicor polymerase chain reaction (PCR) using the Comprehensive Bio-Analytical System (COBAS) automated PCR analyzer in our laboratory. DESIGN: Endocervical swab specimens for both EIA and PCR were collected from a total of 193 women. EIA for chlamydia was performed using the MicroTrak Chlamydia Kit (Wampole Labs, Cranbury, NJ). PCR was performed using Roche Amplicor reagents on the COBAS instrument. SETTING: Louisiana State University Health Sciences Center at Shreveport, Shreveport LA. PATIENTS: All cervical swab specimens, (n = 193), collected from patients presenting either to the Women's Health or Primary Care Clinic (Obstetrics and Gynecology and Family Practice) were included in this study. RESULTS: Most of the specimens, 138/193 or 71.5%, tested negative by both techniques. Three of the 193 specimens, 1.5%, were inhibitory for PCR since the internal control was negative. Fifty-one specimens, 26.4%, tested positive by both techniques or by PCR alone. No specimens were positive by EIA only. Twenty-eight of the 51 were positive by both methods, (14.5% of the total tested; 54.9% agreement among the specimens testing positive). An additional 23 were positive by PCR alone, i.e., 11.9% total discrepant positive specimens; 45% discordant results among the specimens testing positive). Seventeen PCR-positive specimens divided among four separate runs were retested by PCR. Of these, 15 were repeat positive, giving the test a reproducibility of 88.2%. CONCLUSIONS: Our results concur with previously published comparison data for EIA and PCR testing. We conclude that the PCR should detect a significantly increased number of chlamydia infections among our LSUHSC-S population, but there are drawbacks to using this technique. Specimen preparation time for PCR is almost twice as long as EIA, and the Roche PCR assay is not licensed for ocular specimens as is our EIA procedure. In addition, since neither technique is accepted for testing for medicolegal purposes, we must continue the use of culture for cases of suspected sexual abuse.     

Anti chlamydia antibodies in patients with thoracic and abdominal aortic aneurysms

BACKGROUND: Chlamydia species are suspected of being involved in the pathogenesis and progression of aortic aneurysms. We investigated serum levels of Chlamydia antibodies in patients with thoracic aortic aneurysms (TAA) and abdominal aortic aneurysms (AAA) compared to levels in healthy individuals. METHODS: We included 35 consecutive patients with TAA, 42 patients with AAA and 42 age- and sex-matched healthy controls in a case control study. Serum antibodies (IgM and IgG) against Chlamydia lipopolysaccharide (LPS), Chlamydia pneumoniae and Chlamydia trachomatis were measured by recombinant ELISA and quantified by measurement of optical density. RESULTS: Patients with TAA exhibited median immunoglobulin levels against Chlamydia LPS (IgM 0.090, IgG 0.266), C. pneumoniae (IgM 0.023, IgG 0.264) and C. trachomatis (IgG 0.247) comparable to those of healthy subjects [Chlamydia LPS IgM 0.209 (p = 0.1), IgG 0.301 (p = 0.2); C. pneumoniae IgM 0.051 (p = 0.07), IgG 0.516 (p = 0.1); C. trachomatis IgG 0.153 (p = 0.2)]. Patients with AAA had higher serum levels of IgG against Chlamydia LPS (0.560) compared to healthy individuals [0.301 (p = 0.04)], but no significant elevation of antibodies against C. pneumoniae [IgM 0.029 (p = 0.1), IgG 0.545 (p = 0.9)] and C. trachomatis [IgG 0.219 (p = 0.3)]. CONCLUSION: Thoracic aortic aneurysms were not associated with signs of Chlamydia infection or immunopathogenicity. In contrast, patients with abdominal aortic aneurysms exhibited elevated levels of immunoglobulin against Chlamydia LPS, reflecting an unspecific Chlamydia immunopathogenicity. However, elevated levels of antibodies against distinct Chlamydia species were also not found in AAA patients.     

Correlation of the percent of positive Chlamydia trachomatis direct fluorescent antibody detection tests with the adequacy of specimen collection

Chlamydia trachomatis is an obligate, intracellular parasite infecting the columnar and transitional cells lining the endocervix, uterus, fallopian tubes, rectum, urethra, and epididymis. We determined if the percent of specimens positive for C. trachomatis in the Microtrak Direct Specimen Test depended on the quality of specimens obtained. Female genital slides (649) were evaluated by the direct fluorescent antibody (DFA) test for the presence and numbers of (a) C. trachomatis elementary bodies and (b) columnar, transitional and squamous epithelial cells, and polymorphonuclear neutrophils (PMNs). Only 138 (21.3%) of the 649 slides were considered to be adequately taken, that is, containing columnar/transitional cells either alone or in conjunction with squamous cells and/or PMNs. Of the 138 adequate slides, 10 (7.2%) were C. trachomatis positive. However, 511 (78.7%) of the 649 slides were judged inadequate; 395 contained only squamous cells and/or PMNs, 19 were too thick to determine cell types, 46 contained only cell debris, and 51 contained neither cells nor debris. Only four (0.78%) of 511 were C. trachomatis positive. Thus adequate specimens containing columnar/transitional cells for C. trachomatis detection had a tenfold increase in the percent of positive results compared to inadequately collected specimens. By using the DFA test, one has the advantage of determining the adequacy of the specimens obtained as well as the presence of chlamydiae.     

Chlamydia trachomatis in patients with genital contact infections in Austria--studies of 3,367 patients

In order to evaluate the epidemiological importance of Chlamydia trachomatis (C. trachomatis) as a genital microorganism, data were obtained from 3,367 patients with sexually transmitted diseases in Vienna and analyzed by computer-assisted methods. C. trachomatis was cultured in 26.1% of 2,594 patients investigated for the first time. The microorganism was found more often in male patients (31.3%) than in female patients (21%). 32.2% of positive Chlamydia cultures were obtained from patients with non-gonococcal urethritis (NGU) and 64% from postgonococcal urethritis (PGU) patients. A high coincidence with Neisseria gonorrhoeae (N. gonorrhoeae) was detected in males (31.2%) and females (43.5%). Data on Mycoplasma hominis (M. hominis), and Ureaplasma urealyticum (U. urealyticum) show that, in contrast to the low incidence of M. hominis and U. urealyticum in males, the organisms were found predominantly in females.