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PubMed1997

Reproducibility problems with the AMPLICOR PCR Chlamydia trachomatis test.

In an attempt to use an expanded "gold standard" in an evaluation of an antigen detection test for Chlamydia trachomatis, the AMPLICOR (Roche Diagnostics Systems, Inc., Branchburg, N.J.) PCR Chlamydia trachomatis test and culture were used with 591 sets of cervical specimens. Of the 591 specimens assayed, 35 were retested due to either an equivocal result by the PCR (19 samples) or a discrepancy between the results of culture, PCR, and the antigen detection method. During the repeat testing of the samples with equivocal and discrepant results, all but one interpretation change was due to the PCR result. In addition, upon repeat testing the PCR assay value measured in optical density units varied widely for 13 of these specimens. These 13 specimens were then tested in triplicate by the manufacturer with primers to the chlamydia plasmid and in duplicate with primers to the major outer membrane protein. Only 3 of the 13 specimens gave the same interpretation with these five replicates. In summary, reproducibility problems with the AMPLICOR test should be considered before it is incorporated as part of routine testing or used as an expanded gold standard for chlamydia testing.

Cervix Uteri↗

PubMed1997

Serological cross-reactions between Bartonella and Chlamydia species: implications for diagnosis.

Diagnosis of Chlamydia or Bartonella infections continues to rely mainly on serology. However, serological cross-reactions between members of these genera have recently been described. Sera from eight patients originally diagnosed as having Chlamydia pneumoniae endocarditis reacted with both Chlamydia sp. and Bartonella quintana antigens (microimmunofluorescence technique). Adsorption of sera with B. quintana or C. pneumoniae antigens removed anti-C. pneumoniae antibodies, whereas adsorption with C. pneumoniae antigens did not change antibody titers to B. quintana. Western blot analysis confirmed the presence of cross-reacting antigens and showed antibody patterns in all sera to be compatible with a Bartonella infection. These patients were therefore probably suffering from Bartonella-induced rather than Chlamydia-induced endocarditis. In contrast, sera from 10 patients presumed to be suffering from C. pneumoniae pneumonia did not display anti-B. quintana antibodies, although cross-reacting antigens were revealed by Western blotting. This work highlights the possibility that cases of infective Bartonella endocarditis are erroneously diagnosed as chlamydial infections.

Adsorption↗

PubMed1999

Impact of reference standard sensitivity on accuracy of rapid antigen detection assays and a leukocyte esterase dipstick for diagnosis of Chlamydia trachomatis infection in first-void urine specimens from men.

A total of 128 previously frozen first-void urine (FVU) specimens from selected asymptomatic men were centrifuged and tested by three Chlamydia trachomatis rapid antigen detection tests and with a leukocyte esterase (LE) dipstick. When the results were compared to those of a reference standard of positivity determined by the Chlamydiazyme enzyme immunoassay as confirmed by a blocking assay, the sensitivities of the Testpack Chlamydia (Abbott), Clearview Chlamydia (Unipath), and Surecell Chlamydia (Kodak) tests and the LE dipstick test were 76.4, 76.4, 67.3, and 88.6%, respectively. Use of the ligase chain reaction (LCR), whose results were confirmed by direct fluorescent-antibody staining of elementary bodies, as the reference standard reduced the sensitivities to 70.9, 67.7, 62.9, and 87.5%, respectively. The specificities by use of LCR as the reference standard were 95.5, 95.5, 100, and 92.4%, respectively. These rapid chlamydial antigen tests performed reasonably well with FVU specimens, but the simple LE dipstick test, which had the highest sensitivity, would have enabled treatment of the greatest number of infected male patients.

Antigens, Bacterial↗

PubMed2001

Multicenter evaluation of the BDProbeTec ET System for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens, female endocervical swabs, and male urethral swabs.

The performance of the Becton Dickinson BDProbe Tec ET System Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays (BD Biosciences, Sparks, Md.) was evaluated in a multicenter study. Specimens were collected from 2,109 men and women, with or without symptoms, attending sexually transmitted disease, family planning, and obstetrics and gynecology clinics. Both swab and urine samples were collected, and the results obtained from 4,131 specimens were compared to those from culture and the LCx nucleic acid amplification test (Abbott Industries, Abbott Park, Ill.). PCR and cytospin of the culture transport medium with chlamydia direct fluorescent antibody staining were used to adjudicate chlamydia culture-negative results. Sensitivity and specificity were calculated both with and without use of the amplification control (AC), with little apparent difference in the results. Without the AC result, sensitivity for C. trachomatis and N. gonorrhoeae were 92.8 and 96.6%, respectively, for cervical swabs and 80.5 and 84.9% for urine from women. C. trachomatis and N. gonorrhoeae sensitivities were 92.5 and 98.5%, respectively, for male urethral swabs and 93.1 and 97.9% for urine from men. This amplified DNA system for simultaneous detection of chlamydial and gonococcal infections demonstrated superior sensitivity compared to chlamydia culture and has performance characteristics comparable to those of other commercially available nucleic acid-based assays for these organisms.

Cervix Uteri↗

PubMed2003

Quantitative detection of Chlamydia psittaci and C. pecorum by high-sensitivity real-time PCR reveals high prevalence of vaginal infection in cattle.

Bovine vaginal cytobrush specimens were analyzed for the presence of Chlamydia spp. by a high-sensitivity, high-specificity quantitative PCR. The 53% prevalence of low-level Chlamydia psittaci and C. pecorum genital infection detected in virgin heifers suggests predominantely extragenital transmission of Chlamydia in cattle and conforms to the high seroprevalence of anti-Chlamydia antibodies.

Animals↗

PubMed1994

Persistent chlamydiae: from cell culture to a paradigm for chlamydial pathogenesis.

Chlamydiae are medically important bacteria responsible for a wide range of human infections and diseases. Repeated episodes of infection promote chronic inflammation associated with detrimental immune system-mediated pathologic changes. However, the true nature of chlamydial pathogenesis may encompass repeated infection superimposed upon persistent infection, which would allow for heightened immune reactivity. During the course of chlamydial infection, numerous host elaborated factors with inhibitory or modifying effects may cause alterations in the chlamydia-host cell relationship such that the organism is maintained in a nonproductive stage of growth. Abnormal or persistent chlamydiae have been recognized under a variety of cell culture systems. The numerous factors associated with altered growth suggest an innate flexibility in the developmental cycle of chlamydiae. This review evaluates in vitro studies of chlamydial persistence and correlates these model systems to features of natural chlamydial disease.

Anti-Bacterial Agents↗

PubMed2001

Optimised sample DNA preparation for detection of Chlamydia trachomatis in synovial tissue by polymerase chain reaction and ligase chain reaction.

OBJECTIVE: Molecular biology techniques such as polymerase chain reaction (PCR) and ligase chain reaction (LCR) are routinely used in research for detection of C trachomatis DNA in synovial samples, and these methods are now in use in some clinical laboratories. This study aimed at determining the method best suited to molecular diagnosis of C trachomatis by examining four standard DNA preparation methods using chlamydia spiked synovial tissue and chlamydia infected monocytes. METHODS: Synovial tissue from a chlamydia negative patient with rheumatoid arthritis was spiked with defined numbers of C trachomatis elementary bodies (EB). Purified human peripheral monocytes from normal donors were infected with the organism at a multiplicity of infection 1:1 in vitro and harvested after four days. DNA was prepared from all samples by four methods: (1) QIAmp tissue kit; (2) homogenisation in 65 degrees C phenol; (3) incubation at 97 degrees C; (4) proteinase K digestion at 97 degrees C. DNA from methods 1 and 2 was subjected to PCR using two different primer sets, each targeting the C trachomatis omp1 gene. LCR was done on DNA prepared by each method. RESULTS: In synovial tissue samples spiked with EB, and in monocytes persistently infected with the organism, preparation of template using the QIAmp tissue kit (method 1) and the hot phenol extraction technique (method 2) allowed sensitive detection of C trachomatis DNA. These methods also produced template from both sample types for LCR. DNA prepared by heat denaturation (method 3) allowed only low sensitivity chlamydia detection in LCR and did not work at all for PCR. Proteinase K digestion plus heat denaturation (method 4) gave template that did not allow amplification in either PCR or LCR assays. CONCLUSIONS: The sensitivity of detection for C trachomatis DNA in synovial tissue by PCR and LCR depends strongly on the method used for preparation of the amplification template. LCR targeting the multicopy chlamydial plasmid and two nested PCR assay systems targeting the single copy omp1 gene showed roughly equivalent sensitivity. Importantly, template preparation method and the specific PCR primer system used for screening must be optimised in relation to one another for highest sensitivity.

Chlamydia Infections↗

PubMed1997

Lowering the cut off value of an automated chlamydia enzyme immunoassay and confirmation by PCR and direct immunofluorescent antibody test.

AIMS: To increase the sensitivity of an automated chlamydia enzyme immunoassay by significantly lowering its cut off value, and to maintain specificity by confirmation with polymerase chain reaction (PCR) and direct immunofluorescent antibody test (DFA). METHODS: Over five months, the cut off value of the enzyme immunoassay used to screen urogenital samples for chlamydia antigen was reduced from 80 to 10. Samples with a test value of 10 or above were further tested with a commercial PCR assay. All samples during the first three months and discrepant samples during the last two months of the study were also tested with the DFA. RESULTS: 3250 urogenital swabs (1246 urethral, 1335 endocervical, 669 pooled urethral/endocervical) from 1246 males and 2004 females were processed. Using the manufacturer's recommended cut off of 80, the enzyme immunoassay identified chlamydia antigen in 134 samples (4.1%). Using the lower cut off value of 10 and either PCR or DFA as the confirmatory test, Chlamydia trachomatis was identified in 178 samples (5.5%). Thus, 45 additional positive samples were identified and the confirmed detection rate was increased by 33.8% (45/133). Excluding equivocal PCR results, the concordance between DFA and PCR was 91.8%. This strategy increased the detection rate by 2.1% in men and 0.9% in women (significant only in men). In female patients, pooled urethral/endocervical swabs as a specimen gave a significantly higher yield than endocervical swabs regardless of whether the lower cut off strategy was used. CONCLUSIONS: This strategy of significantly lowering the cut off test value with confirmation on the same specimen by either PCR or DFA is feasible and cost effective. The use of pooled urethral/ endocervical specimens in females should be considered routinely as detection rate was significantly improved.

Chlamydia Infections↗

PubMed1977

Isolation of Chlamydia trachomatis from the male urethra.

Chlamydia trachomatis was isolated from 26% of urethral swabs taken from 509 men with urethritis. The highest yield of 68% was obtained from a selected group of men with nonspecific urethritis (NSU) who had a frank urethral discharge. This is a higher than in previous reports, and is significantly higher than the isolation of C. trachomatis from men with less severe urethritis. The higher yield was similar to C. trachomatis isolation rates reported among patients with severe trachoma in hyperendemic areas. Men with a previous history of NSU had low isolation rates. Overall, 30% of 385 men with NSU had positive chlamydial culture results, 7% of 59 men with gonococcal urethritis alone were Chlamydia-positive, 15% of 59 men with gonorrhoea followed by NSU (post-gonococcal urethritis) were Chlamydia-positive, and only 3% of 61 men without urethritis harboured Chlamydia. Swabs taken from the cervical os of 28 of 108 female contacts of men with NSU had a positive result for C. trachomatis. Significantly more pairs of sexual partners had the same chlamydial culture result than had different results. The chlamydial isolation rate was higher among men admitting a casual sexual contact than in men claiming only regular partnerships. The findings provide further evidence for the sexual transmission of C. trachomatis and for its aetiological role in NSU.

Chlamydia Infections↗

PubMed1981

Chlamydia trachomatis in women attending a gynaecological outpatient clinic with lower genital tract infection.

In a study of 3794 consecutive women attending a gynaecological outpatient clinic with symptoms of lower genital tract infection (LGTI) 350 (9.2%) harboured Chlamydia trachomatis and 83 (2.2%) Neisseria gonorrhoeae. One hundred and ninety-five patients who were later found to have acute salpingitis and 109 other women in whom the chlamydial cultures were spoiled were excluded from the series. Of the remaining 3490 women, 281 were infected with C trachomatis, 42 with N gonorrhoeae, and 17 with both. Of the 3150 women who were infected with neither organism, 146 were randomly selected as controls. The chlamydia-positive patients were younger (P less than 0.001), did not complain of pelvic discomfort or pain (P less than 0.01), and used oral contraceptives (P less than 0.001) more frequently than did the controls; intrauterine devices were used more often (P less than 0.01) by the controls. Increased vaginal discharge was reported significantly more often in chlamydia-positive patients than in the controls (P less than 0.05). Of 266 women harbouring C trachomatis the organism was still present in 22 (8.3%) when they were followed up from two to more than eight weeks after finishing treatment with doxycycline. Of 91 male consorts of chlamydia-positive women, 53 (58.2%) were infected with C trachomatis.

Adult↗

PubMed1981

Post-gonococcal cervicitis and post-gonococcal urethritis. A study of their epidemiological correlation and the role of Chlamydia trachomatis in their aetiology.

In a study of 157 men and 141 women with gonorrhoea post-gonococcal urethritis (PGU) in men was significantly more common among chlamydia-positive (76%) than among chlamydia-negative (22.5%) patients. Clinical investigations of PGU detected 95% of the patients infected with C trachomatis. PGU was, however, asymptomatic in over half of the patients and a careful follow-up for 3-6 weeks was necessary to detect between 80% and over 90% of cases. PGU was not related to age, past history of gonorrhoea or non-gonococcal urethritis, severity of gonococcal infection, or chlamydial inclusion count. Although post-gonococcal cervicitis (PGC) in women was an identifiable entity, it was detected in only one-third of chlamydia-positive patients. PGC was significantly associated with the 20-29 year-old age group but was not related to symptoms or chlamydial inclusion count. In the absence of facilities for culturing chlamydia, selection on an epidemiological basis of all female consorts of men with PGU, together with the remaining women with PGC, would have resulted in some unnecessary treatments and left untreated up to 30% of those harbouring C trachomatis.

Adolescent↗

PubMed1990

Use of the Cytobrush for concurrent endocervical cytology and chlamydia sampling.

In 899 women attending a genitourinary medicine clinic Chlamydia trachomatis was tested for using both a Cytobrush and a conventional swab. In 425 cases, the Cytobrush was used for concurrent cytology and chlamydia sampling. Both methods were equally effective in the detection of chlamydia, and, in addition, the Cytobrush gave a higher yield of inclusion bodies per sample. The use of the same instrument for both cytology and chlamydia screening may represent a saving in time and money.

Chlamydia Infections↗

PubMed1999

Pathogenesis of Chlamydia induced pelvic inflammatory disease.

Further research is necessary to elucidate the pathogenesis of chlamydial PID. It is hoped that these endeavours will eventually lead to a vaccine to prevent not only chlamydia infection, but also chlamydia associated infertility, ectopic pregnancy, and chronic pelvic pain. In the meantime we need to develop strategies to prevent primary and secondary chlamydia infection and its sequelae. Recently, Scholes et. al demonstrated that a population based approach to identify and test women at high risk for cervical C trachomatis infection effectively reduced risk of PID. Hopefully, through the use of public health measures, we can see similar decreases of chlamydia associated genital tract disease worldwide.

Antibodies↗

PubMed1999

Impact of menstrual cycle on the diagnostic performance of LCR, TMA, and PCE for detection of Chlamydia trachomatis in home obtained and mailed vaginal flush and urine samples.

OBJECTIVES: To assess the impact of the menstrual cycle on the diagnostic performance of various assays for detection of Chlamydia trachomatis in home obtained and mailed vaginal flush and urine specimens. METHODS: A ligase chain reaction assay (LCR; Abbott Laboratories), a transcription mediated amplification assay (TMA; Gen-Probe), and an enzyme amplified immunoassay (PCE; Dako Diagnostics) were evaluated for their validity in detecting C trachomatis in vaginal flush, first void urine, and midstream urine specimens obtained by female high school students at home and mailed directly to the diagnostic laboratory. RESULTS: C trachomatis was detected in 45 of 889 females (5.1%). The vaginal flush material was positive by TMA and LCR in 84% and 82% of the chlamydia positive females, respectively. First void urine was positive by TMA in 73% and by LCR in 49% of the cases. Midstream urine was positive by TMA and LCR in 69% and 42% of the females, respectively. On a pool of first void and midstream urine, PCE detected 49% of the chlamydia positive females. The overall prevalence of C trachomatis increased with increasing time after the last menstrual bleeding. In urine samples, but not vaginal flush specimens, obtained 3 weeks after the last menstrual bleeding, the sensitivities of TMA, LCR, and PCE decreased markedly suggesting that inhibitors to the assays are excreted in the urine but not in vaginal secretions at this time. CONCLUSION: Vaginal flush samples are superior to urines for detection of chlamydia infections in females. In screening of young asymptomatic females, samples should be obtained in the latter part of the menstrual cycle.

Adolescent↗

PubMed1999

Knowledge of Chlamydia trachomatis genital infection and its consequences in people attending a genitourinary medicine clinic.

OBJECTIVES: To assess knowledge of Chlamydia trachomatis infections, with a comparison of knowledge of Neisseria gonorrhoeae infections. METHODS: A cross sectional survey, by self completed questionnaire, of 200 subjects attending a genitourinary outpatient clinic. RESULTS: The response rate was 82% (90 male and 73 female). 51% of men (60% of females) had heard of chlamydia. 65 (82%) were unaware of the potential consequences of infection. 66% were unaware that the disease could be asymptomatic. Significantly more men (77%) than women (60%) had heard of gonorrhoea. Most participants (68%-82%) knew little of the possible consequences of this infection, and only 26% were aware that it could be asymptomatic. Knowledge was higher regarding fertility topics. There was no correlation between knowledge and either age or socioeconomic status. However, greater knowledge was displayed by those who read health information leaflets always or often. For both men and women, the preferred source of health information was the doctor. Other popular sources were health information leaflets, women's magazines, and television. CONCLUSIONS: Barely half the participants had heard of chlamydia and gonorrhoea. Further knowledge of either infection was very poor. There are serious implications for public health. The reasons for this are unclear and require exploration before targeted health promotion. Doctors and the popular media are acceptable, and potentially effective, sources of information. Acquisition of knowledge is important, both to reduce sexual risk taking behaviour and its consequences, and to allow for informed consent for chlamydia screening programmes.

Adolescent↗

PubMed1978

Chlamydiae, rickettsiae, and their cell wall defective variants.

Inapparent chlamydial and rickettsial infections are an important source of the dissemination of the parasites and may cause explosive outbreaks of severe diseases in man and animal. However, it is engimatic how these obligate intracellular microbes induce latency and why or how inapparent infections convert into active disease. Currently, microbiologists believe that chlamydiae and rickettsiae are gram-negative bacteria unique in their intracellular habitat. This review presents evidence that these organisms have another peculiarity; namely, defective cell walls present throughout much of their life cycle. In this survey, the properties of the small and large forms of chlamydiae and rickettsiae are reexamined with regard to the current knowledge of cell wall defective variants of free-living bacteria. Data are presented in support of the concept that chlamydiae and rickettsiae are cell wall defective microbes whose small 'bacterial' forms have lost the ability to reproduce as bacteria during evolution; the large forms including ultrafilterable phases of the life cycle of these parasites are responsible for inapparent infections of healthy carriers, whereas conversion into small 'bacterial forms may cause, under appropriate conditions manifest diseases. This concept may provide challenging and profitable directions in the search to explain puzzling phenomena associated with chlamydiae and rickettsiae.

Biological Evolution↗

PubMed2000

[Screening of Chlamydia trachomatis: is the diagnostic efficacy good enough?].

OBJECTIVE: In the background of discrepant results of C. trachomatis testing in women with suspected genital infections, three different tests have been compared. METHOD: 594 endocervical swabs were collected from women visiting the family planning clinic in Aarau. Each of the following tests was evaluated: Cobas Amplicor Chlamydia trachomatis, IF Chlamyset, and Chlamydia IF direct. If one of these three tests was positive, the fixed material on the slides was scraped off, and a PCR was performed. RESULTS: 15 out of 594 samples were "true'-positive. PCR recognized 14 of them, the IF Chlamyset 13, and the Chlamydia IF 8. With the IF Chlamyset 37 samples were false-positive. CONCLUSIONS: PCR testing exhibits a good sensitivity and a high specificity, but we think that the sensitivity can be increased by improving the sample preparation step. The Chlamydia IF direct has a good specificity, but a rather low sensitivity. It should be noted that the PCR has the potential to become a new gold standard for the detection of C. trachomatis.

Chlamydia Infections↗

PubMed1993

Tear anti-Chlamydia antibodies in males with chlamydial urethritis.

Conjunctival Chlamydia trachomatis was studied in 50 males with chlamydial urethritis. Conjunctival samples from 49 patients were negative for chlamydial antigen by enzyme immunoassay. However, tear anti-Chlamydia IgA antibodies were found in high titers (> or = 400) in 20 out of the 50 patients. Secretory IgA against Chlamydia in corresponding titers was found in 8 patients. The titers differed significantly from those of the 22 negative control subjects. IgG antibodies were not detected. Tear anti-Chlamydia IgA antibodies are not diagnostic for chlamydial conjunctivitis, but occur concomitantly in patients with chlamydial urethritis.

Adolescent↗