TThe Syva MicroTrak Chlamydia enzyme immunoassay (EIA; Syva Company, San Jose, Calif.) with cytospin and direct fluorescent-antibody assay (DFA) confirmation was evaluated on 43,630 urogenital specimens over a 1-year period in the Provincial Laboratory in Regina, Saskatchewan, Canada. This was a two-phase study intended to define a testing algorithm for Chlamydia trachomatis that would be both highly accurate and cost-effective in our high-volume (> 3,000 tests per month) laboratory. The prevalence of C. trachomatis infection in our population is moderate (8 to 9%). In phase 1, we tested 6,022 male and female urogenital specimens by EIA. All specimens with optical densities above the cutoff value and those within 30% below the cutoff value were retested by DFA. This was 648 specimens (10.8% of the total). A total of 100% (211 of 211) of the specimens with optical densities equal to or greater than 1.00 absorbance unit (AU) above the cutoff value, 98.2% (175 of 178) of the specimens with optical densities of between 0.500 and 0.999 AU above the cutoff value, and 83% (167 of 201) of the specimens with optical densities within 0.499 AU above the cutoff value were confirmed to be positive. A total of 12% (7 of 58) of the specimens with optical densities within 30% below the cutoff value were positive by DFA. In phase 2, we tested 37,608 specimens (32,495 from females; 5,113 from males) by EIA. Only those specimens with optical densities of between 0.499 AU above and 30% below the cutoff value required confirmation on the basis of data from phase 1 of the study. This was 4.5% of all specimens tested. This decrease in the proportion of specimens requiring confirmation provides a significant cost savings to the laboratory. The testing algorithm gives us a 1-day turnaround time to the final confirmed test results. The MicroTrak EIA performed very well in both phases of the study, with a sensitivity, specificity, positive predictive value, and negative predictive value of 96.1, 99.1, 90.3, and 99.7%, respectively, in phase 2. We suggest that for laboratories that use EIA for Chlamydia testing, a study such as this one will identify an appropriate optical density range for confirmatory testing for samples from that particular population.
Among 830 women attending a clinic for sexually transmitted disease, Chlamydia trachomatis was isolated from 180 (22%) and Neisseria gonorrhoeae from 84 (10%). Retrospective analysis showed that 43 of the women were given outpatient treatment for acute pelvic inflammatory disease because they had low abdominal pain, deep dyspareunia, or unusual vaginal bleeding, or all of these, for less than 2 months in association with cervical motion or adnexal tenderness, or both. None had adnexal masses. C. trachomatis was isolated from 22 and N. gonorrhoeae from 15 of this subgroup of 43 women. This presentation of pelvic inflammatory disease occurred in 10 of the 37 women in the whole study with both C. trachomatis and N. gonorrhoeae, 12 of 143 women with C. trachomatis alone, five of 47 women with N. gonorrhoeae alone, and 16 of 603 women with neither organism. Thus, in North America, C. trachomatis is associated with a syndrome usually diagnosed as mild pelvic inflammatory disease and managed on an outpatient basis.
Purified chlamydial bodies were solubilized by detergent solutions used in the following sequence: 1) 1% sarcosil, 2) 1% sarcosil + 10 mM dithiotreitol, 3) 2% sodium dodecyl sulfate + 10 mM dithiotreitol. After the third stage a good yield of protein, corresponding to major outer membrane protein as to its molecular weight and antigenic properties was obtained.
New cases of gonorrhoea (Neisseria gonorrhoeae) and chlamydia (Chlamydia trachomatis) infections have been steadily increasing in Scandinavian countries over the last decade. There is a particular urgency in reducing new infections as isolation of multiple drug resistant strains of gonorrhoea is becoming more frequent. The aim of this study was to determine the prevalence and sites of infection of common sexually transmissible infections (STIs) in men who have sex with men (MSM).
We have performed a retrospective analysis of the three major STIs, gonorrhoea, chlamydia and Mycoplasma genitalium in urogenital, anorectal and oropharyngeal samples from MSM that attended two STI clinics in Oslo.
One hundred and thirty-six men (6.0%) out of 2289 MSM tested were found to be positive for gonorrhoea using a porA gene targeted nucleic acid amplification test (NAAT). Of these, 106 (77.9%) would not have been identified through testing first-void urine alone. Two hundred and twenty eight (10.0%) patients from 2289 tested were found to be positive for chlamydia, 164 (71.9%) of which were identified through anorectal specimens. Ninety-one (5.1%) patients from 1778 tested were found to be positive for M. genitalium, with 65 (71.4%) identified through testing of anorectal specimens.
Our results supports the European findings that the MSM population carries a high burden of STIs and that testing the anorectum and oropharynx will identify a significantly higher percentage of infected patients and reservoirs of STIs.
OBJECTIVE--To assess the cost-effectiveness of identifying asymptomatic carriers of Chlamydia trachomatis among adolescent males. DESIGN--Cost-effectiveness analysis based on cohort analytic studies previously reported and average salaries and costs of medical care in Sweden. SETTING--Adolescent males attending a primary care center for routine health checks. PARTICIPANTS--Estimates of costs and benefits are based on a cohort of 1000 adolescent males and their female contacts. INTERVENTION--Screening with enzyme immunoassay (EIA), either on leukocyte esterase (LE)--positive urine samples (LE-EIA screening) or on all urine samples (EIA screening), was compared with no screening (no treatment or contact tracing). The effects of confirming positive EIA results with a blocking assay and alternative antibiotic regimens on the outcome of the screening strategies were also evaluated. RESULTS--Compared with no screening, the LE-EIA and EIA screening strategies reduced the overall costs when the prevalence of chlamydial infection in males exceeded 2% and 10%, respectively. Enzyme immunoassay screening achieved an overall cure rate that was 12.2% to 12.6% (95% confidence interval) better, but reduced the incremental savings by at least $2144 per cured male, in comparison with LE-EIA screening. Confirmation of positive EIA results reduced the overall cost of the LE-EIA screening strategy when the prevalence of C trachomatis among males was less than 8%. Compared with a 7-day course of doxycycline, a single oral dose of azithromycin administered under supervision in the clinic improved the cure rates of both EIA and LE-EIA screening strategies by 15.1% to 16.3% and 11.2% to 12.0%, respectively, while reducing the corresponding overall costs by 5% and 9%, respectively, regardless of the prevalence of chlamydial infection in males. CONCLUSION--The use of LE-EIA screening combined with treatment of positive cases with azithromycin was the most cost-effective intervention strategy focusing on asymptomatic male carriers of C trachomatis. Positive EIA results should be confirmed when screening low-risk populations.
Comment In: JAMA. 1993 Nov 3;270(17):2097-88411579
Sexually Transmitted Diseases (STD) are a major health problem all over the world. The diseases are often spread by unsuspecting asymptomatic individuals. One important means of controlling STD is thus the identification of asymptomatic persons. The purposes of this thesis were a) to describe methods of identifying infected individuals through contact tracing and screening, b) to evaluate contact tracing routines, c) to compare epidemiological characteristics of two different groups of chlamydia-infected women and their partners and d) to see if data from contact tracing could be used in a model describing partner choice and STD spread. A microepidemic of penicillinase-producing gonococci was effectively controlled through contact tracing by cooperating counsellors. Serotyping of gonococci and graphic description proved of great help in mapping the contact chain. Contact tracing integrated in the psychosocial long-term care of HIV-infected patients resulted in identification of a great number of previously unidentified individuals. Screening for Chlamydia trachomatis (Ct) among asymptomatic patients of family planning clinics revealed a 7.3% Ct prevalence. Four factors were significantly correlated to the risk of being infected: age 18-23, duration of present relationship less than 1 year, failure to use condoms and no previous history of genital infection. Abstention from testing was especially high in areas with low socio-economic status. In these areas, increased resources for health care are needed. Five different levels of management of Ct infections were compared. Increased measures to verify that reported partners were examined decreased reinfections and after Ct was included in the STD Act more reported partners than before came for examination. Index patients found by chlamydia screening and their partners have a lower average number of recent partners than index patients visiting an STD clinic and their partners. Partners of female patients in the STD clinic group were also more often Ct-positive. The differences between the groups are small and do not justify different ambitions in partner management. Choice of steady partner was rather restricted and choice of casual partner followed a more random pattern. Our data thus do not support a pure random mixing model for STD spread.
BACKGROUND: Sexually transmitted infections are leading causes of morbidity for Canadian Aboriginal women. To date, very few initiatives have been successful in screening, treating, and limiting these infections among these populations. OBJECTIVES: To evaluate the efficacy of universal screening, treatment and contact tracing as a means of capturing a more accurate count of chlamydia and gonorrhea prevalence and limiting transmission among Inuit communities. METHODS: 181 participants were screened for chlamydia and gonorrhea and interviewed in a cross-sectional survey (Aug-Sept/03). Information was collected on demographics, use of health services, sexual histories and STI knowledge among others. A random sample (n = 100) from the cross-sectional group was selected for the longitudinal cohort. Individuals were followed every two months post baseline for four visits (Oct/03-May/04). At each visit, participants were screened for chlamydia/gonorrhea. All positive cases and their partners were treated and contact tracing completed. Logistic Regression analysis and the McNemar Test of Correlated Proportions were used to analyze the data. RESULTS: Overall, 35 cases of chlamydia were detected, with 21 detected at baseline and 14 during follow-up. The baseline prevalence was 11.6% in comparison with 2.7% that was previously estimated. No gonorrhea was detected. The strongest factor associated with a positive chlamydia was having recent STI (OR 9.82, CI: 2.70, 35.77). CONCLUSIONS: Consistent with the literature, the results support the use of universal screening followed by prompt treatment and contact tracing in populations with greater than 10% chlamydia prevalence.