Sexually Transmitted Diseases - Current Issue
Chlamydia Test Results Were Associated With Sexual Risk Behavior Change Among Participants of the Chlamydia Screening Implementation in the Netherlands
Sunday, March 01, 2015 1:00 AM
imageObjective: To examine the effect of a laboratory-confirmed Chlamydia trachomatis (Ct) test result on subsequent sexual risk behavior in a large population-based screening program. Methods: The study population consisted of 16- to 29-year-old participants of the Chlamydia Screening Implementation who completed Ct testing and questionnaires in 2 or more rounds. The influence of a Ct test result on sexual behavior was analyzed by generalized estimating equation models, in which the Ct test result of the previous round was the independent variable and 1 of the 8 sexual risk behavior indicators was the dependent variable, adjusted for covariates. Results: Of 48,910 Chlamydia Screening Implementation participants with completed questionnaires and test results, 14.1% (n = 6802) and 2.6% (n = 1272) completed 2 and 3 rounds, respectively, and were included in this study. Analysis showed that Ct positives less often reported to “never” use condoms with a casual partner (%change pretest/posttest = −5.7% [−10.3 to −0.9]), whereas Ct negatives less often reported to “always” use condoms with a casual partner (−4.6% [−6.4 to −2.8]; odds ratio [95% confidence interval], 1.75 [1.09 to 2.80]). Ct positives also had more sexual partners in the subsequent round than did participants with a Ct-negative test result (relative risk [95% confidence interval], 1.14 [1.01 to 1.29]). Conclusions: Ct test results were associated with subsequent sexual risk behavior. In general, Ct positives were more likely to change their behavior after a Ct test result in a more positive and protective direction than Ct negatives, who were more likely to change their behavior toward more risky behavior. Effects over time after a Ct test should be investigated further, especially in the Ct negatives.
Association of the In Vitro Susceptibility of Clinical Isolates of Chlamydia trachomatis With Serovar and Duration of Antibiotic Exposure
Sunday, March 01, 2015 1:00 AM
imageBackground: The presence of persistent Chlamydia trachomatis infection after treatment does not always correlate with in vitro susceptibility testing. Methods: The in vitro minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of azithromycin, clarithromycin, roxithromycin, doxycycline, tetracycline, ofloxacin, and penicillin were tested against 61 clinical isolates of C. trachomatis on 6 serovars, and the MIC/MBC of azithromycin and ofloxacin at different points in time after antibiotic administration to infected cultures. Results: Of the 7 antibiotics tested, clarithromycin showed the greatest activity against C. trachomatis isolates with MIC90 of 0.032 μg/mL and MBC90 of 0.064 μg/mL, followed by doxycycline with MIC90 0.064 μg/mL and MBC90 0.064 μg/mL, and azithromycin with MIC90 0.160 μg/mL and MBC90 0.320 μg/mL. Azithromycin had roughly the same MIC50 values (0.08 μg/mL) as the other serovars isolates tested, and other antibiotics showed a 2- to 4-fold difference in MICs50 between serovars. In addition, an increase in the azithromyin MIC was observed by 8 hours and the ofloxacin MIC by 16 hours. At 24 hours, the azithromycin MICs were greater than 40 μg/mL and ofloxacin MICs were greater than 64 μg/mL. Conclusions: The current data demonstrated that the antimicrobial susceptibility of C. trachomatis was influenced by both the serovar type and the duration of exposure to antibiotics in infected cultures.
Confirmation of High Specificity of an Automated Enzyme Immunoassay Test for Serological Diagnosis of Syphilis: Retrospective Evaluation Versus Results After Implementation
Sunday, March 01, 2015 1:00 AM
imageBackground: The optimal algorithm for serological syphilis screening is still a matter of debate. We have previously evaluated the performance of the Bioelisa Syphilis 3.0, using a selection of archived sera, and in this study compare these results with the Bioelisa results after clinical implementation. Methods: All Bioelisa Syphilis 3.0 results obtained since clinical implementation were analyzed. Bioelisa-positive or borderline samples were retested using Treponema pallidum particle agglutination, rapid plasma reagin test, fluorescent treponemal antibody-absorption test, and/or immunoblot. On sera sent in together with cerebrospinal fluid, occasionally both the T. pallidum particle agglutination and Bioelisa were performed. Results: The Bioelisa was performed on 14,622 sera. Bioelisa-positive samples, which were not retested by the previously described assays, were withdrawn from the database (n = 36). In 1.3% of the samples (187/14,586), the Bioelisa was positive or borderline and, ultimately, 115 sera were considered true positive (prevalence 0.8%). The specificity of the Bioelisa was 99.5%. Conclusions: Based on the results of all performed diagnostic assays, the specificity of the Bioelisa of 99.5% is very consistent with that found in the initial study (100%; 95% confidence interval was 98.0%–100%). Interpreting (positive) test results is difficult in the absence of a gold standard, especially when the disease prevalence is low. Results should be viewed in the light of the patients’ characteristics.
