The increased sensitivities of nucleic acid amplification tests such as ligase chain reaction (LCR) have the potential to simplify specimen collection for gonorrhea diagnosis. In this study patients took their own vaginal swab specimens for gonorrhea culture and LCR testing. Immediately following specimen collection by patients, a trained clinician obtained endocervical swab specimens for the same tests. By using LCR to diagnose gonorrhea, 54 (17.5%) of 309 patients had positive tests. Forty-five patients with positive cervical LCR tests also had positive vaginal LCR tests; for one patient, only a cervical LCR specimen was positive, and for eight patients, only vaginal specimens were positive. For specimens from patients whose gonorrhea cultures were positive, all vaginal swab specimens were positive by LCR and 42 (91%) of 46 cervical swab specimens were positive by LCR. LCR-positive specimens from eight patients with negative cultures (four with positive vaginal specimens only, one with a positive cervical specimen only, and three with positive vaginal and cervical specimens) were further evaluated with unrelated probe sets for gonococcal pilin B. Following resolution of the discrepancies between culture-negative and LCR-positive specimens, a diagnosis of gonorrhea could be confirmed for 52 of 54 patients with positive LCR tests. LCR testing with vaginal swabs was 100% sensitive and 99.6% specific and had a positive predictive value of 98.1% and a negative predictive value of 100%. In this study LCR testing of vaginal swab specimens obtained by patients themselves was significantly more sensitive for gonorrhea diagnosis of women than cervical LCR or culture (100% versus 84.6% for cervical LCR or culture; Mantel-Haenszel chi-square test result, 8.58; P ؍ 0.003).
Chlamydia trachomatis infections are the most prevalent sexually transmitted diseases (STDs) in the United States. In acute-care settings such as clinics and emergency rooms, a desirable chlamydia screening assay should exhibit good sensitivity and good specificity and should provide test results while the patient is still present. The Biostar Chlamydia OIA (Biostar, Inc., Boulder, Colo.) is an optical immunoassay (OIA) that provides test results in less than 30 min and that uses a test format that allows office-based testing. This assay is performed entirely at room temperature without the need for rotators or other specialized equipment. The goal of this study was to compare the performance of the Biostar Chlamydia OIA for the detection of C. trachomatis with the performance of cell culture, direct fluorescent-antibody (DFA) assay (Syva MicroTrak; Syva Co., Palo Alto, Calif.), and PCR (Roche Amplicor Chlamydia trachomatis; Roche, Branchburg, N.J.) for the detection ofC. trachomatis infections in women attending an urban STD clinic. For calculations of relative test performance (sensitivity, specificity, and positive and negative predictive values), patient specimens that yielded positive results by two or more of the four assays (cell culture, DFA assay, PCR, and OIA) were classified as “true infections.” By these criteria, 42 of 306 total specimens were classified as positive for C. trachomatis (positive prevalence, 13.7%), 11 (3.6%; 10 by PCR and 1 by DFA assay) were positive by a single assay, and 253 (82.7%) were negative by all four tests. All culture-positive specimens were also positive by at least one other assay. Among the culture-negative specimens, 14 (5%) specimens were positive by two of the three non-culture-based assays used. By using the criterion that positivity by at least two of the tests indicated a true infection, the relative sensitivities were as follows: culture and PCR, 92.9% each; Biostar Chlamydia OIA, 73.8%; and DFA assay, 59.5%.
volume of 50 mL of semen could be chosen for the diagnostic of these bacteria with Aptima assays. In ESwab medium, the LODs of CT, NG and MG were equivalent (between 1 and 10 IFU, CFU or CCU/mL) whatever the volume of ESwab added in the APTIMA Ò specimen transfer tubes. A volume of 200 ml of ESwab allowed performing several different Aptima assays and the LOD of bacteria remained low whatever the storage conditions. Conclusion Aptima Combo 2 for CT/NG and Aptima Mycoplasma genitalium assays can be used to detect these three sexually transmitted pathogens in semen and in clinical specimens preserved in ESwab medium. Disclosure No significant relationships.
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