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Vaginal Swabs Are the Specimens of Choice When Screening for Chlamydia trachomatis and Neisseria gonorrhoeae: Results From a Multicenter Evaluation of the APTIMA Assays for Both Infections

Schachter, Julius PhD*; Chernesky, Max A. PhD; Willis, Dean E.; Fine, Paul M. MD§; Martin, David H. MD; Fuller, Deanna; Jordan, Jeanne A.**; Janda, William††; Hook, Edward W. III MD‡‡

doi: 10.1097/01.olq.0000190092.59482.96

Background: Vaginal swabs were recently U.S. Food and Drug Administration-cleared for detecting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) using Gen-Probe Incorporated’s APTIMA COMBO2 Assay (AC2). We assessed the APTIMA CT Assay (ACT) for CT, APTIMA GC Assay (AGC) for GC, and AC2 for both organisms using patient- and clinician-collected vaginal swabs.

Method: Women attending family planning, obstetrics and gynecology, or sexually transmitted disease (STD) clinics had first-catch urines (FCUs), patient-collected vaginal swabs, clinician-collected vaginal swabs, and endocervical swabs tested by ACT, AGC, and AC2. A second endocervical swab and FCU were tested using BD ProbeTec (Becton Dickinson) for CT and GC. We calculated sensitivity and specificity using vaginal swabs to detect CT and GC.

Results: Of 1464 subjects enrolled, 180 had CT and 78 GC. ACT sensitivities and specificities for patient-collected vaginal swabs were 98.3% and 96.5%, respectively; for clinician-collected vaginal swabs, 97.2% and 95.2%, respectively. AGC sensitivities and specificities for patient-collected vaginal swabs were 96.1% and 99.3%, respectively; for clinician-collected vaginal swabs, 96.2% and 99.3%, respectively. AC2 results were similar. If an FCU tested positive for CT or GC, >94% of matching vaginal swabs were positive. Positive endocervical swabs showed slightly less concordance (>90% and >88%, respectively). More infected patients were identified using vaginal swabs than FCUs. With AC2, 171 CT-infected patients were identified using FCUs and 196 using patient-collected vaginal swabs. This difference was more pronounced for CT than for GC.

Conclusions: Vaginal swab specimens allowed sensitive and specific detection of CT and GC in the APTIMA assays. Vaginal swabs identified as many infected patients as endocervical swabs and more than FCUs, and may well be the specimen of choice for screening.

When screening for Chlamydia trachomatis, vaginal swabs seem to be the specimens of choice. Vaginal swabs detect more infections than can be detected through the use of first-catch urine and as many as are found using cervical swabs.

From the *University of California, San Francisco, California; †St. Joseph’s Healthcare, Hamilton, Ontario, Canada; ‡Florida State Department of Health, Jacksonville, Florida; §Planned Parenthood of Houston and Southeast Texas, Houston, Texas; ∥Louisiana State University Medical Center, New Orleans, Louisiana; ¶Wishard Memorial Hospital, Indianapolis, Indiana; **McGee Women’s Research Institute, Pittsburgh, Pennsylvania; the ††University of Illinois, Chicago, Illinois; and the ‡‡University of Alabama, Birmingham, Alabama

The authors thank Jeannine R. Lane and Songbai Wang (Gen-Probe, Inc.) for their assistance in the data analysis.

Preliminary reports based on parts of this study were presented at the International Society for Sexually Transmitted Diseases Research Congress (July 27–30, 2003, Ottawa, Ontario, Canada), International Society for Infectious Diseases (March 4–7, 2004, Cancun, Mexico), 2004 National STD Prevention Conference (March 8–11, 2004, Philadelphia, Pennsylvania), the 104th General Meeting of the American Society for Microbiology (May 23–27, 2004, New Orleans, Louisiana), the 5th Meeting of the European Society for Chlamydial Research (September 1–4, 2004, Budapest, Hungary), and at the 42nd Annual Meeting of the Infectious Diseases Society of America (September 30–October 3, 2004, Boston, Massachusetts).

The authors acknowledge the funding of Gen-Probe Inc. for this study. The study sponsor had no role in the conduct of the study, the interpretation of the data, or in approval of the manuscript. They provided kits and reagents at no cost to each of the study sites and assisted in the collection and analysis of the data.

Dr. Schachter wrote the manuscript, had full access to all of the data in the study, and takes responsibility for the integrity of the data and the accuracy of the data analysis. Each author is responsible for the results obtained at a participating clinic site and participated in the critical revision of this manuscript.

Correspondence: Julius Schachter, PhD, Chlamydia Research Laboratory, Department of Laboratory Medicine, University of California, San Francisco, 1001 Potrero Avenue, SFGH 3416, San Francisco, CA 94110.

Received for publication January 25, 2005, and accepted April 22, 2005.

© Copyright 2005 American Sexually Transmitted Diseases Association