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.
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.


METHODS
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 1,464 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.
Schachter
Julius
J
Chlamydia Research Laboratory, Department of Laboratory Medicine, University of California, San Francisco, 1001 Potrero Avenue, SFGH 3416, CA 94110, USA.
Chernesky
Max A
MA
Willis
Dean E
DE
Fine
Paul M
PM
Martin
David H
DH
Fuller
Deanna
D
Jordan
Jeanne A
JA
Janda
William
W
Hook
Edward W
EW
D000328:Adult; D002584:Cervix Uteri / Q000382:microbiology; D002690:Chlamydia Infections / Q000175:diagnosis / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D006069:Gonorrhea / Q000175:diagnosis / Q000382:microbiology; D006801:Humans; D008403:Mass Screening; D009344:Neisseria gonorrhoeae / Q000235:genetics / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012648:Self Care; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D014556:Urine / Q000382:microbiology; D014621:Vagina / Q000382:microbiology*
D011933:Reagent Kits, Diagnostic