title: Comparison of three assays for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in SurePath Pap samples and the role of pre- and postcytology testing.
abstract: Chlamydia trachomatis and Neisseria gonorrhoeae are common causes of sexually transmitted infections, and there is interest in screening SurePath liquid-based Pap (L-Pap) samples with Aptima Combo 2 (AC2), Amplicor (AMP), and ProbeTec ET (PT) assays. SurePath L-Pap samples and a cervical swab (CS) were collected from 394 women attending health clinics in Hamilton and Toronto, ON, Canada. L-Pap samples were tested with the three assays prior to being processed for cytology, and the CS sample was tested with AC2. The prevalence of C. trachomatis was 8.9%, and that of N. gonorrhoeae was 1.5%. By using the positives from CS testing, as well as CS negatives corresponding to L-Pap samples that tested positive in 2 of 3 assays, the sensitivities of AC2, AMP, and PT for C. trachomatis in precytology samples were calculated to be 97.1% (34 of 35 positive samples were detected), 91.4% (32 of 35 were detected), and 77.1% (27 of 35 were detected), respectively. Six women were infected with N. gonorrhoeae. After cytology processing, the results of testing the remaining liquid in the L-Pap vial and the cell-enriched fraction for C. trachomatis by AC2 showed positive agreements of 98.9% (kappa [k], 0.93) and 98.7% (k, 0.92), respectively, with the results of testing precytology L-Pap samples. Although all testing showed high specificity, testing for C. trachomatis by AC2 was significantly more sensitive than testing by PT for SurePath samples (P = 0.02). Newer versions of AMP (Cobas 4800) and PT (Q(x) with XTR technology) need published evaluations for detecting C. trachomatis and N. gonorrhoeae in L-Pap samples. C. trachomatis testing can be performed with similar results on pre- and postcytology SurePath samples.
authors.affiliation: St. Joseph’s Healthcare/McMaster University, Hamilton, ON, Canada. chernesk@mcmaster.ca
authors.forename: M
authors.initials: M
authors.lastname: Chernesky
authors.forename: D
authors.initials: D
authors.lastname: Jang
authors.forename: E
authors.initials: E
authors.lastname: Portillo
authors.forename: M
authors.initials: M
authors.lastname: Smieja
authors.forename: J
authors.initials: J
authors.lastname: Kapala
authors.forename: C
authors.initials: C
authors.lastname: Doucette
authors.forename: J
authors.initials: J
authors.lastname: Sumner
authors.forename: R
authors.initials: R
authors.lastname: Ewert
authors.forename: C
authors.initials: C
authors.lastname: MacRitchie
authors.forename: J
authors.initials: J
authors.lastname: Gilchrist
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002584:Cervix Uteri / Q000382:microbiology; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000453:epidemiology; D002692:Chlamydia trachomatis / Q000235:genetics*; D005260:Female; D006069:Gonorrhea / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D009344:Neisseria gonorrhoeae / Q000235:genetics*; D021141:Nucleic Acid Amplification Techniques; D015995:Prevalence; D012680:Sensitivity and Specificity; D055815:Young Adult