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 andC hlamydia trachomatis and Neisseria gonorrhoeae infections are the most frequently reported bacterial sexually transmitted diseases in North America (1). Because of the high rates of asymptomatic infection, which may lead to upper genital tract complications such as pelvic pain, ectopic pregnancy, and infertility, control requires some form of screening to identify and treat infected patients and their partners (9). Specimens from cervical cancer screening programs are being considered for C. trachomatis and N. gonorrhoeae screening by testing of PreservCyt ThinPrep (Hologic) or SurePath (BD Diagnostics-TriPath) samples. Nucleic acid amplification tests such as the Aptima Combo 2 (AC2), Amplicor (AMP), and ProbeTec ET (PT) assays are cleared by the U.S. FDA for the detection of C. trachomatis and N. gonorrhoeae using swabs and urine samples. AC2 and AMP are cleared for use on ThinPrep liquid-based Pap (L-Pap) samples; AC2 has been validated using SurePath samples, and AMP and PT protocols for SurePath testing have been presented at scientific meetings. The objective of this study was to compare the performances of the three assays for precytology SurePath L-Pap samples collected from patients attending clinics for routine Pap testing. A secondary objective was to compare L-Pap samples before and after processing for cytology. MATERIALS AND METHODSStudy design. This was a cross-sectional study which enrolled 394 women between 15 and 71 years of age attending health clinics for routine care in Hamilton and Toronto, Ontario, Canada. Patients signed informed-consent forms prior to participation. Patients with antibiotic use in the past 3 weeks and those pregnant past the first trimester were excluded from the study. Each collection package included information about the study, an informed-consent form, and collection kits for each assay. Each item was prelabeled with a unique identifier. The clinician collected three samples in the following order: (i) a SurePath L-Pap sample obtained using an established procedure with a Cervex-Brush, (ii) a cervical swab (CS) sample obtained using an Aptima unisex swab (Gen-Probe Inc.) and placed into specimen transport medium, and (iii) a second L-Pap SurePath sample. Samples were shipped on the day of collection to Gamma-Dynacare Medical Laboratories in Brampton, Ontario, Canada.Testing. The cytology technologist removed the two L-Pap vials from the study package, carefully subjected the samples to a vortex, and then combined and mixed the samples to ensure homogeneity. The mixed samples were then divided back into the original vials. One vial was used for Pap cytology, and the other (referred to herein as a precytology L-Pap sample) was placed back into the study collection package containing the CS and study forms and shipped overnight to St. Joseph's Healthcare Infections Research Laboratory (IRL) in Hamilton, Ontario, Canada, where upon receipt, aliquots were transferred into respective assay transport tubes and tested by the three assays within 48 ...

Workflow and Maintenance Characteristics of Five Automated Laboratory Instruments for the Diagnosis of Sexually Transmitted Infections

“…With clearance by the U.S. Food and Drug Administration and other regulatory agencies in Europe and elsewhere of several systems, automated molecular testing has become routine in clinical laboratory practice, ensuring diagnostic accuracy and improved result turnaround time (TAT). Studies have been published assessing clinical performances of molecular assays (2)(3)(4)(5)(6)(7)(8), and workflow and maintenance characteristics of automated instruments (9)(10)(11)(12)(13)(14)(15)(16). In addition to performance and instrumentreagent costs, hands-on time required for testing and maintenance, in-process interaction, and time to results and test capacity are key metrics that should be considered because they can influence efficiency and labor costs.…”

Performance of the Abbott Real Time CT/NG assay in urines and cervico-vaginal samples from Senegal

“…The similarity in the data may be related to our small sample size because discordances in data from larger data sets have previously been identified [10][11][12]18]. Indeed, an overall agreement of 98.5% between the results from the Abbott RealTime and Roche Cobas Amplicor assays in the diagnosis of CT on cervical swab samples was reported in 96.3% (26/27) of the positive results and in 100% (40/40) of the negative results [12].…”

Effect of Preanalytical Processing of ThinPrep Specimens on Detection of High-Risk Human Papillomavirus by the Aptima HPV Assay

“…3A), apart from analytical variance related to the Cervista assay, suggests that the risk for cross-contamination related to the Tigris DTS itself is also very minimal. Chernesky et al (18) reported Ͼ98% agreement of Aptima Combo 2 (Hologic/Gen-Probe) Chlamydia trachomatis results in precytology and postcytology fractions of 394 SurePath (BD Diagnostics-TriPath, Burlington, NC) collections. The data in our study not only were generated on the basis of a different microbe and an alternative liquid-based cytology medium but also were assessed with an automated platform for nucleic acid amplification testing and an automated means of cytology processing.…”