P2.002 Evaluation of a Real-Time PCR-Based Test For Bacterial Vaginosis

Abstract

Nucleic Acid Amplification Tests (NAATs) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) have become routine. These methods are validated for use with urogenital samples and have a faster turn-around-time for results with automation. Testing of non-validated samples is common which raises concerns about assay performance. In Australia, the 2005 Public Health Laboratory Network (PHLN) guideline recommends repeat testing of all initial positive GC NAAT results with a suitable alternate NAAT assay. In this study, results from > 70,000 patient samples from 2 laboratories were reviewed in accordance with the PHLN recommendations. The laboratories used the APTIMA Combo 2 (AC2) and APTIMA Neisseria gonorrhoeae (AGC) assays with the PANTHER instrument.72,253 AC2 results were available for analysis which included 1,174 (1.68%) initially AC2 reactive (positive or equivocal) samples which also had results for the AGC assay used as the confirmatory assay. For the reactive samples, the agreement between the AC2 and AGC assays occurred in 97.19% of samples; 1135 were positive in both assays and 6 were equivocal in both assays. Sample types tested included those with manufacturer's validation claims; urine, ThinPrep, vaginal, endocervical and urethral swabs and non-validated samples including throat, rectal, eye and joint fluids. Samples from throat swabs showed the highest numbers of discordant results followed by rectal swab samples. The percentage agreement of results obtained from all sample types was excellent, with an overall PPV of > 99%.Without confirmatory testing, false positive results would have been reported for 13 samples representing 0.02% of all samples tested. This study demonstrates that the initial AC2 results can be accepted with high confidence. Background Bacterial vaginosis (BV) is the most common cause of vaginal discharge in women. Since BV is associated with significant morbidity, accurate tools for diagnosing the disease are important. The Amsel criteria (AC) and Nugent score (NS) are currently used for BV diagnosis. Recently, a number of PCR-based tests providing objective, sensitive and specific BV detection have been described. This study aimed to evaluate a newly developed BV test based on quantitative detection of Gardnerella vaginalis, Atopobium vaginae, Lactobacillus spp. and total Bacteria using multiplex PCR. Methods PCR criteria were elaborated based on the relative counts of the targeted bacteria to classify vaginal microflora as BV, no BV or intermediate. Vaginal samples for the test evaluation were obtained from 274 patients addressing a gynaecologist for routine examination. All participants were of reproductive age, not pregnant and not menstruating at the time of enrollment. BV was diagnosed using the AC and NS. Results According to the NS results, 66 patients were BV positive, 156 were BV negative, and 52 were classified as intermediate. All patients positive by the NS were positive by the AC, and all patients negative by the NS were negative by the AC. Among 66 BV posi...

Utility of Microscopic Techniques and Quantitative Real-time Polymerase Chain Reaction for the Diagnosis of Vaginal Microflora Alterations

“…concentration (lg [Lacto] j lg [Gv + Av] G 0.5). 13 For statistical analysis, GraphPad Prism V.4.00 (GraphPad Software, Inc., La Jolla, CA) software was used.…”

“…This circumstance led us to aim to develop a method that gives an opportunity to standardize the procedure of BV diagnosis, based on quantitative real-time PCR, by estimating the total amount of bacteria in the sample, a key feature of BV, on the one hand, and the relative amount of lactoflora, Gardnerella vaginalis and Atopobium vaginae, on the other. 13 …”