269. Performance Characteristics of the Focus Technologies Simplexa Direct Combined Influenza A/B and RSV Real-Time RT-PCR Assay during the 2012-2013 Influenza Season
Session: Poster Abstract Session: Diagnostic Microbiology; Novel Molecular Methods
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background:
Since 2009 our institution has used a combination of antigen-based testing (ABT) and nucleic-acid based testing (NAT) to diagnose patients with influenza. During the 2012-13 influenza season, the known inaccuracy of ABT (Response RAMP Flu A+B) resulted in an overwhelming demand for follow-up NAT testing to ensure proper patient treatment and infection control practices. During the final week of 2012 our laboratory received 775 specimens for influenza ABT, which due to confirmatory testing, resulted in an additional 181 requests (effectively doubling the cost of testing). The goal of this study was to determine if our present combination of assays for influenza diagnosis could be replaced by the Focus Technologies Simplexa Direct Real-Time RT-PCR assay.

Methods:

We performed testing on 168 archived adult and pediatric patient specimens from the 2012-13 influenza season. The sample set included positive samples for Influenza A (IA) n=50, Influenza B (IB) n=40, as well as flu-negative samples n=80 (including samples positive for respiratory syncytial virus, rhinovirus, metapneumovirus, and a subset which demonstrated influenza false-positivity on ABT). Samples with concordant results on ABT, Simplexa NAT, and Cepheid Xpert Flu (a second NAT-based method) testing were considered to be true positives/negatives. Any sample which showed discordance between these three tests was tested by a gold-standard test (Luminex xTAG RVP multiplex PCR).

Results:

ABT showed a sensitivity and specificity of 63% and 89% for IA, and 98% and 82% for IB, respectively. Samples tested on the Simplexa had a 100% sensitivity and specificity for IA and IB, outperforming the Xpert Flu assay which showed sensitivity and specificity of 98% and 96% for IA, and 100% and 93% for IB, respectively.

Conclusion:

The Simplexa assay demonstrates a great improvement in diagnostic accuracy compared with ABT. We expect to see more directed use of antiviral medication and a reduction in nosocomial transmissions (via appropriate patient isolation) after its implementation. Additionally, we will simplify testing for our providers. We project that the added cost of replacing ABT with NAT will be offset by reduced confirmatory testing.

Randin Nelson, MD1, Philip Gialanella, MS1, Rizwan Naeem, M.B., B.S.1, Belinda Ostrowsky, MD, MPH2, Iona Munjal, MD3 and Michael Levi, ScD1, (1)Pathology, Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, NY, (2)Infectious Diseases, Montefiore Medical Center, Bronx, NY, (3)Pediatrics and Infectious Diseases, Montefiore Medical Center and the Albert Einstein College of Medicine, Bronx, NY

Disclosures:

R. Nelson, None

P. Gialanella, None

R. Naeem, None

B. Ostrowsky, None

I. Munjal, None

M. Levi, None

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