Assessment of Directigen™ Ez Flu a Plus B Rapid Antigen Diagnostic Test for Pandemic Influenza a (H1n1)

Abstract

Objective: Pandemic influenza A (H1N1) cases that has begun to be seen in Southern hemisphere at the beginning of summer 2009 is gradually increasing also in Northern hemisphere nowadays, at the beginning of winter. A few diagnostic tests have been developed for diagnosis of this viral disease that is difficultly detected due to its novel antigenic structure. Although sensitivity and specifity of these molecular tests are high, they may not commonly be used as they are expensive. Rapid tests that have been developed alternatively to these tests are criticized because of their low sensitivity although they are cheap. In this study, effectiveness of Directigen EZ Flu A+B test, one of the rapid tests, was investigated for diagnosis of pandemic influenza A (H1N1). Material and Methods: In the study, nasopharyngeal and pharyngeal smears concurrently obtained from 52 patients who were admitted to our hospital with suspicion of pandemic influenza were examined using Infl/H1 LC/RG Real Time-PCR test (Kit, Qiagen, Rotor-gene Q Japan) together with rapid Directigen EZ Flu A+B antigen test (Becton Dickinson, USA). Results: Positivity was detected with Directigen TM EZ Flu A+B in 17 (33%) out of 52 patients included in the study and in 35 (67%) with RT-PCR. Influenza A was detected to be positive with rapid diagnostic test in 17 (49%) of 35 patients in whom H1N1 was detected to be positive with PCR and rapid test results were negative for all patients whose results were negative with PCR. Sensitivity of Directigen TM EZ Flu A+B test for H1N1 was found as 49% and specifity was found as 100%. Conclusion: According to these results, we may conclude that Directigen TM EZ Flu A+B may be used as a screening and prediagnosis test for diagnosis of pandemic influenza A (H1N1). Although positive results are diagnostic, negative results should be confirmed with molecular microbiologic methods.