Prospective Evaluation of Rapid Antigen Tests for Diagnosis of Respiratory Syncytial Virus and Human Metapneumovirus Infections

Hartford Hospital and Clinical Laboratory Partners, Hartford, CT 06102; Children's Memorial Hospital, and Northwestern University, the Feinberg School of Medicine, Chicago, IL 60614; and Departments of Medicine and Pathology, Vanderbilt University School of Medicine, Nashville, TN 37232

^* To whom correspondence should be addressed. Email: Jaslanz{at}harthosp.org.

	Abstract

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two important viral pathogens causing respiratory tract infections in the pediatric population. Rapid detection of these agents allows for the prompt isolation and treatment of infected patients. In this prospective study, we evaluated the performances of four rapid antigen detection assays including a rapid chromatographic immunoassay (CIA) for RSV (Directigen^TM EZ RSV, Becton Dickinson, Sparks, MD); a DFA test for RSV (Bartels, Trinity Biotech Carlsbad, CA) and two DFA tests for hMPV manufactured by DHI (Diagnostic Hybrids Inc. Athens, OH) and Imagen (Oxoid Ltd., Basingstike, Hampshire, U.K.). Clinical specimens tested were 515 nasopharyngeal aspirates submitted to the Clinical Microbiology Laboratory at Hartford Hospital from November 1, 2006 to April 21, 2007. Compared to real-time reverse-transcription PCR (RT-PCR), the CIA had a sensitivity of 79.8% and a specificity of 89.5 %. RSV DFA using Bartels reagents showed a sensitivity of 94.1% and a specificity of 96.8%. For hMPV, the sensitivity and specificity was 62.5% and 99.8% for DHI DFA, and 63.2% and 100% for Imagen DFA, respectively. The hands-on and test turnaround times for CIA were 10 and 30 to 60 minutes and the hands-on and test turnaround time for RSV and hMPV DFA were 30 and 105 minutes respectively. We conclude that while RSV CIA is user friendly, it lacks sensitivity and specificity especially during off peak months. In contrast, RSV DFA is more sensitive and specific but is subjective and it demands technical time and expertise. Similarly, both hMPV DFA are highly specific in comparison to RT-PCR, but sensitivity awaits further improvement.