Prospective evaluation of rapid antigen tests for diagnosis of respiratory syncytial virus and human metapneumovirus infections
Abstract number: P1597
Aslanzadeh J., Zheng X., Li H., Ratkiewicz J., Meng S., Hamilton P., Tang Y.W.
Objectives: Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are two important viral pathogens causing respiratory tract infections in paediatric population. The use of rapid antigen detection tests allows for the prompt isolation and treatment of infected patients.
Methods: In a prospective study, using PCR as the "gold standard", we evaluated four rapid antigen tests including an EIA test for RSV (Directigen 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, UK). We performed the 4 tests on 515 consecutive nasopharyngeal aspirates, which had adequate volumes and cells, submitted to the Clinical Microbiology Laboratory at Hartford Hospital from November 1, 2006 to April 21, 2007. Total nucleic acid was extracted by an easyMAG (bioMerieux) from each sample and was subjected to two user developed real-time TaqMan RT-PCR amplifications for RSV and hMPV.
Results: The TaqMan assays detected 238 (46%) RSV and 32 (6.2%) hMPV among all the submitted specimens. The rapid RSV EIA antigen assay was positive for 219 specimens, giving a sensitivity of 79.8% and a specificity of 89.5%. In contrast, RSV DFA was positive for 233 specimens with a sensitivity of 94.1% and a specificity of 96.8%. The DHI DFA detected hMPV in 21 specimens, giving a sensitivity of 62.5% and a specificity of 99.8%. All inconsistent results between PCR and antigen assays were confirmed with another RT-PCR directed to a second target in the RSV or hMPV gemone. The sensitivity, specificity, positive and negative predictive value for Imagen DFA for hMPV was 99%, 63.2%, 100% and 100% respectively.
Conclusion: We conclude while RSV EIA 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.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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