Comparison of SmartCycler real-time reverse transcription-PCR assay in a public health laboratory with direct immunofluorescence and cell culture assays in a medical center for detection of influenza A virus.

A single-tube real-time (fluorogenic) reverse transcription (RT)-PCR with the SmartCycler instrument (SmartCycler RT-PCR) for influenza A virus detection was evaluated with 238 respiratory specimens. Direct immunofluorescence antibody staining (DFA) and primary rhesus monkey kidney cell culture were performed on-site at Yale-New Haven Hospital. Specimens were transported to the Connecticut Department of Public Health Laboratory for real-time RT-PCR. Cell culture detected influenza A virus in all 150 influenza A virus-positive specimens, DFA detected the virus in 148 influenza A virus-positive specimens, and SmartCycler RT-PCR detected the virus 143 influenza A virus-positive specimens. The sensitivity and specificity of RT-PCR were 95.3 and 100%, respectively. The high sensitivity and specificity and the rapid turnaround time made the SmartCycler RT-PCR valuable for the rapid diagnosis of influenza A, especially in a public health laboratory. The closed real-time RT-PCR system avoided cross-contamination possible with RT-PCR and the excessive manipulations required for conventional RT-PCR analysis and saved time and labor as well. In a medical center, rapid diagnosis by DFA was labor intensive but was 98.7% sensitive and 100% specific compared to the results of culture and provided results within 2 h throughout operating hours, helping with bed allocation on admission and patient management.