Comparison of a commercial qualitative real-time RT-PCR kit with direct immunofluorescence assay (DFA) and cell culture for detection of influenza A and B in children.
BACKGROUND
Institutional pandemic planning prompted a study of the molecular detection of influenza virus from respiratory specimens in children, compared to conventional diagnostics.


OBJECTIVE
To evaluate the performance of a commercial qualitative real-time RT-PCR kit (rRT-PCR), the artus Influenza LC RT-PCR (Qiagen). STUDY DESIGN (METHODS): Specimens were pre-selected to include a high percentage of positives by direct immunofluorescence assay (DFA) or culture. The sensitivity and specificity of the kit for detection of influenza A and B in children were determined against the gold standard, DFA and culture. Specimens yielding discordant results between artus and the gold standard were tested against a reference rRT-PCR assay (Centers for Disease Control) to create an "expanded gold standard".


RESULTS
When compared to DFA or cell culture, the sensitivity of the rRT-PCR artus kit was 96.2% and the specificity was 94%. It detected influenza RNA in 6.0% of clinical samples negative by DFA or culture. Using the expanded gold standard, the revised sensitivity was 98.7% (98.6% for influenza A and 97.6% for influenza B) and the specificity was 100%.


CONCLUSIONS
The artus Influenza LC RT-PCR kit is an effective alternative to virus isolation and DFA for the detection of influenza A and B in pediatric clinical specimens.
Gharabaghi
Farhad
F
Division of Microbiology, Department of Paediatric Laboratory Medicine, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8 Canada. farhad.gharabaghi@sickkids.ca
Tellier
Raymond
R
Cheung
Rose
R
Collins
Carol
C
Broukhanski
George
G
Drews
Steven J
SJ
Richardson
Susan E
SE
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D009981:Influenza B virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000175:diagnosis* / Q000821:virology; D009666:Nose / Q000821:virology; D012367:RNA, Viral / Q000032:analysis; D011933:Reagent Kits, Diagnostic; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods; D014776:Virus Cultivation
D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic