Lab Med Online.  2011 Jan;1(1):26-34.

Clinical Characteristics and Comparison of the Various Methods Used for the Diagnosis of the New Influenza A Pandemic in Korea

• Kwon MJ
• Lee CK
• Roh KH
• Nam MH
• Yoon SY
• Lim CS
• Cho YJ
• Kim YK
• Lee KN

Abstract

BACKGROUND
Laboratory diagnosis of new influenza A (H1N1) is crucial for managing patients and establishing control and prevention measures. We compared the diagnostic accuracies of the real time RT-PCR (rRT-PCR) test recommended for the confirmation of the new flu and the viral culture method used conventionally for viral disease with that of the rapid antigen test (RAT).
METHODS
We performed RAT, R-mix culture, and real-time PCR by using 861 respiratory samples collected from December 2009 to January 2010 and evaluated the abilities of these methods to detect new influenza A. The relationship among the positive rates of RAT, grades of culture, and the cycle threshold (Ct) values of rRT-PCR was also evaluated.
RESULTS
Of the 861 patients, 308 (35.8%) were diagnosed with new influenza A. The sensitivities, specificities, positive predictive values, and negative predictive values of the tests were respectively as follows: 59.7%, 99.5%, 98.4%, and 81.6% for RAT; 93.2%, 100%, 100%, and 96.3% for R-mix culture; and 95.8%, 100%, 100%, and 97.7% for rRT-PCR. Samples with weak positive grade in culture and those with Ct values of 30-37 in rRT-PCR showed positivities as low as 25.3% and 2.3% in RAT, respectively. The hospitalization rate and death rate of the confirmed patients were 3.2% and 0.3%, respectively, and gastrointestinal symptoms were observed in 7.2% of the patients.
CONCLUSIONS
R-mix culture and rRT-PCR tests showed excellent reliability in the diagnosis of new influenza A and could be very useful, especially for samples with low viral load.

Keyword

New influenza; Rapid antigen test; Culture; Real-time RT-PCR

MeSH Terms

Animals
Clinical Laboratory Techniques
Hospitalization
Humans
Influenza, Human
Korea
Pandemics
Rats
Real-Time Polymerase Chain Reaction
Viral Load
Virus Diseases

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