Comparison of four clinical specimen types for detection of influenza A and B viruses by optical immunoassay (FLU OIA test) and cell culture methods

Although laboratory diagnosis of respiratory viruses has been widely studie d, there is a relative insufficiency of literature examining the impact of specimen type on the laboratory diagnosis of influenza A and B. In a clinic al study comparing the FLU OIA test with I l-day cell culture, clinical spe cimens from nasopharyngeal swabs, throat swabs, nasal aspirates, and sputum were obtained from patients experiencing influenza-like symptoms. A total of 404 clinical specimens were collected from 184 patients. Patients were d efined as influenza positive if the viral culture of a specimen from any sa mple site was positive. Patients were defined as influenza negative if the viral cultures of specimens from all sample sites were negative. By this go ld standard, culture and FLU OIA test results for each sample type were com pared. For each of the four specimen types, the viral culture and FLU OIA t est demonstrated equal abilities to detect the presence of influenza A or B virus or viral antigen. Sputum and nasal aspirate samples were the most pr edictive of influenza virus infection. Throat swabs were the least predicti ve of influenza virus infection, with both tests failing to detect influenz a virus in nearly 50% of the throat samples studied.