The presence of the Streptococcus pneumoniae in samples that can be easily obtained in clinics and emergency rooms may predict risk of severe disease in H1N1 pandemic influenza. Reports that H1N1 pandemic influenza in Argentina was associated with higher morbidity and mortality than in other countries led investigators in the Center for Infection and Immunity (CII) at the Mailman School of Public Health of Columbia University, their colleagues at Argentina's National Institute of Infectious Diseases (INEI), and Roche 454 Life Sciences to look for viral mutations indicative of increased virulence and for co-infections that could contribute to disease.
Complete genome sequencing of nasopharyngeal samples representing severe or mild disease revealed no evidence of evolution toward a more virulent phenotype or development of antiviral resistance. However, MassTag PCR, a method for sensitive, simultaneous surveillance and differential diagnosis of infectious diseases, found a strong correlation between the presence of Streptococcus pneumoniae and increased risk for severe disease. The findings, which suggest a new strategy for identifying and treating these patients, are currently online in the publication Plos One.
The scientists examined nasopharyngeal samples representing 199 cases of H1N1 pandemic (H1N1pdm) influenza virus infections from Argentina. The sample set included 39 cases classified as severe and 160 cases categorized as mild. "We used a combination of 454 pyrosequencing and classical Sanger sequencing methods to test for viral evolution toward increased virulence. Comparison of viral sequences from Argentina with those obtained from other parts of the world provided no clues to the increase in severity of disease," said Gustavo Palacios, PhD, assistant professor of epidemiology at CII, and a lead and corresponding author. "However, MassTag PCR allowed us to find a new risk factor, independent of obesity, asthma, diabetes or chronic illness. S. pneumoniae was present in the majority of severe cases."