Oseltamivir resistance in an influenza A (H3N2) virus isolated from an immunocompromised patient during the 2014–2015 influenza season in Alberta, Canada

This manuscript describes the identification of an oseltamivir‐resistant influenza A (H3N2) virus in a respiratory specimen collected from an immunocompromised patient in Alberta, Canada, during the 2014–2015 influenza season. Following treatment with oseltamivir, neuraminidase (NA) gene sequencing indicated the presence of an R292K mutation. Phenotypic susceptibility testing by the NA‐Star assay indicated a highly reduced inhibition by oseltamivir and normal inhibition by zanamivir. The use of zanamivir following identification of the oseltamivir‐resistant strain, combined with a partial immune reconstitution, was followed by a suggested decrease in the nasopharyngeal viral load in the nasopharynx and clinical improvement of the patient.