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.