Journal of Antivirals & Antiretrovirals
Open Access

Abstract

Failure to Detect Oseltamivir Resistance by Rolling Circle Amplification and Sequencing Following Use in an Influenza A (H3N2) Outbreak at an Aged Care Facility

Alexander Rosewell, Bin Wang, Nitin K Saksena, C Raina MacIntyre, Richard Lindley, Clayton Chiu, Carol Shineberg, Elizabeth Clarke, Ken McPhie, V Mala Ratnamohan, Robert Booy, Dominic E Dwyer

Background: The recent worldwide emergence of increasing oseltamivir resistance to influenza A H1N1 may have important implications for influenza prevention and control. Objectives: To assess oseltamivir use, the emergence of resistance and the outcome of an influenza A H3N2 outbreak. Patients/Methods: Following identification of an influenza outbreak through active surveillance, the investigators offered treatment and prophylaxis with oseltamivir to both Aged Care Facility (ACF) residents and staff. The investigators conducted genotypic sensitivity testing using sequencing and rolling circle amplfication for known oseltamivir resistance mutations. Results: An influenza A H3N2 outbreak affecting an ACF with 90 residents and 79 staff was identified 6 days after the initial case. Oseltamivir prophylaxis was commenced on day 7. The overall attack rate was 10%, with 13 of 92 residents and 4 of 79 staff infected.There was no evidence of the development of genotypic resistance, even at low levels, to oseltamivir in patients tested whilst on treatment or prophylaxis. Conclusions: There was no clinical or genotypic evidence of oseltamivir resistance, an important observation in the context of recent reported antiviral resistance in other influenza A subtypes.