Oseltamivir resistance in adult oncology and hematology patients infected with pandemic (H1N1) 2009 virus, Australia

Abstract

We describe laboratory-confirmed influenza A pandemic (H1N1) 2009 in 17 hospitalized recipients of a hematopoietic stem cell transplant (HSCT) (8 allogeneic) and in 15 patients with malignancy treated at 6 Australian tertiary centers during winter 2009. Ten (31.3%) patients were admitted to intensive care, and 9 of them were HSCT recipients. All recipients of allogeneic HSCT with infection <100 days posttransplantation or severe graft-versus-host disease were admitted to an intensive care unit. In-hospital mortality rate was 21.9% (7/32). The H275Y neuraminidase mutation, which confers oseltamivir resistance developed in 4 of 7 patients with PCR positive for influenza after > or = 4 days of oseltamivir therapy. Three of these 4 patients were critically ill. Oseltamivir resistance in 4 (13.3%) of 30 patients who were administered oseltamivir highlights the need for ongoing surveillance of such resistance and further research on optimal antiviral therapy in the immunocompromised.

Figure

Date of admission to hospitals in Victoria (A) and New South Wales (B), Australia, for patients with underlying malignancy who were infected with pandemic (H1N1) 2009, April–October 2009. Twelve Victorian and 4 New South Wales patients were recipients of a hematopoietic stem cell transplant. Rates of laboratory detection of all influenza viruses, obtained from population-based epidemic surveillance for Victoria and New South Wales, are given in the Technical Appendix).