Dissipation and removal of oseltamivir (Tamiflu) in different aquatic environments

The antiviral drug oseltamivir (Tamiflu) has received recent attention due to the potential use as a first-line defense against H5N1 and H1N1 influenza viruses. Research has shown that oseltamivir is not removed during conventional wastewater treatments, thus having the potential to enter surface water bodies. A series of laboratory experiments investigated the fate and the removal of oseltamivir in two surface water ecosystems of Japan and in a municipal wastewater treatment plant located in Northern Italy. Persistence of oseltamivir in surface water ranged from non-detectable degradation to a half-life of 53d. After 40d, <3% of radiolabeled oseltamivir evolved as (14)CO(2). The presence of sediments (5%) led to a significant increase of oseltamivir degradation and mineralization rates. A more intense mineralization was observed in samples of the wastewater treatment plant when applying a long incubation period (40d). More precisely, 76% and 37% of the initial radioactivity applied as (14)C-oseltamivir was recovered as (14)CO(2) from samples of the biological tank and effluent water, respectively. Two bacterial strains growing on oseltamivir as sole carbon source were isolated and used for its removal from synthetic medium and environmental samples, including surface water and wastewater. Inoculation of water and wastewater samples with the two oseltamivir-degrading strains showed that mineralization of oseltamivir was significantly higher in both inoculated water and wastewater, than in uninoculated controls. Denaturing gradient gel electrophoresis and quantitative PCR analysis showed that Tamiflu would not affect the microbial population of surface water and wastewater.