BACKGROUND: Neuraminidase inhibitors (NAIs) have been used since 2005 in France. OBJECTIVE: Influenza viruses isolated in hospital and community cases in winter 2005-2006 were evaluated for their sensitivity to NAIs. STUDY DESIGN: Isolates were tested in duplicate with a fluorescence-based neuraminidase assay. The IC50 for oseltamivir or zanamivir was calculated for each strain. Mean IC50 (+/-S.D.) are expressed in nM. Viruses with IC50 superior or very superior to the upper limit (mean IC50+2.5 S.D.) were considered as outliers or resistant viruses, respectively. HA and NA genes for outliers, resistant strains and for a few sensitive strains were sequenced. RESULTS: Out of 225 B isolates, one was found resistant to both oseltamivir and zanamivir with a D197Y mutation in NA and eight isolates were outliers for oseltamivir and/or zanamivir. Out of 151 A (H1N1) isolates, one was found resistant to oseltamivir but sensitive to zanamivir with a H275Y mutation in NA, two isolates were resistant to zanamivir and three isolates were outliers for oseltamivir and/or zanamivir. New mutations were detected in outliers compared to sensitive viruses. CONCLUSION: Resistant influenza strains to NAIs are circulating at a stable and low level of 1% since the introduction of NAIs in clinical practice.
BACKGROUND: Neuraminidase inhibitors (NAIs) have been used since 2005 in France. OBJECTIVE: Influenza viruses isolated in hospital and community cases in winter 2005-2006 were evaluated for their sensitivity to NAIs. STUDY DESIGN: Isolates were tested in duplicate with a fluorescence-based neuraminidase assay. The IC50 for oseltamivir or zanamivir was calculated for each strain. Mean IC50 (+/-S.D.) are expressed in nM. Viruses with IC50 superior or very superior to the upper limit (mean IC50+2.5 S.D.) were considered as outliers or resistant viruses, respectively. HA and NA genes for outliers, resistant strains and for a few sensitive strains were sequenced. RESULTS: Out of 225 B isolates, one was found resistant to both oseltamivir and zanamivir with a D197Y mutation in NA and eight isolates were outliers for oseltamivir and/or zanamivir. Out of 151 A (H1N1) isolates, one was found resistant to oseltamivir but sensitive to zanamivir with a H275Y mutation in NA, two isolates were resistant to zanamivir and three isolates were outliers for oseltamivir and/or zanamivir. New mutations were detected in outliers compared to sensitive viruses. CONCLUSION: Resistant influenza strains to NAIs are circulating at a stable and low level of 1% since the introduction of NAIs in clinical practice.
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Authors: Andrew J Burnham; Jianling Armstrong; Anice C Lowen; Robert G Webster; Elena A Govorkova Journal: J Virol Date: 2015-02-11 Impact factor: 5.103
Authors: Anwar M Hashem; Anathea S Flaman; Aaron Farnsworth; Earl G Brown; Gary Van Domselaar; Runtao He; Xuguang Li Journal: PLoS One Date: 2009-12-17 Impact factor: 3.240
Authors: Tiffany G Sheu; Varough M Deyde; Margaret Okomo-Adhiambo; Rebecca J Garten; Xiyan Xu; Rick A Bright; Eboneé N Butler; Teresa R Wallis; Alexander I Klimov; Larisa V Gubareva Journal: Antimicrob Agents Chemother Date: 2008-07-14 Impact factor: 5.191
Authors: Gallen B Triana-Baltzer; Larisa V Gubareva; Alexander I Klimov; David F Wurtman; Ronald B Moss; Maria Hedlund; Jeffrey L Larson; Robert B Belshe; Fang Fang Journal: PLoS One Date: 2009-11-06 Impact factor: 3.240