Oseltamivir-Resistant Pandemic (H1N1) 2009 | CDC EID

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Volume 16, Number 10–October 2010
Dispatch
Emergence of Oseltamivir-Resistant Pandemic (H1N1) 2009 Virus within 48 Hours
Masafumi Inoue, Timothy Barkham , Yee-Sin Leo, Kwai-Peng Chan, Angela Chow, Christopher W. Wong, Raphael Tze-Chuen Lee, Sebastian Maurer-Stroh, Raymond Lin, and Cui Lin
Author affiliations: Agency for Science, Research and Technology, Singapore (M. Inoue, C.W. Wong, R.T.-C. Lee, S. Maurer-Stroh); Tan Tock Seng Hospital, Singapore (T. Barkham, A. Chow); Communicable Disease Center, Singapore (Y.-S. Leo); Singapore General Hospital, Singapore (K.-P. Chan); and Ministry of Health, Singapore (R. Lin, L. Cui)

Suggested citation for this article

Abstract
An oseltamivir-resistant influenza A pandemic (H1N1) 2009 virus evolved and emerged from zero to 52% of detectable virus within 48 hours of a patient’s exposure to oseltamivir. Phylogenetic analysis and data gathered by pyrosequencing and cloning directly on clinical samples suggest that the mutant emerged de novo.

Early descriptions of emergence of H275Y mutants in pandemic (H1N1) 2009 virus showed resistance after 11 and 23 days of therapy in immunosuppressed patients (1). Also in previous reports, transmission of mutant viruses occurred in immunosuppressed patients (2), although a cluster among healthy persons demonstrated that H275Y mutants could replicate and cause disease in the absence of drug pressure (3). Additional reports noted decreasing times to detection of resistance, from 14 to 4 days after therapy (4–6). We report development of oseltamivir-resistant pandemic (H1N1) 2009 virus in an infected woman in Singapore within 48 hours of drug treatment.

full-text:
Oseltamivir-Resistant Pandemic (H1N1) 2009 | CDC EID

Suggested Citation for this Article
Inoue M, Barkham T, Leo Y-S, Chan K-P, Chow A, Wong CW, et al. Emergence of oseltamivir-resistant pandemic (H1N1) 2009 virus within 48 hours. Emerg Infect Dis [serial on the Internet]. 2010 Oct [date cited].
Available from http://www.cdc.gov/EID/content/16/4/1633.htm

DOI: 10.3201/eid1610.100688


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Address for correspondence: Timothy Barkham, Department of Laboratory Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433; email: timothy_barkham@ttsh.com.sg