title: Occurrence and characterization of oseltamivir-resistant influenza virus in children between 2007-2008 and 2008-2009 seasons.
abstract: OBJECTIVE
  There was a global increase in the prevalence of oseltamivir-resistant influenza viruses during the 2007-2008 influenza season. This study was conducted to investigate the occurrence and characteristics of oseltamivir-resistant influenza viruses during the 2007-2008 and 2008-2009 influenza seasons among patients who were treated with oseltamivir (group A) and those that did not receive oseltamivir (group B).
  
  
  METHODS
  A prospective study was conducted on 321 pediatric patients who were hospitalized because of influenza during the 2007-2008 and 2008-2009 influenza seasons. Drug resistance tests were conducted on influenza viruses isolated from 91 patients.
  
  
  RESULTS
  There was no significant difference between the clinical characteristics of groups A and B during both seasons. Influenza A/H1N1, isolated from both groups A and B during the 2007-2008 and 2008-2009 periods, was not resistant to zanamivir. However, phenotypic analysis of the virus revealed a high oseltamivir IC50 range and that H275Y substitution of the neuraminidase (NA) gene and partial variation of the hemagglutinin (HA) gene did not affect its antigenicity to the HA vaccine even though group A had a shorter hospitalization duration and fewer lower respiratory tract complications than group B. In addition, there was no significant difference in the clinical manifestations between oseltamivir-susceptible and oseltamivir-resistant strains of influenza A/H1N1.
  
  
  CONCLUSIONS
  Establishment of guidelines to efficiently treat influenza with oseltamivir, a commonly used drug for treating influenza in Korean pediatric patients, and a treatment strategy with a new therapeutic agent is required.
authors: Department of Pediatrics, Busan St. Mary's Medical Center, Busan, Korea.
authors: Seoung Geun
authors: SG
authors: Kim
authors: Yoon Ha
authors: YH
authors: Hwang
authors: Yung Hae
authors: YH
authors: Shin
authors: Sung Won
authors: SW
authors: Kim
authors: Woo Sik
authors: WS
authors: Jung
authors: Sung Mi
authors: SM
authors: Kim
authors: Jae Min
authors: JM
authors: Oh
authors: Na Young
authors: NY
authors: Lee
authors: Mun Ju
authors: MJ
authors: Kim
authors: Kyung Soon
authors: KS
authors: Cho
authors: Yeon Gyeong
authors: YG
authors: Park
authors: Sang Kee
authors: SK
authors: Min
authors: Chang Kyu
authors: CK
authors: Lee
authors: Jun Sub
authors: JS
authors: Kim
authors: Chun
authors: C
authors: Kang
authors: Joo Yeon
authors: JY
authors: Lee
authors: Man Kyu
authors: MK
authors: Huh
authors: Chang Hoon
authors: CH
authors: Kim
keywords: Child; Influenza; Oseltamivir; Resistance
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