title: Oseltamivir-resistant pandemic influenza a (H1N1) 2009 viruses in Spain.
abstract: BACKGROUND
  Pandemic influenza A (H1N1) 2009 virus appeared in Spain on April 25, 2009 for the first time. This new virus was adamantane-resistant but it was sensitive to neuraminidase (NA) inhibitors oseltamivir and zanamivir.
  
  
  OBJECTIVE
  To detect oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses by the Spanish Influenza Surveillance System (SISS) and a possible spread of oseltamivir-resistant viruses in Spain since starting of the pandemic situation.
  
  
  METHODS
  A total of 1229 respiratory samples taken from 413 severe and 766 non-severe patients with confirmed viral detection of pandemic influenza A (H1N1) 2009 viruses from different Spanish regions were analyzed for the specific detection of the H275Y mutation in NA between April 2009 and May 2010.
  
  
  RESULTS
  H275Y NA substitution was found in 8 patients infected with pandemic influenza A (H1N1) 2009 viruses collected in November and December 2009 and in January 2010. All oseltamivir-resistant viruses were detected in severe patients (8/413, 1.93%) who previously received treatment with oseltamivir. Six of these patients were immunocompromised.
  
  
  CONCLUSIONS
  In Spain, the number of oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses is until now very low. No evidence for any spread of oseltamivir-resistant H1N1 viruses is achieved in our Country.
authors: Centro Nacional de Gripe, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. jledesmam@isciii.es
authors: Juan
authors: J
authors: Ledesma
authors: Diego
authors: D
authors: Vicente
authors: Francisco
authors: F
authors: Pozo
authors: Gustavo
authors: G
authors: Cilla
authors: Sonia Pérez
authors: SP
authors: Castro
authors: Jonathan Suárez
authors: JS
authors: Fernández
authors: Mercedes Pérez
authors: MP
authors: Ruiz
authors: José María
authors: JM
authors: Navarro
authors: Juan Carlos
authors: JC
authors: Galán
authors: Mirian
authors: M
authors: Fernández
authors: Jordi
authors: J
authors: Reina
authors: Amparo
authors: A
authors: Larrauri
authors: María Teresa
authors: MT
authors: Cuevas
authors: Inmaculada
authors: I
authors: Casas
authors: Pilar Pérez
authors: PP
authors: Breña