Ledesma, JuanVicente, DiegoPozo Sanchez, FranciscoCilla, GustavoPérez Castro, SoniaSuárez Fernández, JonathanPérez-Ruiz, MercedesNavarro, José MaríaGalán, Juan CarlosFernández, MirianReina, JordiLarrauri, AmparoCuevas, Maria TeresaCasas Flecha, InmaculadaPerez-Breña, PilarSpanish Influenza Surveillance System (SISS)Jimenez-Jorge, Silvia2025-01-272025-01-272011-07Ledesma J, Vicente D, Pozo F, Cilla G, Castro SP, Fernández JS, Ruiz MP, Navarro JM, Galán JC, Fernández M, Reina J, Larrauri A, Cuevas MT, Casas I, Breña PP; Spanish Influenza Surveillance System (SISS). Oseltamivir-resistant pandemic influenza a (H1N1) 2009 viruses in Spain. J Clin Virol. 2011 Jul;51(3):205-8.1386-6532https://hdl.handle.net/20.500.12105/26140Background: 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. Objectives: 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. Study design: 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. Conclusion: 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.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/InfluenzaNeuraminidaseH275Y mutationOseltamivir-resistanceAdultAgedAmino Acid SubstitutionAntiviral AgentsChildChild, PreschoolDrug Resistance, ViralHumansInfantInfluenza A Virus, H1N1 SubtypeInfluenza, HumanMaleMutation, MissenseNeuraminidaseNucleic Acid HybridizationOseltamivirPandemicsPrevalenceReverse Transcriptase Polymerase Chain ReactionSequence Analysis, DNASpainViral ProteinsAttribution-NonCommercial-NoDerivatives 4.0 International21592854513205-20810.1016/j.jcv.2011.04.0081873-5967Journal of clinical virology: the official publication of the Pan American Society for Clinical Virologyopen access