title: First case in Italy of acquired resistance to oseltamivir in an immunocompromised patient with influenza A/H1N1v infection.
abstract: A pandemic influenza A/H1N1v strain with the neuraminidase H274Y mutation was detected in nasal secretions of a 2-year-old leukemic patient with influenza-like illness after 18 days of treatment with oseltamivir. At baseline, no drug-resistant virus was found, while 4 days after treatment initiation a mixture of wild-type and mutated virus was detected. After treatment interruption, the wild type influenza virus re-emerged and became prevalent in nasal secretions after a few days, suggesting the lower fitness of the mutated virus strain. The patient slowly improved concurrently with a decrease in virus load, which resulted negative 42 days after diagnosis. No other drug-resistant influenza A/H1N1v virus strains have been detected in Italy (up to the end of November 2009) since the first case of the novel A/H1N1v virus was identified in the country (May 2009).
authors.affiliation: Molecular Virology Unit, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Campanini
authors.forename: Antonio
authors.initials: A
authors.lastname: Piralla
authors.forename: Francesca
authors.initials: F
authors.lastname: Rovida
authors.forename: Simona
authors.initials: S
authors.lastname: Puzelli
authors.forename: Marzia
authors.initials: M
authors.lastname: Facchini
authors.forename: Franco
authors.initials: F
authors.lastname: Locatelli
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Minoli
authors.forename: Elena
authors.initials: E
authors.lastname: Percivalle
authors.forename: Isabella
authors.initials: I
authors.lastname: Donatelli
authors.forename: Fausto
authors.initials: F
authors.lastname: Baldanti
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000998:Antiviral Agents / Q000494:pharmacology*; D012634:Bodily Secretions / Q000821:virology; D002675:Child, Preschool; D024882:Drug Resistance, Viral; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000302:isolation & purification; D007251:Influenza, Human / Q000188:drug therapy / Q000821:virology*; D007558:Italy; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009439:Neuraminidase; D009666:Nose / Q000821:virology; D053139:Oseltamivir / Q000494:pharmacology* / Q000627:therapeutic use; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D016896:Treatment Outcome; D019562:Viral Load; D014764:Viral Proteins; D028761:Withholding Treatment
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral; D014764:Viral Proteins; D053139:Oseltamivir; C487630:NA protein, influenza A virus; D009439:Neuraminidase