title: Cluster of oseltamivir-resistant 2009 pandemic influenza A (H1N1) virus infections on a hospital ward among immunocompromised patients--North Carolina, 2009.
abstract: BACKGROUND
  Oseltamivir resistance among 2009 pandemic influenza A (H1N1) viruses (pH1N1) is rare. We investigated a cluster of oseltamivir-resistant pH1N1 infections in a hospital ward.
  
  
  METHODS
  We reviewed patient records and infection control measures and interviewed health care personnel (HCP) and visitors. Oseltamivir-resistant pH1N1 infections were found with real-time reverse-transcription polymerase chain reaction and pyrosequencing for the H275Y neuraminidase (NA) mutation. We compared hemagglutinin (HA) sequences from clinical samples from the outbreak with those of other surveillance viruses.
  
  
  RESULTS
  During the period 6-11 October 2009, 4 immunocompromised patients within a hematology-oncology ward exhibited symptoms of pH1N1 infection. The likely index patient became febrile 8 days after completing a course of oseltamivir; isolation was instituted 9 days after symptom onset. Three other case patients developed symptoms 1, 3, and 5 days after the index patient. Three case patients were located in adjacent rooms. HA and NA sequences from case patients were identical. Twelve HCP and 6 visitors reported influenza symptoms during the study period. No other pH1N1 isolates from the hospital or from throughout the state carried the H275Y mutation.
  
  
  CONCLUSIONS
  Geographic proximity, temporal clustering, presence of H275Y mutation, and viral sequence homology confirmed nosocomial transmission of oseltamivir-resistant pH1N1. Diagnostic vigilance and prompt isolation may prevent nosocomial transmission of influenza.
authors.affiliation: Program for Infection Prevention and Healthcare Epidemiology, Duke University Medical Center, Durham, North Carolina 27710, USA. luke.chen@duke.edu
authors.forename: Luke F
authors.initials: LF
authors.lastname: Chen
authors.forename: Natalie J M
authors.initials: NJ
authors.lastname: Dailey
authors.forename: Agam K
authors.initials: AK
authors.lastname: Rao
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Fleischauer
authors.forename: Ian
authors.initials: I
authors.lastname: Greenwald
authors.forename: Varough M
authors.initials: VM
authors.lastname: Deyde
authors.forename: Zack S
authors.initials: ZS
authors.lastname: Moore
authors.forename: Deverick J
authors.initials: DJ
authors.lastname: Anderson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Duffy
authors.forename: Larisa V
authors.initials: LV
authors.lastname: Gubareva
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sexton
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
authors.forename: Arjun
authors.initials: A
authors.lastname: Srinivasan
authors.forename: Cameron R
authors.initials: CR
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000494:pharmacology*; D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000821:virology; D004196:Disease Outbreaks; D024882:Drug Resistance, Viral; D006761:Hospitals; D006801:Humans; D016867:Immunocompromised Host; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology*; D007407:Interviews as Topic; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D053139:Oseltamivir / Q000494:pharmacology*; D058873:Pandemics; D010802:Phylogeny; D012189:Retrospective Studies
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir