title: Nosocomial transmission of New Delhi metallo-β-lactamase-1-producing Klebsiella pneumoniae in Toronto, Canada.
abstract: METHODS
  An analysis of a cluster of New Delhi metallo-β-lactamase-1-producing Klebsiella pneumoniae (NDM1-Kp) and a retrospective case-cohort analysis of risk factors for acquisition in contacts of NDM1-Kp-positive patients.
  
  
  METHODS
  A 1,100-bed Canadian academic tertiary care center.
  
  
  METHODS
  Two index patients positive for NDM1-Kp as well as 45 contacts (roommates, ward mates, or environmental contacts) were investigated.
  
  
  METHODS
  Retrospective chart reviews of all patients colonized or infected with NDM1-Kp as well as contacts of these patients were performed in order to describe the epidemiology and impact of infection prevention and control measures. A case-cohort analysis was conducted investigating 45 contacts of NDM1-Kp-positive patients to determine risk factors for acquisition of NDM1-Kp. Rectal swabs were screened for NDM1-Kp using chromogenic agar. Presence of bla(NDM-1) was confirmed by multiplex polymerase chain reaction. Clonality was assessed with pulsed-field gel electrophoresis (PFGE) using restriction enzyme XbaI.
  
  
  RESULTS
  Two index cases carrying NDM1-Kp with different PFGE patterns were identified. Nosocomial transmission to 7 patients (4 roommates, 2 ward mates, and 1 environmental contact) was subsequently identified. Risk factors for acquisition of NDM1-Kp were a history of prior receipt of certain antibiotics (fluoroquinolones [odds ratio (OR), 16.8 (95% confidence interval [CI], 1.30-58.8); [Formula: see text]], trimethoprim-sulfamethoxazole [OR, 11.3 (95% CI, 1.84-70.0); [Formula: see text]], and carbapenems [OR, 16.8 (95% CI, 1.79-157.3); [Formula: see text]]) and duration of exposure to NDM1-Kp-positive roommates (26.5 vs 6.7 days; [Formula: see text]).
  
  
  CONCLUSIONS
  Two distinct clones of NDM1-Kp were transmitted to 7 inpatient contacts over several months. Implementation of contact precautions, screening of contacts for NDM1-Kp carriage, and attention to environmental disinfection contributed to the interruption of subsequent spread of the organism. The appropriate duration and frequency of screening contacts of NDM1-Kp-positive patients require further study.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Lowe
authors.forename: Julianne V
authors.initials: JV
authors.lastname: Kus
authors.forename: Natasha
authors.initials: N
authors.lastname: Salt
authors.forename: Sandra
authors.initials: S
authors.lastname: Callery
authors.forename: Lisa
authors.initials: L
authors.lastname: Louie
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Khan
authors.forename: Mary
authors.initials: M
authors.lastname: Vearncombe
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Simor
mesh_terms: D002353:Carrier State / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission; D016358:Contact Tracing; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D004196:Disease Outbreaks / Q000517:prevention & control*; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D017053:Infection Control / Q000379:methods; D007710:Klebsiella Infections / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000201:enzymology*; D015999:Multivariate Analysis; D009864:Ontario / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D001618:beta-Lactamases
chemical_list: D001618:beta-Lactamases; C552864:beta-lactamase NDM-1