title: The epidemiology of Staphylococcus aureus transmission in the anesthesia work area.
abstract: BACKGROUND
  Little is known regarding the epidemiology of intraoperative Staphylococcus aureus transmission. The primary aim of this study was to examine the mode of transmission, reservoir of origin, transmission locations, and antibiotic susceptibility for frequently encountered S aureus strains (phenotypes) in the anesthesia work area. Our secondary aims were to examine phenotypic associations with 30-day postoperative patient cultures, phenotypic growth rates, and risk factors for phenotypic isolation.
  
  
  METHODS
  S aureus isolates previously identified as possible intraoperative bacterial transmission events by class of pathogen, temporal association, and analytical profile indexing were subjected to antibiotic disk diffusion sensitivity. The combination of these techniques was then used to confirm S aureus transmission events and to classify them as occurring within or between operative cases (mode). The origin of S aureus transmission events was determined via use of a previously validated experimental model and links to 30-day postoperative patient cultures confirmed via pulsed-field gel electrophoresis. Growth rates were assessed via time-to-positivity analysis, and risk factors for isolation were characterized via logistic regression.
  
  
  RESULTS
  One hundred seventy S aureus isolates previously implicated as possible intraoperative transmission events were further subdivided by analytical profile indexing phenotype. Two phenotypes, phenotype P (patients) and phenotype H (hands), accounted for 65% of isolates. Phenotype P and phenotype H contributed to at least 1 confirmed transmission event in 39% and 28% of cases, respectively. Patient skin surfaces (odds ratio [OR], 8.40; 95% confidence interval [CI], 2.30-30.73) and environmental (OR, 10.89; 95% CI, 1.29-92.13) samples were more likely than provider hands (referent) to have phenotype P positivity. Phenotype P was more likely than phenotype H to be resistant to methicillin (OR, 4.38; 95% CI, 1.59-12.06; P = 0.004) and to be linked to 30-day postoperative patient cultures (risk ratio, 36.63 [risk difference, 0.174; 95% CI, 0.019-0.328]; P < 0.001). Phenotype P exhibited a faster growth rate for methicillin resistant and for methicillin susceptible than phenotype H (phenotype P: median, 10.32H; interquartile range, 10.08-10.56; phenotype H: median, 10.56H; interquartile range, 10.32-10.8; P = 0.012). Risk factors for isolation of phenotype P included age (OR, 14.11; 95% CI, 3.12-63.5; P = 0.001) and patient exposure to the hospital ward (OR, 41.11; 95% CI, 5.30-318.78; P < 0.001).
  
  
  CONCLUSIONS
  Two S aureus phenotypes are frequently transmitted in the anesthesia work area. A patient and environmentally derived phenotype is associated with increased risk of antibiotic resistance and links to 30-day postoperative patient cultures as compared with a provider hand-derived phenotype. Future work should be directed toward improved screening and decolonization of patients entering the perioperative arena and improved intraoperative environmental cleaning to attenuate postoperative health care-associated infections.
authors.affiliation: From the *Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; †The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire; ‡Department of Anesthesiology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa; §Department of Pathology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; and ∥Departments of Anesthesiology and Surgery, University of Massachusetts Medical School and UMass Memorial Medical Center, Worcester, Massachusetts.
authors.forename: Randy W
authors.initials: RW
authors.lastname: Loftus
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Koff
authors.forename: Jeremiah R
authors.initials: JR
authors.lastname: Brown
authors.forename: Hetal M
authors.initials: HM
authors.lastname: Patel
authors.forename: Jens T
authors.initials: JT
authors.lastname: Jensen
authors.forename: Sundara
authors.initials: S
authors.lastname: Reddy
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Ruoff
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Heard
authors.forename: Mark P
authors.initials: MP
authors.lastname: Yeager
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Dodds
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000758:Anesthesia / Q000009:adverse effects; D000776:Anesthesiology / Q000295:instrumentation / Q000379:methods; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004866:Equipment Contamination; D008826:Microbial Sensitivity Tests; D009873:Operating Rooms; D010641:Phenotype; D011184:Postoperative Period; D011446:Prospective Studies; D012307:Risk Factors; D012867:Skin / Q000187:drug effects; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000635:transmission; D013211:Staphylococcus aureus; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents