title: Acquisition and cross-transmission of Staphylococcus aureus in European intensive care units.
abstract: OBJECTIVE
  To study the acquisition and cross-transmission of Staphylococcus aureus in different intensive care units (ICUs).
  
  
  METHODS
  We performed a multicenter cohort study. Six ICUs in 6 countries participated. During a 3-month period at each ICU, all patients had nasal and perineal swab specimens obtained at ICU admission and during their stay. All S. aureus isolates that were collected were genotyped by spa typing and multilocus variable-number tandem-repeat analysis typing for cross-transmission analysis. A total of 629 patients were admitted to ICUs, and 224 of these patients were found to be colonized with S. aureus at least once during ICU stay (22% were found to be colonized with methicillin-resistant S. aureus [MRSA]). A total of 316 patients who had test results negative for S. aureus at ICU admission and had at least 1 follow-up swab sample obtained for culture were eligible for acquisition analysis.
  
  
  RESULTS
  A total of 45 patients acquired S. aureus during ICU stay (31 acquired methicillin-susceptible S. aureus [MSSA], and 14 acquired MRSA). Several factors that were believed to affect the rate of acquisition of S. aureus were analyzed in univariate and multivariate analyses, including the amount of hand disinfectant used, colonization pressure, number of beds per nurse, antibiotic use, length of stay, and ICU setting (private room versus open ICU treatment). Greater colonization pressure and a greater number of beds per nurse correlated with a higher rate of acquisition for both MSSA and MRSA. The type of ICU setting was related to MRSA acquisition only, and the amount of hand disinfectant used was related to MSSA acquisition only. In 18 (40%) of the cases of S. aureus acquisition, cross-transmission from another patient was possible.
  
  
  CONCLUSIONS
  Colonization pressure, the number of beds per nurse, and the treatment of all patients in private rooms correlated with the number of S. aureus acquisitions on an ICU. The amount of hand disinfectant used was correlated with the number of cases of MSSA acquisition but not with the number of cases of MRSA acquisition. The number of cases of patient-to-patient cross-transmission was comparable for MSSA and MRSA.
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, the Netherlands. a.l.a.bloemendaal@umcutrecht.nl
authors.forename: Alexander L A
authors.initials: AL
authors.lastname: Bloemendaal
authors.forename: Ad C
authors.initials: AC
authors.lastname: Fluit
authors.forename: Wouter M T
authors.initials: WM
authors.lastname: Jansen
authors.forename: Menno R
authors.initials: MR
authors.lastname: Vriens
authors.forename: Tristan
authors.initials: T
authors.lastname: Ferry
authors.forename: Laurent
authors.initials: L
authors.lastname: Argaud
authors.forename: Jose M
authors.initials: JM
authors.lastname: Amorim
authors.forename: A C
authors.initials: AC
authors.lastname: Resende
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
authors.forename: Lorena
authors.initials: L
authors.lastname: López-Cerero
authors.forename: Stefania
authors.initials: S
authors.lastname: Stefani
authors.forename: Giacomo
authors.initials: G
authors.lastname: Castiglione
authors.forename: Penelope
authors.initials: P
authors.lastname: Evangelopoulou
authors.forename: Sophia
authors.initials: S
authors.lastname: Tsiplakou
authors.forename: Inne H M Borel
authors.initials: IH
authors.lastname: Rinkes
authors.forename: Jan
authors.initials: J
authors.lastname: Verhoef
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D024881:Drug Resistance, Bacterial; D005060:Europe / Q000453:epidemiology; D005838:Genotype; D006235:Hand Disinfection / Q000379:methods; D006801:Humans; D017053:Infection Control / Q000379:methods; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008712:Methicillin / Q000494:pharmacology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D008712:Methicillin