title: How important is patient-to-patient transmission in extended-spectrum beta-lactamase Escherichia coli acquisition.
abstract: BACKGROUND
  Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is an emerging pathogen. The causal role of antibiotic selective pressure versus patient-to-patient transmission has not been assessed. The objective of this study was to quantify the amount of patient-to-patient transmission among patients who acquire an ESBL-producing E coli infection using perianal surveillance cultures in an intensive care unit (ICU) population.
  
  
  METHODS
  A prospective cohort of patients admitted between September 1, 2001, and September 1, 2004, to the medical and surgical ICUs at a tertiary care hospital was studied. Patients had perianal cultures on admission, weekly, and upon discharge. Strain typing by pulsed-field gel electrophoresis (PFGE) and epidemiologic criteria were used to quantify the amount of patient-to-patient transmission.
  
  
  RESULTS
  There were 1806 patients admitted to the ICUs. There were 74 patients who had ESBL-producing E coli on admission to the ICU and 23 patients who acquired ESBL-producing E coli. Among these 23 patients, there were 14 PFGE types, and 3 (13%) patient acquisitions were defined as patient-to-patient transmission by similar PFGE type and overlapping time in the hospital.
  
  
  CONCLUSIONS
  Our data suggest that patient-to-patient transmission is not an important cause of the acquisition of ESBL-producing E coli colonization in the ICU setting.
authors.affiliation: Department of Epidemiology and Preventive Medicine, University of Maryland, 100 North Greene Street, Baltimore, MD 21201, USA. aharris@epi.umaryland.edu
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Harris
authors.forename: Mamuka
authors.initials: M
authors.lastname: Kotetishvili
authors.forename: Simone
authors.initials: S
authors.lastname: Shurland
authors.forename: Judy A
authors.initials: JA
authors.lastname: Johnson
authors.forename: J Glenn
authors.initials: JG
authors.lastname: Morris
authors.forename: Lucia L
authors.initials: LL
authors.lastname: Nemoy
authors.forename: J Kristie
authors.initials: JK
authors.lastname: Johnson
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D001003:Anal Canal / Q000382:microbiology; D015142:Baltimore; D003428:Cross Infection / Q000382:microbiology* / Q000635:transmission*; D003470:Culture Media; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission*; D006801:Humans; D007362:Intensive Care Units; D011159:Population Surveillance; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D003470:Culture Media; D001618:beta-Lactamases