High colonization rates of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in Swiss travellers to South Asia- a prospective observational multicentre cohort study looking at epidemiology, microbiology and risk factors

BMC Infect Dis. 2014 Oct 1;14:528. doi: 10.1186/1471-2334-14-528.


Background: International travel contributes to the worldwide spread of multidrug resistant Gram-negative bacteria. Rates of travel-related faecal colonization with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae vary for different destinations. Especially travellers returning from the Indian subcontinent show high colonization rates. So far, nothing is known about region-specific risk factors for becoming colonized.

Methods: An observational prospective multicentre cohort study investigated travellers to South Asia. Before and after travelling, rectal swabs were screened for third-generation cephalosporin- and carbapenem-resistant Enterobacteriaceae. Participants completed questionnaires to identify risk factors for becoming colonized. Covariates were assessed univariately, followed by a multivariate regression.

Results: Hundred and seventy persons were enrolled, the largest data set on travellers to the Indian subcontinent so far. The acquired colonization rate with ESBL-producing Escherichia coli overall was 69.4% (95% CI 62.1-75.9%), being highest in travellers returning from India (86.8%; 95% CI 78.5-95.0%) and lowest in travellers returning from Sri Lanka (34.7%; 95% CI 22.9-48.7%). Associated risk factors were travel destination, length of stay, visiting friends and relatives, and eating ice cream and pastry.

Conclusions: High colonization rates with ESBL-producing Enterobacteriaceae were found in travellers returning from South Asia. Though risk factors were identified, a more common source, i.e. environmental, appears to better explain the high colonization rates.

Publication types

  • Multicenter Study
  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Asia / epidemiology
  • Child
  • Child, Preschool
  • Cohort Studies
  • Enterobacteriaceae / classification
  • Enterobacteriaceae / enzymology
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / isolation & purification
  • Enterobacteriaceae Infections / epidemiology
  • Enterobacteriaceae Infections / microbiology
  • Escherichia coli / classification
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification*
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / microbiology
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Feces / microbiology
  • Female
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Phylogeny
  • Prospective Studies
  • Risk Factors
  • Switzerland
  • Travel
  • Young Adult
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*


  • Escherichia coli Proteins
  • beta-Lactamases