title: Travel-associated faecal colonization with ESBL-producing Enterobacteriaceae: incidence and risk factors.
abstract: OBJECTIVE
  To study the acquisition of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) among the faecal flora during travel, with a focus on risk factors, antibiotic susceptibility and ESBL-encoding genes.
  
  
  METHODS
  An observational prospective multicentre cohort study of individuals attending vaccination clinics in south-east Sweden was performed, in which the submission of faecal samples and questionnaires before and after travelling outside Scandinavia was requested. Faecal samples were screened for ESBL-PE by culturing on ChromID ESBL and an in-house method. ESBL-PE was confirmed by phenotypic and genotypic methods. Susceptibility testing was performed with the Etest. Individuals who acquired ESBL-PE during travel (travel-associated carriers) were compared with non-carriers regarding risk factors, and unadjusted and adjusted ORs after manual stepwise elimination were calculated using logistic regression.
  
  
  RESULTS
  Of 262 enrolled individuals, 2.4% were colonized before travel. Among 226 evaluable participants, ESBL-PE was detected in the post-travel samples from 68 (30%) travellers. The most important risk factor in the final model was the geographic area visited: Indian subcontinent (OR 24.8, P < 0.001), Asia (OR 8.63, P < 0.001) and Africa north of the equator (OR 4.94, P = 0.002). Age and gastrointestinal symptoms also affected the risk significantly. Multiresistance was seen in 77 (66%) of the ESBL-PE isolates, predominantly a combination of reduced susceptibility to third-generation cephalosporins, trimethoprim/sulfamethoxazole and aminoglycosides. The most common species and ESBL-encoding gene were Escherichia coli (90%) and CTX-M (73%), respectively.
  
  
  CONCLUSIONS
  Acquisition of multiresistant ESBL-PE among the faecal flora during international travel is common. The geographical area visited has the highest impact on ESBL-PE acquisition.
authors.affiliation: Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Ase
authors.initials: A
authors.lastname: Ostholm-Balkhed
authors.forename: Maria
authors.initials: M
authors.lastname: Tärnberg
authors.forename: Maud
authors.initials: M
authors.lastname: Nilsson
authors.forename: Lennart E
authors.initials: LE
authors.lastname: Nilsson
authors.forename: Håkan
authors.initials: H
authors.lastname: Hanberger
authors.forename: Anita
authors.initials: A
authors.lastname: Hällgren
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005260:Female; D005838:Genotype; D006801:Humans; D015994:Incidence; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D014195:Travel; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases
keywords: CTX-M; antibiotic resistance; travel medicine