title: Frequent acquisition of low-virulence strains of ESBL-producing Escherichia coli in travellers.
abstract: International travel is a risk factor for intestinal colonization with ESBL-producing Enterobacteriaceae (EPE). This prospective cohort study focuses on molecular features of and risk factors for travel-acquired EPE.
  
  
  
  Rectal swabs and survey data were collected from 188 Swedes travelling to four regions of high EPE prevalence. Samples were plated onto selective agars. ESBL producers were determined using phenotypic methods. Molecular characterization regarding virulence factors and phylogenetic grouping of ESBL-producing Escherichia coli was done using PCR. Isolates were also screened for the plasmid-mediated colistin resistance gene mcr-1.
  
  
  
  Among 175 pre-travel EPE-negative participants, 32% were positive upon return. No carbapenemase-producing Enterobacteriaceae were found, but one CTX-M-producing E. coli harboured mcr-1 (travel to Thailand). Most E. coli strains (43.1%) belonged to phylogroup A and were rarely associated with extraintestinal infections and a few (9.2%) expressed uropathogenicity pap genes. During 10-26 months of follow-up, no clinical infections were observed. Colonization rates varied by visited region: the Indian subcontinent, 49.2%; northern Africa, 44.0%; South-East Asia, 19.1%; and Turkey, 9.5%. Travellers' diarrhoea (OR 2.5, P = 0.04) or antimicrobial treatment during the trip (OR 5.9, P = 0.02) were both independent risk factors for EPE colonization.
  
  
  
  EPE acquired during travel have seemingly low pathogenicity, possibly indicating a low risk of clinical infection. Pre-travel advice should emphasize avoiding unnecessary antibiotic treatment during travel.
authors: Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden malin.vading@ki.se.|Department of Infectious Diseases, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
authors: M
authors: M
authors: Vading
authors: Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: M H
authors: MH
authors: Kabir
authors: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet, Stockholm, Sweden.
authors: M
authors: M
authors: Kalin
authors: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.
authors: A
authors: A
authors: Iversen
authors: Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet, Stockholm, Sweden.|Department of Infection Control and Hospital Hygiene, Stockholm County Council, Stockholm, Sweden.
authors: S
authors: S
authors: Wiklund
authors: Department of Infectious Diseases, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.|Department of Medicine Solna, Infectious Diseases Unit, Karolinska Institutet, Stockholm, Sweden.
authors: P
authors: P
authors: Nauclér
authors: Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.|Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.
authors: C G
authors: CG
authors: Giske
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001431:Bacteriological Techniques; D003091:Colistin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D012007:Rectum / Q000382:microbiology; D013548:Sweden / Q000453:epidemiology; D014195:Travel; D037521:Virulence Factors / Q000235:genetics; D055815:Young Adult; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D001618:beta-Lactamases; D003091:Colistin