Travel-associated faecal colonization with ESBL-producing Enterobacteriaceae: incidence and risk factors

To study the acquisition of extended-spectrum -lactamase-producing Enterobacteriaceae (ESBL-PE) among the faecal flora during travel, with a focus on risk factors, antibiotic susceptibility and ESBL-encoding genes. 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. 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, P0.001), Asia (OR 8.63, P0.001) and Africa north of the equator (OR 4.94, P0.002). 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. 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.