Duration of travel-associated faecal colonisation with ESBL-producing Enterobacteriaceae - A one year follow-up study

Background In a previous study, we found that 30% of individuals travelling outside Scandinavia acquired extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) in their faecal flora. The aim of this study was to determine the duration of travel-associated faecal colonisation with ESBL-PE, to assess risk factors for prolonged colonisation and to detect changes in antibiotic susceptibility during prolonged colonisation. Methods Individuals with travel-associated colonisation with ESBL-PE submitted faecal samples every 3rd month over a one-year period. A questionnaire was completed at the beginning and end of follow-up. All specimens were analysed for ESBL-PE, and all isolates underwent confirmatory phenotype testing as well as molecular characterisation of ESBL-genes. Minimum inhibitory concentrations (MIC) for beta-lactam and non-beta-lactam agents were determined using the Etest. Results Among 64 participants with travel-associated colonisation with ESBL-PE, sustained carriage was seen in 20/63 (32%), 16/63 (25%), 9/63 (14%) and 7/64 (11%) at 3, 6, 9 and 12 months after return from their journey, respectively. The majority, 44 (69%) of travellers were short-term carriers with ESBL-PE only detected in the initial post-travel stool sample. Evaluation of risk factors demonstrated a decreased risk of becoming a long-term carrier among travellers with diarrhoea while abroad and a history of a new journey during the follow-up period. High susceptible rates were demonstrated to carbapenems (97-100%), temocillin (95%), mecillinam (97%), amikacin (98%), fosfomycin (98%), nitrofurantoin (99%) and tigecycline (97%). Conclusion Travel-associated faecal colonisation with ESBL-PE appears to be transient and generally brief. Diarrhoea while abroad or a new trip abroad during the follow-up period decreased the risk of becoming a long-term carrier. Only 11% of travellers who acquired ESBL-PE during their travels had sustained colonisation 12 months after return.