Epidemiology of Extended-Spectrum β-Lactamase Producing Escherichia coli in the Stools of Returning Japanese Travelers, and the Risk Factors for Colonization

ObjectiveTravel overseas has recently been considered a risk factor for colonization with drug-resistant bacteria. The purpose of this study was to establish the epidemiology and risk factors associated with the acquisition of drug-resistant bacteria by Japanese travelers.MethodsBetween October 2011 and September 2012, we screened the stools of 68 Japanese returning travelers for extended-spectrum β-lactamase (ESBL) producing Escherichia coli. All specimens were sampled for clinical reasons. Based on the results, the participants were divided into an ESBL-producing E. coli positive group (18 cases; 26%) and an ESBL-producing E. coli negative group (50 cases; 74%), and a case-control study was performed. Microbiological analyses of ESBL-producing strains, including susceptibility tests, screening tests for metallo-β-lactamase, polymerase chain reaction amplification and sequencing of blaCTX-M genes, multilocus sequence typing, and whole genome sequencing, were also conducted.ResultsIn a univariate comparison, travel to India was a risk factor (Odds Ratio 13.6, 95% Confidence Interval 3.0–75.0, pConclusionWe must be aware of the possibilities of acquiring ESBL-producing E. coli during travel in order to prevent the spread of these bacteria not only in Japan but globally.