Epidemiology of extended-spectrum β-lactamase producing Escherichia coli in the stools of returning Japanese travelers, and the risk factors for colonization.
OBJECTIVE
Travel 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.


METHODS
Between 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.


RESULTS
In a univariate comparison, travel to India was a risk factor (Odds Ratio 13.6, 95% Confidence Interval 3.0-75.0, p<0.0001). There were no statistical differences in the characteristics of the travel, such as backpacking, purpose of travel, interval between travel return and sampling stool, and duration of travel. Although 10 of 13 analyzed strains (77%) produced CTX-M-15, no ST131 clone was detected.


CONCLUSIONS
We 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.
Department of Infectious Diseases, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Kenichiro
K
Yaita
Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan.
Kotaro
K
Aoki
Department of Infectious Diseases, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Takumitsu
T
Suzuki
Department of Infectious Diseases, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Kazuhiko
K
Nakaharai
Department of Infectious Diseases, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Yukihiro
Y
Yoshimura
Department of Infectious Diseases, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan.
Sohei
S
Harada
Department of Microbiology and Infectious Diseases, Toho University School of Medicine, Tokyo, Japan.
Yoshikazu
Y
Ishii
Department of Infectious Diseases, Yokohama Municipal Citizen's Hospital, Yokohama, Japan.
Natsuo
N
Tachikawa
D000328:Adult; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D014195:Travel; D001618:beta-Lactamases / Q000235:genetics* / Q000302:isolation & purification
C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases