Wide dissemination of extended-spectrum β-lactamase-producing Escherichia coli in community residents in the Indochinese peninsula Tatsuya Nakayama,1 Shuhei Ueda,2 Bui Thi Mai Huong,3 Le Danh Tuyen,3 Chalit Komalamisra,4 Teera Kusolsuk,4 Itaru Hirai,2 Yoshimasa Yamamoto1,5 1Global Collaboration Center, Osaka University, Osaka, Japan; 2Faculty of Medicine, University of The Ryukyus, Okinawa, Japan; 3National Institute for Nutrition, Hanoi, Vietnam; 4Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; 5Osaka Prefectural Institute of Public Health, Osaka, Japan Abstract: Recent studies have reported a widespread distribution of extended-spectrum β-lactamase (ESBL)-producing bacteria, not only in the nosocomial setting, but also in the community; some local communities in Southeast Asia have been reported to show a high prevalence of ESBL-producing bacteria. However, the details regarding the quantitative/qualitative state of ESBL-producing bacterial spread in Southeast Asia are currently unclear. Thus, the aim of this study was to assess the state of ESBL-producing bacterial spread in community residents from the Indochinese peninsula, as a representative region of Southeast Asia. In order to achieve this aim, local community residents in Laos and Vietnam were examined for fecal carriage of ESBL-producing Enterobacteriaceae, and the findings were compared with data from a previous study in Thailand which was conducted in the same manner as this study. Between 47.0%–70.2% of the Laotian and Vietnamese residents carried ESBL-producing CTX-M genotype Enterobacteriaceae. The most common sub-genotypes of CTX-M were CTX-M-1 (33.0%–47.5%) and CTX-M-9 (47.5%–64.1%), and these rates were similar among all three countries. Taken together, these results confirmed that ESBL-producing Enterobacteriaceae are widely disseminated in Indochinese countries, such as Thailand, Laos, and Vietnam. Keywords: extended-spectrum β-lactamase (ESBL), rural residents, Indochinese peninsula, fecal carriage