Detection of Escherichia coli Producing CTX-M-1-Group Extended-Spectrum beta-Lactamases from Pigs in Aichi Prefecture, Japan, between 2015 and 2016

作者：Norizuki Chihiro; Kawamura Kumiko; Wachino Jun ichi; Suzuki Masahiro; Nagano Noriyuki; Kondo Takaaki; Arakawa Yoshichika

来源：Japanese Journal of Infectious Diseases, 2018, 71(1): 33-38.

DOI：10.7883/yoken.JJID.2017.206

We investigated the prevalence and characteristics of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from Japanese pigs. A total of 345 pig fecal specimens were collected from 30 farms in the Aichi prefecture of Japan between June 2015 and April 2016, and 22 unique ESBL-producing E. coli were isolated from 16 samples spanning 8 farms. The ESBL types included CTX-M-15 (54.5%), CTX-M-55 (27.2%), CTX-M-3 (0.9%), and CTX-M-14 (0.9%). The predominant plasmid replicon type was IncN, and the isolates carried bla(CTX-M-55). Nine sequence type (ST)s, including ST117, ST1706, ST38, and ST10, were detected in the ESBL-producers, but no B2-O25-ST131 was found. ESBL producers were highly resistant to cefotaxime, ceftiofur, and tetracycline, but were susceptible to imipenem, amikacin, and fosfomycin (FOM), although 2 ST354 isolates showed resistance to ciprofloxacin. All 11 chloramphenicol-resistant isolates, including ST117 (n = 6) and ST38 (n = 3) isolates, harbored fioR, and the 2 FOM-resistant ST38 isolates harbored fosA3. Our results suggest that pigs do not act as direct reservoirs in the transmission of ESBL genes to E. coli in humans. However, ST117 E. coli carrying IncN-type plasmids mediating bla(CTX-M-55) were isolated from several different farms, suggesting the potential for future spread in Japan. Therefore, plasmid sequence analyses and continuous surveillance are necessary from an epidemiological point of view and are required to better protect against ESBL-producer transmission.

• 出版日期2018-1