Prevalence of CTX-M-Type Extended-Spectrum β-Lactamase-Producing <i>Escherichia coli</i> B2-O25-ST131 <i>H30</i> R Among Residents in Nonacute Care Facilities in Japan

Abstract

We investigated the prevalence and characteristics of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli among 258 residents of long-term care facilities (LTCFs) in Japan. Out of 258 fecal samples collected from nine LTCFs between November 2015 and March 2017, we recovered 59 ESBL-producing E. coli isolates. All isolates carried bla CTX-M genes, mainly bla CTX-M-27 (42.4%), bla CTX-M-14 (23.7%), and bla CTX-M-15 (18.6%). The isolates showed 7 serotypes (STs), including ST131 ( n = 49, 83.1%) and ST38 ( n = 4, 6.8%), and 47 (79.7%) out of 49 isolates belonging to ST131 were identified as H30 R. The 59 ESBL producers were divided into four groups, B2 (86.4%), D (8.5%), A (3.4%), and C (1.7%); 44 (74.6%) were epidemic clone B2-O25-ST131 H30 R, of which 21, 11, and 6 harbored bla CTX-M-27 , bla CTX-M-15 , and bla CTX-M-14 , respectively. Most plasmids were of IncF replicon types ( n = 33), and 22 bla CTX-M-27 -carrying plasmids showed multiple replicon types, including IncFII, FIA, and FIB. The ESBL producers were susceptible to imipenem, amikacin, and fosfomycin, but resistant to ceftazidime (49.2%), and ciprofloxacin (88.1%); in particular, the isolates harboring the bla CTX-M-15 gene showed significantly high resistance rate to ceftazidime ( p &lt; 0.01). Our findings indicate that a considerable proportion of the examined LTCF residents carried ESBL-producing E. coli isolates in feces and had high prevalence of epidemic clone B2-O25-ST131. Furthermore, continuous investigations would be very necessary to monitor actual carriage states of ESBL-producers among the LTCF residents from the viewpoint of both public health and healthcare viewpoints.