Prevalence of ESBL/AmpC genes and specific clones among the third-generation cephalosporin-resistant Enterobacteriaceae from canine and feline clinical specimens in Japan

In recent years, besides the widespread occurrence of extended-spectrum beta-lactamase (ESBL)- and/or plasmid-mediated AmpC (pAmpC)-producing Enterobacteriaceae in both healthcare and community settings of humans, the third-generation cephalosporin (3GC)-resistant microbes have also been reported from companion animals worldwide. Here, we characterized ESBL- and/or pAmpC-producing Enterobacteriaceae clinical isolates from companion animals. Among the 487 clinical isolates mainly from urine of dogs and cats between May and September 2016, 104 non-repetitive isolates were resistant to the 3GC, and they consisted of 81 of 381 (21.3%) Escherichia coil, 21 of 50 (42.0%) Klebsiella pneumoniae, and 2 of 56 (3.6%) Proteus mirabilis isolates. In the 81 E. coil, the predominant bla genes were bla(CTX-M-27) and bla(CMY-2) (n = 15 each), followed by bla(CTX-M-15) (n = 14), bla(CTX-M-14) (n = 10), and bla(CTX-M-55) (n = 5). In 21 K. pneumoniae, 10 bIa gene types including bla(CTX-M-15) (n = 4), bla(CTX-M-2) (n = 4), and bla(CTX-M-14) (n = 3) were found. The bla(CTX-M-2) was identified in 2 P. mirabilis. Twenty-four of the 42 E. coil belonging to phylogroup B2 were O25b-ST131 clone, mostly associated with uropathogenic E. coil pathotype, and 22 isolates of this clone were identified as specific H30R subclone. High prevalence of the bla(CTX-M-27)-harboring isolates were noted among the H30R/non-Rx lineage (13/19, 68.4%) (p < 0.05). The genetic environment of bla(CTX-M-27) of most isolates of this lineage was identical to that of human isolates, but unique flanking genetic structures were also identified. Newly emerging virulent lineage B2-non-O25b-ST1193 was also confirmed in 5 isolates. The fosA3 and/or armA genes were detected in E. colt and K. pneumoniae isolates. These data suggest that companion animals serve as a potential reservoir of antimicrobial resistant E. colt and K. pneumoniae. This also has considerable veterinary importance, since urinary tract infections are an important disease causing therapeutic challenges worldwide.