Antimicrobial Susceptibility of Enterococcal Species Isolated from Antibiotic-Treated Dogs and Cats

In this study, we examined the antimicrobial susceptibility of the enterococci isolated from dogs and cats in Japan during 2011-2012. Fecal samples were collected from 84 dogs and 16 cats that underwent antibiotic treatment. Enterococci were detected in 70 of 84 dogs (83.3%) and 7 of 16 cats (43.8%). The most prevalent Enterococcus species was Enterococcus faecalis (64.9%); Enterococcus faecium and Enterococcus durans were also isolated from 14 of 77 (18.2%) and 5 of 77 (6.5%) of these animals, respectively. The most active resistance was observed for erythromycin (44.2%) and oxytetracycline (44.2%), and there was considerable resistance to lincomycin (41.6%), gentamicin (31.2%) and kanamycin (31.2%). Compared with the results of a similar study conducted in 2006 and 2007, enterococci susceptibility to enrofloxacin and ampicillin had significantly increased. Enterococcus gallinarum harboring vanC1 and Enterococcus casseliflavus harboring vanC2/3 were isolated from 4 of 77 enterococcal isolates. However, no enterococcal isolates were resistant to vancomycin. Multidrug resistance was found for as few as two and as many as nine antimicrobials regardless of the class. These results demonstrate that dogs and cats treated with antibiotics are commonly colonized with antimicrobial-resistant enterococci.