Antibiotic resistance patterns and genetic relatedness of enterococcus faecalis and E. faecium isolated from military working dogs in Korea

Abstract

Enterococcus spp. are normally present in the gastrointestinal tracts of animals and humans, but can cause opportunistic infections that can be transmitted to other animals or humans while harboring antibiotic resistance genes. To investigate whether this is a potential risk for handlers of military working dogs (MWDs), we analyzed antibiotic resistance patterns and genetic relatedness of Enterococcus spp. isolated from fecal samples of MWDs of various ages (n = 65). The isolation rate of Enterococcus spp., and specifically of E. faecalis and E. faecium, was 87.7% (57/65), 59.6% (34/57), and 56.1% (32/57), respectively, as determined by bacterial culture and multiplex PCR. The isolation rate of E. faecalis gradually decreased with age. Rates of resistance to the antibiotics ciprofloxacin, gentamycin, streptomycin, sulfamethoxazole–trimethoprim, imipenem, and kanamycin among Enterococcus spp. increased in adolescents and adults and decreased in senior dogs, with some isolates showing three different antibiotic resistance patterns. We also confirmed transmission of antibiotic resistant strain by pulsed-field gel electrophoresis. These results suggest that antibiotic resistance genes are transmitted among MWDs and that surveillance studies should be periodically carried out to monitor changes in antibiotic resistance that may necessitate modification of antibiotic regimens to manage antibiotic resistance transmission.