The occurrence of virulence traits among high-level aminoglycosides resistant Enterococcus isolates obtained from feces of humans, animals, and birds in South Korea

Enterococcus isolates (1500) obtained from the feces of 48 humans, 209 domesticated food animals, and 155 wild geese in South Korea were characterized with respect to species status by PCR analyses and resistance to antibiotics. Of the 1500 strains examined, the majority (n = 577) were Enterococcus faecalis from 224 (54.4%) of the samples feces, while 299 were of E. faecium from 125 of the samples (30.3%), 224 were E. hirae from 101 (24.5%) of the samples, 94 were E. casseliflavus from 43 (10.4%) of the samples, and one was E. gallinarum. While 305 isolated from 125 (30.3%) of the samples were unidentified species. Approximately 15, 60, 50, 55, 3, and 40% of samples obtained from beef cattle, chickens, ducks, swine, wild geese, and humans, respectively, yielded Enterococcus isolates that were resistant to high-levels of aminoglycosides (i.e., of gentamicin, kanamycin, and streptomycin, minimum inhibitory concentrations were > 1000 mg/l). The 180 Enterococcus isolates that showed high levels of resistance to aminoglycoside antibiotics (HLAR) were screened for virulence genes encoding for aggregation substance (agg), cytolysin activator (cylA), gelatinase (gelE) and surface protein (esp). Of those, the gelE gene was found most frequently in chickens and ducks of the HLAR isolates, while 56 E. faecalis and 13 E. faecium HLAR were gelatinase positive and showed hemolysin activity. Multiple antibiotic resistant Enterococcus isolates carrying virulence genes were most frequently isolated from poultry and swine, and were mostly E. faecalis or E. faecium. These findings suggest that restriction of the use of antibiotics in food animal operations in South Korea, especially those involved in poultry and swine production would be desirable.