Comparison of antimicrobial resistance phenotypes and resistance genes in Enterococcus faecalis and Enterococcus faecium from humans in the community, broilers, and pigs in Denmark

Enterococcus faecalis and E. faecium isolated from humans in the community (98 and 65 isolates), broilers (126 and 122), and pigs (102 and 88) during 1998 were tested for susceptibility to 12 different antimicrobial agents an d for the presence of selected genes encoding resistance using PCR. Further more, the presence of vancomycin resistant enterococci was examined in 38 h uman stool samples using selective enrichment. Widespread resistance to chl oramphenicol, macrolides, kanamycin, streptomycin, and tetracycline was fou nd among isolates from all three sources. All E. faecium isolates from huma ns and pigs were susceptible to avilamycin, whereas 35% of isolates from br oilers were resistant. All E. faecium isolates from humans were susceptible to vancomycin: whereas 10% and 17% of isolates from broilers and pigs. res pectively, were resistant. A vancomycin resistant E. faecium isolate was fo und in one of the 38 human fecal samples examined using selective enrichmen t. All vancomycin resistant isolates contained the vanA gene, all chloramph enicol resistant isolates the cat(pIP501) gene, and all five gentamicin res istant isolates the aac6-aph2 gene. Sixty-one (85%) of 72 erythromycin resi stant E. faecalis examined and 57 (90%) of 63 erythromycin resistant E. fae cium isolates examined contained ermB. Forty (91%) of the kanamycin resista nt E. faecalis and 18 (72%) of the kanamycin resistant E. faecium isolates contained aphA3. The tet(M) gene was found in 95% of the tetracycline resis tant E. faecalis and E. faecium isolates of human and animal origin, examin ed. tet(K) was not observed, whereas tet(L) was detected in 17% of tetracyc line resistant E. faecalis isolates and in 16% of the E. faecium isolates. tet(O) was not detected in any of the isolates from pigs, but was observed in 38% of E. faecalis isolates from broilers, in two E. faecalis isolates f rom humans and in three E. faecium isolates from broilers. tet(S) was not d etected among isolates from animals, but was observed in 31% of E. faecalis and one E. faecium isolate from humans: This study showed a frequent occur rence of antimicrobial resistance and the presence of selected resistance g enes in E. faecalis and E. faecium isolated from humans, broilers and pigs. Differences in the occurrence of resistance and tetracycline resistance ge nes were observed among isolates from the different sources. However, simil ar resistance patterns and resistance genes were detected frequently indica ting that transmission of resistant enterococci or resistance genes takes p lace between humans, broilers, and pigs. O 2000 Elsevier Science Inc. All r ights reserved.