Streptogramin Resistance and Shared Pulsed-Field Gel Electrophoresis Patterns in vanA -Containing Enterococcus faecium and Enterococcus hirae Isolated from Humans and Animals in Spain

ABSTRACT

The present study was performed to determine if any of the 45 vanA-containing Enterococcus faecium or 18 vanA-containing E. hirae strains were shared by chickens (32 E. faecium/17 E. hirae) and humans (13 E. faecium/1 E. hirae) using pulsed field gel electrophoresis (PFGE) and to study quinupristin-dalfopristin (Q-D) resistance. Seven of the 45 E. faecium isolates (from 2 outpatients and from 5 poultry products) were resistant to Q-D (MIC ≥ 16 μg/ml); one strain was shown to have satA by PCR and sequencing and, in the other six isolates, the recently described satG gene was demonstrated. Six different PFGE patterns were detected among the 7 Q-D E. faecium-resistant isolates. None of the E. hirae isolates showed Q-D resistance. Among the 45 vanA-containing E. faecium strains, 25 unrelated clones were found by PFGE with highly diverse patterns and an indistinguishable PFGE pattern was observed in vanA-containing E. faecium strains from two humans and two poultry products. A single PFGE pattern was detected in 17 of 18 vanA-containing E. hirae isolates, obtained from one human and 16 chicken samples. Based on the presence of indistinguishable PFGE patterns among VR E. faecium and E. hirae from humans and chickens, we conclude that horizontal transfer of these strains could occur between both groups.