Isolation of streptogramin-resistant Enterococcus faecium from human and non-human sources in a rural community

OBJECTIVES: To detect quinupristin-dalfopristin and virginiamycin M1 resistance in Enterococcus faecium from human, food and environmental sources. MATERIALS AND METHODS: Enterococcal isolates derived from human faeces and urine, meat and seawater were screened for resistance to quinupristin-dalfopristin and virginiamycin M1 by an agar dilution method. Identification of all E. faecium strains and the presence of streptogramin acetyltransferase genes were confirmed using a PCR method. RESULTS: No high-level quinupristin-dalfopristin-resistant strains were isolated. Two isolates from faeces and five from seawater were confirmed to be high-level virginiamycin M1-resistant E. faecium (MIC 32 mg/L); none of these carried the vat(D) or vat(E) acetyltransferase genes that mediate high-level resistance to streptogramin A compounds. CONCLUSION: High-level quinupristin-dalfopristin-resistant strains of E. faecium are uncommon in Cornwall. However streptogramin A-resistant strains were detected from human and animal sources.