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.