Prevalence of glycopeptide and aminoglycoside resistance in Enterococcus and Listeria spp. in low microbial load diets of neutropenic hospital patients

Low microbial load diets for patients with haematological malignancy were examined for enterococci and listeria using pre-enrichment, enrichment and selective plating. Enterococci were highly prevalent and their ecology diverse; 100/211 samples yielded 132 isolates made up of 67 strains distinguishable by PFGE. Listeria monocytogenes was not found. Screening of enterococci for antibiotic resistance showed low level vancomycin resistance (6–12 μg/ml) in six isolates of E. gallinarum and high level streptomycin resistance (≥1000 μg/ml) in eight isolates from various foods. No strains showing high level glycopeptide or gentamicin resistance were found. The high prevalence of enterococci in food processed for safety indicates a possible route for the acquisition of antibiotic-resistant strains by vulnerable hospital patients.