title: Horizontal transfer of antibiotic resistance from Enterococcus faecium of fermented meat origin to clinical isolates of E. faecium and Enterococcus faecalis.
abstract: Enterococcus species are part of the normal intestinal flora of a large number of mammals including humans and consequently, they can be used as indicators of faecal contamination in food and water for human consumption. Their presence in large numbers in foods may indicate a lapse in sanitation and their ability to serve as a genetic reservoir of transferable antibiotic resistance is of concern. In the present study, Enterococcus spp., isolated from commercially fermented meat and human clinical specimen were studied to determine genetic relationships. SmaI pulsed-field gel electrophoresis (PFGE) patterns exhibited genomic heterogeneity within and between both groups of isolates. However, in spite of this heterogeneity there were still substantial phenotypic similarities which suggested that food might be a potential vehicle for distribution of resistant bacteria among humans. In vitro conjugation experiments demonstrated transfer of the tetracycline resistant determinant, tet(M), from Enterococcus faecium S27 isolated from fermented sausage to clinical isolates of both E. faecium and Enterococcus faecalis. The streptomycin resistance of E. faecium S27 was also transferred to a clinical strain, E. faecalis 82916, which was confirmed by the presence of the streptomycin resistance gene, aadA, in the donor and transconjugant strains. Since the aadA gene is associated with a class 1 integron, results also suggested that resistance transfer might have occurred via an integron. It appears this is the first identification of a class 1 integron in E. faecium isolated from food. The importance of food enterococci as a reservoir of antibiotic resistance genes and the potential for their genetic transfer to human strains following consumption of uncooked or undercooked contaminated meat is underlined by this work.
authors: Department of Food Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors: Musarrat
authors: M
authors: Jahan
authors: Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3E 3P5, Canada.
authors: George G
authors: GG
authors: Zhanel
authors: Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors: Richard
authors: R
authors: Sparling
authors: Department of Food Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. Electronic address: rick_holley@umanitoba.ca.
authors: Richard A
authors: RA
authors: Holley
mesh_terms: D000818:Animals; D004352:Drug Resistance, Microbial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D013293:Enterococcus faecalis / Q000235:genetics*; D016984:Enterococcus faecium / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D022761:Gene Transfer, Horizontal; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology* / Q000635:transmission; D006801:Humans; D032023:Integrons / Q000235:genetics; D008460:Meat / Q000382:microbiology*
keywords: Antibiotic resistance transfer; Enterococci; Integron; PFGE