The genus Enterococcus has an exceptional ability to acquire and transmit antibiotic resistance genes and is considered to be a major vector in their dissemination. Enterococci are part of the normal gut microbiota of humans and animals and are frequently encountered in food products including dry fermented sausage. Since fermented sausages are not heat-treated before consumption they might be a vehicle for transmitting resistance and virulence traits of enterococci by conjugation with commensal bacteria present in the human gut and pathogenic bacteria that might be present, such as Listeria species. A PCR-based assay was developed to detect enterococci in dry fermented sausage meat at the generic level by targeting a 16S rRNA sequence and a total of 29 Enterococccus strains (15 E. faecalis, 13 E. faecium, and one E. gallinarum) were identified. The susceptibility of these enterococci to antibiotics was tested and it was found that 27/29 were resistant to more than one antibiotic and possessed antibiotic resistance determinants. All strains were positive for at least one virulence gene. Strong biofilm formation occurred at lower than optimum temperature in all three species of enterococci and probably contributed to their survival in the harsh conditions experienced during dry sausage fermentation and drying. SmaI pulsed-field gel electrophoresis (PFGE) patterns exhibited genomic heterogeneity within and between the two larger groups of isolates. In spite of this heterogeneity, the phenotypic similarities observed suggested that food could still be a vehicle for distribution of antibiotic resistant bacteria among humans. In vitro conjugation experiments demonstrated transfer of the tetracycline resistant determinant, tet(M), from E. faecium S27 isolated from fermented sausage to clinical isolates of both E. faecium and E. 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. E. faecium S27 also transferred tet(M) and streptomycin resistance to Listeria monocytogenes GLM-2 by in vitro mating. Evidence suggests that enterococci in fermented meats may contribute to the spread of resistance determinants. / October 2015
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/30656 |
| Date | January 1900 |
| Creators | Jahan, Musarrat |
| Contributors | Holley, Richard (Food Science), Zhanel, George (Medical Microbiology) Sparling, Richard (Microbiology) Khafipour, Ehsan (Medical Microbiology) LaPointe, Gisèle (Food Science, University of Guelph) |
| Publisher | Elsevier Limited |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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