Biocide and antibiotic resistance of Enterococcus faecalis and Enterococcus faecium isolated from the swine meat chain.

In this study nine strains of Enterococcus faecalis and 12 strains of Enterococcus faecium, isolated from different sample types in the swine meat chain and previously characterized for the presence of antibiotic resistance genes, were examined for phenotypic tolerance to seven biocides (chlorexidine, benzalkonium chloride, triclosan, sodium hypochlorite, 2-propanol, formaldehyde and hydrogen peroxide) and resistance to nine antibiotics (ampicillin, vancomycin, gentamicin, kanamycin, streptomycin, erythromycin, clindamycin, tetracycline and chloramphenicol). Moreover, the presence of efflux system encoding genes qacA/B, qacC, qacE, qacEΔ1, emeA, and stress response genes, sigV and gsp65, involved in the tolerance to biocides, was analysed. Most strains were not tolerant to the biocides, but showed minimum inhibitory concentrations (MICs) higher than the recommended cut-off values for all the antibiotics tested, except for vancomycin and chloramphenicol.

Horizontal gene transfer among microorganisms in food: current knowledge and future perspectives.

The possibility of horizontal gene transfer (HGT) among microorganisms in food matrices has been specifically targeted in a few investigations, though most current knowledge has been obtained indirectly or derived from genome sequence analyses. In this review, we have assembled reported examples of the HGT events that probably occurred in food matrices since the bacterial partners involved are commonly found in association in a food matrix or are specifically adapted to it. Exchanged genes include those encoding for substrate utilization, bacteriocin, exopolysaccharide and biogenic amine (BA) production, immunity to bacteriophages and antibiotic resistance (AR).

Diversity of Streptococcus thermophilus in bacteriocin production; inhibitory spectrum and occurrence of thermophilin genes.

The bacteriocin-producing Streptococcus thermophilus strains that can dominate in natural dairy ecosystems, may also enhance safety in products obtained from natural cultures. In this study, we sought to identify bacteriocin production and bacteriocin genes in 75 strains of dairy and plant origin. The strains were tested for antimicrobial activity against pathogens or pathogen models, spoiling bacteria, and lactic acid bacteria associated with dairy products.

Molecular characterization and genotypic antimicrobial resistance analysis of Campylobacter jejuni and Campylobacter coli isolated from broiler flocks in northern Italy.

Genetic variability and genotypic antimicrobial resistance (AMR) of Campylobacter jejuni and Campylobacter coli from commercial broiler farms were investigated in this study. Campylobacter isolates were genetically characterized by random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) and flaA-SVR and flaB-SVR sequence-based typing. Eight RAPD types were identified in C.

Effect of chemico-physical parameters on the histidine decarboxylase (HdcA) enzymatic activity in Streptococcus thermophilus PRI60.

Unlabelled: In this study the activity of the histidine decarboxylase (HdcA) of Streptococcus thermophilus PRI60 was determined during growth and in crude enzyme preparations to evaluate its hazardousness in dairy products. The effect of different pH values, lactose availability, NaCl concentration, and growth temperature on histamine production was evaluated in M17 medium during 168 h incubation. In each case, the production of histamine increased concomitantly with the cell number with a relatively small further rise during the stationary phase.