Resumo

Bacteria of the genus Enterococcus are lactic acid bacteria found in different environments, they grow and survive in adverse conditions. In foods, they may be used as starter cultures, probiotic or adjuvant technology. Until recently, bacteria were considered of low virulence. However, they assumed clinical importance and are now considered “opportunistic pathogens” in foods. Therefore, new isolates should be evaluated for virulence factors before use. The aim of the present study was to evaluate the antibiotics susceptibility and the activity of β-hemolysin of isolates of enterococci with probiotic and bacteriocinogenic potential from milk and artisan cheeses from the Northwestern Frontier region of RS. The evaluation of the antimicrobial sensitivity of the isolates was performed by the disk diffusion method, using Mueller-Hinton agar. Four antibiotics were used: ampicillin, penicillin G, vancomycin and tetracycline. The level of susceptibility to antibiotics was reported as resistant, intermediate or sensitive. The activity of the enzyme β-hemolysin was verified by visualization of clear zones around the colonies grown on blood agar. It can be noticed that all isolates demonstrated sensitivity to ampicillin, 87.5% to tetracycline, 75% to 50% for vancomycin and penicillin, respectively. The highest resistance was observed for penicillin, where a all isolates with bacteriocinogenic characteristics (50%) were resistant to this antibiotic. All isolates with probiotic characteristics were sensitive to all antibiotics tested. Some authors report that few Enterococci isolated from food are resistant to antibiotics from clinical and that isolates of the hospital environment have higher frequency of virulence factors. In this study, no isolates showed activity of the enzyme β-hemolysin. This is one of the phenotypic characteristics commonly used as a marker of pathogenicity. Although the absence of this enzyme activity does not necessarily mean that the isolate does not have pathogenic potential in sight there can be other virulence factors. The absence of these virulence factors combined with the probiotic and bactericinogenic potential suggests that these isolates may be used as starter cultures in food. Additional tests should be conducted to confirm the safety of these isolates.