Caracterização molecular e sensibilidade a antimicrobianos de Listeria monocytogenes isoladas de carcaças bovinas no sul do Brasil

Abstract

Listeria monocytogenes is a foodborne pathogen that can cause listeriosis, both in humans and in animals. The contamination by this microorganism is difficult to control, given its wide dissemination and physiological adaptability, which allow its development under conditions which are usually unfavorable to other pathogenic bacteria. Therefore, this pathogen has become of concern to the food industry as well as consumers, since it is highly pathogenic, especially in relation to risk group and may be fatal in 30% of cases of listeriosis. Although any isolate of L. monocytogenes can be considered potentially pathogenic for humans, several studies suggest that this micro-organism has a heterogeneous pathogenicity of the strains, which makes it essential to know the gene expression of the pathogen can be understood that the differences in their virulence mechanisms, and how different potential pathogenicity. The present study aimed to verify the occurrence of. L. monocytogenes in slaughterhouses in southern Rio Grande do Sul, and through the isolates, assess their sensitivity to antibiotics, and perform a genotypic characterization by verifying the presence of virulence genes. L. monocytogenes occured in 6% of the samples, detected after bleeding at the point where the collect was held in the leather of the animal, and point 4 (pre-cooling after washing).Twelve isolates were obtained, which were evaluated for sensibility to 15 antimicrobials, of which 100% were susceptible to most antibiotics tested. Resistance to gentamycin (8%), ampicilin (8%), kanamycin (8%) and sulfonamide (83%) were observed in some isolated of L. monocytogenes. Intermediate susceptibility to clindamycin (60%) and erythromycin (8%) was observed, and multidrug-resistant strains were also observed. Proceeded to evaluate the presence of virulence genes (hlyA, plcA, inlA, inlB, inlC, inlJ, plcB, iap, actA, mpl and PrfA) and, through the results of PCR, it was observed that all isolates possessed the evaluated genes, also confirmed the expression of the gene of internalin A by RT-PCR, showing the potential pathogenic strains of L. monocytogenes isolated from food in southern Brazil.