Resistencia a metales pesados y antimicrobianos en cepas de enterococos aisladas de cerdos del Valle Inferior del Río Chubut - Argentina

The objective of this work was to determine the presence of virulence factors, heavy metal resistance and antibiotic in 65 Enterococcus strains isolated from fecal content of pigs, collected in the Valle Inferior del Rio Chubut. Exopolysaccharides production was the most frequent virulence factor and was detected in 45 strains, while gelatinase activity was displayed by only one strain; same result was obtained for hemolytic activity. Agar plates test revealed that 25 strains were resistant to zinc (≥12 mM) while 64 strains exhibited intermediate copper resistance (4-12 mM). All strains selected on the basis of their resistance to zinc exhibited resistance to tetracycline, two of them resistance to vancomycin and only one resistance to teicoplanin. All strains selected were sensitive to ampicillin. PCR techniques allowed the amplification of tetM gen in 22 strains among the 25 that showed resistance to tetracycline. The results obtained in this study would evidence the widespread usage of zinc and tetracycline as growth promoters in pig feeding. This practice exerts selective pressure in animal bacterial species and contributes to the spread of antibiotic resistance.