Antimicrobial activity and antibiotic resistance of lactic acid bacteria isolated from Armada cheese (a Spanish goats' milk cheese)

Thirty-one lactic acid bacteria isolated from Armada cheese and previously selected in accordance with their technological properties, were screened for antimicrobial activity one against another. Four strains showed inhibitory activity against 14 strains when tested by well diffusion assay after the effects of organic acid and hydrogen peroxide were eliminated. Extracts of the strains did not show inhibitory activity after treatment with proteinase K, trypsin, α-chymotrypsin or pepsin. None of the strains showed antimicrobial activity against several pathogenic and spoilage reference strains. Eighteen representative strains were tested for their antibiotic resistance. None of the strains were totally susceptible to all antibiotics tested and multiple resistance was observed. Most of the tested strains were resistant to cefotoxin, oxacillin, vancomycin, teicoplanin, nitrofurantoin and trimethoprim.