Microbiological quality and antimicrobial susceptibility of informally traded milk in Cruz das Almas county, Bahia

Abstract

The microbiological quality as well as the antimicrobial susceptibility of bacteria isolated from raw milk obtained from 25 food stores in Cruz das Almas, Bahia were evaluated. The analysis included counts of mesophilic and psicrotrophic microorganisms, molds and yeast, Staphylococcus spp., coagulase-positive Staphylococcus, coliforms (at 35ºC and 45ºC), and the presence of Salmonella spp. and Escherichia coli. The average count for mesophilic and psicrotrophic microorganisms, molds and yeast, and coliforms at 35°C and 45°C were 1.6 x 109 CFU.mL-1, 9.6 x 104 CFU.mL-1, 3.8 x 108 CFU. mL-1, 4.0 x 105 MPN.mL-1 and 3.8 x 105 MPN.mL-1, respectively. Coagulase positive Staphylococcus was found in 44% of the samples (mean value of 7.3 x 105 CFU.mL-1), and E. coli was present in 76% of them. Salmonella was not detected in any of the samples tested. E. coli showed resistance (57.9%) to tetracycline, to ampicillin and chloramphenicol (10.5%), and cephalotin (5.3%), while coagulase-positive Staphylococcus strains were resistant to amicacin (18%) and vancomicin (18%). The raw milk besides to present poor microbiological quality, becoming a health risk of the consumers, it may contribute to the dissemination of resistant bacteria to various antimicrobial agents.