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Updated: Feb 15, 2026

Evaluation of Microbial Safety of Dairies using Bacterial Proteomic Profiling via MALDI Approach
Published on: October 7, 2025
Identification and antimicrobial suceptibility profile of bacteria causing bovine mastitis from dairy farms in
C H Freitas1, J F Mendes2, P V Villarreal1
1Laboratório de Micologia e Bioprospecção, Programa de Pós-Graduação em Parasitologia, Departamento de Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas - UFPel, Av. Eliseu Maciel, CEP 96160-000, Capão do Leão, RS, Brazil.
Abstract:
Mastitis is an inflammatory process of the udder tissue caused mainly by the bacteria Staphylococcus aureus. The indiscriminate use of antibiotics fosters conditions that favor the selection of resistant microorganisms, suppressing at the same time susceptible forms, causing a serious problem in dairy cattle. Given the importance in performing an antibiogram to select the most adequate antimicrobial therapy, the aim of this study was to identify bacteria isolated from cow's milk with mastitis, in dairy farms situated in the city of Pelotas, Rio Grande do Sul, and to determinate the susceptibility profile of these isolates against the antibiotics used to treat this illness. A total of 30 isolates of Staphylococcus spp., were selected from milk samples from the udder quarters with subclinical mastitis whose species were identified through the Vitek system. The susceptibility profile was performed by the disk diffusion assay, against: ampicillin, amoxicillin, bacitracin, cephalexin, ceftiofur, enrofloxacin, gentamicin, neomycin, norfloxacin, penicillin G, tetracycline and trimethoprim. In the antibiogram, 100.0% of the isolates were resistant to trimethoprim and 96.7% to tetracycline and neomycin, three strains of Staphylococcus spp., (10.0%) presented resistance to the 12 antibiotics tested and 24 (80.0%) to at least eight. These results showed the difficulty in treating mastitis, due to the pathogens' resistance.
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