Coagulase gene polymorphism and antimicrobial susceptibility of Staphylococcus aureus isolated from bovine subclinical mastitis milk in Sidi-Bel-Abbes, Algeria

Abstract

The study was conducted to identify and characterize Staphylococcus aureus in raw milk derived from subclinical mastitis in Sidi-Bel-Abbes Algeria. In this paper, we explore the possibility of detection of the coagulase gene (coa), which encodes the coagulase enzyme, by PCR analysis in antibiotic-resistant isolates, with the latex agglutination phenotype and free coagulase.Out of 336 samples of raw milk examined with California mastitis test (CMT) posi-tive; a total of 142 samples were bacteriologically positive with 56.34% Staphylococcus isolates, 21 (26.25%) isolates were confirmed as S.aureus. Nineteen (90.48%) isolates of S.aureus showed free coagulase on the tube agglutination test. Two atypical S.aureus strains (9.52%) were defective for the clumping factor and / or protein A , determined with the Staphytect plus test and the tube coagulase test. The isolates of S.aureus were resistant to penicillin and tetracycline with 76.19%. Two isolates (9.52%) of S.aureus re-sistant to meticillin (MRSA) were detected in this study, with a MIC of ≥4 μg / liter and a cefoxitin screen test with a MIC of ≥8 μg / liter, and 13 (61.9%) isolates were with a multiresistance phenotype. The 21 isolates were sub-jected to PCR amplification of the 3' end of the coa gene, 18 (85.71%) were revealed on a 1% agarose gel with a single band between 547 bp and 875 bp. The use of the PCR genotypic test to identify the profile of the coa gene can be used as an appropriate identification criterion for differentiating coagulases from S.aureus and for understanding their epidemiology.