Antibiogram and antibiotic resistance genes among coagulase-negative staphylococci recovered from bovine mastitis

Abstract

Coagulase-negative Staphylococci (CoNS) have emerged as an important Staphylococci species implicated in bovine mastitis in dairy herds. This study was conducted to determine the prevalence, antibiogram, and antibiotic resistance genes among coagulase-negative Staphylococci recovered from cattle suffer from subclinical mastitis in Egypt. A total of 110 (36.7%) milk samples collected from 300 lactating cows were positive for the California mastitis test. On the Mannitol Salt Agar medium, out of 110 subclinical mastitis samples 62 (56.36%) were identified as CoNS isolates. Antibiotic sensitivity test conducted against nine types of antibiotics for CoNS strains that exhibited high susceptibility to most of the tested antibiotics, with particularly resistance pattern to oxicillin (41.9 %), and 11 (17.7%) CoNS isolate exhibited multidrug resistance (MDR). A total of 15 randomly selected isolates were subjected for detection of antibiotic-resistant genes among CoNS. The results indicated that mecA (73.3%) was the most identified gene, followed by tetK (60%) and ermB (13.3%) genes, whereas no detection for blaZ and vanA genes. In conclusion, our results indicate the importance of the regular surveillance of phenotypic and genotypic profiles of CoNS, isolates to ensure effective control measures and minimize the evolution of MDR strains and recommended the applying of antibiotic sensitivity test before treatment or random selection of antibiotics in field cases to avoid the emerging of resistance phenomena.