Determinants of Infection as Genetic Indicators in Cows Mastitis

Abstract

The resistance to antimicrobial substances severely impacts public health and the abuse of antibiotics leads to antimicrobial resistance (AMR) or the antibiotic "resistome" (Wright, 2007). Bovine mastitis is largely diagnosed in dairy farms and is caused by a variety of pathogens including Streptococcus spp., Staphylococcus spp. and Escherichia coli. AMR gene expression testing in bacteria involved in mastitis in dairy cows was performed. Milk samples were subjected to the California Mastitis Test. Positive samples were transferred using eSwab, cultured on Columbia blood agar and on MacConkey agar. The Qiagen DNeasy kit was used for DNA extraction and qPCRs were run using an Agilent thermocycler. In most of the samples tested (n = 42, from three different lactating farms), the presence of ampC (36 out of 42; 85.7%) and blaZ (95.2%), correlated with confirmed resistance to beta-lactam and cephalosporin antibiotics. A variable presence of other tested AMR genes was detected, including ermB, resistance to lincosamide, macrolide (35.7%), ermC (28.6%), erythromycin resistance, mecA,methicillinresistance (42.9%), and tetK, tetracyclineresistance (78.6%). The phenomenon of antimicrobial resistance is present in dairy farms in West Romania. Multiple AMR genes were detected intested samples, with the highest resistance observed to beta-lactam antibiotics and cephalosporins.