Occurrence of mastitis pathogens and their antibiotic resistance in dairy cows in Slovakia

Mastitis is a major health problem in dairy industry as well as a major threat to profitability of dairy farms. Mastitis is also the main reason for the application of antibiotic treatment during lactation or at dry period. The aim of our study was to determine the prevalence of the most common mastitis pathogens in dairy cows and the antibiotic resistance under the conditions of Slovak dairy farms in 2017-2023. The samples came from 52 samplings in 2017 (47 farms), from 32 samplings in 2018 (29 farms), from 31 samplings in 2019 (29 farms), from 44 samplings in 2020 (41 farms), from 40 samplings in 2021 (35 farms), from 33 samplings in 2022 (31 farms) and form 38 samplings in 2023 (35 farms). A total of 2236 quarter udder milk samples were collected. The milk samples were taken from dairy cows based on high somatic cell count or California mastitis test or visible abnormalities in milk. Up to 88.62% of the identified isolates were the Coagulase-negative staphylococci (36.89%) followed by <i>Escherichia coli</i> (24.26%), <i>Streptococcus uberis</i> (16.21%), <i>Staphylococcus aureus</i> (8.41%) and <i>Streptococcus agalactiae</i> (2.86%). The most effective antibiotic was amoxicillin/clavulanic acid and antibiotic with the highest resistance was streptomycin. In conclusion, identification of mastitis pathogens in dairy cows and detection of antibiotic resistance is very important for the mastitis treatment and prevention of antibiotic resistance.