Susceptibility to commonly used antiseptics such as dipping and the alternative use of alcoholic extract of propolis in mastitis pathogens and detection of Brucella spp. in samples from dairy cows housed in a compost barn system

Abstract

Mastitis and bovine brucellosis are two important diseases that burden dairy farming in Brazil and around the world. Mastitis is mainly caused by infectious pathogens such as Escherichia coli and Staphylococcus aureus, and is associated with the frequent and extensive use of antimicrobials in dairy cattle, which contributes to increased bacterial resistance. Brucellosis is a zoonotic disease that affects the reproductive tract of animals and is transmitted mainly through contact with contaminated fetal membranes and fomites. Due to the importance of these two diseases, one of the works carried out in this study evaluated the in vitro efficacy of antimicrobial agents frequently used as dipping to prevent bovine mastitis to sensitive and multidrug resistant (MDR) strains of S. aureus and E. coli. The second experiment evaluated the susceptibility of these MDR strains of S. aureus and E. coli to four alcoholic extracts of propolis, as an alternative antimicrobial compound for the prevention of mastitis. The third study investigated the presence of bovine brucellosis in dairy cows housed in a compost barn system, a type of intensive confinement for raising dairy herds, which consists of bedding with organic matter turned over daily. The results found in the first work demonstrate that in general, all strains of E. coli and S. aureus were susceptible at concentrations below those recommended for use for all antiseptics used as dipping, except for sodium hypochlorite. The increase in the minimum inhibitory concentration according to the year of isolation of the pathogens, suggesting the emergence of resistant strains in response to the selection pressure exerted by exposure to disinfectants. Results contained in the second work reveal the antimicrobial action of propolis extract at 5.0 mg/mL to inhibit most MDR isolates of E. coli and S. aureus. The third study demonstrated gene amplification specific forBrucella spp. in samples from [17/20 (85%)] properties that use the compost barn system for breeding. In conclusion, the findings of these experiments strongly suggest that continuous exposure to antiseptics can lead to the selection of less susceptible strains in dairy farming, in addition to indicating the potential of propolis extract for use as an antimicrobial agent for the control and prevention of bovine mastitis. Finally, it also demonstrated the presence of Brucella spp. in animals housed in a compost barn system.