In vitro evaluation of the sensitivity of strains ofStaphylococcus spp. isolated from goat mastitis against commercial disinfectants

Abstract

The use of disinfectants in the prophylaxis of mastitis is a practice adopted in its control program. The use of post milking teat antisepsis (post-dipping) has been shown to reduce the rates of mammary infections by reducing the colonization by microorganisms on the skin of the teats. The aim of this study was to evaluate the in vitro susceptibility of 101 strains ofStaphylococcus spp. isolated from goat mastitis against four disinfectants: iodine 2, 1 and 0.5%, sodium hypochlorite 2.5, 1.25 and 0.62%, chlorhexidine 2.0, 1.0 and 0.5% and quaternary ammonia 0.68, 0.34 and 0.17%. It was found that all concentrations of disinfectants were effective for complete removal of the agent at the times of 30 and 60 minutes. We observed the following percentages of resistance to disinfectants: 15.8% to iodine in a 0.5% concentration; 10.8% to sodium hypochlorite (0.62%) and 7.9% to the quaternary ammonium (0. 17%). Chlorhexidine has demonstrated to eliminate 100% of the strains of staphylococci in vitro, at all times and concentrations tested, showing a broad spectrum of action without causing irritation to the skin of animals. As it provides a low cost disinfection, it becomes an economically viable product to be used in the goat mastitis control program.