Staphylococcus aureus of raw cow's milk

Abstract

The presence of Staphylococcus aureus in raw milk is considered a direct danger to consumers. Almost all types of dairy products normalize the amount of Staphylococcus aureus in 1 g (cm3) of product, due to their ability to produce thermostable enterotoxins. The aim of the study was to investigate the role of incision of teats of healthy and sick mastitis cows and milking equipment for irradiation of cow's milk with Staphylococcus aureus. Sanitation of milking equipment in farms was carried out with alkaline detergents based on sodium hypochlorite and acid based on phosphoric acid. Blood agar with 5 % sodium chloride was used to isolate staphylococci from washes and milk. Species identification of pure cultures of staphylococci was performed using RapID Staph Plus kits. At the same time before and after milking the skin of teats with Udder Wash and Udder Forte reduces the incidence of Staphylococcus aureus to 4.1 ± 0.3 % of cases. Quantitative determination of staphylococci, including golden on the skin of the teats revealed a decrease in the latter from 283.5 ± 21.2 to 27.6 ± 2.1 CFU/cm3 flush after milking. It has been established that the number of staphylococci, including golden, on the skin of teats increases sharply under subclinical or clinical ointment. Thus, it was found that in the subclinical form of staphylococcal mastitis from the skin of teats isolated S. aureus in the amount of 790.6 ± 65.4 CFU/cm3 of wash. At the same time, in the clinical form of mastitis, the amount of S. aureus increased, on average to 8 thousand CFU/cm3 of flush. It was found that under the condition of sanitary treatment of milking equipment with alternate use of alkaline and acid detergents and disinfectants, only 25 % of washes were staphylococci, and gold – up to 5 % of samples. It was found that in 43.7 ± 3.9 % of raw milk samples Staphylococcus aureus was not detected in 1 cm3. The number of milk samples containing Staphylococcus aureus up to 100 CFU/cm3 was 39.1 ± 3.3 %, and 17.2 ± 1.4 % of milk samples were contaminated with Staphylococcus aureus in the amount of 101 to 200 CFU/cm3. Therefore, the presence of more than 200 CFU/cm3 in freshly milked Staphylococcus aureus in milk indicates the ineffectiveness of antimastitis measures, skin remediation of teats and sanitation of milking equipment.