The slime production by yeasts isolated from subclinical mastitic cows

The aim of this study was to isolate yeasts from subclinical mastitic cows and to investigate the slime production by the isolated yeasts. The material used in this study included 339 milk samples from 152 dairy cows with subclinical mastitis. Milk was plated onto blood agar, MacConkey agar and Sabouraud dextrose agar. Forty-one samples were found positive for the yeast by API 20 C AUX identification system. The isolated yeasts were classified into four genera: Candida, Trichosporon, Cryptococcus and Saccharomyces. The following Candida species were determined: C. krusei, C. kefyr, C. guilliermondii, C. famata, C. rugosa and C. utilis. Other yeasts were identified as Trichosporon mucoides, T. asahii, Cryptococcus laurentii, C. neoformans and Saccharomyces cerevisiae. C. krusei and C. kefyr were the most common isolated strains. Slime production was tested on Congo red brain heart infusion agar and evaluated according to Congo red phenomenon. Fifteen strains (36.6%) were slime factor positive: seven were C. krusei, four C. kefyr, one C. guilliermondii, one C. famata, one T. asahii, and one C. laurentii. The strong slime production found in some strains can lead to serious problems during the therapy.