Slime production and DNase activity of Staphylococci isolated from raw milk

In this study, 851 Staphylococci isolates isolated from 38 raw milk samples were investigated for DNase activity and slime production. The 851 Staphylococci isolates were identified as 704 Staphylococcus aureus and 147 coagulase negative staphylococci. Coagulase - negative staphylococci isolates were classified as 32.7% S. cohnii, 19.7% S. hominis, 19.1% S. xylosus, 12.9% S. epidermidis, 8.2% S. capitis, 4.8% S. haemolyticus, 1.4% S. simulans and 1.4% S. saprophyticus by using Dichotomous scheme. DNase agar was used to investigate for DNase activity. DNase activity was found in 93.6% of 704 S. aureus and 10.2% of 147 coagulase - negative staphylococci. DNase activity was positive in 42.9% of S. haemolyticus, 20.7% of S. hominis,17.9% of S. xylosus and 2.1% of S. cohnii isolates. No DNase activity was found in S. epidermidis, S. capitis, S. simulans and S. saprophyticus isolates. Slime production of S. aureus and coagulase - negative staphylococci from raw milk samples was investigated by using Congo Red Agar method. Slime production was positive in 5.1% of S. aureus and 42.2% of 147 coagulase - negative staphylococci. Slime production was positive in 100% of S. simulans, 68.4% of S. epidermidis, 50% of S. cohnii, 50% of S. saprophyticus, 37.9% of S. hominis, 32.1% of S. xylosus and 16.7% of S. capitis isolates. None of the 7 S. haemolyticus isolates had slime production. In conclusion, slime production and DNase activity are important virulence factors to identify pathogenic staphylococci.