[Antibiotic resistance in Staphylococcus aureus mastitis in sheep, sheep milk and its products]

A study of current resistance to antibiotics was conducted in 500 strains of Staphylococcus aureus isolated from ewes with clinical and latent mastitis, from sheep milk and products made from it (sheep lumpy cheese, bryndza cheese). A diffusion disk method was used to assay 14 kinds of antibiotics (AMP, BAC, CEF, ERY, GEN, CMP, KAN, LIN, OXA, PEN, RIF, SPI, VAN, TET) and one chemotherapeutic drug (COT). The highest resistance was observed in the cases of clinical mastitis (from 8% and 10% in COT and KAN to 68% and 69% in PEN and TET). Resistance significantly decreased in 13 kinds of antibiotics in the group of cases with latent mastitis (from 3% in SPI to 30% in PEN), it increased in KAN (13%) and COT (12%) only. Resistance also decreased in bulk samples of sheep milk; it was the highest in PEN (27%) and AMP (17%) and the lowest in CEF, RIF and SPI (5%). Sheep lumpy cheese and bryndza cheese are mostly made from unpasteurized milk. Resistance continued to decrease even in these dairy products. It ranged from 2% in CEF to 16% in OXA in sheep lumpy sugar, while it varied from 0% in SPI to 14% in TET in bryndza cheese. The results demonstrate that sheep milk and products made from it are not any important sources of antibiotic resistance of S. aureus in Central Slovakia.