Occurrence and antimicrobial sensitivity in staphylococci isolated from goat, sheep and cow’s milk

Abstract

The aim of this study was to compare the sensitivity to selected antibiotics in staphylococci isolated from goat (n = 60), sheep (n = 60) and cow’s milk (n = 120). The individual milk samples were inoculated onto Blood agar cultivated at 36 °C/24 h.The isolated species of staphylococci were identified using biochemical tests, namely STAPHYtest and identification program TNW pro 6.5. We examined the sensitivity of strains to the spectrum of antibiotics, as follows: vancomycin (VA), amoxicillin/clavulanic acid (AMC), penicillin (P), rifampicin (RD), oxacillin (OX), tetracycline (TE), erythromycin (E), chloramphenicol (C), clindamycin (DA), gentamicin (CN), ciprofloxacin (CIP), teicoplanin (TEC), cefoxitin (FOX) and novobiocin (NOV). Altogether, 97 staphylococcal isolates were obtained; 70 from cow’s milk, 11 from goat’s milk and 16 from sheep’ milk. Staphylococcus aureus was the most frequent species in milk of all animal origin tested, was detected in 54 (45%) cow’s milk, 10 (17%) goat’s and 15 (25%) sheep’ milk samples. S. lentus was identified only in goat’s and sheep’ milk whereas in cow’s milk there were representation of staphylococcal species as follows: S. haemolyticus (n = 7), S. chromogenes (n = 2), S. warneri (n = 2), S. xylosus (n = 2), S. epidermidis (n = 2) and unclassified staphylococci (n = 1). The results of S. aureus sensitivity are similar for all tested antibiotics and for all monitored milk: No resistance to vancomycin, rifampicin, chloramphenicol and teicoplanin was recorded in obtained S. aureus isolates whereas the resistance to ciprofloxacin was found out most often.

Keywords

• milk
• <i>Staphylococcus</i> spp.
• antibiotics