3,000 half-udder milk samples from 8 goats flocks reared in Sardinia were collected and analysed for mastitis pathogens. From 469 positive samples, 421 Coagulase Negative Staphylococci, 25 S. aureus, 4 Micrococcus spp, and 21 other species were isolated and identified. Four of the strains were not identified. Antibiotic susceptibility tests were carried out on 25 S. aureus and 75 CNS randomly selected strains. Minimum Inhibitory Concentrations (MICs) were determined by using the broth micro-dilution method according to the guidelines and standards of The Clinical and Laboratory Standards Institute (CLSI). The MIC values were compared to break- points of ampicillin (AMP), cephalothin (KF), cefoperazone (CFP), ceftriaxone (CRO), cloxacillin (OB), kanamycin (K), novobiocin (NV), ofloxacin (OFX), oxytetracycline (OT) and vancomycin (VA). More than 96 % or over of the strains were susceptible to all the antimicrobial agents tested, with the exception of AMP (70.0%), K (74.0%), OT (92.0%) and OFX (94.0%). The MIC90 for these antimicrobial agents were, respectively, 4.0, 0.25, 4.0, 8.0, 1.0, 64.0, 0.5, 1.0, 2.0 and 4 μg/ml. Multiple resistance was detected in 8 strains.
Antibiotic Susceptibility of Staphylococcus spp Strains Isolated from Sub-clinical Mastitis in Goat Milk / S., Virdis; G., Corgiolu; Scarano, Christian; A. L., Pilo; P., Marongiu; DE SANTIS, Enrico Pietro Luigi. - In: BULLETIN - FÉDÉRATION INTERNATIONALE DE LAITERIE. - ISSN 0250-5118. - (2007). ((Intervento presentato al convegno 5th International Symposium on the Challenge to Sheep and Goats Milk Sectors nel 18-20 april 2007.