title: Antimicrobial susceptibility of Staphylococcus aureus causing bovine mastitis in Argentine dairy herds.
abstract: We assessed the in vitro activity of selected antimicrobial agents against 95 Staphylococcus aureus strains causing both clinical and subclinical bovine mastitis belonging to 61 dairy farms from the Central dairy area of Argentina. Minimal inhibitory concentrations (MICs) of penicillin, oxacillin, gentamicin, erythromycin, enrofloxacin and florfenicol were estimated. In addition, the agar diffusion test was performed. MIC50 and MIC90 were as follows: penicillin, 0.05 and 4 microg/ml; oxacillin, 0.25 and 0.25 microg/ml; gentamicin, 0.25 and 0.5 microg/ml; erythromycin 0.125 and 0.25 microg/ml; enrofloxacin 0.25 and 0.5 microg/ml, and florfenicol 4 and 8 microg/ml. Beta-lactamase activity was detected in 89% of 46 penicillin-resistant strains. Apart from penicillin, antimicrobial resistance in S. aureus causing bovine mastitis remains rare in Argentine dairy farms.
authors.affiliation: Facultad de Ciencias Veterinarias, Universidad Nacional del Litoral, Rvdo. Padre Kreder 2805 (3080) Esperanza, Pcia. de Santa Fe, Argentina.
authors.forename: N B
authors.initials: NB
authors.lastname: Russi
authors.forename: C
authors.initials: C
authors.lastname: Bantar
authors.forename: L F
authors.initials: LF
authors.lastname: Calvinho
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001118:Argentina; D002417:Cattle; D003612:Dairying; D008414:Mastitis, Bovine / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents