Date of Defense
Jeffrey L. Watts, Pharmacia & Upjohn
Silvia Rossbach, Biological Sciences
Susan F. Kotarsky, Pharmacia & Upjohn
Minimum inhibitory concentrations were determined with 700 strains of Staphylococcus aureus isolated from cases of bovine mastitis in nine countries. The countries and number of isolates included England (92), Finland (95), Germany (103), Iceland (22), Ireland (42), Norway (101), Sweden (123), Switzerland (69), and United States (53). The antimicrobial agents tested were ampicillin, oxacillin, cephalothin, ceftiofur, amoxicillin+clavulanate, penicillin+novobiocin, erythromycin, lincomycin, clindamycin, pirlimycin, neomycin, and premafloxacin. The MIC90 for these antimicrobial agents for all strains were 2.0, 1.0, 0.5, 1.0, <= 0.06, 0.13, 0.5, 16.0, 2.0, 1.0, 2.0, and <=0.0078 µg/ml, respectively. Overall, only small variation was observed for lincomycin, clindamycin, and neomycin. Isolation of methicillin-resistant S. aureus was low with only 12 of 700 (1.7%) S. aureus strains resistant to oxacillin. Of the strains tested, 58.3% were positive for β-lactamase production. Of the 257 ampicillin resistant β-lactamase positive S. aureus strains, only 1 strain was resistant to amoxicillin+clavulanate and 2 strains were resistant to penicillin+novobiocin. Erythromycin, clindamycin, and pirlimycin demonstrated good activity against the S. aureus strains, with only 3.4%, 6.1%, and 3.0% resistance to these agents, respectively. Premafloxacin showed excellent activity against all strains tested, with the overall MIC90 of <=0.0078 µg/ml.
de Oliveira, Andrea, "Antimicrobial Susceptibility of Staphylococcus Aureus Isolated from Bovine Mastitis in Europe and the United States" (1997). Honors Theses. 171.
Honors Thesis-Campus Only