JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 80 No. 2 413-421
© 1997 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Thornsberry, C.
Right arrow Articles by Yancey., R. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Thornsberry, C.
Right arrow Articles by Yancey., R. J., Jr.

The Activity of a Combination of Penicillin and Novobiocin Against Bovine Mastitis Pathogens: Development of a Disk Diffusion Test

C. Thornsberry 1, P. J. Burton 1, Y. C. Yee 1, J. L. Watts 2, and R. J. Yancey. Jr. 2

1 Microbiology Reference Laboratories, Pharmaceutical Services, 357 Riverside Drive, Franklin, TN 37064
2 Pharmacia & Upjohn Animal Health, 7923-190-MR, Kalamazoo, MI 49001

The combination of penicillin and novobiocin is currently available for the treatment of bovine mastitis, but methods are not available for susceptibility testing of the combination by veterinary diagnostic laboratories. The minimum inhibitory concentration (MIC) and disk diffusion data were determined for penicillin, novobiocin, and a combination of the two in a 1:2 ratio for 225 staphylococcal, streptococcal, and Gram-negative isolates from bovine intramammary infections. Based on the drug concentrations in milk following infusion, linear regression analysis, and error rate bounding, the interpretive zone diameters selected were le16 mm for resistant isolates and ge 17 mm for susceptible isolates with a disk containing 10U of penicillin and 30 µg of novobiocin. Additionally, MIC breakpoints of le2 µg/ml of penicillin and 4 µg/ml of novobiocin were selected to categorize isolates as susceptible and ge 4 µg/ml of penicillin and 8 µg/ml of novobiocin were selected to categorize isolates as resistant. The MIC and disk diffusion results, as well as studies to monitor bacterial killing by antimicrobial agents over time, indicated that the combination of penicillin and novobiocin in a 1:2 ratio was more active than were the individual drugs. Kinetics of the kill curves with the penicillin and novobiocin combination (1:2 ratio) showed that the combination was bactericidal for Staphylococcus aureus and Staphylococcus xylosus.

Key Words: minimum inhibitory concentration • antimicrobial susceptibility tests • Staphylococcus aureus

Submitted on September 28, 1995
Accepted on April 29, 1996




This article has been cited by other articles:


Home page
 J DAIRY SCIHome page
P. Moroni, G. Pisoni, M. Antonini, G. Ruffo, S. Carli, G. Varisco, and P. Boettcher
Subclinical Mastitis and Antimicrobial Susceptibility of Staphylococcus caprae and Staphylococcus epidermidis Isolated from Two Italian Goat Herds
J Dairy Sci, May 1, 2005; 88(5): 1694 - 1704.
[Abstract] [Full Text] [PDF]

Home page
 J DAIRY SCIHome page
E. Gentilini, G. Denamiel, A. Betancor, M. Rebuelto, M. R. Fermepin, and R. A. De Torres
Antimicrobial Susceptibility of Coagulase-Negative Staphylococci Isolated from Bovine Mastitis in Argentina
J Dairy Sci, August 1, 2002; 85(8): 1913 - 1917.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1997 by the American Dairy Science Association ®.