Technical note: Antimicrobial susceptibility of Portuguese isolates of Staphylococcus aureus and Staphylococcus epidermidis in subclinical bovine mastitis
Research output: Contribution to journal › Journal article › Research › peer-review
To evaluate the antimicrobial resistance traits of staphylococci responsible for subclinical bovine mastitis in Portugal, the minimum inhibitory concentrations (MIC) of 7 antimicrobial agents, frequently administered for mastitis treatment, were determined for 30 Staphylococcus aureus and 31 Staphylococcus epidermidis field isolates. Beta-lactamase production was detected through the use of nitrocefin-impregnated discs. The MIC that inhibited 90% of the isolates tested (MIC90) of penicillin, oxacillin, cefazolin, gentamicin, sulfamethoxazole/trimethoprim, oxytetracycline, and enrofloxacin were, respectively, 4, 0.5, 1, 1, 0.25, 0.25, and 0.06 microg/mL for Staph. aureus and > or = 64, 8, 1, 32, > or = 64, > or = 64, and 0.06 microg/mL for Staph. epidermidis. All Staph. aureus isolates showed susceptibility to oxacillin, cefazolin, gentamicin, sulphamethoxazole/trimethoprim, and enrofloxacin. Beta-lactamase production was detected in 20 of these isolates (66.7%), all of which were resistant to penicillin. Of the 31 Staph. epidermidis tested, 24 (77.4%) were beta-lactamase positive. All isolates were susceptible to both cefazolin and enrofloxacin. Nine Staph. epidermidis isolates were resistant to oxacillin, with MIC values ranging from 4 to 8 microg/mL. The MIC values of 5 antimicrobial agents tested were higher than those reported in other countries. Enrofloxacin was the only exception, showing lower MIC values compared with other reports. Overall, the antimicrobial agents tested in our study, with the exception of penicillin, were active against the 61 isolates studied.
Original language | English |
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Journal | Journal of Dairy Science |
Volume | 90 |
Issue number | 7 |
Pages (from-to) | 3242-6 |
Number of pages | 5 |
ISSN | 0022-0302 |
DOIs | |
Publication status | Published - Jul 2007 |
- Animals, Anti-Infective Agents, Cattle, Drug Resistance, Bacterial, Mastitis, Bovine, Microbial Sensitivity Tests, Portugal, Staphylococcal Infections, Staphylococcus aureus, Staphylococcus epidermidis, Journal Article, Research Support, Non-U.S. Gov't
Research areas
ID: 183245418