Antimicrobial Susceptibility of Portuguese Isolates of Staphylococcus aureus and Staphylococcus epidermidis in Subclinical Bovine Mastitis

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 Staphyl...

Full description

Saved in:
Bibliographic Details
Published in:Journal of dairy science 2007-07, Vol.90 (7), p.3242-3246
Main Authors: Nunes, S F, Bexiga, R, Cavaco, L M, Vilela, CL
Format: Article
Language:English
Subjects:
Staphylococcus aureus
Staphylococcus epidermidis
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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. {szligbeta}-Lactamase production was detected through the use of nitrocefin-impregnated discs. The MIC that inhibited 90% of the isolates tested (MIC sub(90)) of penicillin, oxacillin, cefazolin, gentamicin, sulfamethoxazole/trimethoprim, oxytetracycline, and enrofloxacin were, respectively, 4, 0.5, 1, 1, 0.25, 0.25, and 0.06 mu g/mL for STAPH: aureus and greater than or equal to 64, 8, 1, 32, greater than or equal to 64, greater than or equal to 64, and 0.06 mu g/mL for STAPH: epidermidis. All STAPH: aureus isolates showed susceptibility to oxacillin, cefazolin, gentamicin, sulphamethoxazole/trimethoprim, and enrofloxacin. {szligbeta}-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 {szligbeta}-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 mu g/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.
ISSN:0022-0302