Table 1

In vitro susceptibility of 336 strains of Staphylococcus aureus obtained from clinical and sub-clinical bovine mastitis cases from the West Littoral Region of Uruguay.

MIC1 (μg/ml)
 % Resistance

Antimicrobial Agent
 MIC502
 MIC903
 Range
 Breakpoint
 VETMIC
 Agar disk diffusion test
Penicillin
 0.5
 > 8
 0.12–> 8
 ≥ 0.25
 47.6
 46.1 5
Ampicillin
 0.5
 8
 ≤ 0.12–> 16
 ≤ 0.5
 46.7
 46.6 5
Oxacillin
 ≤ 0.5
 ≤ 0.5
 ≤ 0.5–1
 ≥ 4
 0.0
 2.0 5 6
Cephalotin
 ≤ 4
 ≤ 4
 ≤ 4
 ≤ 32
 0.0
 0.0
Gentamicin
 ≤ 1
 ≤ 1
 ≤ 1–4
 ≥ 16
 0.0
 0.0
Erythromycin
 ≤ 0.5
 ≤ 0.5
 ≤ 0.5–> 4
 ≥ 8
 3.0
 2.6 5
Oxitetracycline
 2
 > 64
 ≤ 0.25–> 64
 ≥ 16
 13.4
 14.0 5 7
Enrofloxacin
 ≤ 0.25
 ≤ 0.25
 ≤ 0.25–0.5
 ≥ 2
 0.0
 0.0
Neomycin
 ≤ 1
 ≤ 1
 ≤ 1–64
 ≥ 64
 0.6
 0.9 5
Clindamycin
 ≤ 1
 ≤ 1
 ≤ 1
 ≥ 4
 0.0
 ....4....
Amoxicillin/Clavulanic acid
 ....4....
 ....4....
 ....4....
 ....4....
 ....4....
 0.0
Trimethoprim/





Sulfamethox.
 0.25
 0.5
 < 0.06–8
 ≥ 4
 0.3
 0.0 5

1 Minimum inhibitory concentration. 2 Lowest concentration inhibiting 50% of the isolated tested.

3 Lowest concentration inhibiting 90% of the isolated tested. 4 Test not performed.

5 No significant differences between methods. 6 All strains were sensitive at the confirmation test.

7 Tetracycline disk were used to perform agar disks diffusion.

Gianneechini et al. Acta Veterinaria Scandinavica 2002 43:31   doi:10.1186/1751-0147-43-31