Table 2.

Susceptibility profiles for equine and human S. aureus isolates

Study no.Source of isolateHemolytic patternSusceptibility (MIC [μg/ml])a
ANAMPFOXCFbCIPXNLCCEGMKOXcPTESXTVAIMP
1EquineBetaSRRSSRSRRRR (4.0)RRRSS
2EquineBetaSRRSSRSRRRR (8.0)RRRSS
3EquineBetaSRRSSRSRRRR (8.0)RRRSS
4EquineBetaSRRSSRSRRRR (8.0)RRRSS
5EquineBetaSRRSSId SRRRR (8.0)RRRSS
6EquineGammaSRRSSRSRRRI (2.0)RRRSS
7EquineBetaSRRSSRSRRRR (4.0)RRRSS
8EquineBetaSRRSSRSRRRR (8.0)RRRSS
9EquineBetaSRRSSRSRRRR (8.0)RRRSS
10EquineBetaSRRSSRSRRRR (16.0)RRRSS
11EquineBetaSRRSSRSRRRR (8.0)RRRSS
12Human 1BetaSRRSSRSRRRR (8.0)RRRSS
13Human 1GammaSRRSSRSRRRI (1.0)RRRSS
14Human 2BetaSRRSSRSRRRR (8.0)RRRSS
15Human 3GammaSRRSSRSRRRI (1.0)RRRSS
  • a AN, amikacin; AMP, ampicillin; FOX, cefoxitin; CF, cephalothin; CIP, ciprofloxacin; XNL, ceftiofur; CC, clindamycin; E, erythromycin; GM, gentamicin; K, kanamycin; OX, oxacillin; P, penicillin; TE, tetracycline; SXT, trimethoprim-sulfamethoxazole; VA, vancomycin; IMP, imipenem; S, susceptible; R, resistant.

  • b In accordance with NCCLS guidelines, anS. aureus isolate resistant to oxacillin should also be considered resistant to all other β-lactams.

  • c For the three gamma-hemolytic isolates, the zone size is intermediate and the MIC range is 1.0 to 2.0 μg/ml.

  • d The zone size for this organism was 20 mm. NCCLS M31-T document-proposed guidelines indicate that resistant organisms have zone sizes of ≤17 mm.