Table 2.

MICs of glycopeptides and capsule typea

StrainMIC (μg/ml)Capsule typeb
VancomycinTeicoplanin
MI6 (I)8 (S)5
MI[P15]4 (S)5 (S)N
MI[P25]4 (S)NDND
MI[P60]2 (S)3 (S)N
MI[VP15]6 (I)ND5*
MI[VP60]6 (I)ND5*
NJ5 (I)5 (S)5
NJ[P15]2–3 (S)4 (S)N
NJ[P60]2–3 (S)
NJ[VP15]5 (I)ND5*
PC5 (I)5 (S)5
PC[P15]2 (S)3 (S)N
PC[P30]NDNDN
PC[VP15]5 (I)ND5
PC[VP30]NDND5
Mu505 (I)5 (S)5
Mu50[P15]2 (S)2 (S)5
Mu50[VP15]5 (I)ND5
Mu32 (S)9 (I)5
Mu3[P15]2 (S)6 (S)ND
Mu3[VP15]2 (S)NDND
  • a [P15], passaged on plain medium for 15 days; [P60], passaged on plain medium for 60 days; [VP15], passaged on vancomycin containing medium for 15 days; [VP60], passaged on vancomycin containing medium for 60 days. Broth dilution MICs were determined as described in Materials and Methods with drug concentrations diluted in arithmetic increments. According to NCCLS criteria (17) isolates are susceptible (S) to vancomycin if their MIC of vancomycin is ≤4 μg/ml. Isolates are susceptible to teicoplanin if their MIC of teicoplanin is ≤8 μg/ml. Since arithmetic dilutions of glycopeptide were used, MICs of vancomycin of >4 and <32 μg/ml and MICs of teicoplanin of >8 and <32 μg/ml are intermediate (I). No clinical S. aureus isolate has been reported to have a resistant MIC of vancomycin or teicoplanin (≥32 μg/ml).

  • b The capsule serotyping was performed as described in Materials and Methods. N, nontypeable; ND, not determined. An asterisk indicates a weaker reaction with capsular antiserum compared with the control strain.