TABLE 4.

MBCs of oxacillin, cefoxitin, and oxacillin in combination with one-fourth the MIC of cefoxitin for wild-type CA-MRSA and HA-MRSA strainsa

StrainNo. of clones testedMBCb μg/ml
OXA 48 hFOX 48 hOXA + 1/4 MIC FOX 48 h
MW2 (USA400) (CA-MRSA)3256>256<1
USA300 (CA-MRSA)3256>256<1
COL (HA-MRSA)3>256>256>256
MRSA252 (HA-MRSA)3>256>256>256
Mu50 (HA-MRSA/VISA)3>256>256>256
  • a MBC was assessed by plating the broth from the MIC wells and from those wells above the MIC for each strain onto appropriate drug-free growth media after 48 h and incubated at 37°C for 24 h. OXA, oxacillin; FOX, cefoxitin.

  • b MIC data for all clinical isolates were reported as median values from at least three independent experiments.