TABLE 1.
Susceptibility of 210 MRSA strains, including S. aureus NCTC8325, to quinazolinones 1 to 5, ceftaroline, linezolid, and vancomycin
| Antibacterial agent | MIC for total MRSA population (n = 210) (μg/ml) |
MIC range for MRSA with following resistance mechanismsa
(μg/ml): |
MIC for MSSAb NCTC8325 (μg/ml) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Range | MIC50 | MIC90 | VRSA (n = 15) | VISA (n = 20) | hVISA (n = 6) | mecC-MRSA (n = 7) | LRSA (n = 6) | ||
| Ceftaroline | 0.125 to 2 | 0.5 | 1 | 0.25 to 2 | 0.25 to 2 | 0.5 to 1 | 0.5 to 1 | 0.5 to 2 | 0.125 |
| Linezolid | 0.5 to >16 | 2 | 2 | 1 to 2 | 0.5 to 2 | 0.5 to 2 | 1 to 2 | 8 to >16 | 1 |
| Vancomycin | >32 | 4 to 8 | 2 to 8 | 1 to 2 | 1 to 4 | 1 | |||
| 1 | 0.03 to >32 | 0.5 | 2 | 0.125 to 2 | 0.25 to 4 | 0.125 to 4 | 0.25 to 2 | 0.25 to 1 | 0.25 |
| 2 | 0.06 to >32 | 1 | 4 | 0.125 to 8 | 0.125 to 8 | 0.25 to 2 | 0.5 to 2 | 1 to 4 | 0.5 |
| 3 | 0.5 to 16 | 2 | 4 | 2 to 16 | 0.5 to 16 | 0.5 to 2 | 1 to 2 | 1 to 4 | 1 |
| 4 | ≤0.03 to >32 | 0.06 | 0.25 | 0.06 to 4 | 0.03 to >32 | ≤0.03 to 0.125 | ≤0.03 to 0.06 | 0.06 to 0.25 | 0.25 |
| 5 | ≤0.03 to >32 | 0.125 | 0.5 | 0.06 to 2 | ≤0.03 to 1 | ≤0.03 to 0.125 | 0.06 to 0.25 | 0.06 to 0.25 | 0.125 |
a
VRSA, vancomycin-resistant S. aureus; VISA, vancomycin-intermediate S. aureus; hVISA, heterogeneous vancomycin-intermediate S. aureus; LRSA, linezolid-resistant S. aureus.
b
MSSA, methicillin-susceptible S. aureus. MIC values for ATCC 29213 (quality control strain) were in the range of those shown by CLSI for ceftaroline, linezolid, and vancomycin.