Table 2.
Susceptibility of Orange County nursing home MRSA isolates (n = 829) to 13 antimicrobial agents
| Antimicrobial agent | MIC data (μg/ml) |
% resistant | ||
|---|---|---|---|---|
| Range | MIC50 | MIC90 | ||
| Chlorhexidine | 0.5–4 | 2 | 4 | NAa |
| Clindamycin | ≤0.12 to >16 | >16 | >16 | 55 |
| Erythromycin | ≤0.25 to >32 | >32 | >32 | 90 |
| Tetracycline | ≤0.5 to >64 | ≤0.5 | ≤0.5 | 4 |
| Trimethoprim-sulfamethoxazole | ≤0.25 to >32 | ≤0.25 | ≤0.25 | 2 |
| Gentamicin | ≤0.5 to >64 | ≤0.5 | 64 | 12 |
| Levofloxacin | ≤0.25 to >32 | 32 | >32 | 98 |
| Vancomycin | 0.5–2 | 1 | 1 | 0 |
| Daptomycin | ≤0.5–4 | ≤0.5 | ≤0.5 | NA |
| Quinupristin-dalfopristin | ≤0.5–4 | ≤0.5 | ≤0.5 | <1 |
| Linezolid | ≤1–8 | 2 | 2 | <1 |
| Rifampin | ≤0.5 to >4 | ≤0.5 | ≤0.5 | 1 |
| Mupirocinb | ||||
| Low-level resistance isolates | 3 | |||
| High-level resistance isolates | 9 | |||
a
NA, not available, because the Clinical and Laboratory Standards Institute has not yet established breakpoints for resistance to this agent.
b
Disk diffusion testing was performed, and so no MICs are reported here.