Table 4.
Colony count changes at different concentrations of vancomycin or teicoplanin combined with a cephalosporin at the inhibitory or sub-inhibitory concentration.
| Glycopeptide concentration | Control | Changes of colony count, log10 CFU/mL | |||||||
|---|---|---|---|---|---|---|---|---|---|
| CFZ | CMZ | CTX | CPM | ||||||
| 8 μg/mLa | 4 μg/mLb | 16 μg/mLa | 8 μg/mLb | 8 μg/mLa | 4 μg/mLb | 8 μg/mLa | 4 μg/mLb | ||
| TIST-5 | |||||||||
| Control | +3.10 | +3.10 | +3.10 | +3.10 | +3.10 | +3.10 | +3.10 | +3.10 | +3.10 |
| VAN 1/2xMIC | +3.09 | −3.00s | −2.75c | −3.00s | −3.60s | −2.49c | −1.94 | −2.64c | −3.00s |
| VAN 1/4xMIC | +3.10 | +3.10 | +3.10 | −1.64 | −3.12s | +3.10 | +3.10 | +3.10 | +3.10 |
| TEC 1/2xMIC | +0.89 | −2.70c | −2.82c | −3.12s | −2.90c | −2.49c | −0.96 | −2.08c | −2.64c |
| TEC 1/4xMIC | +3.10 | +0.92 | +2.97 | −3.60s | −2.82c | +2.72 | +3.10 | +2.98 | +2.82 |
| TIST-10 | |||||||||
| Control | +3.08 | +3.08 | +3.08 | +1.94 | +3.08 | +3.08 | +3.08 | +3.08 | +3.08 |
| VAN 1/2xMIC | +0.42 | −2.39c | −2.30c | −2.66c | −2.36c | −2.47c | −2.30c | −2.36c | −2.44c |
| VAN 1/4xMIC | +3.08 | −1.22 | +0.01 | −3.32s | −2.72c | +0.84 | +3.08 | +1.56 | +3.08 |
| TEC 1/2xMIC | +3.08 | −3.92s | −2.47c | −2.17c | −3.02s | −2.32c | −2.28c | −2.05c | −2.20c |
| TEC 1/4xMIC | +3.08 | −2.54c | −2.84c | −2.54c | −2.26c | −2.92c | +2.64 | +0.04 | +0.96 |
MRSA, methicillin-resistant Staphylococcus aureus; MIC, minimal inhibitory concentration; CFZ, cefazolin; CMZ, cefmetazole; CTX, cefotaxime; CPM, cefepime.
a
Susceptible MIC breakpoints for MRSA isolates.
b
1/2 of susceptible MIC breakpoints for MRSA isolates.
s
Bactericidal with synergistic effect.
c
Bacteriostatic with synergistic effect.
TIST-5 (an isolate of high-cefazolin MIC) and TIST-10 (an isolate of low-cefazolin MIC) were randomly selected, and their bacterial load was measured at 24 h of co-cultivation with or without antibiotics.