Table 2.
In vitro activities of ceftaroline and ceftriaxone against 1,750 recent clinical isolates of Streptococcus pneumoniae sorted according to penicillin resistance category
| Penicillin resistance category | Penicillin MIC (μg/ml) | No. of isolates | Ceftaroline MIC (μg/ml) |
Ceftriaxone MIC (μg/ml) |
||||
|---|---|---|---|---|---|---|---|---|
| MIC50 | MIC90 | Range | MIC50 | MIC90 | Range | |||
| Oral administrationa | ||||||||
| Susceptible | ≤0.06 | 1,066 | 0.008 | 0.008 | ≤0.008–0.06 | 0.03 | 0.06 | ≤0.008–0.5 |
| Intermediate | 0.12–1 | 352 | 0.03 | 0.06 | ≤0.008–0.25 | 0.25 | 1 | 0.03–8 |
| Resistant | ≥2 | 332 | 0.12 | 0.25 | 0.06–0.5 | 1 | 4 | 0.5–16 |
| Parenteral administrationb | ||||||||
| Susceptible | ≤2 | 1,520 | 0.008 | 0.06 | ≤0.008–0.25 | 0.06 | 0.5 | ≤0.008–8 |
| Intermediate | 4 | 224 | 0.12 | 0.25 | 0.06–0.5 | 2 | 4 | 0.5–16 |
| Resistant | ≥8 | 6 | —c | —c | —c | —d | —d | —d |
a
CLSI MIC interpretive criteria for penicillin against Streptococcus pneumoniae when administered orally (3).
b
CLSI MIC interpretive criteria for penicillin against Streptococcus pneumoniae when administered parenterally in the treatment of nonmeningeal infections (3).
c
The ceftaroline MICs of these six strains were as follows: 0.12 μg/ml (n = 1), 0.25 μg/ml (n = 1), and 0.5 μg/ml (n = 4).
d
The ceftriaxone MICs of these six strains were as follows: 2 μg/ml (n = 2), 8 μg/ml (n = 2), and 16 μg/ml (n = 2).