Table 1.
CLSI and EUCAST MIC breakpoints* for S. pneumoniae susceptibility to penicillin
| Criteria for interpretation† | Clinical syndrome and route of administration | |||||
|---|---|---|---|---|---|---|
| Non-meningitis, i.v. penicillin (G)‡ | Meningitis, i.v. penicillin (G) | |||||
| MIC (μg/ml) | MIC (μg/ml) | |||||
| S | I | R | S | I | R | |
| CLSI | ||||||
| Old (pre-2008) breakpoints | ⩽0·06 | 0·12–1 | ⩾2 | ⩽0·06 | 0·12–1 | ⩾2 |
| New breakpoints | ⩽2 | 4 | ⩾8 | ⩽0·06 | – | ⩾0·12 |
| EUCAST | ||||||
| No dosage categorization | – | – | – | ⩽0·06 | – | >0·06 |
| Dosage: 1·2 g×4 | ⩽0·5 | – | >0·5 | – | – | – |
| Dosage: 2·4 g × 4 or 1·2 g × 6 | ⩽1 | – | >1 | – | – | – |
| Dosage: 2·4 g × 6 | ⩽2 | – | >2 | – | – | – |
CLSI, Clinical and Laboratory Standards Institute; EUCAST, European Committee on Antimicrobial Susceptibility Testing; i.v., intravenous; MIC, minimum inhibitory concentration; S, susceptible; I, intermediate; R, resistant.
*
Adapted from CLSI and EUCAST Clinical Breakpoint Table v. 2.0, valid from 1 January 2012.
†
Breakpoints in bold are those applied in the present study; for EUCAST 1·2 g × 4 was chosen because this most closely resembles the Belgian clinical choice of treatment.
‡
In this column, the EUCAST breakpoint set for ‘pneumonia’ are used. EUCAST also has breakpoints for indications other than meningitis and pneumonia.