Table 1.
Ceftazidime and carbapenem susceptibilities of clinical B. pseudomallei isolates and mutant derivatives.
| Strain | Relevant Genotype | MIC (μg/mL)a | ||
|---|---|---|---|---|
| Ceftazidime | Meropenem | Imipenem | ||
| 1026b | Prototype | 4 | 1 | 1 |
| Bp1651 | Parental strainb | 256 | 4 | 16 |
| Bp881 | ΔpenA | 1 | 1 | 0.25 |
| Bp875 | TR70_2767-flgN IR::T24c | 8 | 0.25 | 1 |
| Bp876 | dacC::T24 | 8 | 0.25 | 1 |
| Bp877 | shc::T24 | 64 | 2 | 4 |
| Bp878 | penA::T24 | 2 | 1 | 0.25 |
| Bp879 | TR70_1911::T24 | 4 | 0.25 | 1 |
| Bp880 | TR70_0856::T24 | 128 | 2 | 2 |
aMinimal inhibitory concentration (MIC) was determined using the broth microdilution method performed in triplicate and on three separate occasions. CLSI defined cut-offs are (in μg/ml): ceftazidime ≤8 susceptible, 16 intermediate, ≥16 resistant; imipenem: ≤4 susceptible, 8 intermediate, ≥16 resistant. There are no defined cut-off values for meropenem in the CLSI guidelines for B. pseudomallei. Assuming values for other non-Enterobacteriaceae meropenem cut-offs can be assigned as (in μg/ml) ≤4 susceptible, 8 intermediate, ≥16 resistant.
bBp1651 is the parental strain to Bp875 to Bp881.
cSee Fig. 6 for a graphical representation of transposon insertion sites and gene function explanations.