TABLE 1.
Imipenem-relebactam MIC values for KPC-expressing K. pneumoniae bloodstream isolates stratified by ESBL status, ST258 status, wzi allele, and mutations in ompK35 and ompK36 outer membrane porin genesa
| Isolate type | MIC50 (μg/ml) | MIC90 (μg/ml) | MIC range (μg/ml) |
|---|---|---|---|
| KPC-expressing K. pneumoniae (n = 92) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ESBL (n = 34) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ST258 (n = 77) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| Non-ST258 (n = 15) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| wzi29 (n = 19) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| wzi50 (n = 8) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 0.5/4 |
| wzi83 (n = 7) | ≤0.25/4 | 1/4 | ≤0.25/4 to 1/4 |
| wzi154 (n = 43) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| Wild-type ompK35 and ompK36 (n = 15) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| ompK35 mutation only (n = 45) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ompK35 and ompK36 mutations (n = 31) | ≤0.25/4 | 1/4 | ≤0.25/4 to 1/4 |
| KPC-2-expressing K. pneumoniae (n = 44) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ESBL (n = 19) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ST258 (n = 35) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| Non-ST258 (n = 9) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| wzi29 (n = 18) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| wzi50 (n = 7) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 0.5/4 |
| wzi83 (n = 6) | ≤0.25/4 | 1/4 | ≤0.25/4 to 1/4 |
| wzi154 (n = 4) | ≤0.25/4 | 1/4 | ≤0.25/4 to 1/4 |
| Wild-type ompK35 and ompK36 (n = 9) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| ompK35 mutation only (n = 25) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ompK35 and ompK36 mutations (n = 10) | ≤0.25/4 | 1/4 | ≤0.25/4 to 1/4 |
| KPC-3-expressing K. pneumoniae (n = 48) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| ESBL (n = 15) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 0.5/4 |
| ST258 (n = 42) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| Non-ST258 (n = 6) | ≤0.25/4 | 4/4 | ≤0.25/4 to ≤0.25/4 |
| wzi29 (n = 1) | 0.5/4 | 0.5/4 | 0.5/4 to 0.5/4 |
| wzi50 (n = 1) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| wzi83 (n = 1) | 0.5/4 | 0.5/4 | 0.5/4 to 0.5/4 |
| wzi154 (n = 39) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
| Wild-type ompK35 and ompK36 (n = 6) | ≤0.25/4 | ≤0.25/4 | ≤0.25/4 to ≤0.25/4 |
| ompK35 mutation only (n = 20) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 0.5/4 |
| ompK35 and ompK36 mutations (n = 21) | ≤0.25/4 | 0.5/4 | ≤0.25/4 to 1/4 |
a
The CLSI interpretive criteria for imipenem were applied to imipenem-relebactam.