Table 3.
Colistin Resistance in CRKP and HMV K. pneumoniae Strains
| Isolates | Colistin MIC (µg/mL)a | Carbapenemasesc | Colistin Resistance Genesb | HMV P (n=11) | rmpA (n=5) |
|---|---|---|---|---|---|
| KP104j | 0.5 | blaNDM-1; blaOXA 48 type | mcr-1, mcr-2 | – | – |
| KP194j | 0.5 | blaNDM-1; blaOXA 48 type | mcr-1 | HMV | rmpA |
| KP100j | 1 | – | – | – | – |
| KP124j | 1 | blaOXA 48 type | mcr-1 | – | – |
| KP166j | 1 | blaNDM-1; blaOXA 48 type | mcr-1, mcr-2 | HMV | rmpA |
| KP39j | 2 | blaNDM-1 | mcr-1 | – | – |
| KP64j | 2 | blaNDM-1; blaOXA 48 type; blaKPC | mcr-1 | – | – |
| KP73j | 2 | blaNDM-1; blaOXA 48 type; blaKPC | mcr-1 | – | – |
| KP97j | 2 | blaOXA 48 type | - | HMV | rmpA |
| KP5j | 4 | blaNDM-1; blaOXA 48 type | mcr-1, mcr-2 | HMV | rmpA |
| KP44j | 4 | blaOXA 48 type | mcr-1 | – | – |
| KP56j | 4 | blaNDM-1; blaOXA 48 type; blaKPC | mcr-1, mcr-2 | – | – |
| KP109j | 4 | blaNDM-1 | mcr-2 | – | – |
| KP42w | 4 | - | mcr-1, mcr-2 | – | – |
| KP53w | 4 | blaNDM-1; blaOXA 48 type | mcr-1, mcr-2 | – | – |
| KP36j | 8 | blaNDM-1 | - | HMV | – |
| KP50j | 8 | blaNDM-1 | - | HMV | – |
| KP59j | 8 | blaOXA 48 type; blaKPC | mcr-1, mcr-2 | – | – |
| KP39w | 8 | blaNDM-1 | mcr-1 | HMV | – |
| KP52w | 8 | – | mcr-1, mcr-2 | – | – |
| KP77w | 8 | blaOXA 48 type | mcr-1, mcr-2 | – | – |
| KP82w | 8 | blaOXA 48 type | mcr-1, mcr-2 | – | – |
| KP32j | 16 | blaNDM-1; blaOXA 48 type; blaKPC | mcr-2 | – | – |
| KP135j | 16 | blaNDM-1 | mcr-2 | HMV | rmpA |
| KP20j | 64 | blaNDM-1 | mcr-1, mcr-2 | HMV | – |
| KP111j | 64 | blaNDM-1 | mcr-1, mcr-2 | HMV | – |
| KP114j | 64 | blaNDM-1 | mcr-1, mcr-2 | HMV | – |
| KP83j | 128 | blaNDM-1; blaKPC | – | – | – |
| KP38j | >128 | blaNDM-1 | mcr-1 | – | – |
| KP94w | >128 | blaOXA 48 type | mcr-1, mcr-2 | – | – |
Notes: aAll these strains showed resistance to colistin by the disc diffusion assay, but only those with MIC values of 4 µg/mL or higher (indicated in bold) are designated as colistin resistant as per the specified CLSI breakpoint.30 bmcr genes (mcr-1 or mcr-2, or both) were detected in 25 out of 30 colistin-resistant isolates with 23 (77%) isolates exhibiting co-carriage with at least one carbapenemase gene (blaNDM-1, blaOXA 48 type or blaKPC). Isolates have been arranged according to their degree of colistin resistance. cCarbapenemases (blaNDM-1, blaKPC, blaOXA 48 type).
Abbreviations: MIC, minimum inhibitory concentration; HMV P, hypermucoviscous phenotype; rmpA, regulator of mucoid phenotype gene.