Table 3.
Distribution of colistin minimum inhibitory concentrations (MICs) of mcr-positive and mcr-naïve isolates.
| Organism tested | mcr presence | No. of isolates | Colistin MIC (μg/mL), n (%) | p value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤ 1.0 | 2.0 | 4.0 | 8.0 | 16.0 | 32.0 | 64.0 | 128.0 | ||||
| Proteus spp. | mcr-positive | 17 | – | – | – | – | 1 (5.9) | 1 (5.9) | 4 (23.5) | 11 (64.7) | 0.068 |
| mcr-negative | 35 | 2 (5.7) | 11 (31.4) | – | – | 2 (5.7) | – | 4 (11.4) | 16 (45.7) | ||
| Klebsiella spp. | mcr-positive | 10 | – | – | – | – | – | 3 (30.0) | 1 (10.0) | 6 (60.0) | 0.012 |
| mcr-negative | 20 | – | 9 (45.0) | – | – | – | – | 1 (5.0) | 10 (50.0) | ||
| E. coli | mcr-positive | 9 | – | – | – | – | – | 6 (66.7) | – | 3 (33.3) | 0.000 |
| mcr-negative | 25 | 4 (16.0) | 17 (68.0) | 2 (8.0) | 1 (4.0) | – | – | 1 (4.0) | – | ||
| Salmonella spp. | mcr-positive | 7 | – | – | – | – | – | 3 (42.9) | 1 (14.3) | 3 (42.9) | 0.024 |
| mcr-negative | 9 | 1 (11.1) | 4 (44.4) | 3 (33.3) | – | – | – | – | 1 (11.1) | ||
| Shigella spp. | mcr-positive | 1 | – | – | – | – | – | – | – | 1 (100) | 0.223 |
| mcr-negative | 2 | – | 1 (50.0) | – | 1 (50.0) | – | – | – | – | ||
| Enterobacter spp. | mcr-positive | 2 | – | – | – | – | 1 (50.0) | – | 1 (50.0) | – | 0.007 |
| mcr-negative | 12 | – | 9 (75.0) | 2 (16.7) | – | – | – | – | 1 (8.3) | ||
Italics are used for ‘bacterial names’ as a standard rule in scientific nomenclature.