Table 2.

Colistin MIC frequency distribution tested against a diverse sample of bacterial species

Organism (no. of isolates tested)No. of isolates (%) inhibited at MIC (μg/ml) of:
≤1 2 4 8 1632 64 ≥128
Acinetobacter spp. (60)54 (90.0) 3 (95.0) 1 (96.7) 1 (98.3)1 (100.0)
B. cepacia (12)12 (100.0)
Enterobacterspp. (5) 4 (80.0)a 1 (100.0)b
Indole-positive group (4) 2 (50.0)c 2 (100.0)d
K. pneumoniae (9) 8 (88.9) 1 (100.0)
Proteus mirabilis (2)1 (50.0) 1 (100.0)
P. aeruginosa (80) 79 (98.8) 1 (100.0)
S. marcescens (5)5 (100.0)
S. maltophilia (23) 13 (56.5) 3 (69.6) 1 (73.9)1 (78.3) 2 (87.0) 2 (95.7) 1 (100.0)
All strains (200) 160 (80.0) 8 (84.0) 2 (85.0) 2 (86.0)2 (87.0) 4 (89.0) 2 (90.0) 20 (100.0)
  • a E. aerogenes (four strains)

  • b E. cloacae (one strain).

  • c M. morganii (two strains)

  • d P. rettgeri (two strains).