TABLE 2.

Cellular dimensions and average RMS surface roughness of colistin-susceptible and -resistant (ATCC 19606 Col10) cells of A. baumannii ATCC 19606 at mid-logarithmic and stationary growth phases after colistin treatment

Growth phase and colistin concnSusceptibleResistant
Width (μm)Length (μm)Avg RMS surface roughness (nm)Diam (μm)Avg RMS surface roughness (nm)
Mid-log phase
    0.5 μg/ml1.03 ± 0.09a1.63 ± 0.24a8.64 ± 2.4b,c0.95 ± 0.21a11.5 ± 2.1b,c
    4 μg/ml0.94 ± 0.06a1.44 ± 0.17a13.5 ± 5.6b0.98 ± 0.09a23.8 ± 5.2b
    32 μg/ml0.97 ± 0.07a1.59 ± 0.23a19.8 ± 4.3b1.06 ± 0.11a14.3 ± 4.1b
Stationary phase
    0.5 μg/mlNDdND7.81 ± 2.4b,cND11.9 ± 2.8b,c
    4 μg/mlNDND16.7 ± 4.7bND26.1 ± 6.0b
    32 μg/mlNDND15.3 ± 2.9bND14.9 ± 2.9b
  • a Not significantly different from corresponding dimension following treatment at different colistin concentrations (P > 0.05).

  • b Significantly different following treatment at different colistin concentrations (P < 0.05).

  • c Not significantly different from untreated cells.

  • d ND, not determined due to marked morphological heterogeneity.