TABLE 1.

MICs and relative expressions of ramA and acrB of strains used in this study

Klebsiella pneumoniae isolateMIC (μg/ml) and statusaRelative expressiondOrigine
TigecyclinebCiprofloxacincChloramphenicolcramAacrB
VA60482 I0.125 S24.0 R28.9 ± 8.111.6 ± 1.3Gallbladder
UR111002 I4.0 R32.0 R25.1 ± 5.910.9 ± 0.4Urine
VA144192 I>32.0 R>256.0 R40.5 ± 11.414.9 ± 1.6Wound
VA147432 I4.0 R24.0 R48.9 ± 10.57.8 ± 1.0Trachea
VA212662 I0.25 S32.0 R38.9 ± 10.315.8 ± 2.8Pharynx
VA12262-WT0.25 S0.064 S8.0 I11Trachea
VA6048 (ramRVA12262-WT)0.25 S0.012 S1.0 S0.9 ± 0.61.5 ± 0.2
VA6048 (ramRVA6048)2 I0.125 S16.0 R32.4 ± 7.210.9 ± 1.8
VA6048(pACYC177)2 I0.125 S24.0 R46.5 ± 16.418.9 ± 6.6
VA6048 (ramRUR11100)2 I0.125 S24.0 R25.0 ± 11.65.8 ± 0.9
VA6048 (ramRVA14419)2 I0.125 S16.0 R21.2 ± 4.28.4 ± 3.0
VA6048 (ramRVA21266)2 I0.125 S16.0 R29.9 ± 10.714.5 ± 3.3
VA14743 (ramRVA12262-WT)0.25 S0.25 S1.0 S0.8 ± 0.11.5 ± 0.1
VA14743 (ramRVA14743)2 I4.0 R32.0 R50.4 ± 8.917.8 ± 9.3
VA14743(pACYC177)2 I4.0 R32.0 R45.6 ± 5.45.1 ± 0.5
VA14743 (ramRUR11100)2 I4.0 R16.0 R43.8 ± 7.011.0 ± 2.3
VA14743 (ramRVA14419)2 I2.0 R16.0 R57.6 ± 15.322.0 ± 10.2
VA14743 (ramRVA21266)2 I4.0 R32.0 R66.7 ± 30.110.1 ± 4.7
  • a S, susceptible; I, intermediate; R, resistant. Status determinations are according to EUCAST clinical breakpoints (www.eucast.org/).

  • b Tested by broth microdilution.

  • c Tested by Etest.

  • d Measured by quantitative RT-PCR, shown as x-fold expression of VA12262 (expression = 1). Results are means of 3 (ramA) or 2 (acrB) runs ± standard deviations.

  • e All isolates were obtained as a result of this study.