TABLE 1

Characteristics and amino acid changes in MgrB, PhoP, PhoQ, and PmrB in colistin-resistant strains

StrainSourceColistin usage in VGHMICCapsular typeMLSTmRNA relative fold change (mean ± SD)Insertion sites in the mgrB regionaMgrBbPhoPbPhoQbPmrBb
pmrHcpmrKdmgrBe284838626150258157256280
Col4BloodYes>2,048K64ST119.38 ± 0.30Gly
Col7BloodYes1,024K64ST114.61 ± 0.16Gly
Col20Sputum2,048K64ST114.41 ± 0.08Gly
Col21SputumYes512K64ST112.61 ± 0.14Gly
Col22Sputum2,048K64ST112.73 ± 0.02Gly
Col36SputumYes2,048K64ST112.92 ± 0.13Gly
Col44Sputum512K64ST115.66 ± 0.05Gly
Col49Urine128K64ST1110.92 ± 0.94TyrGlyGly
Col38Urine64K64ST1125.40 ± 0.67Pro
Col13SputumYes128K64ST115.33 ± 0.04Deletionf
Col25Bile64K64ST115.35 ± 0.14IS10R in coding region (+68 to +76)
Col27SputumYes128K64ST1114.68 ± 0.970.07 ± 0.02IS10R in promoter region (−27)
Col33SputumYes128K64ST1116.52 ± 1.12IS10R in coding region (+68 to +76)
Col11SputumYes64K24ST152.16 ± 0.060.01 ± 0.002IS5-like in promoter region (−8)g
Col37PusYes16K24ST156.17 ± 0.13Tyr
Col40PusYes64K24ST159.04 ± 0.03TyrPhe
Col23UrineYes32K54ST152.01 ± 0.02Pro
Col28Urine>2,048K54ST295.9 ± 0.13Phe
Col6UrineYes64K62ST483.16 ± 0.16LeuProLeu
Col14BloodYes128K47ST112.83 ± 0.12Deletionf
Col19UrineYes64K28ST373.69 ± 0.060.05 ± 0.004IS10R in promoter region (−27)
Col26SputumYes32K3ST1317.97 ± 0.440.19 ± 0.02IS5-like in promoter region (−34)g
Col32Sputum64K1ST2321.02 ± 1.85IS5-like in coding region (+75 to +83)g
Col24Sputum32Unknown K-typeST4210.22 ± 0.0110.63 ± 0.69Tyr
Col31SputumYes128Unknown K-typeST4210.42 ± 0.0712.72 ± 0.020.01 ± 0.001IS5-like in promoter region (−35)g
Col5Pus8KN3ST11-like0.34 ± 0.024.34 ± 1.31Gly
  • a The nucleotide position aligned with genomic DNA of NTUH-K2044 and IS element-inserted sites.

  • b The amino acid positions of mutations in MgrB, PhoP, PhoQ, and PmrB.

  • c The pmrH mRNA relative fold changes (against NTUH-K2044 strain) of the other 7 colistin-susceptible strains were 0.6 ± 0.02, 1.11 ± 0.02, 1.68 ± 0.11, 0.59 ± 0.04, 1.65 ± 0.07, 0.37 ± 0.01, and 0.9 ± 0.04.

  • d The pmrK mRNA relative fold changes (against NTUH-K2044 strain) of the other 7 colistin-susceptible strains were 4.74 ± 0.69, 0.79 ± 0.28, 1.14 ± 0.51, 6.98 ± 0.82, 0.85 ± 0.08, 3.77 ± 0.78, and 2.01 ± 0.18.

  • e The mgrB mRNA relative fold changes (against NTUH-K2044 strain) of the other 7 colistin-susceptible strains were 0.41 ± 0.06, 1.19 ± 0.17, 1.67 ± 0.64, 0.52 ± 0.11, 1.04 ± 0.13, 0.51 ± 0.03, and 0.66 ± 0.11.

  • f No PCR product was detected, and the deletion site is not known.

  • g The IS5-like elements of Col11, Col26, Col32, and Col31 were 95%, 99%, 95%, and 95% identical to the IS5 element.