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. 2003 Sep;47(9):3030–3033. doi: 10.1128/AAC.47.9.3030-3033.2003

TABLE 3.

Susceptibility of E. coli drug transporter overproducing strains to β-lactams and toxic compounds

Strain MIC (μg/ml)a
AMP OXA MCIPC NAF CAR SBPC CXM FAM CTX CMZ ATM FRPM DOCb SDSb NOVb ERMb TPPb
TG1 1.56 >100 200 >400 1.56 1.56 1.56 0.39 0.025 0.78 0.05 0.39 >40,000 >400 50 50 200
KAM3, KAM3/pHSG398 or pHSG399 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 625 50 0.78 1.56 3.13
KAM3/pHSGacrAB 1.56 >100 100 200 1.56 1.56 1.56 0.39 0.025 0.78 0.05 0.39 >40,000 >400 25 12.5 200
KAM3/pHSGacrD 0.78 12.5 12.5 50 25 50 0.39 0.20 0.012 0.78 0.39 0.10 >40,000 >400 6.25 1.56 3.13
KAM3/pHSGacrEF 0.78 50 100 200 1.56 1.56 0.78 0.39 0.025 0.78 0.05 0.10 >40,000 >400 25 12.5 200
KAM3/pHSGmdtABC 0.78 3.13 6.25 6.25 6.25 12.5 0.20 0.10 0.012 0.39 0.10 0.10 20,000 200 6.25 1.56 1.56
KAM3/pHSGmdtEF 0.78 12.5 12.5 25 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 20,000 200 0.78 12.5 25
KAM3/pHSGemrABc 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 2,500 100 3.13 1.56 1.56
KAM3/pHSGemrKY 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 1,250 50 NDe 1.56 ND
KAM3/pHSGmacAB 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 625 50 0.78 12.5 1.56
KAM3/pHSGmdfA 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 625 50 0.78 1.56 12.5
KAM3/pHSGemrEd 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 625 50 0.78 1.56 3.13
KAM3/pHSGmdtK 0.78 0.39 0.78 1.56 1.56 1.56 0.20 0.10 0.012 0.39 0.05 0.10 625 50 0.39 1.56 25
TG1ΔtolC 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
TG1ΔtolC/pHSGacrAB 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
TG1ΔtolC/pHSGacrD 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
TG1ΔtolC/pHSGacrEF 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
TG1ΔtolC/pHSGmdtEF 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
TG1ΔtolC/pHSGmdtABC 0.78 0.39 0.78 0.78 0.78 1.56 0.20 0.10 0.012 0.39 0.05 0.10 313 ND ND ND ND
a

MIC determination was repeated at least three times. Values in bold differ from the KAM3/pHSG398 or 399 control strain value by ≥4-fold. MIC values of benzylpenicillin (12.5 μg/ml for all strains listed in the table), cephalothin (1.56 μg/ml), cefsulodin (12.5 μg/ml), ceftazidime (0.10 μg/ml), flomoxef (0.025 μg/ml), and imipenem (0.05 μg/ml) were not changed by overexpression of any drug exporters tested in this study. Abbreviations: AMP, ampicillin; SBPC, sulbenicillin; CTX, cefotaxime; CMZ, cefmetazole; DOC, deoxycholate; SDS, sodium dodecyl sulfate; NOV, novobiocin; ERM, erythromycin; TPP, tetraphenylphosphonium bromide.

b

These compounds were used to confirm the overproduction of the pumps. Additionally, CCCP (carbonyl cyanide m-chlorophenylhydrazone) and acriflavine were used to confirm the overproduction of EmrAB and EmrE, as described below.

c

pHSGemrAB conferred CCCP resistance (MIC, 6.25 μg/ml for KAM3 versus 50 μg/ml for KAM3/pHSGemrAB).

d

pHSGemrE conferred acriflavine resistance (MIC, 12.5 μg/ml for KAM3 versus 200 μg/ml for KAM3/pHSGemrE).

e

ND, not determined.