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. 2008 Aug 11;52(10):3795–3800. doi: 10.1128/AAC.00464-08

TABLE 1.

Drug susceptibilities and genotypes of the P. aeruginosa strains and its derivatives in this study

Straina Genotype or phenotype MIC (μg/ml)b
DRPM MEPM IPM CAZ PIPC GM CPFX OFLX
PAO1 Parent 0.2 0.2 0.8 1.6 3.1 1.6 0.2 0.8
PAO1KTL oprD 0.8 1.6 12.5 1.6 3.1 1.6 0.2 0.8
PAO1KTL1 oprD mexAB(Hy)-oprM(Hy) 1.6 6.3 12.5 6.3 12.5 1.6 0.8 3.1
PAO1KTS mexAB(Hy)-oprM(Hy) 0.4 1.6 0.8 6.3 12.5 1.6 0.8 3.1
PAO1IPM46 oprD 0.8 1.6 12.5 1.6 3.1 1.6 0.2 0.8
PAO1SO20 mexAB(Hy)-oprM(Hy) 0.4 1.6 0.8 6.3 12.5 1.6 0.8 3.1
GP4 Wild type 0.2 0.2 0.8 1.6 100 100 0.2 1.6
GP4KT11 oprD 1.6 3.1 12.5 1.6 100 100 0.2 1.6
GP4KT111 oprD mexAB(Hy)-oprM(Hy) 3.1 12.5 12.5 6.3 200 100 0.8 6.3
GP20 Wild type 0.2 0.2 0.8 1.6 100 3.1 0.2 1.6
GP20KT21 oprD 1.6 3.1 12.5 1.6 100 3.1 0.2 1.6
GP37 Wild type 0.2 0.2 0.8 1.6 100 100 0.2 1.6
GP37KT31 oprD 1.6 3.1 12.5 1.6 100 100 0.2 1.6
GP62 Wild type 0.1 0.2 0.8 1.6 100 1.6 0.2 1.6
GP62KT41 oprD 0.8 3.1 12.5 1.6 100 1.6 0.2 1.6
GP61 Wild type, oprD 0.8 1.6 6.3 3.1 3.1 1.6 0.2 1.6
GP61KT51 oprD mexAB(Hy)-oprM(Hy) 1.6 6.3 6.3 12.5 12.5 1.6 0.8 6.3
a

PAO1IPM46 and PAO1SO20 are reported PAO1 mutants with decreased oprD expression and increased mexAB-oprM expression, respectively (18). P. aeruginosa GP4, GP20, GP37, and GP62 are carbapenem-susceptible clinical isolates. The clinical strain GP61 was used as the representative wild-type strain with a higher imipenem MIC. The reduced expression of oprD in GP61 is shown in Fig. 1. During this study, the drug susceptibilities of the mutant strains isolated on the agar plates containing the selective carbapenem drugs DRPM, MEPM, and IPM, respectively, were examined and representative strains are shown. The representative mutant strains PAO1KTL and PAO1KTS were isolated from PAO1, and GP4KT11, GP20KT21, GP37KT31, and GP62KT41 were isolated from GP4, GP20, GP37, and GP62, respectively. The representative mutant strains PAO1KTL1, GP4KT111, and GP61KT51 were isolated from the oprD mutants of PAO1KTL, GP4KT11, and clinical isolate GP61, respectively.

b

DRPM is a new carbapenem that has been developed by Shionogi Pharmaceuticals, Osaka, Japan) (7, 8, 19). Abbreviations for the other antibiotics used are as follows: CAZ, ceftazidime; PIPC, piperacillin; GM, gentamicin; CPFX, ciprofloxacin; and OFLX, ofloxacin.