Differential selection of single-step AmpC or efflux mutants of Pseudomonas aeruginosa by using cefepime, ceftazidime, or ceftobiprole.

@article{Queenan2010DifferentialSO,
  title={Differential selection of single-step AmpC or efflux mutants of Pseudomonas aeruginosa by using cefepime, ceftazidime, or ceftobiprole.},
  author={Anne Marie Queenan and Wenchi Shang and Karen Bush and Robert K. Flamm},
  journal={Antimicrobial agents and chemotherapy},
  year={2010},
  volume={54 10},
  pages={4092-7}
}
Single-step Pseudomonas aeruginosa mutants, selected with ceftobiprole, ceftazidime, or cefepime, were generated at frequencies of 10(-6) to <10(-9) at two and four times the MIC. The chromosomal AmpC β-lactamase activity was increased in all ceftazidime-selected mutants. Mutants selected with cefepime either increased AmpC activity or upregulated expression of the mexXY efflux genes. Mutants selected with ceftobiprole did not overexpress AmpC; 90% of these produced elevated levels of mexXY RNA… CONTINUE READING