Differential Selection of Single-Step AmpC or Efflux Mutants of Pseudomonas aeruginosa by Using Cefepime, Ceftazidime, or Ceftobiprole

作者：Queenan Anne Marie^*; Shang Wenchi; Bush Karen; Flamm Robert K

来源：Antimicrobial Agents and Chemotherapy, 2010, 54(10): 4092-4097.

DOI：10.1128/AAC.00060-10

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 beta-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, indicating that increased efflux, not AmpC derepression, is the predominant response to ceftobiprole during first-step mutations in P. aeruginosa.

• 出版日期2010-10