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

Anne Marie Queenan | Zendy; Wenchi Shang | Zendy; Karen Bush | Zendy; Robert K. Flamm | Zendy

Open Access

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

Author(s) -

Anne Marie Queenan,

Wenchi Shang,

Karen Bush,

Robert K. Flamm

Publication year - 2010

Publication title -

antimicrobial agents and chemotherapy

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.07

H-Index - 259

eISSN - 1070-6283

pISSN - 0066-4804

DOI - 10.1128/aac.00060-10

Subject(s) - cefepime , ceftazidime , efflux , pseudomonas aeruginosa , derepression , microbiology and biotechnology , mutant , biology , chemistry , bacteria , biochemistry , gene , gene expression , genetics , psychological repression

Single-stepPseudomonas 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 themexXY efflux genes. Mutants selected with ceftobiprole did not overexpress AmpC; 90% of these produced elevated levels ofmexXY RNA, indicating that increased efflux, not AmpC derepression, is the predominant response to ceftobiprole during first-step mutations inP. aeruginosa .

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