Oxacillinase-mediated resistance to cefepime and susceptibility to ceftazidime in Pseudomonas aeruginosa - PubMed (original) (raw)

Oxacillinase-mediated resistance to cefepime and susceptibility to ceftazidime in Pseudomonas aeruginosa

D Aubert et al. Antimicrob Agents Chemother. 2001 Jun.

Abstract

Pseudomonas aeruginosa clinical isolate SOF-1 was resistant to cefepime and susceptible to ceftazidime. This resistance phenotype was explained by the expression of OXA-31, which shared 98% amino acid identity with a class D beta-lactamase, OXA-1. The oxa-31 gene was located on a ca. 300-kb nonconjugative plasmid and on a class 1 integron. No additional efflux mechanism for cefepime was detected in P. aeruginosa SOF-1. Resistance to cefepime and susceptibility to ceftazidime in P. aeruginosa were conferred by OXA-1 as well.

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Figures

FIG. 1

FIG. 1

Structure of the class 1 integrons that contain oxa-31 (A) and oxa-1 (B) cassettes. The arrows indicate the transcriptional orientations of the ORFs.

FIG. 2

FIG. 2

Comparison of the amino acid sequence of β-lactamase OXA-31 to those of OXA-1, OXA-4, and OXA-30. Dashes indicate identical amino acids. The numbering is according to DBL (13). The highlighted boxes indicate conserved regions within class D β-lactamases.

FIG. 3

FIG. 3

Intracellular accumulation of cefepime and norfloxacin in P. aeruginosa clinical isolate SOF-1. The intracellular concentrations of radiolabeled norfloxacin (A) and cefepime (B) were measured in cells of P. aeruginosa SOF-1 with (●) or without (□) the energy uncoupler CCCP. Values are means of two independent experiments.

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