Abstract
Ceftazidime-susceptible and -resistant
Pseudomonas aeruginosa
strains were isolated from pulmonary specimens following a treatment with ceftazidime in a patient who developed a nosocomial pneumonia.
The ceftazidime-susceptible and -resistant strains were clonally related and harbored a self-transferable ~155-kb plasmid. These isolates expressed two OXA-10-like oxacillinases, the narrow-spectrum OXA-35
and the expanded-spectrum OXA-19, respectively, differing by one amino acid substitution. This is the first example of
in vivo
selection of an extended-spectrum oxacillinase from a restricted-spectrum
oxacillinase.