Hospital outbreak of carbapenem-resistant Pseudomonas aeruginosa producingVIM-1, a novel transferable metallo-beta-lactamase

A total of 8 Pseudomonas aeruginosa isolates was collected from 7 different patients in different wards of the University Hospital of Verona, Italy, f rom February 1997 to February 1998. The high level of resistance to carbape nems (imipenem minimum inhibitory concentration was always >128 mug/mL) and other broad-spectrum beta -lactams and the rate of imipenem hydrolysis and its inhibition by ethylenediamine-tetra-acetic acid were all suggestive of production of a carbapenem-hydrolyzing metallo-beta -lactamase. A specific DNA probe derived from the recently cloned bla(VIM-1) gene hybridized to a ll the isolates. A genomic DNA finger-printing profile revealed clonal rela tedness for 7 of 8 isolates. A description of this hospital outbreak is rep orted, the occurrence of which confirms that proliferation of metallo-beta -lactamase-producing strains multiply resistant to beta -lactams is already a reality outside Japan. These findings emphasize the need for early recog nition of similar isolates.