Dissemination in five French hospitals ofKlebsiella pneumoniae serotype K25 harbouring a new transferable enzymatic resistance to third generation cephalosporins and aztreonam

Abstract

A strain ofKlebsiella pneumoniae K25 resistant to newerβ-lactam drugs was isolated in clusters in five hospitals in the Paris area. The MICs of ceftazidime and aztreonam (⩾128 mg/l) were higher than that of cefotaxime (16 mg/l) for the strain but when measured in the presence of clavulanic acid, they were ⩽1 mg/l. The donor strains and derivatives produced aβ-lactamase with a pI of 7.75–7.8 and hydrolysing activity against a wide spectrum ofβ-lactams similar to that of SHV-2 and SHV-3, but with significant hydrolysis of ceftazidime. This new enzyme could be designated SHV-4.