Molecular Characterization of the SHV-11 β-Lactamase of Shigella dysenteriae

ABSTRACT

A β-lactamase with an M _r of 29,000 and a pI of 7.6 was partially purified from a clinical isolate ofShigella dysenteriae. The bla gene encoded the SHV-11 enzyme carrying the substitution Leu→Gln at position 35 and was linked to a strong promoter. This variant, unlike the prototype SHV-1 enzyme, hydrolyzed oxacillin, cloxacillin, and oxyiminocephalosporins such as cefotaxime.