-Lactamase Activity in Chromobacterium violaceum

Abstract

A strain of Chromobacterium violaceum isolated from a fatally infected patient was found to produce a β-lactamase. When the organism was grown in drug-free medium, β-lactamase activity was barely detectable, but when it was grown in the presence of penicillin G, a much larger amount of activity was produced. The β-lactamase was active primarily against cephalosporins; it was sensitive to inhibition by cloxacillin but resistant to p-chloromercuribenzoate. Thus this enzyme closely resembled the common type of β-lactamase found in Pseudomonas aeruginosa. The organism was relatively susceptible to ticarcillin, carbenicillin, and cefoxitin, which resisted hydrolysis by its β-lactamase, but was quite resistant to 11 other ~-lactam antibiotics. Production of the β-lactamase appeared to be mediated by chromosomal genes.