Relationship between β-lactamase production by Haemophilus influenzae and sensitivities to penicillins and cephalosporins

Abstract

The in vitro sensitivities of β-lactamase producing and non-producing strains of Haemophllus influenzae to eight penidillins and cephalosporins were investigated and the relative rate of hydrolysis of these antibiotics by H. influenzae β-lactamase determined. Ampicillin and benzyl penicillin were readily hydrolysed by the enzyme and were significantly less active on Mactamase producing strains, whereas carbenidillin was highly active on all strains and relatively resistant to hydrolysis. Cephaloridine and cephamandole were hydrolysed by the enzyme but elevated resistance of the β-lactarnase producing strains could not be demonstrated. Of the eight antibiotics tested only carbenicillin and cephamandole were highly active on both lactarnase and non-lactaniase producing strains.