Modified Peptidoglycan Transpeptidase Activity in a Carbenicillin-Resistant Mutant of Pseudomonas aeruginosa 18s

A carbenicillin-resistant mutant of Pseudomonas aeruginosa 18s was found to possess peptidoglycan transpeptidase activity significantly more resistant to inhibition by benzyl penicillin, ampicillin, carbenicillin, and cephaloridine than that of the parent strain. The mutant was more resistant than the parent strain to all of the beta-lactam antibiotics tested, and 50% inhibition values for these compounds against membrane-bound model transpeptidase activity paralleled this increase. The resistance of the mutant to kanamycin, streptomycin, and chloramphenicol was unchanged.