INACTIVATION OF BETA-LACTAM ANTIBIOTICS BY LEGIONELLA-PNEUMOPHILA

Beta-lactam-inactivating activity has been found in all sero-groups of Legionella pneumophila. The β-lactamase activity could be detected in intact cells and released by ethylenediaminetetraacetic acid treatment, indicating that it is located in the periplasmic space. The enzyme acted primarily as a cephalosporinase hydrolyzing cefamandole, cephalothin, cephaloridine, and also penicillin G and ampicillin. Cefoxitin and cefuroxime were not hydrolyzed. Clavulanic acid and CP-45,899, β-lactamase inhibitors, prevented the hydrolysis of cephalosporins and penicillins. The β-lactamase activity appears to be different from that found in Enterobacteriaceae and Pseudomonas.