Novel R-factor borne beta-lactamase of Escherichia coli confering resistance to cephalosporins.

Strains of Escherichia coli resistant to ceftazidime but susceptible to other third generation cephalosporins were detected in three patients at two different locations (München, Bremen). The resistance was self-transmissible to other E. coli strains. Resistance against ampicillin, kanamycin, chloramphenicol and sulfonamide was co-transferred. The isoelectric point (pI) of the beta-lactamase was similar to the pI of the AER-1 and LCR-1 beta-lactamases. These enzymes, however, do not confer resistance to ceftazidime. Therefore the beta-lactamase described is the first example for a ceftazidimase.