PROPERTIES OF A CEPHALOSPORINASE PRODUCED BY PROTEUS-PENNERI WHICH ISINHIBITED BY CLAVULANIC ACID

P. penneri produces an inducible cephalosporinase, as many Enterobacte riaceae. Nevertheless this betalactamase is susceptible to clavulanic acid which is an exception also encountered for P. vulgaris. The autho rs studied the enzyme produced by P. penneri 14HBC resistant to cefota xime (MIC 16 mg/l) isolated in Spain in 1992. This betalactamase of is oelectric point 6,65 hydrolyzes first generation cephalosporins, amoxy cillin and poorly ticarcillin as it occurs for all cephalosporinases. However this enzyme hydrolyzes strongly oxyimino-cephalosporins : cefu roxime, cefotaxime, cefepime, cefpirome as it occurs with extended-spe ctrum betalactamases. Cephamycins and imipenem are not substrates. Cla vulanic acid has a very good affinity for this betalactamase which is inactivated progressively. These properties are similar to those of th e enzyme of P. vulgaris Ro104 of isoelectric point 8,3 which, contrari ly to other cephalosporinases, belongs to the structural Ambler's clas s A.