title: Semi-quantification of a microbiological method using beta-lactamases in detecting the hydrolysis of beta-lactam antibiotics.
abstract: The so-called "double disc" technique of Masuda et al. for detecting the hydrolysis of beta-lactams by beta-lactamases was semi-quantified. This semi-quantification consisted of using beta-lactamase preparations progressively diluted by a factor of ten. The last dilution producing a detectable hydrolysis of the antibiotic was thus noted. By using the species Escherichia coli (potentially cephalosporinase producer) as a model, we studied the possible applications of this method. Due to its great sensitivity it was possible to analyse and appreciate the degradation of some cephalosporins reputedly resistant to beta-lactamases, such as cefoxitin, cefuroxime, cefamandole and cefotaxime. The carboxy-penicillins (carbenicillin and ticarcillin) were the most stable beta-lactams towards the cephalosporinase of E. coli 0002.
mesh_terms: D002511:Cephalosporins; D004926:Escherichia coli / Q000201:enzymology*; D006868:Hydrolysis; D008722:Methods; D010406:Penicillins; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D001618:beta-Lactamases