DEVELOPMENT, CHARACTERIZATION, AND INITIAL EVALUATIONS OF S1 - A NEW CHROMOGENIC CEPHALOSPORIN FOR BETA-LACTAMASE DETECTION

A novel, chromogenic cephalosporin reagent (S1) far beta-lactamase testing was produced that shares physicochemical characteristics with nitrocefin (formerly 87/312). SI and nitrocefin in a disk-testing format for beta-lactamase performed at 100% agreement for detecting enzyme-producing isolates of Bacteroides fragilis group, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, Staphylococcus aureus, and selected Enterobacteriaceae. The time required to achieve an initial color change or a strong positive reaction was comparable for both chromogenic reagents for all organisms except the Gram-positive species. SZ reaction times were similar to 50% faster than nitrocefin for beta-lactamase-positive enterococci and S. aureus. These results from the developmental studies and a commercially prepared disk lot indicate that S1 is a promising beta-lactamase disk test reagent with the ability to detect all significant enzyme-producing species strains, some significantly earlier than the nitrocefin disk method.