Pyridinium 2-azo-p-dimethylaniline chromophore, a chromogenic reagent for beta-lactamase testing compared to nitrocefin

Abstract

Pyridinium-2-azo-p-dimethylaniline chromophore was evaluated as a test tube, filter paper and spectrophotometric assay for detection ofβ-lactamases from grampositive and gram-negative organisms. Although useful for detection of TEMβ-lactamases inHaemophilus influenzae andNeisseria gonorrhoeae, it was a poor agent for detecting TEM, OXA and PSE enzymes inEnterobacteriaceae. It also proved poor for detecting cephalosporinases inPseudomonas aeruginosa andEnterobacteriaceae, and penicillinases inStaphylococcus aureus when compared to nitrocefin. As a spectrophotometric substrate it was equivalent to nitrocefin and cephaloridine with variousβ-lactamases.