| 摘要 |
<p>The invention provides a way of identifying a beta-lactamase specifically, by monitoring competition reactions between a chromogenic substrate, for example nitrocefin, and various competing substrates, preferably some of the newer beta-lactams, for example cefoxitin, moxalactam, MK 0787 etc. Detailed study of these reactions by the inventor has shown undexpectedly marked variations in the reactivity (affinity) of these enzymes for the different beta-lactams. On this basis the invention provides an assay for identifying "unknown" beta-lactamases based on comparing their behaviour in the competition reaction with affinity data on known beta-lactamases. The chromogenic substrate and a selection of the most useful beta-lactams are provided as a kit. It can contain prepared mixtures of the beta-lactams and chromogenic substrate. The assay can be carried out visually using micro-titre plates and a simple scoring system or more quantitatively by spectrophotometric scanning. It can be used for the rapid identification of beta-lactamases in a hospital laboratory or for the identification of gram-negativebacteria based on the beta-lactamases which they produce.</p> |
