BETA-LACTAMASE ENZYMOGRAM - AGAR ADAPTATION OF THE IODOMETRIC METHOD

Abstract

An agar-gel adaptation of the Perret-Novick iodometric titration of degradation products from .beta.-lactam antibiotics when they are submitted to a .beta.-lactamase action is examined. Petri dishes containing an agar-gel make up from the classical iodine-iodide-starch system initially present a dark blue color. When .beta.-lactam compounds are opened by .beta.-lactamases from crude extracts or whole bacteria, the gel is locally destained. Two experimental variants of this procedure are proposed. This semi-quantitative, inexpensive, accurate and simple method is very convenient for routine experiments. With crude extracts or whole cells, information can be obtained about .beta.-lactamase specific activities, substrate profiles or activity of inhibitors such as cloxacillin or clavulanic acid.