The quest for new techniques for screening inhibitors of phosphoglucose isomerase is crucially important owing to therapeutic control of chronic bacterial infections associated with the biosynthesis of bacterial biofilm. According to the new method, yellowish zones against the purple background could be visually observed where phosphoglucose isomerase activity was inhibited. The new protocol with NADPH/NBT/PMS staining for TLC-autographic method was able to detect PGI inhibition by pure reference substance as mercury(II) chloride.