Microcalorimetric study on the antibiotic activity of clarithromycin and erythromycin

By using LKB-2277 Bioactivity Monitoring System, the heat effect changes in the process of inhibitory action of clarithromycin and erythromycin onEscherichia coli at 37°C were determined. Quantitative analysis showed that relationship between antibiotic concentrationc and rate contantk ofEscherichia coli growth, and half inhibitory ratio concentration IC50: clarithromycin:k=0. 030 03–1. 1736×10−3 c, 8. 45 mg ·L−1; erythromycin:k=0.031 08–8.4657×10−4 c, 14. 45 mg·L−1. As a result of the microcalorimetry experiments, it not only indicated that antibacterial activity of clarithromycin was stronger than that of erythromycin, but also reported the changeable features of thermodynamics of the bacterial cell in biological, biochemical and metabolic process under different drug action.