Calorimetric analysis of the effects of penicillin G, ampicillin and polymyxin B on the growth of Escherichia coli.

Abstract

Calorimetric analysis was performed of the effects of penicillin G, ampicillin and polymyxin B on Escherichia coli grown on bouillon mediumat pH 6.2 and 37°C. The presence of any one of these drugs shifted the patterns of growth thermograms toward longer incubation periods, although the growth rate constant remained almost unchanged. The changes in the thermogram patterns were analyzed by means of a simple mathematical model and parameters needed to characterize the actions of the drugs on the growth ofE. coli were determined. The drug concentrations at which the number of viable cells at the start of incubation decreased by half during the incubation were 6.94, 0.46 and 0.04^moldm~3 for penicillin G, ampicillin and polymyxin B, respectively. Drug potency curves were drawn for the three drugs using the parameters determined. 2855 (1986).

Isothermal microcalorimetry: a novel method for real-time determination of antifungal susceptibility of Aspergillus species

“…1a) delayed the heat production in a concentration‐dependent manner without significant change of the heat‐flow curve profile, indicating its fungicidal activity. A similar killing effect of bactericidal antibiotics was previously described for bacteria [13]. Voriconazole and posaconazole (Fig.…”