1. Microbiological titration of antibiotics

by Pascale NABET

The oldest method for determining the titre of an antibiotic is microbiological titration. The principle is simple: simply measure the inhibition of the growth of a sensitive micro-organism by the antibiotic to be dosed. Titration can be carried out with a micro-organism grown in a solid medium (diffusion titration) or with a micro-organism grown in a liquid medium (turbidimetric titration).

The choice of titration method depends on the antibiotic concentration to be measured, the medium in which the antibiotic is present, the number of analyses to be carried out and the laboratory's automation capability.