Assay of Antibiotics with Agar Diffusion Technique
Laboratory control of antibiotic treatment may be necessary both to ensure therapeutic concentrations, and to avoid toxic side effects in the patients. There is thus a great need in clinical practice for simple and reliable methods for the analysis of antibiotic concentrations in plasma and other body fluids. Quantitative determinations of antibiotic concentrations is often made by microbiological assay techniques and the agar diffusion method is frequently used. The antibiotic in the test sample is allowed to diffuse from a centre towards the periphery. The growth of a test strain is inhibited in a concentric zone around the centre. At the Karolinska Hospital in Stockholm, Sweden, we started many years ago to use filter paper discs as diffusion centres. The principles for the method have been known from the beginning of the antibiotic era, and different variants have been described (Jalling et al 1972, the publication contains a list of references).
KeywordsInhibition Zone Horse Serum Pleural Fluid Test Strain Paper Disc
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