Some factors influencing the efficiency of disk-diffusion test to determine the antibiotic sensitivity of microorganisms
Poliak, M.S.; Tsvetkova, I.A.
Klinicheskaia Laboratornaia Diagnostika 2007(5): 36-39
2007
ISSN/ISBN: 0869-2084 PMID: 17668459 Document Number: 605284
On diffusion of an antibiotic from the disk to the nutrient medium, gel concentration of an antibiotic changes. This process is individual for each antibiotic. The action of different concentrations of the antibiotic at different intervals results in the suppression of microbial growth around the disk (formation of a zone). The relationship between the antibiotic concentration in the disk and the diameter of a microbial growth suppression area is proportional in the limited range of concentrations. The relationship between the concentration of an antibiotic and the diameter of a growth suppression area may greatly vary for various taxonomic groups of microorganisms and for various strains. The established fact may be responsible for the disagreement of results of a microbial antibiotic sensitivity test, by using different methods and makes the standardization of the disk-diffusion test difficult.