[A dry nutrient medium for determining the sensitivity of pneumococci to antibiotics]

A dry nutrient medium for assay of Pneumococcus antibiotic sensitivity was developed. The medium is based on a casein-yeast hydrolysate, a hydrolysis product of casein and nutrient yeasts, which are noneatable raw materials. The chemical ingredients selected to meet the Pneumococcus physiological requirements exclude addition of biological fluids such as blood and serum. Inclusion of 2,3,5-triphenyltetrasolium chloride into the medium provided detection of the Pneumococcus growth initial phases. 2,3,5-Triphenyltetrasolium chloride proved to be the most sensitive substance for revealing Pneumococcus reducing capacity. A procedure providing results of antibiotic sensitivity assay of pneumococci 3-3.5 hours after its initiation was developed. The new medium provided satisfactory growth of pneumococci and clear and light inhibition growth zones around antibiotic disks on light red medium. It was found that the medium modification without agar may be used for assay of Pneumococcus antibiotic sensitivity by the method of serial dilutions.