[Joint action of ethonium and antibiotics on gram-positive and gram-negative microorganisms].

The inhibitory effect of antibiotics and their combinations with ethonium was studied in vitro with 10 strains of Staph. aureus and 10 strains of E. coli, Sh. sonnei and Pr. morganii. Ethonium is an antimicrobial drug of the group of cationic surface-active substances. The study was performed with the method of serial dilutions in a liquid nutrient medium. It was found that under the effect of the subbacteriostatic concentrations of ethonium, sensitivity of the microorganisms to benzylpenicillin, streptomycin, levomycetin and tetracycline increased 4-16, 2-8, 2-32 and 64-256 times, respectively. Along with the increasing of the antibiotic activity, ethonium promoted a decrease in the rate of the Staph. aureus adaptation to the above antibiotics.