[Effect of docecyl guanidine acetate on the in vitro activity of penicillin, streptomycin, levomycetin and chlortetracycline].

Sensitivity of Staphylococcus aureus and gramnegative organisms, such as E. coli, Salmonella, Sh. sonnei and Pr. morganii to penicillin, streptomycin, levomycetin and chlortetracycline, as well as their combinations with dodecylguanidine acetate, a surface active substance from the group of guanidine alkyl derivatives was studied. The activity of the penicillin combination with dodecylguanidine acetate was 16-64 times higher than that of penicillin alone against staphylococci and gramnegative bacteria respectively. Sensitivity of the gramnegative organisms to dodecylguanidine acetate combinations with levomycetin or chlortetracycline was 2-260 or 2-250 times higher respectively than that to the antibiotics alone. Sensitivity of the grampositive and gramnegative organisms to the combination of streptomycin with dodecylguanidine acetate was the same as that to streptomycin alone. Increased sensitivity of the microbes to penicillin, levomycetin and chlortetracycline in the presence of the subbacteriostatic concentrations of dodecylguanidine acetate must be associated with an increase in the antibiotic penetration into the microbes under the effect of the surface active substance.