[Intensification of the action of antibiotics with cationic surface-active substances]

The antimicrobial effect of cationic surface-active substances, such as cetylpyridinyi chloride, alkylmethylbenzylammonium chloride ("roccal" and "catamine AB") and chlorhexidine was studied in vitro. The above compounds had a high bactericidal activity against poly-resistant staphylococcal strains. In non-bactericidal concentrations they significantly increased the efficacy of antibiotcs with different modes of action, i.e. penicillins, tetracyclines, amino-glycosides, macrolides. The effect of the cationic surface-active substances increasing the antibiotic activity against staphylococci did not depend on the resistance type, i.e. chromosomal or extrachromosomal. This was mainly associated with impairement of the function of the bacterial cytoplasmic membrane by these compounds. The cationic surface-active compounds were poor inhibitors of the specific enzyme of Bac. licheninformis 749/C, i.e. penicillinase. A marked inhibition of the enzyme was observed only at concentrations above the bactericidal ones and those damaging the cell membrane of staphylococci.