[Antimicrobial characteristics of a tincture of dequalinium chloride]

Dequalinium is a quaternary ammonium salt. From about 30 years Dequalinium (D.C.) was used in the treatment of the initial respiratory organs infections. It can be given orally and topically yet it cannot be given systemically cause its probable systemic toxicity. D.C. has a wide range of antimicrobial activity that is extended to Gram positive, Gram negative bacteria, protozoa and yeast. Its mechanism of action is directed to the cytoplasmatic membrane where D.C. caused its damage and consequently release of cellular components. Our study has been evaluated the antimicrobial activity of D.C. both as commercial product that pure substance. We tested 27 Gram positive bacteria, 49 Gram negative bacteria, 83 strains of fungi, we also tested the antimicrobial activity of D.C. commercial product and pure substance against 8 strains of protozoa; Trichomonas vaginalis. The antimicrobial activity was estimated in some experimental conditions, (cultural and no cultural conditions); in these experiments we can observed that the commercial product presents higher activity than pure substance. In cultural condition commercial product presents antimicrobial activity against Gram positive and negative bacteria and yeast; its interesting to evaluate that bacteria, that are resistant to the common antimicrobial agents were inhibited by D.C. tinture and pure substances. Our data exhibit that serum didn't interfere until the 2% concentration with the antimicrobial activity of D.C., moreover this antimicrobial activity is not influenced by the inoculum size until 10(5) cell/ml. D.C. presents higher activity at alkaline pH than acid pH but strains of C. albicans were killed by D.C. at acid pH. In no cultural conditions D.C. has demonstrated a rapid antimicrobial activity in short contact time (15 minute); the cells of some microorganisms were killed in 60 minutes. Against mycelial form, the commercial product demonstrates good activity higher than pure substance. The activity of D.C. against the formation of germ-tube from blastospores of C. albicans in N-acetyl-glucosamine solution (no culture medium) was markedly high; this is very important because in C. albicans the germ-tube production and yeast-mycelial conversion are prominent for pathogenicity and resistance to host defences. Our data demonstrate the good activity of D.C. against Trichomonas vaginalis; we can also observed that the antimicrobial activity of commercial product is higher than pure substance.(ABSTRACT TRUNCATED AT 400 WORDS)