[Combined action of nitrofuran preparations and bile acids on staphylococci]

The effect of cholic, glycocholic and deoxycholic bile acids on the antimicrobial activity of furacin, furadonin, furagin and furoxone was studied with the use of collection strains and fresh isolates of staphylococci. The method of dilutions in liquid media was used. Cholic and glycocholic acids lowered the MIC of furacin, furadonin, furoxone and furagin with respect to the collection strains by 4-16, 5, 4-6 and 22-37 times, respectively. The potentiating effect of deoxycholic acid on the nitrofuran drugs was even more pronounced. Thus, when the nitrofurans were used in combination with deoxycholic acid, their MIC dropped by 16-114 times. A significant increase in the antimicrobial activity of the nitrofurans under the effect of the bile acids was also observed with respect to the fresh isolates of Staphylococcus, while it was somewhat lower. The subbacteriostatic doses of cholic, glycocholic and deoxycholic bile acids also increased the bactericidal effect of the nitrofuran drugs. The minimum bactericidal concentrations (MBC) of furacin, furoxone, furadonin and furagin decreased from 12.5, 2.08, 25.0 and 1.82 to 0.78, 0.26, 2.34 and 0.032 micrograms/ml, respectively. The most pronounced decrease in the MBC was observed under the effect of deoxycholic acid. Therefore, the bile acids potentiated the nitrofuran antistaphylococcal activity. The combinations of deoxycholic acid with furagin or furoxone were the most effective.