Hexachlorophene. Secondary microorganism resistance to hexachlorophene. Conjugative transfer inhibition by the R-plasmid-coded resistance by hexachlorophene.

Strain resistance of the genus Escherichia, Salmonella, and Pseudomonas to hexachlorophene is inducible. Secondary resistance of the Gram-negative microorganisms to hexachlorophene is an inherited property of these strains. There are not any explicit differences of primary sensitivity to hexachlorophene between sensitive strains and those resistant to antibiotics. The secondary resistance level of Gram-negative microorganisms to hexachlorophene is also not dependent on the natural resistance (or sensitivity) of strains to antibiotics. Hexachlorophene, in concentration of 10 micrograms/ml of conjugation mixture, causes 100% inhibition of the conjugation transfer of the resistance determinants to antibiotics from tested strains with conjugative R-plasmid. The indirect secondary resistance conjugation transfer to hexachlorophene was verified in two cases. The resistance to hexachlorophene was transferred, coupled with resistance to chloramphenicol, tetracycline, and streptomycin, from the Escherichia coli strains (No. 8) and Salmonella typhimurium (No. 4) to the recipient Escherichia coli strain K 12, SZK-Ec-329/74 (No. 2).