Mechanisms of bacterial insusceptibility to biocides

Bacterial insusceptibility to biocides is of two types. intrinsic and acqui red. Intrinsic insusceptibility is a natural property of an organism and is shown by bacterial spores, mycobacteria, and gram-negative bacilli. Cellul ar impermeability is a major factor, and in some cases active efflux pumps play an important role. A special example is that of phenotypic (physiologi cal) adaptation to intrinsic resistance found in bacteria present in biofil ms. Acquired resistance arises through mutation or via the acquisition of p lasmids or transposons efflux of biocide is a major mechanism, although pla smid-mediated inactivation has also been shown to occur. An additional aspe ct that must be considered is the stringent response elicited in bacteria o n exposure to inimical agencies. There is a possible linkage between certai n biocides and antibiotic resistance under experimental conditions.