Mechanisms of bacterial insusceptibility to biocides

Bacterial insusceptibility to biocides is of two types. intrinsic and acquired. Intrinsic insusceptibility is a natural property of an organism and is shown by bacterial spores, mycobacteria, and gram-negative bacilli. Cellular impermeability is a major factor, and in some cases active efflux pumps play an important role. A special example is that of phenotypic (physiological) adaptation to intrinsic resistance found in bacteria present in biofilms. Acquired resistance arises through mutation or via the acquisition of plasmids or transposons efflux of biocide is a major mechanism, although plasmid-mediated inactivation has also been shown to occur. An additional aspect that must be considered is the stringent response elicited in bacteria on exposure to inimical agencies. There is a possible linkage between certain biocides and antibiotic resistance under experimental conditions.