Bacterial resistance to disinfectants

Abstract

A ntiseptics and disinfectants (biocides) are widely employed in controlling hospital infection. Their activity depends upon several factors, notably concentration, period of contract, pH, temperature, the type, nature and numbers of microorganisms to be inactivated and the presence of organic soil or other interfering material.

Bacteria vary considerably in their response to antiseptics and disinfectants. Bacterial spores are the least susceptible, followed by mycobacteria (including glutaraldehyde-resistant Mycobacterium chelonae) and then by Gram-negative bacteria, notably pseudomonads. Gram-positive cocci, including antibiotic-resistant staphylococci, are readily inactivated by disinfectants. Enterococci, including vancomycin-resistant strains, are also susceptible but somewhat less so than staphylococci.

Resistance is often intrinsic in nature, but may be acquired either by mutation or by the acquisition of genetic elements. Disinfectant rotation is practised in several hospitals but the issue remains contentious, although hospital isolates are often more resistant to biocides than laboratory or ‘standard’ strains.