• biocide
• increased tolerance
• cross resistance
• infection prevention
• mechanism of resistance

Two boys were among the first patients to have benefited from the use of biocides (antiseptics and disinfectants). Joseph Lister described in 1867 how he used carbolic acid to prevent infection in their injured limbs, thereby saving them from amputation.1 Ever since then we have relied on antiseptics and disinfectants to prevent infection by reducing the burden of bacteria in wounds, catheters, ventilators and the environment of susceptible patients, such as neonates. Should biocides fail, we may once again live in a more hostile world, in which deaths linked to caesarean sections, preterm births, invasive procedures, burns and accidents are commonplace. Our dependence on biocides has once again increased in importance in the light of potentially untreatable infections caused by multidrug-resistant (MDR) organisms, as prevention of infections (by using biocides) is once again better than cure (use of failing antibiotics). However, there is mounting evidence of bacteria also becoming resistant to biocides when used at in-use concentrations for the recommended length of time. From laboratory studies, we are also aware of a growing body of evidence of cross-resistance to antibiotics. These worrying observations are being studied to understand the relevance of observational studies and laboratory findings to infection prevention procedures in the clinic and whether the use of certain biocides can lead to inadvertent selection of bacteria that are also more resistant to frontline antibiotics.

Biocides are used to decontaminate patients and staff before operations using hand and body washes and skin preparation before surgery. They can support healing in burns victims and prevent infection of susceptible patients from environmental contamination, such as Pseudomonas aeruginosa contaminating patients on a neonatal ward.2 Though infection prevention procedures depend on the efficacy of the applied biocides, standards to test the efficacy of biocides (EN 1040 and EN 13727) are not very …