Antiseptics are commonly used topically with the aim of reducing bacterial load on both intact and broken skin. Antiseptics differ from antibiotics in that they have usually have multiple methods of killing bacteria, fungi or viruses, whereas the mechanism of action of antibiotics tends to be on a particular intracellular target.1 Antiseptics destroy (are cidal) or inhibit (are static) the growth of microorganisms in or on living tissue. Disinfectants act mainly in an inhibitory fashion and are applied to inanimate surfaces.
The most common antiseptics used are alcohols, phenols, iodine and chlorine.1 Examples include povidone iodine, bleach, hydrogen peroxide, triclosan, chlorhexidineand hexachlorophene (the active ingredient of Phisohex®), chloroxylenol (the active ingredient of Dettol®) and potassium permanganate. Antiseptics have been proven to reduce bacterial load in a wound but some can be toxic to living cells (fibroblasts, keratinocytes and leukocytes).2 They may potentially delay healing of damaged skin, especially in high concentrations.1
Most of these active agents demonstrate broad-spectrum antimicrobial activity; however, little is known about the mode of action of these agents in comparison to antibiotics.1
Interestingly, povidone iodine has not been proven to increase or decrease the rate of wound healing, although it does reduce bacterial load in contaminated skin.1
The main proven use of hydrogen peroxide is to chemically debride an area, as it does not affect bacteria count in damaged skin and has no proven effect on wound healing.1
Chlorhexidine appears safe to use in damaged skin and may act as an antiseptic rinse. However, there is no clear evidence that it actually prevents infection in wounds.
Bacterial load is also not the only predictor of infection – other predictors include the presence of foreign bodies in the wound, the patient’s co-morbidities and the virulence of the bacteria present.2
The good news is that antiseptics do not usually increase bacterial resistance, possibly because of their multiple modes of action. Very rarely has there been noted bacterial resistance to povidine iodine, despite its use for over one and a half centuries.2 There has been no report of bacterial resistance to hydrogen peroxide, possibly because it has no effect on bacterial count.2 Pseudomonas aeruginosa has occasionally become resistant to quaternary ammonium antiseptics and triclosan, and Staphylococcus has been documented to become resistant to chlorhexidine.2
1. Mcdonell, G., Denver Russell A. Antiseptics and Disinfectants: Activity, Action, and Resistance. Clinical Microbiology Reviews, 1999 Jan; 12(1): 147–179.
2. Topical antibiotics: very few indications for use. Best practice Journal, 2014, 64