There are a number of potential advantages with antiseptics including ease of application, outpatient therapy and reduced cross resistance to systemically used antimicrobials. However, there are also a number of possible disadvantages including minimal penetration to deeper tissue, local hypersensitivity and toxicity, interference with wound healing, difficult dosing, systemic absorption from large wounds and even the potential for the antiseptic source to become contaminated with bacteria or fungi with repeated applications from the same bottle.
Antiseptics available in the British National Formulary include:
- Alcohols e.g. methylated spirits
- Phenolics e.g. Triclosan
- Potassium Permanganate
- Hydrogen peroxide
In addition to those listed in the BNF there is an increasing body of literature regarding silver compounds and also honey.
Methylated spirits and ethanol have activity against bacteria, fungi and some viruses. Alcohols are normally used for skin preparation before venepuncture (remember a pocket full of those red square packets mixed in with sachets of salt and pepper from the canteen!?! Ah the good old days of white coat pockets). Although cheap and well tolerated alcohols have two main disadvantages limiting their efficacy, 1) they are not sporicidal and 2) effectiveness is concentration dependant; as concentration decreases, so does effectiveness. Most alcohol preparations are diluted to between 60% and 90% but evaporation can further reduce the concentration making them less effective.
Chlorhexidine is active against both Gram-positive and Gram-negative bacteria; it has a residual activity up to 6 hours after application. Widely used as a hand scrub and surgical skin preparation it has recently become the skin preparation of choice prior to venepuncture in the UK, although Chlorhexidine has been around in clinical practice since the early 1950s. It is well tolerated with adverse effects on soft tissue being rare. Its main disadvantages are that its activity is greatly reduced in the presence of organic material, so there is the need to remove all of this from the hands or skin before using Chlorhexidine as an antiseptic, and resistance has been described, particularly in Staphylococcus aureus.
Cetrimide is active against most bacteria and fungi but is NOT ACTIVE against Pseudomonas aeruginosa. Cetrimide’s main use is for superficial wounds, it is the main ingredient in Savlon®. It is reported as being less toxic to soft tissue than many of the other topical antiseptics, although local irritation can occur. Resistance rates are not documented.
Iodine based compounds have been used since the early 1800s and are very broad spectrum, showing activity against bacteria, fungi, viruses and parasites. Povidone-iodine is widely used as a surgical scrub and skin disinfectant on minor wounds. It is not recommended for use on large wounds as there are concerns about cytotoxicity and systemic absorption causing metabolic acidosis, hypernatraemia and renal failure. For these reasons iodine is no longer available over the counter in the UK. Iodine compounds are inactivated by organic matter, so there is the need to remove all of this from the hands or skin before applying. Resistance has not been described.
Phenolics - Triclosan
Triclosan is primarily active against Gram-positive bacteria, with more limited effectiveness against Gram-negatives and fungi. Triclosan is used in many cosmetics, soaps, detergents, shampoos and toothpaste; it’s the main ingredient in Colgate Total® toothpaste. Although Triclosan at high doses hit the headlines as causing liver cancer in mice, evidence suggests low concentrations of Triclosan are safe and do not lead to drug-resistance.
Potassium Permanganate is used as a skin cleanser and deodoriser and is often used on weeping ulcers. It is active against bacteria and parasites. Solutions of 0.05% of potassium permanganate are less effective against skin bacteria compared to other antiseptics and at this concentration it is harmful to tissue causing skin irritation. The non-irritating 0.01% concentration’s activity is even weaker and slower, requiring submersion in solution for more than 1 hour to kill bacteria. It does colour the patient’s skin a nice purple though...
Hydrogen peroxide is an oxidising agent that has activity against Gram-positive and Gram-negative bacteria. Used as a dilute solution for skin disinfection and cleaning wounds and ulcers, it was more commonly used in the 1980s to bleach hair! The major drawbacks to hydrogen peroxide are that it is rapidly inactivated by contact with organic matter and it has been linked to the production of air emboli when used on traumatised tissue as well as causing localised pain and irritation. There is insufficient evidence to support the clinical use of hydrogen peroxide. Resistance is unknown.
Silver compounds are now available in both topical antiseptics and in wound dressings. Silver ions are bactericidal against a broad spectrum of Gram-positive and Gram-negative bacteria, including MRSA and VRE but as VRE is not a skin pathogen it begs the question how useful this might be as a topical treatment. Silver dressings are promoted for their infrequent application however silver ions are rapidly inactivated by organic material making these dressing less active over time. There have been few published comparative trials on silver compounds. Adverse effects are uncommon although skin can be stained and healing even delayed! Resistance is infrequent (but has been described).
Honey...my favourite, however I like it served on buttered toast! Honey is inhibitory to many species of bacteria and has been shown to hasten wound healing with few adverse reactions, toxicity or side-effects, although clinical trials are few and generally of poor quality. It is used for dressing wounds but it is important to use medical grade honey (e.g. Manuka) as nonmedical honeys (bee-it supermarket or local...ha ha) contain spores of bacteria such as Clostridia spp. and have unpredictable antibacterial activity.
So what evidence exists for the use of topical antiseptics?
Unfortunately there is very little reliable data on any of the antiseptics assessing their effectiveness in the treatment of superficial wounds or skin disinfection. The published trials are not comparable, do not define specific patient groups, have inappropriate controls or inadequate sample sizes. In other words there is no conclusive evidence either for or against their use.
I have found 7 systematic reviews since 2000, including 5 Cochrane reviews, which have all failed to show any effectiveness of topical antiseptics and state that the evidence was of poor quality. The recommendation of these reviews has been for further study into these agents, their effectiveness and safety.
So what is my “gold standard” treatment protocol for wounds?
Begin with debridement of all dead or diseased tissue, removal of foreign bodies, careful dressing and correction of any underlying arterial, venous or metabolic problems. In my opinion clinically infected wounds require systemic antimicrobials whereas clinically uninfected wounds do not require antimicrobials at all, systemic or otherwise. By clinically infected I mean those where the secretions from the wound are purulent and there are signs of inflammation including pain and surrounding erythema (see blog on Wounds).
The only specific scenario where topical antiseptics have been shown to be of value is in the context of burns where destruction of blood vessels to the area of the burn can prevent systemic treatment being completely effective and in this scenario the addition of a topical antiseptic can be of benefit.
So currently there is no evidence to support the use of topical antiseptics BUT that might just be the point…THERE IS JUST NO EVIDENCE. In the era of increasing antimicrobial resistance, with no new antimicrobials on the horizon, perhaps there should be a concerted effort to conduct good quality randomised trials to assess the effectiveness of these treatments and perhaps expand our armament in the fight against infection. I for one think we should keep an open mind…