December 17, 2013

expert reaction to the US Food and Drug Administration statement on antibacterial soap

The Food and Drug Administration (FDA) in the US warned that ingredients in antibacterial soaps might pose health risks, calling for a safety review.

Professor Jean-Yves Maillard, Professor of Pharmaceutical Microbiology, Cardiff University, said:

“Antimicrobial biocides are important to control and reduce microbial bioburden on surfaces including hands when used appropriately (at the right concentration and contact time) and play an important role in infection control.

“Antimicrobial biocides such as triclosan used at an inappropriate (often low) concentration in consumer but also healthcare products may not control microbial bioburden and may contribute to emerging and maintenance of antimicrobial resistance in bacteria.

“In Europe, since the 1st September 2013, manufacturers of products containing antimicrobial biocide need to show that their product will not increase the risk of antimicrobial resistance in bacteria (Biocidal Product Regulation).”

Dr Katie Laird, a Society for Applied Microbiology (SfAM) subcomittee member, said:

“Although cross-resistance from disinfectants to antibiotics can be observed in some bacteria, more research is required before this can be generalized to antibacterial soaps. The FDA are required to ensure that the safety of the products bought by consumers is met and are just requesting that manufactures are able to justify their ‘antimicrobial’ claims.”

Professor Mark Fielder, Medical Microbiologist, Kingston University and Hon Gen Sec, SfAM, said:

“Whilst there is some evidence that bacteria have developed resistance to antimicrobial chemicals such as triclosan (amongst others) in the laboratory, this has not been reproducibly observed in the clinical or home based settings. What is clear is that there is a knowledge gap here that needs to be further studied to ensure we have a full understanding of how any changes may occur to effectively limit the potential of the emergence of antibiotic resistance in the future. We need to fully determine whether or not the inclusion of antimicrobial chemicals in ‘over the counter’ products provides any real benefit or greater efficacy when compared to what might be termed as ‘traditional’ products.

“Concerns regarding the inclusion of antimicrobial agents in ‘over the counter’ products such as soaps, is not new and the question has recently been raised again by the FDA. Some of these concerns relate to the possible development of antibiotic cross-resistance in some bacteria. Historically, the development of resistance following the inclusion of chemicals such as triclosan in products has been of limited concern. This is largely due to the broad spectrum activity of the chemical coupled with the targeting of multiple bacterial targets. This, in general terms, means that development of resistance is more difficult. However some studies have called this thinking into question following observations that certain bacterial components (an enzyme called enoyl‐acyl carrier protein reductase) can be affected by the action of the chemical. It has been suggested that the overproduction of this enzyme, blocking the transfer of triclosan into the cell or active pumping of the chemical out of the cell all might help lead to resistance to triclosan occurring. Another interesting observation is that at higher concentrations of chemicals such as triclosan work against several bacterial cell targets, but at lower concentrations (below those that are normally routinely used) the chemical becomes more selective in its targets.

“The link between chemicals like triclosan and antibiotic resistance have been examined and the findings suggest that, typically, the use of triclosan (at the correct concentration) was effective against many bacteria, with the exception of Pseudomonas aeruginosa, which is naturally resistant to the action of triclosan. Some studies have shown that in the laboratory the exposure to chemicals such as triclosan might help decrease bacterial sensitivity to some antibiotics in some strains. However, this correlation has not been reported in studies from a clinical setting, nor has it been shown in the home setting. Some laboratory based studies have shown that isolates of Salmonella species and E. coli have shown evidence of cross- resistance between antibiotics and antimicrobials used in the clinical setting. However, the study notes that this has not been confirmed in the clinical setting. So it is clear, especially in light of the ongoing concern with antibiotic resistance that we need to study any potential link with antimicrobial chemicals and the development of any antibiotic resistance.”

Dr Mark Webber, Senior Research Fellow, School of Immunity and Infection, University of Birmingham, said:

“I welcome the FDA’s intention to require the makers of antibacterial soaps to demonstrate they have an added benefit compared to soap and water. Prevention of infection is very important but there is essentially no evidence that the vast majority of antibacterial soaps work better than traditional soap and water. There is in fact potential for these products to be damaging; we at Birmingham and others have shown they can select for resistant bacteria under certain conditions.  For routine household use soap and water is a perfectly good way to wash your hands.”

Professor Jodi Lindsay, Reader in Microbial Pathogenesis, St George’s, University Of London, said:

“There has been little research on these antibacterial agents despite their widespread use.  Publically funded research does not prioritise this topic because the benefit of these agents to human health is likely to be minimal.   Industry has not funded the research because there has been no regulatory requirement. Soap and water on its own is an effective handwashing agent.  The addition of agents like triclosan to soaps and body washes may increase selection of resistant bacteria such as MRSA.”