Anti-bacterial soap doesn’t help prevent illness

21 August, 2007:

Washing hands with an anti-bacterial soap is no more effective at reducing bacterial levels or preventing illness than washing with ordinary soap, researchers in the United States have said.

What is more, anti-bacterial soaps, most of which contain the anti-microbial Triclosan, produced worrisome antibiotic cross-resistance among different species of bacteria, according to a study reported in a supplement to the September 1, 2007, issue of Clinical Infectious Diseases.

Triclosan, a phenoxyphenol anti-microbial, kills bacteria at high concentrations, but has been shown to be relatively ineffective at inhibiting the growth of gram-negative bacteria, such as pseudomonas aeruginosa or serratia marcescens, according to Allison E Aiello and colleagues, of the University of Michigan, the United States.

Moreover, several studies have demonstrated evidence of Triclosan-adapted cross-resistance to antibiotics, such as amoxicillin, among different species of bacteria, the researchers said.

Though bacterial resistance has not been detected at the population level, they noted that E. coli has, in laboratory experiments, showed resistance to as little as 0.1% wt/vol Triclosan soap, an amount common in these products.

Only a few studies have attempted to assess the relationship between the biocide-containing soap and the emergence of antibiotic resistance in a community setting, the researchers said.

To throw light on the subject, the researchers searched the PubMed database for English-language articles published from 1980 through 2006, and found 27 relevant articles.

Their review concluded that soaps containing Triclosan within the range of concentrations commonly used in the community setting (0.1%-0.45% wt/vol) were no more effective than plain soap at reducing bacterial levels on the hands or preventing symptoms of infectious illness, including cough, congestion, diarrhea, sore throat, fever, and vomiting.

Many of the available bacterial-reduction studies have shown that increased application time tends to result in greater efficacy, a practice not typical in real-world practice, the researchers said.

However, even health care professionals generally wash their hands for a much shorter time, and community studies indicate suboptimal hand-washing practice, the researchers noted.

The results of the new review call into question the marketing of soaps containing Triclosan as a product providing efficacy beyond the use of plain soap in the community setting.

There are still too few studies conducted in the community setting to assess adequately whether the emergence of antibiotic resistance in that setting is associated with consumer soaps containing Triclosan, the researchers said.

The United States Food and Drugs Administration (FDA) does not regulate the levels of Triclosan used in consumer products, the researchers noted. The current findings, they argued, warrant further evaluation by governmental regulators regarding claims and advertising by antibacterial products.