Antibacterial Resistance from Soap: Hazard or Hype?

Over the past several years, there have been a number of reports claiming that the use of antibacterial hand soaps may lead to the development of “supergerms.” According to these reports, supergerms would be resistant not only to the antibacterial agents used in soap products, but would likely develop resistance to commonly used antibiotics as well. Despite the attention-grabbing headlines such reports have generated, the facts simply do not support these assertions.

It is generally accepted that control of microorganisms found on the skin of individuals is important to public health. The potential for transmission of opportunistic pathogens to oneself or to others is significant, in the home, in work and social environments, and in healthcare institutions. The risk of infection or acquisition of disease from such microorganism transmission can be correlated to specific tasks in all of these settings. The exposure and, consequently, the risk to populations of varying susceptibilities determines the antimicrobial drug performance desired, and the attributes necessary to mitigate the risk.

As background, it is important to note that FDA in 1978 found sufficient support by scientific data to consider the reduction of both transient and resident microflora a benefit to health. The agency has embraced the reduction of skin flora by a pre-specified amount as a valid surrogate end-point for the efficacy of topical over-the-counter (OTC) antimicrobial products.

Today’s generation of topical OTC antimicrobials provides a public health benefit by reducing bacteria on skin. Such products are formulated with active ingredients that have the capability of reducing transient or resident organism populations with greater effectiveness and efficiency than can be achieved through the use of non-antimicrobial products. This additional reduction translates to risk reduction in the transmission of potentially pathogenic organisms and in the potential for disease acquisition (Breneman et al. 1998, Rose and Haas 1999). Coupled with numerous additional studies (Hammond et al. 2000; Sugimoto et al. 1997; Akiyama et al. 1997; Guinan et al. 2002; Fendler et al. 2002; Dyer and Shinder, 2002; and Falsey et al. 1999), there is no shortage of strong scientific evidence supporting the concept that reduction of certain transient and resident microflora on the hands can help mitigate infection.

Topical OTC antimicrobial products are currently available in many forms (bars, liquids, gels, wipes, etc.), and usually contain a single antimicrobial ingredient. In general, these products should be used to appropriately address the risks associated with the specific tasks being performed. Such tasks include:

• Changing diapers;
• Caring for sick, elderly or invalid family members;
• Preparing family meals;
• Having contact with pets;
• Attending daycare;
• Attending school or work;
• Using public restrooms and toilets

The question of resistance development to the antimicrobials used in today’s hand soaps and the development of cross resistance to antibiotics has been studied in some detail. The most relevant studies are those conducted in natural environments.

Lear et al. (2002) conducted a study involving 10 isolates collected from triclosan and para-chloro-meta-xydenol (PCMX) manufacturing sites. The minimum inhibitory concentration (MICS) of these isolates was compared to culture collection strains never exposed to these antimicrobials. There was no evidence that residual levels of biocide present in the factory environment led to any change in bacterial susceptibility.

Marshall et al. (2003) compared the incidence of bacteria, including antibiotic resistant bacteria, in the homes of users and non-users of antibacterial agents. The authors concluded that high frequencies of antibiotic-resistant bacteria occurred in the home environment of both groups. However, there were no significant differences in the overall titers of bacteria, potential pathogens, or frequencies of antibiotic resistance in a single-time analysis of homes, whether using or not using antibacterial-containing products.