Q:

How Clean Is a Bar of Soap?

Is bar soap clean because it’s soap, or can it transfer bacteria commonly spread among athletes like MRSA?

How effective is that bar of soap?     Photo: Dana Ward/Shutterstock

A:Just because it’s soap doesn’t mean it’s clean. Several studies over the past three decades have shown that bar soap used in both public and private settings often harbors several types of bacteria. Among the bacteria researchers have found on bar soap are E. coli, which can cause diarrhea, along with other issues, and Staph. aureus, the leading cause of skin infections including antibiotic-resistant MRSA.

Authors of a 2006 study on bar soap used in dental clinics wrote that a contaminated bar of soap may “serve as a continuous source of infection and re-infection for the users” and that bar soap has been involved in the “outbreak of infections in the hospital.”

However, just because bacteria is on the soap doesn’t necessarily mean you will get infected. One study published in 1988 found that “washing with contaminated bar soap is unlikely to transfer bacteria.” In that study, researchers inoculated soap with 70 times more bacteria than is typically found on used soap bars. Sixteen people then washed their hands with the soap, and did not subsequently have detectible levels of the bacteria on their hands. Though that study has been held up as proof that bar soap won’t spread germs, it’s important to note that the makers of Dial soap backed the research. 

So where does that leave you? The Centers for Disease Control recommend using liquid soap over bar soap to prevent a MRSA infection, noting that antimicrobial soap is unnecessary. If you still want to use bar soap, do not share it, and leave it somewhere where it will dry off easily after use.

THE BOTTOM LINE: Bar soap is not inherently clean. If you’re worried about getting MRSA or other bacterial infections from a family member or teammate, use liquid soap instead.

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