Friday, December 12, 2014

Germs found on credit cards, but there's hope for civilization

Regular readers of my blog know that I am a connoisseur of studies about bacteria in the environment and on human tissue. If you click on the "Infection" label to your lower right, you can read my previous posts on the subject. Not surprisingly, I am skeptical of inflammatory headlines claiming that germs on various surfaces are dangerous.

Money has been the subject of many studies, most of them showing it is covered with bacteria. A recent video from the Cleveland Clinic discussed a study from England which found bacteria on the hands of 11% of people tested, on 8% of the credit cards tested, and either 14% or 6% of paper money [the accompanying story was contradictory].

This is old news. A 2012 study from the European Cleaning Journal [not a peer-reviewed journal] found that 26% of paper money, and 47% of credit cards showed "high levels of bacteria including E.coli and Staphylococcus aureus," and "around 80% of banknotes and 78% of credit cards tested showed traces of bacteria, and some carried more germs than [wait for it…] the average toilet seat."

For those of you new to the field of culturing everything in sight, the toilet seat has been the gold standard for comparison of contamination as I noted in a 2013 post.

A Cleveland Clinic infectious disease physician, who appeared very uncomfortable on camera, advocates washing hands "as much as possible" or use alcohol-based hand sanitizers. Since I'm not aware of too many epidemics caused by contaminated money or credit cards, I wonder if it might actually be worse to obsessively wash hands and use sanitizers.

It's almost 2015. I can't remember the last time I handed my credit card to someone. The state of the art is the machine that lets you swipe it yourself.
But there's a groundbreaking new development noted in a recent article headlined "Public Restrooms No Germier Than Your Home."

Investigators studied four restrooms after giving them a thorough cleaning. Then they allowed access to the public and periodically cultured surfaces such as toilet seats, soap dispensers, and floors.

Although at first fecal bacteria colonized all the surfaces, bacteria found on human skin cells gradually took over. It turns out that fecal bacteria can't survive for long outside of the intestines. "Restroom surfaces are dry, barren and resource-poor," the researchers concluded. "As such, these surfaces probably do not support considerable microbial growth."

"Overall, the research suggests that the restroom is no more healthy or unhealthy than your home," the lead investigator said.

This puts the lid on the toilet seat as the bacterial contamination benchmark. I have alerted the Nobel Prize judges.


frankbill said...


Like this quote.
" I wonder if it might actually be worse to obsessively wash hands and use sanitizers."

It was always my understanding that we build up a immunity to germs. With all the use on the sanitizers are we not on a path of stopping the built up immunity to germs? Once this happens how do we stop the germs from taking over?

Les said...

@frankbill, good point. I remember a microbiology lab experiment wa-ay back when I was an undergrad where the instructor had us touch a petri dish with unwashed hands then to touch a fresh petri dish about 10 minutes after washing our hands. The post washing plates had more colonies on them than the plates that were touched before we washed our hands. The skin produces bacteriostatic oils that are washed away with soap and water or ethanol based hand gels. I can't remember how many minutes it takes for the oils to be replenished on the skin surface.

Anonymous said...

Yep - toilet seat has been gold standard for most colonized ever item in human experience. And jumbo jets have been the standard units for lives lost. And football fields for area. Does anyone really know what the respective quantities are? Amen if the lid has been closed on the toilet seat. Maybe the jumbo jet metaphor should be put in mothballs and the football fields should be benched?

Skeptical Scalpel said...

Frank and Les, I agree with you. I've written about the problems associated with too much hand washing before. In the interest of space, I didn't include that here.

Murray, nice comment. Thanks. I doubt if we've seen the last of the toilet seat though.

davidp said...

Toilet seats and toilet areas in business buildings with regular cleaning are relatively clean. For a nasty contaminated space, try the kitchen dish-wash cloth. Often contains salmonella too. Anecdote: My wife made the the mistake of using the wash cloth to cool a burn once. It promptly got infected.

Skeptical Scalpel said...

Yes, kitchen sponges and cloths are notoriously contaminated. That's one area I won't argue about.

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