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New Twist on Natural MRSA

Posted by | September 23, 2009

Twice a week I slog through some reps at the gym to keep my core muscles and arms strong enough I can do basic outdoor tasks. I assure you, my workout regime is modest, based on small “ladies” weights – some of them even colored pink.

But whether you use pink weights or the contortion machines that defy description, gyms ask you to wipe down your equipment with alcohol when you’re done. The main reason for that rule is a type of bacteria called staph, and a strain of staph called MRSA (that’s pronounced ‘mersa’ by the medicos).

Here’s the basic picture about staph.

Whether we work at a desk or in the great outdoors, all of us human beings have simple bacteria living on our skin. One set of bacteria belongs to the group called staph organisms. They are pretty tolerant of salt – so they live happily on our skin where many other bacteria die off. And, normally, the staph stay on the outer parts of our skins, coexisting with us without drama.

But, occasionally, a cut or scrape introduces staph into the interior of our bodies, and significant infections result. Hospitals have long struggled with staph infections in patients after surgeries or procedures.

Because staph is a bacterium, it can be combated by antibiotic drugs. But some staph strains are resistant to antibiotics, and a few are resistant to pretty much our whole arsenal of antibiotics.

The abundance of antibiotic-resistant staph on our skin was really driven home to me when I was recently an instructor in a class here at Washington State University. Like doubting Thomas, I had to see to really believe – but see I did!

Other instructors and I had 120 willing freshmen swab their skin and then smear the swab on slightly salty “gelatin” that lay in Petri dishes.  We gave each student six tiny paper disks to place on the gelatin. Each of the six disks had been soaked in a different antibiotic, so the gelatin near each disk was influenced by penicillin, amoxicillin, and four other common antibiotics.

Then we covered the dishes and kept them in a nice, warm place for a week.

What the students saw when we examined the dishes again was that most of them had staph strains on their skin that had grown over much of the gelatin, some grown happily right up to several of the little disks, and sometimes staph even growing on top of some of the antibiotic-rich papers.

Staph on our innocent freshmen was indeed resistant to many antibiotics. It was quite impressive.

The most drug-resistant sort of staph is MRSA, and it can cause infections that are life-threatening.  But my friend Phil Mixter, an immunologist on the faculty of Washington State University, just told me about MRSA that has been found not in hospitals – where we might suspect long-term use of antibiotics would select for it – but out in the natural environment of the world. A recently announced study shows that MRSA lives at the beach, up and down the Pacific coast. It’s no surprise that mildly salty samples of sand – they’re salty like your skin – have staph bacteria in them. But it did take scientists by surprise to learn the sands also have MRSA in them.

“This is natural MRSA,” Mixter said to me. “It suggests that antibiotic-resistant staph is not a new thing, and it’s everywhere, more than can be due to human overuse of penicillin and similar drugs.”

One way to think of how this came to be is that penicillium fungi have been around in the natural world a long time, making “penicillin juice” (as I think of it) that kills microbes near the fungi. Staph bacteria, over equally long periods, have been selected for resistance to the natural antibiotic makers.

There’s a microscopic arms-race and an on-going war out there, one that can promote a lot of antibiotic resistant bacteria.

But don’t you get caught in the crossfire at the gym. Wipe down the equipment. Shower with soap and warm water before you return to work.

Let the microbes fight it out among themselves.