We're kicking off the "Ask a Microbiologist" series with...surprise! A question about MRSA. I received an email the other day from a reader who'd suffered from a MRSA infection and was wondering why we as grapplers are more susceptible to these types of infections than other athletes.
After multiple days of IV treatment in a hospital he was left with some questions...
- If I get staph from the staph already on my body, what does wrestling with another person have to do with it?
- If I'm getting staph from the mats, why are cases of staph higher among grapplers than, say, Yogis or Gymnasts ?
- If I'm getting it from someone else, and it's just a matter of grinding bodies together, surely staph rates among college students would be high ?
Multiple papers have shown that people who participate in contact sports, or use shared equipment are at a higher risk for MRSA or other skin infections. There are a few things to consider here. First, you’re right, S. aureus and its cousins (like S. epidermidis) are pretty ubiquitous as far as the human microbiome goes, and they seem to be, for the most part, well tolerated by our immune systems. They serve a purpose by occupying biological niches that other “harmful” bacteria may be trying to colonize. When you’re coming into contact with someone else, you’re being exposed to whatever is living on their body and vice versa. The difference between grappling and a casual handshake is that most times when you shake someone’s hand, you aren’t sweating profusely. An increase in body temperature, coupled with an increase in sweating is a perfect recipe for a bacterial smorgasbord. Both the “good” and “bad” bacteria are going to go through a huge population explosion. They can go through more than three generations in an hour depending on the species. When the prolonged contact happens, now with these increased numbers of bacteria, it’s easier to pass them on from person to person, and since both bodies are nice and warm and sweaty, as soon as the bacteria land, they can just keep on growing.
The bacteria you pick up this way may not be species that your body is used to, and with their increased numbers, can throw off the natural balance of your own flora. So, just using S. aureus as an example, you may carry one type of S. aureus, like Methicillin Sensitive Staphylococcus aureus (MSSA), or strains of S. aureus that can still be treated with antibiotics like penicillin, while your grappling partner may be a carrier for Methicillin Resistant Staphylococcus aureus (MRSA), the kind of S. aureus that can’t. Sometimes, the kinds of MRSA that cause community acquired (CA) infections, or MRSA infections not normally seen in hospitals, tend to grow much, much faster than “normal” MRSA, or other MRSA strains acquired in hospitals (hospital acquired MRSA or HA-MRSA). In that case, they can out-compete your normal bacterial flora for their niche, or biological space, and it’s in those situations where you can get some pretty nasty skin infections. Any environment where there are lots of people using shared equipment, and especially if that environment is warm and moist, can be a perfect breeding ground for all bacteria, not just pathogenic ones. So yes, you’re correct in thinking about your infection in this case in terms of colliding populations of flora from two different people. (I love the ant colony analogy!)
The compositions of our personal flora are always changing, and this change is due to an abundance of factors. For instance, I have a dog who loves to roll around in the grass. I’m subject to colonization by whatever bacteria he may have picked up rolling around in the grass that day. I might only be “transiently” colonized, meaning that the bacteria may only be able to hold onto whatever biological niche it occupied for a short period of time before my normal flora reclaim it, or it may be around for the long haul. A lot of our microbiome is determined when we’re kids, and there are certain species of bacteria that you would expect to find in all people, all of the time. The ratios might change however, and that ratio is determined by lots of different factors like the underlying health of the individual, diet, location, pets etc. Stress is most definitely a determining factor in the health of an individual, and can influence which bacteria might be around in which ratios.
The cool thing (to me anyways) about S. aureus is that it’s such a versatile pathogen. It can colonize many areas of the human body causing infections. It’s not that the bacteria gets more aggressive when it colonizes some areas necessarily, it’s that the strains that can cause these infections often times have some competitive advantage over the bacteria that would normally live there. For instance, S. aureus makes a bunch of different virulence factors that allow it to attach to multiple types of body tissue, cause massive cellular destruction, and even virulence factors that hide its presence from your immune system.
I hope all of this helps. The balance between being healthy and having an infection is very delicate. There are lots of factors that can influence the transition in either direction, especially when it comes to bacterial infections. I think the safest and soundest thing though is maintaining good hygiene. If you’re active and you participate in contact sports, make sure that you take a shower as soon as you can after you’re done. Glad you’re feeling better and thanks for the question!
Thanks as always to Brea for her amazing answers!!