Wednesday, September 9, 2009

Will Swimming Pools Kill MRSA?

These are common questions I get fairly often.

Can I transmit MRSA to someone else in a swimming pool?

Can I get MRSA from a swimming pool?

Amazingly, I just heard from someone who has MRSA and apparently their doctor advised them to go into a swimming pool as the doctor said the pool will kill the MRSA on their body.

Is this good advice? Or not? Well, first of all, I'm not a doctor but I can share with you my research on this matter as well as my experience as a Microbiologist.

According to a recent study, swimming pools will kill MRSA and Staph bacteria in the water IF they are properly maintained. Now, let me break this down into some very important points.

First of all, it's generally advised to avoid using pools, spas, or whirlpools if you have open wounds. Most swimming pools have adopted policy's that do not allow people to enter the water with open wounds. You may have seen this policy at your local pool. This policy is used because there is a chance of transmitting bacteria to other people in improperly disinfected water. Therefore, if you have an active infection, I think it's wise to stay out of the water. You don't want to chance giving your infection to someone else and you don't want your open wound to become infected with more bacteria.

Secondly, yes, chlorine will kill MRSA and Staph at proper swimming pool or spa concentrations, but not all pools and spas are maintained at the proper levels of chlorine. There are many factors that come into play with maintaining proper levels of chlorine. And, there have been many instances, particularly with sporting teams where MRSA has been isolated from improperly maintained spas. And these improperly maintained spas have been implicated in transmitting MRSA from player to player (Kazakova et al. 2005). See below for CDC's guidelines on how to determine if your pool or spa is being properly maintained.

Thirdly, as a Microbiologist I know that swimming pools will not kill all of the bacteria on your skin. Swimming pools and spas have disinfectants like chlorine in them to disinfect the water. These levels are not high enough to kill all the bacteria on your body, nor should they be. It would be quite chemically-toxic to enter. Sure, some bacteria will probably die from your skin, but not all of them. And, as I've said before, it's important to remember that many of the bacteria living on your skin are there to protect you from "bad" bacteria. And, bacteria have many defenses including the formation of biofilms. Biofilms are like houses over the bacteria that help protect them from disinfectants and other threats.

In summary, swimming pools or spas will not cleanse your body of MRSA, Staph or any other bacterial skin infection. Chlorine in the pool is meant to reduce or eliminate free-floating bacteria and parasites that come off of people into the water, making the pool a safer environment for all. When pools and spas are maintained appropriately, they will kill MRSA and Staph bacteria in the water fairly quickly making it fairly unlikely for anyone to get MRSA from a pool (see article Tolba, O., et al. below). However, improperly maintained pools or spas have had MRSA isolated from them and they are suspect in transmitting MRSA from person to person.

Here's a neat little chart from the CDC with chlorine disinfection times for some common pool germs:

The CDC has posted some great information about swimming pool and spa "health" and how you can better determine how well swimming pools and spas are maintained. You can learn more from the CDC about healthy swimming here:

Be well,

Michelle Moore
Microbiologist, Staph Researcher and Natural Health Advocate
Natural MRSA Treatment Options


Tolba, O., et al., Survival of epidemic strains of healthcare (HA-MRSA) and community-associated (CA-MRSA) meticillin-resistant Staphylococcus aureus (MRSA) in river-, sea- and swimming pool water Int. J. Hyg. Environ. Health (2007), doi:10.1016/j.ijheh.2007.06.003

Centers for Disease Control, Healthy Swimming:

Kazakova, S.V., Hageman, J.C., Matava, M., Srinivasan, A., Phelan, L., Garfinkel, B., Boo, T., McAllister, S., Anderson, J., Jensen, B., Dodson, D., Lonsway, D., McDougal, L.K., Arduino, M., Fraser, V.J., Killgore, G., Tenover, F.C., Cody, S., Jernigan, D.B., 2005. A clone of Methicillin resistant Staphylococcus aureus among professional football players. N. Engl. J. Med. 352, 468–475


Anonymous said...

Is herpes a staph infection??

Michelle and Les Moore said...


That's a great question. Herpes is actually a virus and Staph is a bacteria. Both can cause infection in people.

There are two main types of Herpes - one causing common cause of cold sores on the lips and the other causing genital warts. Herpes hides within the nervous system. You can read a "wiki" article here:

Staph is a bacterial infection and is a common inhabitant on human skin and in the nose and upper airways. Breaks or scrapes in the skin make an entry way for Staph to enter and cause infection.


Anonymous said...

We have our own pool, treaeted with minimal amounts of bromine and chlorine. Only the family swim in the pool, but I have recurring staph boils. I don't use the pool if the skin is broken, but is it ok to go in otherwise, without infecting anyone else.

Michelle and Les Moore said...

Check the CDC's website above to see if they have advice on bromine. And I'd suggest carefully following the recommendations on maintenance with your pool - closely monitoring the levels of chlorine and bromine as well as the other quality indicators of the water.

It appears by the research done and by studies I've seen, it's unlikely to transfer MRSA if following recommended levels of disinfectant. Again, check with the CDC or with your pool manufacturer on what those should be.

In one study I saw, chlorinated pools were kept at free chlorine concentration of 2.90 parts per million (ppm) and a combined chlorine concentration of 1.00 ppm, giving an overall chlorine concentration of 3.90 ppm. The MRSA bacteria did not survive in this level of chlorine for this particular study.

The disinfectant levels should be closely monitored. When too low, you increase your risk for spreading MRSA.

Linda said...

If well maintained pools can kill mrsa, what about a diluted amount of household clorox?

L. H.

Michelle and Les Moore said...

Hi Linda,

I've replied to your post about bleach here:


Anonymous said...

This is a very useful post -- thanks! I had a bad cut 2 1/2 weeks ago that seems to be healing well (most of the skin is now pinkish, although a very small section is still yellowish; there is no scab since I have kept the wound covered and fairly moist). My pool is maintained by a reputable gym, and always smells like chlorine, but I don't know for sure how well it is maintained. How do I know when it is safe to go back to regular swimming? Thanks again.

Anonymous said...

Staph is a nast infection i caught it from my local swimming pool but i did have atheletes foot made me ill for three weeks resulting in celulitus