I've noticed on this forum that everyone seems to have this view of MRSA as if it's some weird new bug that's somehow more exotic and more dangerous than other bacterial infections. I just wanted to shed a little bit of light just to clear up some misconceptions.
MRSA stands for Methicillin resistant Staphylococcus aureus.
MSSA stands for Methicillin sensitive Staphylococcus aureus.
Staphyloccus aureus is a bacterium which lives on the skin and in the nose in many people. It is often part of the normal skin flora, and doesn't really cause a problem unless, for some reason, it is introduced in to a cut or scrape, when it can then become virulent and cause invasive infection. In other people it can sometimes cause an infection even without a cut in the skin, but that is less likely, and additionally MRSA IS NO MORE LIKELY TO DO THIS THAN GARDEN-VARIETY MSSA!
When penicillin was first discovered in the 1940s, you could use it to kill Staphylococcus aureus. Over years and years of use, eventually Staphylococcus aureus became resistant to normal penicillin. Research brought out what were called "semi-synthetic penicillins" which were able to kill Staph aureus. These were METHICILLIN and its brothers oxacillin, cloxacillin and flucloxacillin and dicloxacillin. Keep in mind, there were (and still are) other antibiotics that can be used to treat Staph aureus. Staph aureus strains which are susceptible to the newer penicillins are called MSSA.
In the 80s, for the first time, strains of Staphylococcus aureus came out which were resistant to even Methicillin and its brothers! These strains became known as Methicillin resistant Staphylococcus Aureus or MRSA. Other than the fact that MRSA is resistant to those penicillins, there is nothing all that special about it. I notice the name MRSA seems to strike fear in many people's hearts, including a lot of people on these healthboards. In reality, MRSA is no more virulent (i.e. has no more potential to cause disease) than MSSA. The only difference is, you're somewhat more limited in the antibiotics you can use to treat it. While MRSA CAN cause life-threatening infection, it is no more likely to do that than MSSA which ALSO can cause life-threatening infection (and actually does so more often than MRSA!)
Generally, MSSA is treated with either a semi-synthetic penicillin (listed above) or a first/second generation cephalosporin such as cephalexin, cefazolin or cefoxitin. While MRSA is resistant to all of those, it is NOT resistant to: doxycycline, tetracycline, rifampin, trimethoprim-sulfamethoxazole (i.e. bactrim or septra), vancomycin, linezolid, quinuprisin-dalfopristin, tigecycline, moxifloxacin, levofloxacin, daptomycin, fosfomycin etc. etc. We have many agents which can treat MRSA, though being judicious with antibiotic use is important so as not to allow MRSA strains to become even more resistant.
The point of me bringing all of this up is that, the only real difference with MRSA vs. MSSA is that you have to use different antibiotics to treat it up front, and you have to be vigilant in looking out for it if your initial antibiotic regimen is not working. I am not saying that MRSA or MSSA infections are anything to be happy about--far from it--I just hope this little blurb helps people realize there is nothing monstrous or magical about MRSA. It is just a VERY old dog who has learned a new trick, and so far, we are still able to treat it.
Last edited by harka; 08-05-2008 at 11:12 AM.