Re: what is mercer disease
It's funny you mention "Mercer" disease, because I've seen other people say that before. It's not "Mercer" but someone just pronouncing all the letters of the abbreviation MRSA (as you mention) so it comes out as "Mersah".
There is nothing magical about MRSA. Staphylococcus aureus is a bacterium that lives on the skin in most people and is of no consequence. Staph only becomes a problem when it gets in to areas of the body "under the skin" so to speak where it causes infections such as abscesses and cellulitis, and if it gets in to the bloodstream it can cause infections in almost any organ.
In the 1940s when antibiotics first came available, one of the first drugs which was found to be able to kill Staph aureus (herein known as SA) was one of the sulfonamides. These drugs still exist today, better known to most Americans as Bactrim and Canadians as Septra. Penicillin then came available in the 50s, and because of marketing ploys relating to the war (and the fact that it treated syphilis in the soliders VERY effectively) people started using penicillin like water. It USED to kill Staph aureus, but soon in the 60s SA developed resistance against it. Scientists then developed what they call the "semi-synthetic penicillins" of which naficillin, oxacillin and cloxaclliln are examples. These became the mainstay of treatment for SA. SA being the resourceful bug it is developed resitance to these semi-synthetic penicillins as well, and this group of SA was known as MRSA or methicillin resistant penicillin (methicillin is a type of semi-synthetic penicillin which is no longer used because it has toxic effects on the kidney).
SOOOOOOOOO, MRSA was around, but for many years (and even today) drugs like cloxacillin have been used to treated SA. Isolates which are still susceptible to clox and its brothers are known as MSSA or Methcillin SENSITIVE SA. In the past 15 years or so, the prevalence of MRSA has increased to the point where a significant number of people are having infections with MRSA instead of MSSA and cloxacillin can't be used anymore. But that doesn't make MRSA necessarily any more deadly. There are still PLENTY of drugs that can be used to combat MRSA including: vancomycin, doxycycline, Septra/Bactrim, ceftibiprole, linezolid, daptomycin, tigecycline, rifampin etc. etc. etc.
So, other than causing a few different types of infections when compared to MSSA, MRSA is really not that exotic. Both can cause mild infections which are treatable, and BOTH can cause serious infections which can ultimately lead to death. Just remember, though, that SA is a normal part of the human flora, and in the vast majority of the cases it lives with us in harmony. It is only when MSSA or MRSA start to repeatedly cause invasive infection where you have to undergo a decolonization protocol (like the one you described coradronet.