MRSA: The Scarlet Letters

I am fascinated at the current trend we see in our hospitals, nationwide, toward precautions for methicillin resistant Staphylococcus aureus (MRSA). Much of this in the USA has arisen since last year’s “present on admission” criteria that limited reimbursement for the increased complexity of treating these patients if the infection was not “present on admission”. A cottage industry now has sprung up in diagnostics and protective gear seemingly overnight to deal with this medical/fiscal issue. Indeed, now patients who are identified as being “carriers” of MRSA (swabbed in the nose and other regions on admission to hospital) are branded with these scarlet letters for life.

One point for thought, though: how often is the MRSA that grows out of the swab of the patient’s nose the actual bug causing the infection which led to the hospital admission? Our initial experience has been that this may be the exception, rather than the rule. While this is the case, many patients are receiving drugs to treat the MRSA while the actual infecting organism (for example in a foot wound) may get second billing. Is this good medicine? Is this good infection control practice? We offer this up for discussion, as it is a frequent topic raised in our SALSA bowl.

David G. Armstrong

Dedicated to amputation prevention, wound healing, diabetic foot, biotechnology and the intersection between medical devices and consumer electronics.


  • Dr Armstrong asks some very important, pertinent questions that, unfortunately, for the most part, cannot be answered with much science. At our institution ALL patients admitted with a DFI (or for that matter any SSSI) are empirically started on anti-MRSA therapy based on a, perhaps unfounded, fear that MRSA is so prevalent as to render such therapy necessary. When I first started at this particular hospital the routine overuse of anti-MRSA therapy drove me crazy, and I fought against it, until I was called in one evening to see a patient in the ED. This 38 y/o healthy male was seen in the ED for an infection of the right hallux. He had dropped a trashcan on the foot at work while wearing his shoe. He thought nothing of it until 3 days later the entire foot was red, hot and swollen. He had absolutely no medical history of note, had not been hospitalized or taking antibiotics for as long as he could remember AND when I asked if anyone in his family had ever been diagnosed with MRSA his response was “what’s that”. Given you have to pretty much live in outer space to NOT know what MRSA is, I had to assume that he had never been exposed at home or he would certainly be aware of it. I turned to the Resident and pretty much said…”if this guy has MRSA, I will eat my hat!” so we started him on non-MRSA coverage. I think you see where this is going. 3 days later we had positive CA-MRSA cultures back from the lab. What does this have to do with routine screening? I have grown to rather appreciate it. Yes, it is over interpreted, there is no question. BUT, we frequently see patients admitted from a nursing home or SNF. I can usually have the answer long before I receive the wound cultures. I think that there is a decent negative predictive value. Generally, if the patient is negative on screening I can stop the MRSA therapy being fairly certain I won’t find it in the foot. If it is positive, yes, I still keep them on therapy until I have the wound cultures back. If wound cultures do not grow MRSA, I D/C MRSA treatment regardless of the nasal screening. When the pt is re-admitted, as they seem to inevitably be, I do not re-start therapy based of the nasal screen but rather on the last wound culture. As for the wound organism(s) playing second fiddle to the MRSA, I don’t usually see it as a problem. I rarely, if ever ONLY begin anti-MRSA therapy so all potential comers are covered. Besides, any anti-MRSA drug will effectively cover even the susceptible aerobic gram positives that cause the vast majority of these infections so there is no-harm in that regard. The greatest harm is, as with any overuse of antibiotics, causing adverse drug events and resistance.Sorry for the long winded, rambling response.

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