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MRSA: Methicillin Resistant Staphylococcus Aureus

There is an ongoing battle between the best science can offer and bacteria. When penicillin was first discovered to treat infections, humans arrogantly thought that they had won the war on infectious disease. But, like any organism or creature, there is adaptation, an evolution if you will. This was the case with staphylococcus aureus, a type of gram positive aerobic bacteria.1

The resistance

When being treating for an infection it is always important to finish the full course of antibiotics prescribed by your doctor. Bacteria have the ability to evolve and adapt. They continually demonstrate that they are smarter than us. After penicillin was developed, staph countered with finding a way to inactivate the penicillin. The bacteria produced an enzyme called penicillinase that woud cut part of the penicillin structure, the beta-lactam ring. With this change to the penicillin, it was useless against the staph.1 Of course, science came up with another group of drugs to combat this (Methicillin was among these). But, then, the organisms evolved again and changed the protein that penicillin binds to on the cell wall. Without binding, the drug wouldn’t work.1 This strain of staph is called MRSA (Methicillin Resistant Staphylococcus Aureus), pronounced either [MER-SA], or simply, M.R.S.A.

Who is at risk for developing a MRSA infection?

Risk factors that increase the chance of a MRSA infection include:

1. Previous antibiotic therapy within the past year,1 especially if the course of antibiotics were not completed
2. Recent hospitalization
3. Recent nursing home stay
4. Chronic illness
5. IV drug use 1


With increased risk factors, what can be done to avoid getting or spreading the MRSA? The answer is awfully basic: personal hygiene and proper wound care if there is a wound. Washing your hands for at least 15 seconds with soap and water, paying attention to cleaning under the nails and between the fingers. Next, do not share personal items, such as towels, bar soap, razors, or clothing. Obviously, showering after athletic activity such as games or practices (it hurts that such a statement needs to be made, but sadly it does).

MRSA Prevention

If there is a wound care, seek medical care if there are signs of infection. Keep wounds clean and covered. Avoid contact with other people’s wounds or bandages, and throw away any soiled bandages.

How is MRSA diagnosed?

For those that are at increased risk of developing MRSA, the nursing staff perform a nasal or wound swab. The microbiology department will incubate the wound swab to grow out bacteria and then perform tests to identify the organism. Identification can take between 1 and 3 days. Nasal swabs return the results much faster using PCR (polymerase chain reaction), and the answer can be known within hours. If the MRSA strain of bacteria is present, but not causing an active infection, the patient is colonized. To have a MRSA infection, there are signs of infection.

MSRA Treatment


Vancomycin is one of four drugs that is used to treat a MRSA infection. But, it is only effective in the intravenous form of delivery. No pills, daily IV doses are required. If the patient does not have a wound, but is colonized in the nose only, decolonization with Mupirocin 2% ointment is prescribed.

1. Joseph, Warren. Handbook of Lower Extremity Infections 3rd edition. Maryland, 2009
2. Mehta, MS. Dose-ranging Study to assess the application of intranasal 2% mupirocin calcium ointment to eradicate staphylococcus Aureus Nasal Colonization. Surgical Infections. Volume 14 Number 1, 2013.