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What Is a MRSA Infection and What Does MRSA Look Like?

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Updated May 16, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

MRSA under an electron microscope looks like berries in grape-like bunches.

MRSA under an electron microscope looks like berries in grape-like bunches.

CDC - PHIL Image Library

MRSA is pronounced "MER-suh" and stands for methicillin-resistant Staphylococcus aureus. It is a form of bacteria that causes infections in human beings. MRSA infections can be deadly because most people infected are immunocompromised, combined with the antibiotic-resistant nature of the bacteria. Since MRSA infections are often acquired during a hospital stay, it's important to know everything you can about MRSA so you can prevent it when you are hospitalized. You'll want to know what it is, how it spreads, and what MRSA looks like.

What's In a Name? Where Does the Name MRSA Come From?

To better understand MRSA and why it's so deadly, let's break down the name.

Staphylococcus aureus is the extended name for what we commonly refer to as a staph infection. There are actually dozens of kinds of staph germs that infect humans, but most infections come from the aureus type.

In Greek, staphyle means bunch of grapes, and kokkos means berry. Aureus means golden in Latin. When combined they describe what MRSA looks like under a microscope.

Methicillin is a type of antibiotic -- a form of penicillin intended to kill many staphylococcal infections -- that was first developed in the late 1950s.

Of course, part of the MRSA name is "methicillin-resistant," meaning that MRSA is not effectively treated with methicillin. In fact, over time, so many staph and other germs became resistant to methicillin that doctors stopped prescribing it, and methicillin is no longer manufactured. It's this resistance to antibiotics -- not just methicillin but many other antibiotics, too -- that make MRSA so problematic to treat, and possibly deadly.

Why Did Staphylococcus aureus Become Resistant to Methicillin?

You'll remember Charles Darwin from high school biology. His theory of natural selection said that species survive by becoming the "fittest," meaning they must evolve with their environment. It's this theory that explains how Staphylococcus aureus became resistant to methicillin.

Methicillin was developed to kill those staph germs. Over time, however, treatment with these antibiotics has led to the emergence of strains of staph bacteria that are resistant to their action.

This continues today. New antibiotic drugs are constantly being researched and developed to kill off infection-causing bacteria. But we can only keep up with the bacteria as they evolve. Each new drug causes a shift in the DNA of the bacteria, which causes the need for a shift in the way the drug is developed. In too many cases, bacteria are evolving faster than man's ability to develop the drugs to kill them.

Prevention of a MRSA Infection is Important

Because of its infectious and resistant nature, we need to work hard to prevent a MRSA infection to begin with. Unfortunately, human bodies are highly susceptible to MRSA and other hospital-acquired infections. When caught early, some antibiotics will have some effect, but it takes a long time to rid a body of a MRSA infection -- if it's possible at all. In too many cases, particularly in patients whose immune systems are impaired, it is not.

Prevention takes the form of being sure everything that touches a patient -- from people to equipment, from bedrails and linens to the bathroom fixtures in the hospital room -- stays clean and sanitized.

Included in prevention are IV's that carry MRSA and other pathogens directly into patients' bloodstreams. IV's should never be in place in a patient unless there is a good cause. When not in use, or no longer in use, they should be removed immediately. If you or a loved one is the patient with an IV, and you aren't sure how necessary it is, ask your doctor or nurse how soon it can be removed.

Does Anyone Survive a MRSA Infection?

Yes. MRSA infections can be treated, and most treatment is eventually successful. However, it can take a very long time to rid a body of MRSA, and it can cause problems over a long period of time. Further, according to the CDC, about 100,000 American patients die from hospital-acquired infections each year. MRSA is one of those infections.

Ironically, about 30% of us carry MRSA on our skin all the time without any problems. That means two things:

  • It means that we may have a natural resistance until our immunity becomes compromised. Being in the hospital means immunity is compromised.

  • It means that those of us who are healthy and carrying MRSA on our skin can cause someone else to acquire a MRSA infection if their immunity is compromised. If you visit someone who is sick, or elderly, or in the hospital, be sure your hands and anything else that touches them are washed and/or sanitized. (Learn more about how to safely visit someone in the hospital.)

For those who acquire a MRSA infection and get sick from it, there are drug regimens and procedures that can be administered to try to kill the infection (as described here by the CDC.)

Next: What Does MRSA Look Like?

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