MRSA (Methicillin-Resistant Staphylococcus aureus) Infections

MRSA Slideshow

Medical Author: Charles Davis, MD, PhD
Medical Editor: Melissa Conrad Stöppler, MD

• What is methicillin-resistant Staphylococcus aureus (MRSA)?
• What are the signs and symptoms of MRSA infection?
• What does MRSA look like?
• How is MRSA infection transmitted?
• How is MRSA diagnosed?
• How can people prevent MRSA infection?
• What is the prognosis (outlook) and complications for people with MRSA infections?
• If MRSA is so resistant to many antibiotics, how is it treated or cured?
• Where are other MRSA information sources?
• MRSA Infections At A Glance
• Pictures of MRSA - Slideshow
• Patient Discussions: MRSA - Describe Your Experience
• Find a local Infectious Disease Specialist in your town

Superbug Staph Spread in Community Medical Author: Melissa Conrad Stöppler, MD Medical Editor: Barbara K. Hecht, PhD MRSA, or methicillin-resistant Staphylococcus aureus, is a bacterium that can cause serious infections. It is resistant to numerous antibiotics of the beta-lactam family, including methicillin and penicillin. MRSA belongs to the large group of bacteria known as Staphylococci, often referred to as Staph. About 25%-30% of all people have Staph within the nose, but it normally does not cause an infection. In contrast, only about 1% of the population have MRSA. Infections with MRSA are most common in hospitals and other institutional health-care settings, such as nursing homes, where they tend to strike older people, those who are very ill, and people with a weakened immune system. In health-care settings, MRSA is a frequent cause of surgical wound infections, urinary tract infections, bloodstream infections (sepsis), and pneumonia. MRSA outbreaks, however, are appearing increasingly in the community. Infections can occur in people who have not been hospitalized or had a medical procedure performed in the past year, and who do not have immune deficiency. These infections are termed community-associated MRSA infections (CA-MRSA). The U.S. Centers for Disease Control and Prevention (CDC) estimates that about 12% of MRSA infections are now community-associated, but this percentage can vary by community and patient population. Learn about symptoms of MRSA infections » Top Searched MRSA Infection Terms: staph infection, super bug, pneumonia, care and treatment, what does MRSA stand for, how is MRSA spread, information, can you die from MRSA, diagnose, staph aureus, methicillin resistant staphylococcus aureus, symptoms, MRSA picture slideshow

What is methicillin-resistant Staphylococcus aureus MRSA?

MRSA stands for methicillin-resistant Staphylococcus aureus (S. aureus) bacteria. This organism is known for causing skin infections in addition to many other types of infections. There are other designations in the scientific literature for these bacteria according to where the bacteria are acquired by patients, such as community-acquired MRSA (CA-MRSA), hospital-acquired or health-care-acquired MRSA (HA-MRSA), or epidemic MRSA (EMRSA). A number of Web and popular press articles are titled or include the erroneous term "MRSA virus." This is a misnomer; there is no contagious MRSA virus, and if readers examine these articles, they may realize the content is usually about MRSA bacteria.

Although S. aureus has been causing infections (Staph infections) probably as long as the human race has existed, MRSA has a relatively short history. MRSA was first noted in 1961, about two years after the antibiotic methicillin was initially used to treat S. aureus and other infectious bacteria. The resistance to methicillin was due to a penicillin-binding protein coded for by a mobile genetic element termed the methicillin-resistant gene (mecA). In recent years, the gene has continued to evolve so that many MRSA strains are currently resistant to several different antibiotics such as penicillin, oxacillin, and amoxicillin (Amoxil, Dispermox, Trimox). HA-MRSA are often also resistant to tetracycline (Sumycin), erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone), and clindamycin (Cleocin). In 2009, research showed that many antibiotic-resistant genes and toxins are bundled and transferred together to other bacteria, which speed the development of toxic and resistant strains of MRSA. S. aureus is sometimes termed a "superbug" because of its ability to become resistant to several antibiotics. Unfortunately, MRSA can be found worldwide.

What are the signs and symptoms of MRSA infection?

Most MRSA infections are skin infections that produce the following signs and symptoms:

• cellulitis (infection of the skin or the fat and tissues that lie immediately beneath the skin, usually starting as small red bumps in the skin),



• boils (pus-filled infections of hair follicles),



• abscesses (collections of pus in under the skin),



• sty (infection of eyelid gland),



• carbuncles (infections larger than an abscess, usually with several openings to the skin),
and


• impetigo (a skin infection with pus-filled blisters).

One major problem with MRSA is that occasionally the skin infection can spread to almost any other organ in the body. When this happens, more severe symptoms develop. MRSA that spreads to internal organs can become life-threatening. Fever, chills, low blood pressure, joint pains, severe headaches, shortness of breath, and "rash over most of the body" are symptoms that need immediate medical attention, especially when associated with skin infections. Some CA-MRSA and HA-MRSA infections become severe, and complications such as endocarditis, necrotizing fasciitis, osteomyelitis, sepsis, and death may occur.

What does MRSA look like?

On the skin, it may begin as a reddish lesion that looks like a pimple or small boil. Often it progresses to an open, inflamed area of skin (as pictured below) that may weep pus or drain other similar fluid. See the first Web citation for more MRSA pictures.

What does MRSA look like?

MRSA - Describe Your Experience

The MedicineNet physician editors ask:

Please describe your experience with MRSA.

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