November 30, 2015

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What is methicillin-resistant Staphylococcus aureus (MRSA)? (Continued)

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 be resistant to several antibiotics.

In addition, these organisms have been termed "flesh-eating bacteria" because of their occasional rapid spread and destruction of human skin. Additionally, a number of older (2004-2008) web and popular press articles are titled or include the erroneous term "MRSA virus." This is a misnomer that has confused many people; there is no contagious MRSA virus, and if readers examine these articles, they may realize the content is usually about MRSA bacteria.

Unfortunately, MRSA strains of bacteria can be found worldwide. In general, healthy people with no cuts, abrasions, or breaks on their skin are at low risk for getting infected. However, the bacteria can be passed from person to person by direct contact with infected skin, mucus, or droplets spread by coughs in both adults and children. Indirect contact also can spread the bacteria; for example, touching items like towels, utensils, clothing, or other objects that have been in contact with an infected person can spread the bacteria to other uninfected individuals. Investigators estimate that about one out of every 100 people in the U.S. are colonized with MRSA (have the organisms in or on their body but not causing infection), and these individuals may transmit MRSA bacteria to others by the same methods listed above. Another term for people colonized with MRSA is "carrier" which means the person carries the organism in or on the body and may transfer the organism to another person who subsequently may become infected. A common place for carriers to harbor MRSA organisms is the nose. Continue Reading

Reviewed on 2/4/2015