Staphylococcus aureus bacteria normally live on the skin and mucous membranes of many people without causing disease. Still, S aureus is a pathogenic species of bacteria, and can cause diseases of the skin and other areas of the body, called Staph infections, particularly if introduced beyond the skin's surface, such as through a wound, puncture or surgical incision.
The human immune system can often fight bacterial infections without the help of antibiotics. But sometimes antibiotic medication is required to eliminate an infection.
What Is MRSA?
MRSA, which stands for methicillin-resistant Staphylococcus aureus, is a collection of antibiotic-resistant strains of S. aureus. While beta-lactam antibiotics—including penicillin, methicillin, amoxiciilin, oxicillin and the like—usually work well against Gram-positive bacteria such as Staphylococcus, MRSA is resistant to the action of beta-lactams, so MRSA infections are challenging to cure, even with the use of antibiotics.
Transmission of MRSA
MRSA infections are most often nosocomial, meaning that they typically occur in people who are, or have recently been, in a heath care facility, such as a hospital or nursing home. Sick people often have weakened immune systems; couple that with a higher level of exposure to pathogenic microbes in heath care facilities, and the result is a nosocomial infection.
A study recently published in Medscape Medical News estimated that 4% of medical workers are MRSA carriers, meaning that they harbor the bacteria. These workers are not ill from the infection, but can potentially transmit the bacteria to their patients.
MRSA can also be acquired outside of health care environments. This type of MRSA infection is called CA-MRSA, or community-associated MRSA infection. CA-MRSA infections can occur in otherwise healthy people, and often manifest as skin lesions or pimple-like abscesses.
Spider Bites & MRSA Infections
MRSA skin infections often manifest as a raised bump with a lesion at the center, a wound that can look very much like a spider bite. These infections are actually referred to as “false spider bites” in the medial literature. But spider bites do not cause MRSA infections any more than MRSA infections cause spider bites. Yet, most patients who see their physician with a soft-tissue infection testing positive for MRSA originally attribute their wound to spider bite.
The most sensible course of action in dealing with a possible spider bite, particularly when no spider was caught in the act, is to see a health care provider and rule out the possibility that the wound is the result of a MRSA infection. When in doubt, get it checked out!
Sources
Hitt, Dr. Emma (2010) “MRSA Found in 4% of Healthcare Workers; Most Are Healthcare-Related Strains” from the Fifth Decennial International Conference on Healthcare-Associated Infections (ICHAI), Medscape Medical News.
Peck, Peggy (Nov. 2004) “If the patient says spider bite, think MRSA, says Assembly speaker.” American Academy of Family Physicians, FP Report Online.
Tami Port - Tami Port is a college professor of cell and microbiology and creator of ScienceProfOnline.com, a free science education website.
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