MRSA Infections: More Common Than Spider Bites

MRSA (Methicillin-Resistant Staphylococcus aureus) appeared in the Los Angeles HIV community in 2002. Patients often mistake MRSA infection, which looks like an infected pimple, for spider bites. MRSA uses a gene (MecA) that can produce a novel protein that penicillin cannot bind well to.

To determine whether an infection is MRSA or a common type of staph that responds to penicillin, a doctor tests a culture of the drainage. Test results usually take three days, so a doctor must decide which antibiotic to prescribe before knowing the results. The choice is difficult. If MRSA treatment is prescribed and the infection is not MRSA, the therapy may be less than adequate. But if ordinary staph treatment is prescribed and the culture shows MRSA, the infection will likely worsen due to the time lost. The physician must therefore make his or her best guess, which requires knowing what bacteria exist in different populations. In the Los Angeles HIV community, for instance, MRSA infections are common, so the possibility of MRSA must be taken into account when prescribing.

In Los Angeles, MRSA has also been seen among children, athletes in contact sports, inmates and gay men (including some who are HIV-negative). These varieties of MRSA tend to spread person-to-person more easily than MRSAs found in hospitals.

If the skin is cut or broken, bacteria like MRSA can get inside. Scratching or shaving can introduce bacteria -- another reason not to share personal items like razors. Towels should be used on gym benches.

An MRSA infection should be covered with clean dry bandages. People who have close physical contact should frequently wash their hands or shower with antibacterial soap. Clothing should be washed in hot water and dried in a hot dryer.

Outpatient treatment typically involves draining as much pus as possible. If the cavity is deep, it can be packed with sterile gauze to keep it open and draining to the outside. If the infection is small, oral antibiotics, e.g. Bactrim, trimethoprim sulfa twice daily may be effective. This may be prescribed with rifampin or clindamycin. A more expensive, and probably more effective, treatment option is Zyvox (linezolide). It, like the intravenous antibiotic vancomycin, is usually reserved for deeper or more severe MRSA infections.

MRSA often colonizes the nostrils and may spread from there to other areas of the body. Bactroban cream is prescribed to MRSA patients to prevent skin infections from recurring -- which they unfortunately often do. Showers with the antibacterial solution Hibiclens (chlorhexidine) may also help reduce skin colonization.

If treated promptly and properly, MRSA skin infections are relatively easy to treat. However, if MRSA spreads to the bloodstream, lungs or other vital organs, it becomes much more serious. Early treatment with the right antibiotic can prevent more serious infection and should help further reduce the risk of MRSA's spread through the community.

Back to other news for June 4, 2004