A Quick Primer On Diagnosing And Treating HA-MRSA and CA-MRSA

It is not uncommon for patients to present to healthcare facilities with skin and soft tissue infections. Skin and soft tissue infections account for more than 14 million outpatient visits per year, and researchers expect this number to grow.¹ Of the causative organisms, Staphylococcus aureus is the leading cause of bacterial infections and methicillin-resistant Staphylococcus aureus (MRSA) remains a prevalent pathogen.² Understanding the risk factors associated with MRSA skin and soft tissue infections is important in making an accurate diagnosis and providing prompt treatment.

Methicillin-resistant Staphylococcus aureus is endemic to hospitals throughout the world and can lead to morbidity and mortality.² Healthcare-associated MRSA (HA-MRSA) is defined as a MRSA infection that occurs less than 48 hours following hospitalization or a MRSA infection that occurs outside of the hospital, but within 12 months of exposure to healthcare-related settings.² These healthcare-related settings include hospitalizations, dialysis, surgery and any long-term stay in a nursing home or rehabilitation center within the last 12 months. In addition, indwelling medical devices and implants increase the risk of MRSA infection, and are potential areas for possible seeding of the bacteria.²

Community-associated MRSA (CA-MRSA) differs from HA-MRSA in that it occurs in the absence of healthcare exposure. We can define CA-MRSA as a positive MRSA culture obtained within 48 hours of admission to a hospital in a patient with no history of hospitalization, surgery, or time spent in a long-term care facility, and the absence of indwelling devices.³ The most common presentation of CA-MRSA is a skin or soft tissue infection in an otherwise healthy individual.³ Researchers believe CA-MRSA is genetically different from HA-MRSA because HA-MRSA typically is resistant to multiple drugs.⁴ Unfortunately, an effective strategy for decolonization and treatment of CA-MRSA carriers in the community does not currently exist.³

Prevention of both CA- and HA-MRSA begins with hand hygiene and environmental cleaning. There are a variety of biocides in household cleaning agents. These biocides include triclosan, quaternary ammonium compounds and chlorhexidine.³ When washing the hands, research has shown that plain soap is just as efficacious as antibacterial soap in reducing bacteria.³

Treatment of any MRSA infection should begin with incision and drainage of the abscess, and wound debridement when indicated. Many skin infections can resolve following adequate incision and drainage alone.⁵ When intravenous antimicrobial therapy is necessary, vancomycin remains the mainstay of treatment.⁴

References

1. Rajan S. Skin and soft-tissue infections: classifying and treating a spectrum. Cleveland Clin J Med.  2012; 79(1):57.
2. DeLeo FR, Otto M, Kreiswirth BN, Chambers HF. Community-associated methicillin-resistant Staphylococcus aureus. Lancet. 2010; 375(9725):1557-68.
3. Skov R, Christiansen K, Dancer SJ, et al. Update on the prevention and control of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA). Int J Antimicrob Agents. 2012; 39(3):193-200.
4. Iyer S, Jones DH. Community-acquired methicillin-resistant Staphylococcus aureus skin infection: a retrospective analysis of clinical presentation and treatment of a local outbreak. J Am Acad Dermatol. 2004; 50(6):854-858.
5. Uhlemann AC, Otto M, Lowy FD, DeLeo FR. Evolution of community-and healthcare-associated methicillin-resistant Staphylococcus aureus. Infect Genet Evol. 2014; 21:563-574.