New MRSA guidelines released

The Infectious Diseases Society of America has developed its first clinical practice guidelines for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children.

Methicillin-resistant Staphylococcus aureus (MRSA) is the predominant cause of skin infections among patients presenting to the emergency department, and it can also cause more serious, invasive infections that account for about 18,000 deaths in the United States per year.

“The guidelines establish a framework to help physicians evaluate and treat uncomplicated, as well as invasive, infections due to MRSA,” Catherine Liu, MD, lead author of the guidelines, told Orthopedics Today’s sister publication, Infectious Disease News.

Soft-tissue infections

The guidelines address a variety of infections caused by MRSA, including skin and soft-tissue infections, recurrent skin and soft-tissue infections, invasive infections such as bacteremia and endocarditis, pneumonia, osteomyelitis and central nervous system infections.

For skin and soft-tissue infections, incision and drainage are the recommended primary treatment, and antibiotic therapy is only recommended for severe or extensive disease and for those with associated comorbidities. For outpatients with purulent cellulitis, empirical therapy for community-associated MRSA (CA-MRSA) is recommended pending culture results. Treatment for beta-hemolytic streptococci is likely unnecessary for this group.

Nonpurulent cellulitis

However, for those with nonpurulent cellulitis, empirical treatment with a beta-lactam antibiotic for beta-hemolytic streptococci is recommended. The role of CA-MRSA for this particular entity is unknown. If patients do not respond to the beta-lactam antibiotic, or if they are systemically ill, then treatment for MRSA should be given.

Patients with recurrent MRSA skin and soft-tissue infections should be educated on proper wound care and personal and environmental hygiene. If a recurrence occurs despite these measures, decolonization strategies may be offered in the form of nasal decolonization and/or topical body decolonization regimens. Further research is needed to determine the optimal approach to prevent recurrent infections, the panel noted.

“In addition to antibiotic therapy, the management of all MRSA infections should include identifying, eliminating and/or debriding the primary source and other sites of the infection,” Liu said.

Regimen and doses

For adults with uncomplicated MRSA bacteremia, a 2-week course of intravenous vancomycin or daptomycin (Cubicin, Cubist Pharmaceuticals) is recommended. In adults with complicated MRSA bacteremia or endocarditis, 4 to 6 weeks of the treatment is recommended. Follow-up blood cultures should be performed at 2 to 4 days, and as needed thereafter, to document that the infection has been cleared.

The guidelines also recommend that when intravenous vancomycin is used, the dosage should be 15 mg/kg to 20 mg/kg per dose, every 8 to 12 hours and not exceed 2 g per dose. Trough vancomycin concentrations should be used to guide dosing and achieve target concentrations of 15 mcg/mL to 20 mcg/mL in patients with serious MRSA infections, such as bacteremia, infective endocarditis, osteomyelitis, meningitis, pneumonia and severe skin and soft-tissue infections, such as necrotizing fasciitis.

The guidelines also discuss the management of patients with MRSA isolates with reduced susceptibility to vancomycin, vancomycin treatment failures and the use of alternatives to vancomycin therapy. — by Emily Shafer

Reference:
Liu C. Clin Infect Dis. Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children: executive summary. 2011;53:285-322.

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