What is the treatment for cellulitis in patients at risk for Methicillin-resistant Staphylococcus aureus (MRSA)?

From the Guidelines

For patients with cellulitis who are at risk for methicillin-resistant Staphylococcus aureus (MRSA), empiric antibiotic therapy should include coverage for this pathogen, with the recommended first-line treatment being trimethoprim-sulfamethoxazole (TMP-SMX) at a dose of 1-2 double-strength tablets (160mg/800mg) twice daily for 5-10 days, as supported by the most recent guidelines 1. The choice of antibiotic therapy should be based on the severity of the infection and the presence of risk factors for MRSA, such as previous MRSA infection, recent hospitalization, residence in long-term care facilities, recent antibiotic use, injection drug use, or living in areas with high MRSA prevalence. Some key points to consider when treating cellulitis in patients at risk for MRSA include:

• The importance of proper wound care, including incision and drainage of any abscesses, as recommended by the Infectious Diseases Society of America 1
• The need to elevate the affected area and maintain good hygiene to promote healing and prevent further infection, as suggested by the guidelines 1
• The recommendation to use antibiotic therapy for 5-10 days, with the duration of treatment individualized based on the patient's clinical response, as stated in the guidelines 1
• The option to use alternative antibiotics, such as doxycycline, clindamycin, or linezolid, in patients who are unable to tolerate TMP-SMX or have a history of allergy to this medication, as recommended by the guidelines 1
• The importance of considering the patient's underlying health status and the presence of any comorbidities when selecting an antibiotic regimen, as suggested by the guidelines 1 In terms of specific antibiotic regimens, the following options are recommended:
• For outpatients with purulent cellulitis, empirical therapy for CA-MRSA is recommended pending culture results, with options including clindamycin, TMP-SMX, a tetracycline, or linezolid, as stated in the guidelines 1
• For hospitalized patients with complicated SSTI, empirical therapy for MRSA should be considered pending culture data, with options including IV vancomycin, oral or IV linezolid, daptomycin, telavancin, or clindamycin, as recommended by the guidelines 1 Overall, the treatment of cellulitis in patients at risk for MRSA requires a comprehensive approach that includes proper wound care, antibiotic therapy, and consideration of the patient's underlying health status and risk factors for MRSA, as supported by the most recent guidelines 1.

From the FDA Drug Label

The cure rates by pathogen for microbiologically evaluable patients are presented in Table 18. Table 18 Cure Rates at the Test-of-Cure Visit for Microbiologically Evaluable Adult Patients with Complicated Skin and Skin Structure Infections Pathogen Cured ZYVOX n/N (%) Oxacillin/Dicloxacillin n/N (%) Staphylococcus aureus 73/83 (88) 72/84 (86) Methicillin-resistant S aureus 2/3 (67) 0/0 (-)

A separate study provided additional experience with the use of ZYVOX in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. The cure rates in microbiologically evaluable patients with MRSA skin and skin structure infection were 26/33 (79%) for linezolid-treated patients and 24/33 (73%) for vancomycin-treated patients

Treating Cellulitis in Patients at Risk for MRSA:

• Linezolid is effective against MRSA, with a cure rate of 79% in microbiologically evaluable patients with MRSA skin and skin structure infection 2.
• Vancomycin is also effective against MRSA, with a cure rate of 73% in microbiologically evaluable patients with MRSA skin and skin structure infection 2.
• The cure rate for Methicillin-resistant S aureus was 71% (12/17) in the linezolid-treated patients with diabetic foot infections 2.
• Daptomycin has been shown to be effective in treating MRSA bacteremia, with a success rate of 44% in the ITT population 3.

From the Research

Treatment Options for Cellulitis in Patients at Risk for MRSA

• Empiric outpatient therapy with trimethoprim-sulfamethoxazole, cephalexin, or clindamycin can be effective for treating cellulitis in patients at risk for MRSA 4
• Trimethoprim-sulfamethoxazole and clindamycin have been shown to be more effective than cephalexin in treating cellulitis, especially in patients with risk factors for MRSA such as obesity and presence of abscesses 4, 5
• Linezolid, daptomycin, and ceftaroline are alternative therapies that can be used to treat MRSA infections, including cellulitis, and have been shown to be effective in certain cases 6, 7, 8

Risk Factors for MRSA Cellulitis

• Obesity and presence of abscesses are independent risk factors for MRSA cellulitis 5
• Lesions involving the head and neck are also associated with an increased risk of MRSA cellulitis 5
• Patients with these risk factors may benefit from empiric therapy with antibiotics active against MRSA 5

Antibiotic Choices

• Vancomycin is a standard therapy for MRSA infections, but has limitations such as nephrotoxicity and rapid target attainment 7
• Linezolid, daptomycin, and ceftaroline are newer agents that have been approved for treating MRSA infections and may be considered as alternative therapies 6, 7, 8
• Trimethoprim-sulfamethoxazole and clindamycin are effective oral antibiotics that can be used to treat cellulitis in patients at risk for MRSA 4