What is the best course of treatment for a 48-year-old male patient with a recurring bilateral hand Methicillin-resistant Staphylococcus aureus (MRSA) infection, previously treated with Bactrim (Trimethoprim/Sulfamethoxazole), Keflex (Cephalexin), and Clindamycin, now being prescribed Linezolid (600 mg twice daily) for 10 days?

From the Guidelines

I recommend prescribing linezolid 600 mg twice daily for 10 days to treat this patient's recurrent bilateral hand MRSA infection, with a follow-up appointment in 14 days. The previous antibiotic regimen of Bactrim, Keflex, and Clindamycin provided some improvement but was ultimately unsuccessful in resolving the infection completely. Linezolid is an appropriate choice for MRSA infections that have failed previous antibiotic therapy because it has excellent tissue penetration and is highly effective against resistant Staphylococcus strains, as supported by studies such as 1. The dosage of 600 mg twice daily is the standard therapeutic dose for adults with skin and soft tissue infections, as recommended by guidelines such as those from the Infectious Diseases Society of America 1. During treatment, the patient should be monitored for potential side effects including headache, nausea, and diarrhea. If the patient is taking serotonergic medications, they should be warned about the risk of serotonin syndrome. Complete blood counts should be monitored if treatment extends beyond 14 days due to potential bone marrow suppression. The patient should take the full course of antibiotics even if symptoms improve before completion to ensure eradication of the infection. Some key points to consider in the treatment of MRSA infections include:

• The importance of appropriate antibiotic selection, with linezolid being a suitable option for skin and soft tissue infections 1
• The need for monitoring of potential side effects, such as headache, nausea, and diarrhea
• The importance of completing the full course of antibiotics to ensure eradication of the infection
• The potential for drug interactions, such as the risk of serotonin syndrome with serotonergic medications.

From the FDA Drug Label

WARNINGS Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported in patients receiving linezolid. In cases where the outcome is known, when linezolid was discontinued, the affected hematologic parameters have risen toward pretreatment levels Complete blood counts should be monitored weekly in patients who receive linezolid, particularly in those who receive linezolid for longer than two weeks, those with pre-existing myelosuppression, those receiving concomitant drugs that produce bone marrow suppression, or those with a chronic infection who have received previous or concomitant antibiotic therapy The patient will be taking linezolid for 10 days, which is less than two weeks. However, complete blood counts should be monitored due to the patient's previous antibiotic therapy and chronic infection.

• The patient should be followed up in 14 days as planned.
• Monitoring of blood counts is crucial to detect any potential myelosuppression early. 2

From the Research

Treatment of MRSA Infections

• The patient has a bilateral hand MRSA infection that was initially treated with Bactrim, Keflex, and Clindamycin, but has shown some improvement with recurring symptoms 3.
• Linezolid (600 mg BID) for 10 days has been prescribed, with a follow-up in 14 days.

Alternative Treatment Options

• Other treatment options for MRSA infections include high-dose daptomycin in combination with an antistaphylococcal β-lactam, ceftaroline, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin 3.
• Ceftaroline alone or in combination with vancomycin or TMP-SMX, and linezolid alone or in combination with a carbapenem or telavancin are also potential treatment options 3.
• The choice of empirical therapy should be based on the site and severity of the infection, with oral antibiotics such as trimethoprim-sulfamethoxazole, clindamycin, doxycycline/minocycline, and linezolid considered for moderate skin and soft tissue infections 4.

Efficacy of Linezolid

• Linezolid has been shown to be effective against MRSA infections, including pneumonia, skin and soft tissue infections, and other serious infections 5.
• However, the efficacy of linezolid compared to other agents such as daptomycin and trimethoprim/sulfamethoxazole is still being studied, with some studies suggesting that trimethoprim/sulfamethoxazole may be a cost-effective alternative 6.

Considerations for Treatment

• The treatment of MRSA infections should take into consideration recent exposure, source control, and available synergy and clinical data 3.
• The growing interest in vancomycin alternatives, such as ceftaroline, ceftobribole, dalbavancin, oritavancin, and tedizolid, and their potential role in treating MRSA infections should also be considered 4.