What is the dose of sulfamethoxazole (Bactrim) for treating Gram-negative skin and soft tissue infections?

From the Guidelines

The dose of sulfamethoxazole (Bactrim) for treating Gram-negative skin and soft tissue infections is 1 or 2 double-strength tablets twice per day orally, or 8-12 mg/kg (based on the trimethoprim component) in either 4 divided doses intravenously or 2 divided doses orally.

Key Points

• The evidence from 1 and 1 supports the use of trimethoprim-sulfamethoxazole (TMP-SMZ) for the treatment of skin and soft tissue infections, including those caused by Gram-negative bacteria.
• The recommended dose of TMP-SMZ is 1 or 2 double-strength tablets twice per day orally, or 8-12 mg/kg (based on the trimethoprim component) in either 4 divided doses intravenously or 2 divided doses orally.
• It is essential to note that the efficacy of TMP-SMZ for treating Gram-negative skin and soft tissue infections is poorly documented, and its use should be guided by clinical judgment and local antimicrobial resistance patterns.
• The guidelines from 1 provide a comprehensive overview of the diagnosis and management of skin and soft tissue infections, including the use of antibiotics such as TMP-SMZ.
• The study from 1 focuses on the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections, but also mentions the use of TMP-SMZ as an option for empirical coverage of MRSA in outpatients with skin and soft tissue infections.

Important Considerations

• The decision to use TMP-SMZ should be based on the severity of the infection, the presence of systemic inflammatory response syndrome (SIRS), and the patient's underlying health status.
• It is crucial to monitor the patient's response to treatment and adjust the antibiotic regimen as needed, based on culture and susceptibility results.
• The use of TMP-SMZ should be guided by local antimicrobial resistance patterns and clinical judgment, taking into account the potential risks and benefits of treatment.

From the Research

Dose of Sulfamethoxazole for Treating Gram-Negative Skin and Soft Tissue Infections

• The standard dose of trimethoprim-sulfamethoxazole (TMP/SMX) is 160 mg/800 mg twice daily for 7 to 15 days 2.
• A higher dose of TMP/SMX, 320 mg/1,600 mg twice daily for 7 to 15 days, has been studied, but it did not show a significant difference in clinical resolution of infection compared to the standard dose 2.
• The combination of trimethoprim and sulfamethoxazole has been shown to be effective against a broad spectrum of gram-negative organisms, including Escherichia coli, Proteus mirabilis, Proteus vulgaris, Klebsiella, Enterobacter, and Citrobacter 3.
• The minimum inhibitory concentrations (MICs) of trimethoprim + sulfamethoxazole against gram-negative strains were less than 2 mg/l for most isolates, making it a potent antimicrobial agent 3.
• A pharmacokinetic and pharmacodynamic evaluation of high and standard doses of trimethoprim/sulfamethoxazole found that both doses exhibited good skin/soft tissue penetration and bactericidal activity against strains of Staphylococcus aureus and β-haemolytic streptococci 4.
• The combination of trimethoprim and sulfamethoxazole has been used successfully to treat various infectious conditions, including skin and soft-tissue infections 5.