From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, sulfamethoxazole and trimethoprim tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. Urinary Tract Infections For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris
The FDA drug label does not answer the question.
From the Research
Staphylococcus aureus urinary tract infections (UTIs) should be treated with trimethoprim-sulfamethoxazole (Bactrim) at a dose of 160/800 mg twice daily for 7-10 days as the first-line treatment, as supported by the most recent and highest quality study available 1.
Treatment Options
- For uncomplicated Staph UTIs, alternatives to trimethoprim-sulfamethoxazole include nitrofurantoin 100 mg four times daily for 7 days, or cephalexin 500 mg four times daily for 7-10 days, depending on susceptibility testing.
- For complicated or catheter-associated Staph UTIs, treatment may require intravenous antibiotics such as vancomycin or cefazolin, especially if MRSA is suspected.
Important Considerations
- Patients should increase fluid intake to help flush bacteria from the urinary tract and complete the full course of antibiotics even if symptoms improve.
- Staph UTIs often indicate potential systemic issues, as S. aureus is not a typical urinary pathogen; its presence may suggest hematogenous spread from another infection site or contamination during specimen collection.
- Follow-up urine cultures after treatment completion are recommended to ensure complete eradication of the infection, as suggested by studies on the treatment of Staphylococcus aureus infections 2.
Antibiotic Resistance
- The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has complicated the treatment of Staph UTIs, and the use of vancomycin or other antibiotics may be necessary in such cases, as discussed in a study on the treatment of MRSA infections 3.
- The use of trimethoprim-sulfamethoxazole has been shown to be effective in treating MRSA infections, including those caused by community-associated MRSA strains, as reported in a study on the efficacy of trimethoprim-sulfamethoxazole against MRSA 1.