Is Bactrim DS (trimethoprim/sulfamethoxazole) appropriate for a patient with Impaired renal function (GFR of 55) and E. coli UTI?

From the Guidelines

Bactrim DS (trimethoprim/sulfamethoxazole) is not the ideal choice for a patient with a GFR of 55 and E. coli UTI due to the potential risk of renal toxicity and hyperkalemia, and alternative antibiotics such as nitrofurantoin or fluoroquinolones should be considered. For a GFR of 55, which represents mild to moderate renal impairment, the risk of adverse effects from Bactrim DS is increased, particularly hyperkalemia and renal toxicity 1. According to the 2014 guidelines, trimethoprim/sulfamethoxazole can be used in patients with GFR > 30 ml/min/1.73 m2, but close monitoring of renal function and electrolytes is necessary 1. However, the 2011 guidelines from the Infectious Diseases Society of America recommend that trimethoprim-sulfamethoxazole be used only if local resistance rates of uropathogens do not exceed 20% or if the infecting strain is known to be susceptible 1. Some key points to consider when treating a patient with a GFR of 55 and E. coli UTI include:

• The patient's renal function and electrolytes should be closely monitored during treatment with Bactrim DS or any other antibiotic.
• Alternative antibiotics such as nitrofurantoin or fluoroquinolones may be more suitable for patients with mild to moderate renal impairment.
• The patient should be advised to maintain adequate hydration while taking the medication.
• Regular assessment of renal function during treatment is advisable, especially if the course extends beyond 5 days.
• If the patient has a history of severe allergic reactions to sulfonamides, significant electrolyte abnormalities, or is taking medications that may interact with Bactrim (like warfarin or methotrexate), alternative antibiotics should be considered.

From the FDA Drug Label

However, patients with severely impaired renal function exhibit an increase in the half-lives of both components, requiring dosage regimen adjustment (see DOSAGE AND ADMINISTRATION section). Perform urinalyses with careful microscopic examination and renal function tests during therapy, particularly for those patients with impaired renal function

• Impaired Renal Function: The patient has a GFR of 55, indicating impaired renal function.
• Dosage Adjustment: The drug label suggests that dosage regimen adjustment is required for patients with severely impaired renal function.
• Monitoring: The patient should be monitored closely, with regular urinalyses and renal function tests. Given the patient's impaired renal function (GFR of 55), Bactrim DS may not be appropriate without dosage adjustment and close monitoring. The drug label recommends adjusting the dosage regimen for patients with severely impaired renal function, and the patient's GFR of 55 may require such adjustment. 2

From the Research

Patient Assessment

• The patient has a GFR of 55, indicating impaired renal function.
• The patient has an E. coli UTI with a count greater than 100,000.
• Bactrim DS (trimethoprim/sulfamethoxazole) has been ordered for treatment.

Treatment Considerations

• According to 3, trimethoprim-sulfamethoxazole can be used to treat urinary tract infections in patients with renal functional impairment.
• However, 4 notes that renal dysfunction changes the pharmacokinetics of both component drugs, and adverse effects may occur more frequently in renally impaired patients.
• 5 reports that acute kidney injury associated with trimethoprim/sulfamethoxazole can occur, especially in patients with hypertension and diabetes mellitus.

Resistance and Efficacy

• 6 suggests that the prevalence of trimethoprim-sulfamethoxazole-resistant E. coli infection is high, and fluoroquinolones may be a preferred empirical treatment for uncomplicated pyelonephritis.
• 7 compares the clinical efficacies of co-trimoxazole and nitrofurantoin in patients with urinary-tract infections and finds co-trimoxazole to be significantly superior.

Dosage and Monitoring

• 4 provides guidelines for appropriate dosing and monitoring of trimethoprim/sulfamethoxazole therapy in renally impaired patients, emphasizing the importance of careful consideration of the patient's renal function when using this medication.