From the Guidelines
Bactrim (trimethoprim-sulfamethoxazole) is not recommended for treating a UTI caused by Enterococcus faecalis due to intrinsic resistance. Enterococcus species are intrinsically resistant to Bactrim due to their ability to utilize exogenous folates, bypassing the drug's mechanism of action 1. For Enterococcus faecalis UTIs, appropriate first-line treatment options include:
- ampicillin (500 mg orally four times daily for 7 days) or
- amoxicillin (500 mg orally three times daily for 7 days) if the strain is susceptible, as recommended by guidelines for the treatment of infections due to multidrug-resistant organisms 1. However, it's crucial to note that ampicillin or ampicillin-based treatments should be used with caution due to potential resistance issues, as highlighted in guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women 1. For patients with penicillin allergies,
- nitrofurantoin (100 mg orally twice daily for 7 days) may be effective for uncomplicated lower UTIs,
- or other alternatives like fosfomycin or pivmecillinam could be considered based on local resistance patterns and availability 1. In complicated cases or for patients with penicillin allergies,
- vancomycin or
- linezolid might be necessary based on susceptibility testing, as recommended for enterococcal infections 1. It's essential to confirm antibiotic susceptibility through culture results before finalizing treatment, as resistance patterns can vary 1. Patients should complete the full course of antibiotics even if symptoms improve and should increase fluid intake to help flush bacteria from the urinary tract. Given the most recent and highest quality evidence, the use of Bactrim for Enterococcus faecalis UTIs is not supported due to resistance concerns 1.
From the Research
Antibiotic Susceptibility of Enterococcus faecalis
- Enterococcus faecalis is a common cause of urinary tract infections (UTIs), and its antibiotic susceptibility is a concern due to its natural resistance to many antibiotics 2.
- A study found that all isolated strains of E. faecalis were sensitive to glycopeptides (vancomycin and teicoplanin) and to nitrofurantoin, while 96% of strains were sensitive to penicillin 2.
- However, the study also found that 17% of E. faecalis strains demonstrated high-level resistance to aminoglycosides, and these strains were also resistant to other antibiotics, including penicillin, tetracycline, and ciprofloxacin 2.
Treatment Options for UTIs Caused by Enterococcus faecalis
- The treatment of UTIs caused by E. faecalis can be challenging due to its resistance to many antibiotics 3.
- Potential oral agents active against E. faecalis that may be considered for acute uncomplicated UTI include nitrofurantoin, fosfomycin, and fluoroquinolones 3.
- However, a study found that exposure of E. faecalis to nitrofurantoin increased virulence properties, which may not be suitable for treatment of enterococcal UTIs 4.
- Trimethoprim-sulfamethoxazole (Bactrim) is not recommended as a first-line treatment for UTIs caused by E. faecalis due to high rates of resistance 5.
Effectiveness of Bactrim Against Enterococcus faecalis
- There is no direct evidence to suggest that Bactrim (Trimethoprim/Sulfamethoxazole) is effective against E. faecalis in the treatment of UTIs 2, 5, 3, 4, 6.
- In fact, a study found that trimethoprim-sulfamethoxazole was one of the least effective antibiotics against ESBL-producing Enterobacteriaceae, which includes E. faecalis 6.