Bactrim (Trimethoprim/Sulfamethoxazole) is NOT Effective for Treating Enterococcus faecalis Infections
Bactrim (trimethoprim/sulfamethoxazole) is not recommended for treating Enterococcus faecalis infections as it has poor efficacy and leads to rapid development of resistance. 1
Understanding E. faecalis and Antimicrobial Resistance
- E. faecalis is a significant pathogen in various infections, particularly in healthcare-associated settings, representing up to 15.9% of aerobic isolates in intra-abdominal infections 2
- E. faecalis poses treatment challenges due to its intrinsic resistance to multiple antibiotics and ability to acquire additional resistance mechanisms 2
- The organism requires prolonged administration (up to 6 weeks) of synergistic bactericidal combinations for effective treatment 2
Evidence Against Bactrim for E. faecalis
- Studies show that even when initially effective, prolonged use of trimethoprim-sulfamethoxazole against E. faecalis leads to rapid development of resistance 1
- In a study of urinary tract infections, resistance developed in all cases where treatment extended beyond two weeks 1
- More recent research confirms that trimethoprim-sulfamethoxazole exposure may actually increase virulence properties of uropathogenic E. faecalis 3
Recommended Treatment Options for E. faecalis Infections
First-Line Options:
- Ampicillin or amoxicillin is the drug of choice for ampicillin-susceptible enterococci 2
- For serious infections, combination therapy with ampicillin plus gentamicin is traditionally recommended for synergistic bactericidal effect 2
For Ampicillin-Resistant Strains:
- Vancomycin should be used if the pathogen is resistant to ampicillin 2
For Vancomycin-Resistant Enterococcus (VRE):
- Linezolid (for monomicrobial infections) 2
- Tigecycline (for polymicrobial infections) 2
- Daptomycin may be used based on susceptibility testing 2, 4
Special Considerations
- Aminoglycoside resistance is increasingly common in enterococci, limiting the effectiveness of traditional synergistic combinations 2
- For patients with high-level aminoglycoside resistance, alternative combinations such as ampicillin-ceftriaxone have shown promising results 5
- Catheter-related bloodstream infections caused by enterococci require catheter removal in cases of insertion site infection, suppurative thrombophlebitis, sepsis, endocarditis, or persistent bacteremia 2
- Antibiotic lock therapy should be used in addition to systemic therapy if an infected catheter must be retained 2
Treatment Duration
- For uncomplicated enterococcal infections: 7-14 days of therapy is typically recommended 2
- For serious infections like endocarditis: 4-6 weeks of therapy is required 2
- For orthopedic infections: Treatment duration varies but typically requires several weeks of therapy 5
Clinical Pitfalls to Avoid
- Do not confuse colonization with true infection; differentiation is essential before initiating treatment 6
- Avoid using Bactrim for E. faecalis even if in vitro testing suggests susceptibility, as clinical resistance develops rapidly 1, 3
- Be aware that antibiotic use itself can lead to E. faecalis colonization by disrupting normal gut microbiota 6
- Monitor for development of resistance during therapy, especially with newer agents like daptomycin 7
In conclusion, ampicillin remains the drug of choice for E. faecalis infections, with vancomycin, linezolid, or daptomycin as alternatives based on susceptibility patterns. Bactrim should not be used due to poor efficacy and rapid development of resistance.