Enterococcus Faecalis
Also known as: E. faecalis, Enterococcus faecalis
Overview
Enterococcus faecalis is a Gram-positive facultative anaerobic bacterium naturally found in the human gut microbiota and various environmental sources. It is utilized in some probiotic formulations for its potential immunomodulatory and antimicrobial properties. However, E. faecalis also functions as an opportunistic pathogen, responsible for healthcare-associated infections such as infective endocarditis and urinary tract infections. This dual nature as both a probiotic and a pathogen complicates its use in supplements. Research on E. faecalis encompasses clinical microbiology, infectious disease, and probiotic efficacy, with studies ranging from randomized controlled trials evaluating probiotic benefits to systematic reviews focusing on its antimicrobial resistance and clinical treatment implications.
Benefits
Probiotic strains of *E. faecalis* have demonstrated immunomodulatory and anti-inflammatory effects, particularly in respiratory diseases. A double-blind placebo-controlled trial involving 136 patients with chronic recurrent bronchitis showed that *E. faecalis* (Symbioflor 1) significantly prolonged the time to relapse (699 vs. 334 days, p=0.01) and reduced relapse severity (p=0.001), leading to fewer antibiotic treatments in the probiotic group. Probiotic mixtures containing *E. faecium* (a closely related species) and other bacteria have also been shown to reduce allergic rhinitis symptoms and decrease the need for corticosteroids and antihistamines in children, suggesting potential benefits in immune-related respiratory conditions. Currently, there is no strong evidence to support *E. faecalis* supplementation for systemic infections or other health conditions outside of these specific respiratory and immunomodulatory contexts.
How it works
Probiotic *E. faecalis* strains are believed to exert their effects primarily by restoring intestinal microbiome homeostasis, which in turn modulates immune responses and reduces inflammation. The bacterium produces bacteriocins and other antimicrobial peptides capable of inhibiting pathogenic bacteria within the gut lumen. Its interaction with host immune cells likely involves the modulation of cytokine profiles, although the precise molecular targets are still under investigation. As *E. faecalis* acts locally within the gut, systemic bioavailability is not a primary concern for its probiotic effects.
Side effects
*E. faecalis* is a potential opportunistic pathogen, especially concerning in immunocompromised individuals or hospital settings where antibiotic-resistant strains are prevalent. Clinical isolates increasingly exhibit resistance to multiple antibiotics, including ampicillin, vancomycin, and linezolid, raising concerns about horizontal gene transfer and the risk of infection. While probiotic strains are generally considered safe for healthy populations, caution is advised for vulnerable groups. Although no significant side effects have been widely reported in probiotic trials, rare cases of bacteremia have been documented. Drug interactions are not well-characterized but could be relevant for patients receiving antibiotics targeting enterococci. Contraindications include immunosuppression and severe underlying illnesses due to the elevated risk of infection.
Dosage
Specific dosing guidelines for *E. faecalis* probiotics vary significantly by product and strain. Clinical trials have utilized doses ranging from 10^8 to 10^10 Colony Forming Units (CFU) per day. The optimal dosage is dependent on the specific formulation and the intended indication, and no standardized dosing regimen has been universally established. Administration is typically oral, taken daily for periods ranging from weeks to several months, depending on the condition being addressed. Since the bacteria primarily act within the gut lumen, absorption factors are less critical. There are no known required cofactors for its efficacy.
FAQs
Is Enterococcus faecalis safe as a probiotic?
Generally, it is considered safe for healthy individuals. However, caution is advised for immunocompromised patients due to potential infection risks and concerns regarding antibiotic resistance of some strains.
Does it help with infections?
It is not used to treat existing infections. Instead, probiotic strains may help prevent respiratory infections or alleviate allergic symptoms through immune modulation.
What about antibiotic resistance?
Clinical strains of *E. faecalis* show increasing antibiotic resistance, which is a significant concern for both safety and the effective treatment of infections caused by pathogenic strains.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11344933/ – This systematic review and meta-analysis of 74 studies across 28 countries highlights the increasing global antibiotic resistance in clinical isolates of *E. faecalis*. It identifies daptomycin and tigecycline as effective antibiotics, but notes the focus on resistance rather than probiotic use and the heterogeneity of studies.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10451534/ – This double-blind randomized controlled trial involving 136 patients with chronic recurrent bronchitis found that an *E. faecalis* probiotic significantly prolonged relapse-free time, reduced relapse severity, and decreased antibiotic use (p=0.01, p=0.001). The study was well-designed but focused on a single strain and specific condition.
- https://academic.oup.com/cid/article/79/5/1162/7718584 – This systematic review and meta-analysis on infective endocarditis treatment compared adjunctive ceftriaxone versus gentamicin for *E. faecalis* infections. It found similar efficacy but less toxicity with ceftriaxone, though it noted the reliance on observational studies and high risk of bias.
- https://www.tandfonline.com/doi/full/10.1080/03079457.2025.2485106?src= – This source discusses the increasing prevalence of antibiotic resistance in *Enterococcus faecalis* and its implications for clinical management. It highlights the challenges in treating infections caused by these resistant strains and the need for new therapeutic strategies.
- https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1505674/full – This article explores the immunomodulatory properties of certain *Enterococcus faecalis* strains, particularly their potential role in modulating host immune responses and reducing inflammation. It delves into the mechanisms by which these probiotic strains interact with the gut microbiota and immune system.