What is the Difference Between Enterococcus faecalis and Enterococcus faecium

The key difference between Enterococcus faecalis and Enterococcus faecium is that Enterococcus faecalis is a bacterium that can be associated with endocarditis, while Enterococcus faecium is a bacterium that can be associated with bacteremia.

Enterococcal species can cause a variety of diseases, including urinary tract infection, endocarditis, bacteremia, and meningitis. Enterococcal species that cause human infections include Enterococcus faecalis, Enterococcus faecium, Enterococcus avium, Enterococcus gallinarum, Enterococcus casseliflavus, Enterococcus durans, and Enterococcus raffinosus. Enterococcus faecalis and Enterococcus faecium are two enterococcal species causing infections.

CONTENTS

1. Overview and Key Difference
2. What is Enterococcus faecalis 
3. What is Enterococcus faecium
4. Similarities – Enterococcus faecalis and Enterococcus faecium
5. Enterococcus faecalis vs Enterococcus faecium in Tabular Form
6. Summary – Enterococcus faecalis vs Enterococcus faecium

What is Enterococcus faecalis?

Enterococcus faecalis is a bacterium that belongs in the genus Enterococcus, which is more likely to be associated with endocarditis. It was formerly classified as part of the group D Streptococcus system. It is a gram-positive, commensal bacterium that inhabits the gastrointestinal tracts of humans. Like other species in the genus Enterococcus, it is found in healthy humans and can be used as a probiotic. The popular probiotic strains of this species include Symbioflor1 and EF-2001. They are characterized by the lack of specific genes related to drug resistance and pathogenesis in humans. The opportunistic strains of Enterococcus faecalis can cause life-threatening infections, especially in the hospital environment. This is because, in the nosocomial environment, Enterococcus faecalis has a higher level of antibiotic resistance, contributing to its pathogenicity.

E. faecalis can cause endocarditis, sepsis, urinary tract infections, meningitis, and other human infections. The virulent factors that contribute to the pathogenesis of opportunistic E. faecalis bacterium include plasmid-encoded hemolysin (cytolysin), plasmid-encoded adhesins, tyrosine decarboxylase enzyme, lytic enzymes like pheromones, lipotecichoic acid, and biofilm formation. This bacterium also shows multiple drug resistance. E. faecalis are typically susceptible to ampicillin but resistant to quinupristin-dalfopristin.

What is Enterococcus faecium?

Enterococcus faecium is a bacterium that belongs to the genus Enterococcus, which is more likely to be associated with bacteremia. Enterococcus faecium is a gram-positive, gamma haemolytic, or non haemolytic bacterium in the genus Enterococcus. It can be a commensal in the gastrointestinal tract of humans and animals. It may also cause pathogenic infections such as bloodstream infections (bacteremia), neonatal meningitis, urinary tract infections, and wound infections. The virulent factors are antibiotic resistance, hyaloronidase gene (hyl), extracellular surface protein (esp), secreted factors (enzyme to break down protein and carbohydrate), aggregation substance (AS), cytosolin, and gelantinase. The vancomycin-resistant Enterococcus faecium is often referred to as VRE.

The genome size of the E. faecium strains varies substantially from 2.5Mb to 3.14Mb. Furthermore, it has been recently reported that E. faecium exhibits tolerance to alcohol-based solutions.

What are the Similarities Between Enterococcus faecalis and Enterococcus faecium?

• Enterococcus faecalis and Enterococcus faecium are two enterococcal species that cause enterococcal infections.
• Both are gram positive, gamma haemolytic species living in the gastrointestinal tract of humans.
• They belong to the genus Enterococcus.
• Both species can be commensals or opportunistic pathogens.
• Moreover, both species can be used as probiotics.
• Both species are resistant to certain antibiotics, including vancomycin.
• They mainly cause nosocomial infections.
• They have similar virulent factors, such as biofilm formations.

What is the Difference Between Enterococcus faecalis and Enterococcus faecium?

Enterococcus faecalis is a bacterium that belongs to the genus Enterococcus, which can be associated with endocarditis, while Enterococcus faecium is a bacterium that belongs to the genus Enterococcus, which can be associated with bacteremia. Thus, this is the key difference between Enterococcus faecalis and Enterococcus faecium. Furthermore, Enterococcus faecalis has more potential pathogenesis for initiating an enterococcal infection, while Enterococcus faecium has less potential pathogenesis for initiating an enterococcal infection.

The below infographic presents the differences between Enterococcus faecalis and Enterococcus faecium in tabular form for side by side comparison.

Summary – Enterococcus faecalis vs Enterococcus faecium

Enterococcal infections can be caused due to Enterococcal species. These species can cause human infections such as urinary tract infection, endocarditis, bacteremia, and meningitis. Enterococcus faecalis and Enterococcus faecium are two Enterococcal species. Enterococcus faecalis can be associated with endocarditis, while Enterococcus faecium can be associated with bacteremia. So, this summarizes the difference between Enterococcus faecalis and Enterococcus faecium.

Reference:

1. “Enterococcus Faecium.” An Overview | ScienceDirect Topics.
2. Watson, Stephanie. “Enterococcus Faecalis: Causes, Symptoms, and Treatments.” Healthline, Healthline Media.

Image Courtesy:

1. “Enterococcus faecalis” By Dr. Sahay – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “CPSE Enterococcus2” By Manurx27 – Own work (CC BY-SA 4.0) via Commons Wikimedia