What is the Difference Between Enterococcus Faecalis and Faecium

The main difference between Enterococcus faecalis and faecium is that E. faecalis tends to be more virulent, whereas E. faecium is less virulent.

E. faecalis and E. faecium are two enterococcal species. They cause various infections, including urinary tract infections, endocarditis, bacteremia, and meningitis. 

Key Areas Covered

1. What is Enterococcus Faecalis
– Facts, Features, Behaviour
2. What is Enterococcus Faecium
– Facts, Features, Behaviour
3. Similarities Between Enterococcus Faecalis and Faecium
– Outline of Common Features
4. Difference Between Enterococcus Faecalis and Faecium
– Comparison of Key Differences

Key Terms 

Enterococcus Faecalis, Enterococcus Faecium

What is Enterococcus Faecalis

E. faecalis is a commensal bacterium that lives in the gastrointestinal tract of humans. Also, it is a Gram-positive bacterium. In healthy humans, it is essential as a probiotic bacterium. However, it can become an opportunistic pathogen in humans, causing life-threatening infections in nosocomial environments. Significantly the antibiotic resistance of the bacterium contributes to its pathogenicity. Additionally, they cause endocarditis, urinary tract infections, sepsis, meningitis, and other infections in humans. Notably, E. faecalis is resistant to many common antibacterial agents, including aminoglycosides, aztreonam, and quinolones. Vancomycin resistance is also common in E. faecalis. 

Figure 1: E. Faecalis

Furthermore, E. faecalis is a nonmotile microorganism that ferments glucose. Therefore, it is a facultative anaerobe. It can use various energy sources, including glycerol, malate, lactate, citrate, arginine, keto acids, and agmatine. This enterococci bacterium can survive in extreme conditions such as highly alkaline pH (9.6) and salt concentrations. Also, it is resistant to bile salts, heavy metals, detergents, azide, ethanol, and desiccation. It grows in temperatures between 10 to 45 °C. 

What is Enterococcus Faecium

E. faecium is another commensal bacterium that lives in the GI tract of humans. It is a Gram-positive, gamma-hemolytic, or non-hemolytic bacterium. Also, it is pathogenic and cause endocarditis and neonatal meningitis. Moreover, this bacterium is resistant to vancomycin. It uses colonization, secretory factors, and multidrug antibiotic resistance as virulence factors. Especially E, faecium has enzymes to degrade carbohydrates, proteins, and fibrin to regulate the adhesion of the bacterium to surfaces. It is also a factor of virulence in this species. Additionally, the bacterium’s surface proteins help aggregate and form biofilms.

Figure 2: Enterococcus Gram-Staining

Furthermore, vancomycin-resistant infections in E. faecalis cause various symptoms, such as urinary tract infections, systemic infections, and wound infections in nosocomial environments. These infections cause soreness, swelling at the wound site, and warm and red skin around wounds. However, E. faecium shows alcohol resistance. It is resistant to the surface disinfection of standard 70% isopropanol. 

Similarities Between Enterococcus Faecalis and Faecium

• Enterococcus faecalis and faecium are two bacteria that cause infections in humans.
• Both are Gram-positive bacteria.
• They are commensal bacteria that live in the gastrointestinal tract of humans.
• They cause endocarditis than bacteremia.
• They are resistant to vancomycin. 

Difference Between Enterococcus Faecalis and Faecium

Definition

Enterococcus faecalis is a gram-positive bacterium that can cause various nosocomial infections, including urinary tract infections. Meanwhile, E. faecium is a Gram-positive, gamma-hemolytic, or non-hemolytic bacterium in the Enterococcus genus.

Virulence

E. faecalis is more virulent than E. faecium.   

Susceptibility to Antibiotics

E. faecalis is more susceptible to ampicillin, while E. faecium is resistant to ampicillin.

Susceptibility to Quinupristin-Dalfopristin

E. faecalis is resistant to quinupristin-dalfopristin, while E. faecium is susceptible to quinupristin-dalfopristin.

Conclusion

In brief, E. faecalis and faecium are two types of Gram-Positive enterococcal bacteria. Also, they are commensal bacteria that live in the gastrointestinal tract of humans. However, they can be pathogenic and cause endocarditis. E. faecalis is more virulent, and it is resistant to quinupristin-dalfopristin. But it is resistant to ampicillin. In comparison, E. faecium is less virulent and is resistant to ampicillin. Also, it is susceptible to quinupristin-dalfopristin. Therefore, the main difference between E. faecalis and faecium is their virulence. 

References:

1. Treatment of enterococcal infections. UpToDate. (n.d.). 

Image Courtesy:

1. “Enterococcus faecalis” By Dr. Sahay– Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Enterococcus histological pneumonia 01” By CDC/Dr. Mike Miller – Own Work (Public Domain) via Commons Wikimedia