Bacteria under Microscope

Enterococcus faecalis

Enterococcus faecalis   
                         microscopy, gram-positive cocci


Gram-positive cocci


Microscopic appearance:

Cocci in clusters, short chains, diplococci and single cocci


Clinical significance:

  • Enterococcus faecalisis a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals.
  • E. faecalis can cause life-threatening infections in humans, especially in the nosocomial (hospital) environment.
  • Urinary tract infections (UTI)
  • Bacteremia
  • Endocarditis
  • Meningitis
  • E. faecalis is resistant to many commonly used antimicrobial agents.
  • VRE (Vancomycin-Resistant Enterococcus)
    Text: Wikipedia

Colony morphology:

Enterococcus facalis identification
A Non-hemolytic (gamma-hemolytic) colonies of Enterococcus faecalis on sheep blood agar. Cultivation 24 hours, aerobic atmosphere, 37°C.  
B Enterococcus faecalis on Bile Esculin Agar (BEA). Members of the genus Enterococcus are capable of growing in the presence of 4% bile and hydrolyzing esculin to glucose and esculetin. Esculetin combines with ferric ions to produce a black complex visible as black zones around colonies. Cultivation 24 hours in an aerobic atmosphere, 37°C.  
C Colonies of Enterococcus faecalis cultivated on Columbia agar with 5% defibrinated sheep blood, 24 hours in an aerobic atmosphere, 37°C. E.faecalis typically exhibits gamma-hemolysis on sheep's blood agar, but some strains are alfa-hemolytic or even beta-hemolytic (a plasmid-encoded hemolysin, called the cytolysin).