Enterococcus faecalis: The Hospital Survivor and Opportunistic Pathogen

Enterococcus faecalis is one of the most important opportunistic pathogens encountered in modern clinical microbiology. It is a major cause of urinary tract infections, infective endocarditis, bacteremia, wound infections, and multidrug-resistant hospital outbreaks.

Morphology

• Gram-positive cocci

• Pairs and short chains

• Catalase negative

• Facultative anaerobe

• Non-spore-forming

Culture Characteristics

• Bile esculin positive

• Growth in 6.5% NaCl

• PYR positive

• Usually non-hemolytic

These features help differentiate enterococci from streptococci.

Virulence Factors

• Biofilm formation

• Aggregation substance

• Cytolysin

• Gelatinase

• Surface adhesins

These promote persistence and hospital survival.

Diseases Caused

• Urinary tract infections

• Infective endocarditis

• Bacteremia

• Intra-abdominal infections

• Catheter-associated infections

• Wound infections

Antibiotic Resistance

• Intrinsic cephalosporin resistance

• High-level aminoglycoside resistance

• Vancomycin-resistant enterococci (VRE)

VRE mediated mainly by vanA and vanB genes.

Treatment

• Ampicillin

• Vancomycin

• Linezolid

• Daptomycin

Combination therapy is often required in severe infections.

Clinical Pearls

• Important nosocomial pathogen

• Survives harsh environments

• Common in catheterized patients

• Biofilm formation complicates treatment

Conclusion

Enterococcus faecalis is a major multidrug-resistant opportunistic pathogen with increasing clinical importance worldwide. Understanding its resistance mechanisms and diagnostic features is essential in modern microbiology and infectious disease practice.