Emery Haley, PhD, Scientific Writing Specialist
Enterococcus faecalis
Clinical Summary
- E. faecalis is recognized as a classical, gram-positive, biofilm-forming, nitrite-negative uropathogen.
- E. faecalis is primarily associated with all types of UTIs, from acute uncomplicated cystitis to complicated, catheter-associated, and hospital-acquired UTIs with life-threatening complications.
- In symptomatic UTI patients, E. faecalis:
- Is not a contaminant (is found in catheter-collected urine specimens).
- Is viable (can grow out on culture).
- Is pathogenic (associated with elevated urine biomarkers of infection).
- Reported severe complications of E. faecalis UTI include pyelonephritis, bacteremia, infective endocarditis, urosepsis, and death.
Bacterial Characteristics
Gram-stain
Gram-positive
Morphology
Coccus
Growth Requirements
Non-fastidious (grows moderately well in standard urine culture conditions)
Facultative anaerobe/microaerophile
Nitrate Reduction
No
Urease
Negative
Biofilm Formation
Yes
Pathogenicity
Colonizer or Pathobiont
Clinical Relevance in UTI
E. faecalis is a gram-positive, biofilm-forming microorganism classically recognized as a uropathogen. E. faecalis is among the most common bacterial pathogens responsible for UTIs and is the most common gram-positive uropathogen. However, E. faecalis lacks nitrate reductase activity, so screening strategies involving urinalysis for nitrite positivity will be false-negative.[1,2] Critically, studies with enhanced urine culture techniques or molecular techniques demonstrate that, despite its non-fastidious nature, E. faecalis frequently goes undetected by standard diagnostic urine culture.[3,4]
E. faecalis is associated with all types of UTIs, from acute uncomplicated cystitis to complicated, catheter-associated, and hospital-acquired UTIs with life-threatening complications, in adults and children.[5,6] The prevalence of E. faecalis is reportedly higher among men than women. [7,8] Risk factors for complicated UTI, including older age, immunocompromise, multimorbidity, hospitalization, use of an indwelling urinary catheter, and urinary tract abnormalities, are also associated with a higher prevalence of E. faecalis UTI.[7,9–12] E. faecalis has also been found within urinary tract epithelial cells of patients with chronic lower urinary tract symptoms.[13] Such an ability to form intracellular bacterial reservoirs is associated with persistent and recurrent UTIs.[6,13–15]
E. faecalis is known for facilitating hard-to-treat polymicrobial infections involving multidrug resistance and biofilms.[5,16,17] In preclinical studies of polymicrobial UTI models, E. faecalis exhibited synergism with E. coli, M. morganii, P. mirabilis, and P. aeruginosa but antagonism with C. albicans, Klebsiella species, and P. stuartii.[5,18]
In a study of older adult males and females with clinically suspected complicated UTI, E. faecalis was detected in both midstream voided and in-and-out-catheter collected specimens indicating that it was truly present in the bladder, not simply a contaminant picked up during voiding.[19] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which E. faecalis was detected, indicating that the presence of E. faecalis was associated with an immune response to urinary tract infection.[20–22]
Severe reported complications of E. faecalis UTI include pyelonephritis, bacteremia, infective endocarditis, urosepsis, and death.[12,23,24] Together, these findings indicate that E. faecalis should be seriously considered as a uropathogen and demonstrate the value of detecting this organism in any individual with symptoms of UTI.
Treatment
Evidence of Efficacy (Checkmarks): Ciprofloxacin, Doxycycline, Fosfomycin, Levofloxacin, Linezolid, Nitrofurantoin, and Vancomycin.