Emery Haley, PhD, Scientific Writing Specialist
Enterococcus faecium
Clinical Summary
- E. faecium is recognized as a classical, gram-positive, biofilm-forming, nitrite-negative uropathogen.
- E. faecium is primarily associated with highly antibiotic-resistant catheter-associated UTIs (CAUTIs), hospital-acquired UTIs (HAUTIs), and complicated UTIs among immunocompromised individuals and individuals with urinary tract abnormalities.
- In symptomatic UTI patients, E. faecium:
- 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. faecium UTI include pyelonephritis, bacteremia, urosepsis, and death.
- Multidrug-resistant E. faecium is a significant and well-studied global health threat.
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. faecium is a gram-positive, biofilm-forming microorganism classically recognized as a uropathogen. E. faecium is the second most commonly reported gram-positive uropathogen (after E. faecalis).[1] However, E. faecium lacks nitrate reductase activity, so screening strategies involving urinalysis for nitrite positivity will be false-negative.[2,3]
E. faecium is known for facilitating hard-to-treat polymicrobial infections involving multidrug resistance and biofilms.[4] In preclinical studies of polymicrobial UTI, E. faecium exhibited synergism with P. aeruginosa.[5] E. faecium is primarily detected in complicated UTIs, especially among immunocompromised individuals and individuals with urinary tract abnormalities or indwelling catheters.[6,7] Most reported E. faecium UTIs are catheter-associated UTIs (CAUTIs) and/or healthcare-acquired UTIs (HAUTIs).[7–10] Compared to E. faecalis, E. faecium UTIs are less common but are significantly more likely to be multidrug or pandrug resistant.[7–10]
In a study of older adult males and females with clinically suspected complicated UTI, E. faecium 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.[11] Furthermore, elevated markers of immune system activation in the urinary tract have been measured from the same clinical urine specimens in which E. faecium was detected, indicating that the presence of E. faecium was associated with an immune response to urinary tract infection.[12–14]
E. faecium is one of the six so-called “ESKAPE pathogens” identified as critical multi-drug resistant bacteria requiring urgent development of effective therapeutics.[15] Severe reported complications of E. faecium UTI include pyelonephritis, bacteremia, urosepsis, and death.[16–18]
Together, these findings indicate that E. faecium should be seriously considered as a uropathogen and demonstrate the value of detecting this organism in any individual with an indwelling catheter, urinary tract abnormality, immunocompromise, or other risk factors for complicated UTI.
Treatment
Evidence of Efficacy (Checkmarks): Ciprofloxacin, Levofloxacin, Linezolid, Nitrofurantoin, and Vancomycin.