Enterococcus faecium

Enterococcus faecium

Background:

Enterococcus faecium: 

• Enterococcus: Two species are common commensal organisms in the intestines of humans: E. faecalis (90-95%) and E. faecium (5-10%).
• Gram-positive cocci that often occur in pairs (diplococci) or short chains.
• Gram-positive, alpha hemolytic or nonhemolytic bacterium. 
• Important clinical infections caused by Enterococcus include urinary tract infections, bacteremia, bacterial endocarditis, diverticulitis, and meningitis.
• Enterococcus species have a high level of intrinsic antibiotic resistance.  Some enterococci are intrinsically resistant to β-lactam-based antibiotics (penicillins, cephalosporins, carbapenems), as well as many aminoglycosides. 
• Enterococci are relatively impermeable to aminoglycosides. Combination therapy with a cell wall-active agent (e.g. beta-lactam) is required in order to raise the permeability of the cell so that an adequate intracellular aminoglycoside concentration can be achieved while reducing the risk of toxicity.
• VRE:  Vancomycin-resistant E. faecium.  Treatment: Linezolid or daptomycin are used to treat VRE infections. The streptogramins, such as quinupristin/dalfopristin, may also be used for vancomycin-resistant E. faecium, but not E. faecalis.

Therapy:

1. (Penicillin G or Ampicillin) +/- (gentamicin or streptomycin) [see comments above]
2. Vancomycin 1 gram  ivpb q12h (patient-specific dosing required)  +/- (gentamicin or streptomycin)

VRE:

1. UTI:  VRE:  Nitrofurantoin 50-100mg q6h or Fosfomycin 3 gm orally x 1 dose
2. Linezolid 600 mg orally or IV q 12h
3. Daptomycin 4 – 6 mg/kg IV once daily. 
4. Quinupristin-Dalfopristin 7.5 mg/kg IV q8h
5. Tigecycline 100 mg IV x 1, then 50  mg q12h