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>Enterococcus faecium (E. 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.
| Important considerations: The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions. Generally, the most common agents/regimens are listed first. Listed dosages may need to be adjusted for renal dysfunction.
- (Penicillin G or Ampicillin) +/- (gentamicin or streptomycin) [see comments above]
- Vancomycin 1 gram ivpb q12h (patient-specific dosing required) +/- (gentamicin or streptomycin)
- UTI: VRE: Nitrofurantoin 50-100mg q6h or Fosfomycin 3 gm orally x 1 dose
- Linezolid 600 mg orally or IV q 12h
- Daptomycin 4 – 6 mg/kg IV once daily.
- Quinupristin-Dalfopristin 7.5 mg/kg IV q8h
- Tigecycline 100 mg IV x 1, then 50 mg q12h