MedCompanion

Enterococcus faecalis

E. faecalis

Morphology: Gram-positive cocci in pairs/short chains, catalase-negative, bile-esculin positive.

EnterococcusGramPosOther

Typical drugs

  1. #1Ampicillin-sulbactam— Ampicillin component covers E. faecalis.
  2. #2Amoxicillin— Outpatient / step-down.
  3. #3Vancomycin— PCN-resistant strains.

Empiric therapy when resistant

Ampicillin (or amoxicillin) is first-line for E. faecalis. Add gentamicin or ceftriaxone for synergy in endocarditis.

Resistance mechanisms

  • Target alteration

    Intrinsically resistant to cephalosporins (low PBP affinity)

    Example: Cefepime, ceftriaxone — never adequate for enterococcus.

Resistance notes

Intrinsic resistance to all cephalosporins. Aminoglycoside synergy needs susceptibility testing.

Pearls

Endocarditis: ampicillin + ceftriaxone (synergy, less nephrotoxic than gentamicin). UTIs in elderly / catheterized.