MedCompanion

Escherichia coli

E. coli

Morphology: Lactose-fermenting gram-negative rod, indole-positive.

PEKHNPEKGramNegOther

Typical drugs

  1. #1Ceftriaxone— Pyelonephritis, bacteremia.
  2. #2Ciprofloxacin— Outpatient pyelo, prostate.
  3. #3Ampicillin-sulbactam— Mixed intra-abdominal.
  4. #4Meropenem— ESBL or severely ill.

Empiric therapy when resistant

ESBL E. coli: meropenem (or ertapenem). Cefepime may work for non-ESBL AmpC. Avoid pip-tazo for serious ESBL infections (MERINO trial).

Resistance mechanisms

  • Enzymatic degradation

    Extended-spectrum β-lactamases (ESBL)

    Example: Hydrolyze 3rd-gen cephalosporins; carbapenems remain active.

Resistance notes

Local resistance varies — check antibiogram. Fluoroquinolone resistance >20% in many US centers.

Common syndromes

Local antibiogram

Pearls

#1 cause of UTI, pyelonephritis, gram-negative bacteremia. ESBL risk: prior abx within 90d, recent hospitalization, travel.