Escherichia coli

Snapshot

• A 76-year-old woman presents to the emergency department for altered mental status. She currently lives in a nursing home and was brought to seek treatment by her daughter. She was noted to be more confused over the course of a few days and developed a fever. Her temperature is 101°F (38.3°C), blood pressure is 133/99 mmHg, pulse is 101/min, and respirations are 20/min. Physical examination is notable for being alert and oriented to self but not time or place and suprapubic abdominal pain. A urinalysis is remarkable for being leukocyte-esterase positive. Urine culture grows Escherichia coli.

Introduction

• Classification
  • a gram-negative bacilli
• Epidemiology
  • incidence
    • the most common cause of UTI in women
• Microbiology
  • reservoir
    • gastrointestinal tract
  • transmission
    • fecal-oral
    • urethral ascension
    • catheter
    • aspiration
  • properties
    • enterotoxins
      • heat labile
        • increases cAMP
      • heat stable
        • increases cGMP
      • shiga-like toxin
        • inhibits the 60s ribosomal subunit, impairing protein synthesis 
    • fimbriae  
    • K-antigen (capsule) 
    • H-antigen (flagella)
• Associated conditions
  • enterotoxigenic (ETEC)
  • enterohemorrhagic (EHEC)
    • can result in hemolytic uremic syndrome
  • enteroinvasive (EIEC)
  • neonatal meningitis
  • urinary tract infection (UTI)

Presentation