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Key Features

Essentials of Diagnosis

  • Diarrhea by several different mechanisms due to E coli

  • Hemorrhagic colitis and hemolytic-uremic syndrome

  • Neonatal sepsis or meningitis

  • Urinary tract infection

  • Opportunistic infections

  • Diagnosis confirmed by culture

General Considerations

  • Enterobacteriaceae

    • Family of gram-negative bacilli that are normal flora in the gastrointestinal tract and are also found in water and soil

    • Cause gastroenteritis, urinary tract infections, neonatal sepsis and meningitis, and opportunistic infections

    • E coli is the organism in this family that most commonly causes infection in children

  • Klebsiella, Morganella, Enterobacter, Serratia, Proteus, and other genera are also important, particularly in the immunocompromised person

  • Klebsiella, Enterobacter, Serratia, and Morganella are normally found in the gastrointestinal tract and in soil and water

  • Klebsiella may cause a bronchopneumonia with cavity formation

  • Klebsiella, Enterobacter, and Serratia

    • Often hospital-acquired opportunists associated with antibiotic usage, debilitated states, and chronic respiratory conditions

    • Frequently cause urinary tract infection or sepsis

Clinical Findings

Symptoms and Signs

  • E coli gastroenteritis

    • May cause diarrhea of varying types and severity

    • Enterotoxigenic E coli (ETEC)

      • Usually produce mild, self-limiting illness without significant fever or systemic toxicity, often known as traveler's diarrhea

      • May be severe in newborns and infants, and occasionally an older child will have a cholera-like syndrome

    • Enteroinvasive E coli (EIEC)

      • Cause a shigellosis-like illness, characterized by fever, systemic symptoms, blood and mucus in the stool, and leukocytosis

      • Uncommon in the United States

    • Shiga toxin-producing E coli (STEC)

      • Cause hemorrhagic colitis

      • Diarrhea initially is watery; progresses to blood streaking or grossly bloody stools

      • Fever usually is absent

      • Abdominal pain and cramping occur

      • Hemolytic-uremic syndrome occurs within a few days of diarrhea in 2–5%; characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure

  • Neonatal sepsis

    • Jaundice, hepatosplenomegaly, fever, temperature lability, apneic spells, irritability, and poor feeding

    • Respiratory distress develops when pneumonia occurs; it may appear indistinguishable from respiratory distress syndrome in preterm infants

    • Meningitis is associated with sepsis in 25–40% of cases

    • Other metastatic foci of infection may be present, including pneumonia and pyelonephritis

    • Sepsis may lead to severe metabolic acidosis, shock, disseminated intravascular coagulation, and death

  • Neonatal meningitis

    • High fever

    • Full fontanelles

    • Vomiting

    • Coma

    • Convulsions

    • Pareses or paralyses

    • Poor or absent Moro reflex

    • Opisthotonos

    • Hypertonia or hypotonia

    • Sepsis coexists or precedes meningitis in most cases

  • Acute urinary tract infection

    • Dysuria, increased urinary frequency, and fever in the older child.

    • Nonspecific symptoms such as anorexia, vomiting, irritability, failure to thrive, and unexplained fever are seen in children younger than age 2 years

    • Young infants may have jaundice

Differential Diagnosis

  • Enteropathogenic E coli (EPEC) infection may resemble salmonellosis, shigellosis, or viral gastroenteritis


  • Serotyping, biochemical and nucleic acid tests for enterotoxin production or invasiveness, and tests for P-fimbriae are performed in research laboratories

  • STEC

    • MacConkey agar with sorbitol substituted ...

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