What are the symptoms of an immunologic reaction to Escherichia coli?

Symptoms of Immunologic Reaction to E. coli

E. coli infections primarily cause gastrointestinal symptoms rather than classic immunologic hypersensitivity reactions, with the most common presentation being bloody diarrhea, severe abdominal cramps, and notably absent or low-grade fever. 1

Primary Clinical Manifestations

Gastrointestinal Symptoms

• Diarrhea (often bloody) is the hallmark symptom, occurring in the majority of symptomatic cases, with bloody stools visible in 5-97% of cases depending on the specific E. coli strain 1, 2
• Severe abdominal cramps and pain occur in 55-74% of cases and can become progressively worse as infection advances 2, 3
• Non-bloody diarrhea may be the initial presentation before progression to hemorrhagic colitis 2, 4
• Nausea and vomiting occur in 52-55% of cases, particularly in early stages 2

Systemic Features

• Fever is notably absent or low-grade in most E. coli O157:H7 infections, which distinguishes it from other bacterial enteritis—fever is documented in less than half of cases 3, 4
• Absence of fever combined with bloody diarrhea is a key distinguishing feature from other enteric pathogens 3

Timeline of Symptom Onset

• Symptoms typically begin 3-4 days after exposure (range 1-10 days), with the incubation period varying by strain 2
• Early detection is critical as bacteria become difficult or impossible to detect in stool after 1 week of illness 2
• Initial symptoms often start as non-bloody diarrhea before progressing to hemorrhagic manifestations 2

Severe Complications (Immune-Mediated)

Hemolytic Uremic Syndrome (HUS)

• HUS represents a severe immune-mediated complication characterized by hemolytic anemia, thrombocytopenia, and acute renal failure 1, 4
• Risk factors for HUS development include extremes of age, elevated white blood cell count (>10 × 10⁹/L), bloody diarrhea, and use of antimotility drugs 3, 4
• HUS typically develops after the diarrheal phase and may occur when the antecedent diarrhea has resolved 4

Thrombotic Thrombocytopenic Purpura (TTP)

• TTP is another severe systemic complication that can occur following E. coli infection, particularly in adults 1, 4

Distinguishing Clinical Features

The combination of these findings strongly suggests E. coli O157:H7 infection: 3

• History of bloody diarrhea
• Visibly bloody stools
• Absence of fever (critical distinguishing feature)
• Leukocyte count >10 × 10⁹/L
• Abdominal tenderness on examination

Important Clinical Pitfalls

• Fecal leukocyte examination findings often suggest a non-infectious cause, which can lead to misdiagnosis 4
• Radiologic and colonoscopic findings may mimic inflammatory bowel disease or ischemic colitis, causing diagnostic confusion 4
• Assuming absence of blood in stool rules out E. coli is incorrect—many cases present initially with non-bloody diarrhea 2
• The absence of fever should not reassure clinicians—it is actually characteristic of E. coli O157:H7 infection 3, 4

Context: True Immunologic Hypersensitivity to E. coli-Derived Products

In the specific context of asparaginase (a chemotherapy drug derived from E. coli), true immunologic hypersensitivity reactions occur in 3-45% of patients and include: 1

• Symptoms consistent with mast cell mediator release
• Anaphylaxis
• Development of anti-asparaginase antibodies
• Decreased asparaginase activity due to antibody formation

This represents a distinct clinical scenario from E. coli infection itself and involves immediate-type hypersensitivity reactions to the bacterial-derived therapeutic protein 1.