What are the treatment options for a patient presenting with rectal bleeding, mucus in stool, and sudden onset of fever?

Management of Rectal Bleeding with Mucus and Fever

Blood and mucus in stool with sudden fever requires immediate stool evaluation for infectious pathogens (particularly Clostridium difficile, bacterial cultures, ova and parasites) while initiating empiric antibiotic therapy if invasive bacterial disease is suspected. 1

Immediate Diagnostic Workup

Essential Stool Studies

• Obtain stool cultures for bacterial pathogens including Salmonella, Shigella, Campylobacter, Escherichia coli O157:H7, and Yersinia species, as these commonly cause bloody diarrhea with fever 1, 2, 3
• Test for Clostridium difficile toxin using either tissue culture cytotoxin assay or rapid enzyme immunoassay, as this is the most common nosocomial gastrointestinal pathogen presenting with bloody/mucoid stools and fever 1, 4
• Check for ova and parasites to exclude amebic dysentery, which presents with bloody diarrhea and more indolent onset 1
• Measure fecal inflammatory markers (fecal lactoferrin or calprotectin) to quantify intestinal inflammation severity 1

Critical Laboratory Tests

• Complete blood count to assess for leukocytosis, anemia from blood loss, and neutropenia if immunocompromised 1
• C-reactive protein (CRP) and ESR as acute phase reactants, with CRP >20 mg/L and ESR >15 mm indicating significant inflammation 1
• Blood cultures if fever is present, as bacteremia may complicate invasive bacterial colitis 1
• Comprehensive metabolic panel to assess hydration status and electrolyte abnormalities 2

Imaging Considerations

• Abdominal/pelvic CT with contrast should be obtained if symptoms suggest grade 2 or higher colitis (4-6+ bowel movements above baseline with colitis symptoms), to evaluate for complications including abscess, perforation, or toxic megacolon 1
• Flexible sigmoidoscopy or colonoscopy may be indicated to differentiate bacterial hemorrhagic enterocolitis from inflammatory bowel disease or ischemic colitis, particularly if diagnosis remains unclear 1, 5

Empiric Antibiotic Therapy

When to Initiate Antibiotics

Start empiric antibiotics immediately if the patient presents with:

• Fever combined with significant bloody diarrhea (suggesting invasive bacterial disease) 1
• Signs of systemic toxicity or hemodynamic instability 1
• Severe abdominal pain with mucoid/bloody stools 3, 5

Antibiotic Selection

• First-line: Fluoroquinolones or cephalosporins are effective for most bacterial causes of traveler's diarrhea and invasive colitis 1
• Alternative: Macrolides (azithromycin) should be used if Campylobacter is suspected, especially with recent travel to Asia where quinolone resistance is common 1
• For suspected C. difficile: Metronidazole 250 mg orally four times daily for 10 days is the recommended first-line therapy 6, 4
• For amebic dysentery: Metronidazole or tinidazole if wet preparation shows amoebic trophozoites 1, 6

Risk Stratification and Severity Assessment

High-Risk Features Requiring Hospitalization

• Hemodynamic instability (tachycardia >90 bpm, hypotension) 1
• Severe dehydration requiring intravenous fluid resuscitation 2
• Toxic megacolon (colonic dilation >6 cm with systemic toxicity) 1
• Signs of perforation or peritonitis on examination or imaging 1
• Immunocompromised status (chemotherapy, immunosuppression, neutropenia) 1

Grading System for Colitis Severity

• Grade 2 colitis includes 4-6 bowel movements above baseline with mild/moderate symptoms (cramping, urgency, blood/mucus, fever) limiting instrumental activities of daily living 1
• Grade 3 colitis includes >6 bowel movements above baseline with severe symptoms, limiting self-care activities, or requiring hospitalization 1
• Grade 4 colitis involves life-threatening complications such as ischemic bowel, perforation, or toxic megacolon requiring urgent intervention 1

Supportive Care Measures

• Intravenous fluid resuscitation to maintain mean arterial pressure >65 mmHg and correct dehydration 1
• Blood transfusion if hemoglobin drops below 7 g/dL (or 9 g/dL if massive bleeding or cardiovascular disease) 1
• Avoid antidiarrheal agents (loperamide, diphenoxylate) in patients with bloody diarrhea and fever, as these may worsen invasive bacterial infections 1
• Isolation precautions with contact and droplet precautions for suspected infectious diarrhea, particularly C. difficile 1

Common Pitfalls to Avoid

• Do not delay stool testing until after empiric treatment fails—obtain cultures before starting antibiotics when possible, though therapy should not be delayed if invasive disease is suspected 1, 2
• Do not assume all bloody diarrhea is infectious—evaluate for other causes including peptic ulcer disease, diverticulosis, angiodysplasia, hemorrhoids, ischemic colitis, and inflammatory bowel disease 1
• Do not overlook C. difficile even in community-acquired cases, as it can present identically to bacterial colitis with fever, bloody/mucoid stools, and severe abdominal pain 4
• Recognize that symptom severity may not correlate with endoscopic findings—fecal lactoferrin has 90% sensitivity for histologic inflammation and can guide need for urgent endoscopy 1

Special Populations

Immunocompromised Patients

• Neutropenic enterocolitis should be suspected in patients with recent chemotherapy presenting with fever, abdominal pain, and bowel wall thickening >10 mm on imaging (associated with 60% mortality) 1
• Broader antimicrobial coverage including antifungal therapy may be needed if no improvement after 48-72 hours of empiric antibiotics 1

Inflammatory Bowel Disease Patients

• Acute severe ulcerative colitis presents with ≥6 bloody stools daily plus fever >37.8°C, tachycardia, anemia, or elevated ESR, requiring urgent gastroenterology consultation 1
• Subtotal colectomy with ileostomy is indicated if no improvement within 48-72 hours of medical therapy or if complications develop 1