What is the treatment approach for infectious colitis versus acute gastroenteritis?

Treatment Approach: Infectious Colitis vs Acute Gastroenteritis

Key Distinction in Management

The primary treatment difference is that infectious colitis (invasive bacterial pathogens causing colonic inflammation) often requires antimicrobial therapy, while acute gastroenteritis (predominantly viral, non-inflammatory) is managed supportively with rehydration alone. 1

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Diagnostic Features That Guide Treatment

Infectious Colitis Indicators:

• Fever and/or bloody diarrhea (dysentery) 1, 2
• Stool inflammatory markers: leukocytes, lactoferrin, or calprotectin 2
• Positive stool culture for invasive pathogens: Shigella, Salmonella, Campylobacter, Shiga toxin-producing E. coli (STEC), or Clostridioides difficile 2
• Colonic inflammation visible on endoscopy 2

Acute Gastroenteritis Indicators:

• Watery diarrhea without blood 1
• Absence of fever or low-grade fever only 1
• No inflammatory markers in stool 2
• Viral etiology most common 3

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Rehydration: Universal First-Line Treatment

Oral Rehydration Solution (ORS):

• ORS is the cornerstone for both conditions in patients with normal mental status who can tolerate oral intake 1
• Continue ORS until clinical dehydration is corrected in mild-to-moderate cases 1
• Replace ongoing stool losses with ORS until diarrhea resolves 1

Intravenous Fluids:

• Administer isotonic IV fluids (lactated Ringer's or normal saline) for severe dehydration, shock, altered mental status, ORS failure, or ileus 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS 1

Nutritional Management:

• Resume age-appropriate diet immediately after rehydration is completed 1
• Continue breastfeeding throughout the illness in infants 1

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Antimicrobial Therapy: The Critical Difference

When to Treat with Antibiotics (Infectious Colitis):

Empiric therapy for febrile dysentery (suspected invasive bacterial pathogens):

• Azithromycin 1000 mg single dose in adults is the preferred empiric treatment for suspected Shigella, Salmonella, or Campylobacter 2
• Alternatively, ciprofloxacin 500 mg twice daily for 5 days reduces symptom duration and pathogen carriage in severe community-acquired gastroenteritis 4

Pathogen-specific therapy once identified:

• Treat all confirmed invasive bacterial pathogens (Shigella, Salmonella, Campylobacter) with appropriate antimicrobials 2
• C. difficile colitis: oral vancomycin or metronidazole for 10 days 5

Critical Exception - STEC:

• Do NOT treat STEC infections with antibiotics 2
• Suspect STEC when acute dysentery occurs with low-grade or absent fever 2
• Test directly for E. coli O157:H7 and Shiga toxin in stool 2

When NOT to Treat with Antibiotics (Acute Gastroenteritis):

• Viral gastroenteritis requires no antimicrobial therapy 3
• Mild bacterial gastroenteritis without inflammatory features can be managed supportively 1
• Asymptomatic carriers in low-risk settings do not need treatment (except Salmonella typhi) 1

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Ancillary Medications: Use with Caution

Antimotility Agents (Loperamide):

• Never give to children <18 years with acute diarrhea 1
• Avoid in inflammatory diarrhea, fever, or bloody stools due to risk of toxic megacolon 1, 6
• May be used in immunocompetent adults with watery diarrhea only after adequate hydration 1
• Contraindicated in AIDS patients with infectious colitis due to toxic megacolon risk 6

Antiemetics (Ondansetron):

• May facilitate oral rehydration in children >4 years and adolescents with vomiting 1
• Use only after adequate hydration is initiated 1

Probiotics:

• May reduce symptom severity and duration in immunocompetent patients with infectious or antibiotic-associated diarrhea 1

Zinc Supplementation:

• Reduces diarrhea duration in children 6 months to 5 years in zinc-deficient regions or malnourished children 1

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Critical Pitfalls to Avoid

Antibiotic-Related Complications:

• Fluoroquinolones and azithromycin increase C. difficile-associated diarrhea (CDAD) risk 7
• Ciprofloxacin can cause QT prolongation, CNS effects (seizures, confusion), and peripheral neuropathy 7
• Always consider CDAD in patients with diarrhea following recent antibiotic exposure 7, 5

Inappropriate Antimotility Use:

• Loperamide can precipitate toxic megacolon in inflammatory colitis 1, 6
• Cardiac arrhythmias and sudden death reported with higher-than-recommended loperamide doses 6

Delayed Recognition of Severe Disease:

• Toxic megacolon (colon diameter ≥5.5 cm with systemic toxicity) requires immediate surgical consultation 1
• Perforation, massive hemorrhage, or peritonitis mandate emergency surgery 1

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Infection Control Measures

• Hand hygiene with soap and water after toilet use, diaper changes, before food preparation, and after animal contact 1
• Use gloves, gowns, and hand hygiene (soap/water or alcohol-based sanitizers) when caring for patients with diarrhea 1
• Isolate patients in healthcare settings until symptoms resolve 1

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Special Populations

Immunocompromised Patients:

• Higher mortality risk with norovirus and other enteric infections 8
• Test for opportunistic pathogens (Cryptosporidium, Cyclospora, CMV, MAC) 8
• Avoid antimotility agents entirely 8

Inflammatory Bowel Disease (IBD):

• Acute severe ulcerative colitis requires IV corticosteroids (hydrocortisone 100 mg four times daily) 1
• Assess response by day 3; consider rescue therapy (infliximab or cyclosporine) or surgery if no improvement 1
• Antibiotics only indicated for superinfection or abscess, not routine use 1