What is the recommended evaluation, diagnostic work‑up, and treatment for a patient with suspected enteritis?

Diagnosis and Treatment of Enteritis

Initial Diagnostic Approach

For suspected enteritis presenting with diarrhea and abdominal cramping without signs of proctitis, the evaluation should prioritize excluding infectious causes through stool testing for Clostridioides difficile and stool cultures or pathogen panels before initiating any immunosuppressive therapy. 1

Clinical Context and Risk Stratification

The diagnostic workup depends heavily on the clinical context and patient risk factors:

• Sexually transmitted enteritis occurs primarily among persons whose sexual practices include oral-anal contact, with Giardia lamblia being the most common pathogen in otherwise healthy individuals 1
• Immunocompromised patients (including HIV-infected persons) require broader evaluation for opportunistic pathogens including CMV, Mycobacterium avium-intracellulare, Salmonella, Campylobacter, Shigella, Cryptosporidium, Microsporidium, and Isospora 1
• Multiple stool examinations may be necessary to detect Giardia, and special stool preparations are required for cryptosporidiosis and microsporidiosis 1

Essential Diagnostic Tests

Stool studies should include:

• Clostridioides difficile testing in all patients 1
• Stool cultures or multiplex pathogen panels (preferred over traditional cultures) 1, 2
• Ova and parasite testing based on patient risk factors and local prevalence 1
• Fecal elastase with qualitative fecal fat testing for patients with steatorrhea or those not responding to typical treatments 1

Additional considerations:

• Stool inflammatory markers (lactoferrin or calprotectin) can help stratify patients and guide need for endoscopy, with lactoferrin showing 90% sensitivity for histologic inflammation 1
• Tissue transglutaminase IgA and total IgA testing is reasonable for new-onset diarrhea to exclude celiac disease 1
• Laboratory blood tests (CBC, CRP, ESR) have low specificity and are rarely informative for diagnosis 1

When Endoscopy is Indicated

Endoscopic examination with biopsies is the reference standard for diagnosis when inflammatory enterocolitis is suspected, particularly in:

• Patients with grade 2 or higher diarrhea with positive stool inflammatory markers 1
• Those not responding to initial management 1
• Immunocompromised patients requiring tissue diagnosis 1

Treatment Approach

Primary Treatment: Rehydration

Oral rehydration therapy (ORT) with reduced osmolarity oral rehydration solution is the cornerstone of treatment and should be initiated immediately, regardless of etiology. 3

Rehydration dosing:

• Mild to moderate dehydration: 50-100 mL/kg over 3-4 hours in infants/children, or 2-4 L in adolescents/adults 3
• Children <10 kg: 60-120 mL ORS after each diarrheal stool (maximum ~500 mL/day) 3
• Children >10 kg: 120-240 mL ORS after each diarrheal stool (maximum ~1 L/day) 3
• Adolescents/adults: Ad libitum ORS, up to ~2 L/day 3
• Severe dehydration: IV isotonic crystalloid (lactated Ringer's or normal saline) boluses of 20 mL/kg until clinical improvement 3

Antimicrobial Therapy

Empiric antimicrobial therapy is generally NOT recommended for most enteritis cases. 3 The key exceptions requiring antimicrobial treatment include:

Indications for antimicrobial therapy:

• Infants <3 months with suspected bacterial etiology 3
• Immunocompromised patients with severe illness and bloody diarrhea 3
• Patients with fever, abdominal pain, bloody diarrhea, and bacillary dysentery 3
• Confirmed Giardia infection 1
• Specific bacterial pathogens identified on culture 4

Pathogen-specific antimicrobial choices:

• Empiric therapy for febrile dysentery: Azithromycin 1000 mg single dose in adults 4
• Campylobacter: Azithromycin 3
• Shigella: Ciprofloxacin or another fluoroquinolone 3
• Salmonella: Ciprofloxacin, TMP-SMX, or amoxicillin (though treatment of uncomplicated Salmonella gastroenteritis in healthy hosts is controversial) 3, 5
• Clostridioides difficile: Pathogen-specific therapy per standard protocols 1

Symptomatic Management

Antimotility agents:

• NEVER use in children <18 years due to risk of complications 3
• NEVER use with bloody diarrhea, fever, or inflammatory diarrhea 3
• Loperamide may be used in immunocompetent adults with acute watery diarrhea: 4 mg initial dose, then 2 mg after each loose stool (maximum 16 mg/day) 3

Antiemetics:

• Ondansetron may be given to children >4 years and adolescents with vomiting to facilitate oral rehydration 3

Adjunctive therapies:

• Probiotics may reduce symptom severity and duration in immunocompetent patients 3
• Zinc supplementation (in children 6 months to 5 years in high-deficiency areas or malnourished children) 3
• Resume age-appropriate diet immediately after rehydration 3

Critical Pitfalls to Avoid

Do not delay rehydration while awaiting diagnostic test results 3

Avoid antibiotics for STEC O157 infections as they increase risk of hemolytic uremic syndrome 3, 4

Never use antimotility agents in children or patients with bloody diarrhea/fever due to risk of toxic megacolon and other complications 3

Do not assume all diarrhea in immunocompromised patients is infectious—consider immune-mediated pancreatic insufficiency, medication effects, and direct HIV effects 1

When to Seek Urgent Medical Evaluation

Patients should seek immediate care for:

• No improvement within 48 hours 3
• Worsening symptoms or clinical deterioration 3
• Severe vomiting preventing oral intake 3
• Persistent fever 3
• Frank blood in stools 3
• Abdominal distension 3

Infection Control

Hand hygiene after toilet use, diaper changes, and before food preparation/eating is essential 3

Gloves, gowns, and proper hand hygiene when caring for patients with diarrhea 3

Asymptomatic contacts do not need treatment but should follow infection prevention measures 3, 6