What is the best course of treatment for a patient with a 10-day history of vomiting and diarrhea, accompanied by severe central abdominal cramps, mixture of formed, semi-formed, and loose bowel movements, and frank red blood in stool, that started after a vacation and has not responded to medications such as loperamide or bismuth subsalicylate?

Immediate Medical Evaluation and Antibiotic Therapy Required

This patient requires immediate medical evaluation with stool studies and empiric antibiotic therapy—specifically azithromycin—because the presence of frank blood in stool after travel-associated diarrhea defines this as severe dysentery, and the 10-day duration with failed symptomatic treatment indicates a likely invasive bacterial pathogen. 1

Why This is Severe Travelers' Diarrhea (Dysentery)

• Frank red blood admixed with stool classifies this as dysentery, which automatically categorizes the illness as severe travelers' diarrhea regardless of other symptoms 1
• The 10-day duration with vomiting, severe cramping, and blood indicates this has progressed beyond simple self-limited gastroenteritis 1
• Symptoms starting during international travel strongly suggest an infectious etiology requiring antimicrobial therapy 1

Critical Management Steps

1. Stop Loperamide and Bismuth Subsalicylate Immediately

• Antimotility agents like loperamide are contraindicated in dysentery (bloody diarrhea) due to risk of toxic megacolon and clinical deterioration 1, 2
• The American College of Physicians and IDSA explicitly recommend avoiding loperamide when fever and bloody stools are present 2
• This explains why the patient's current medications have been ineffective—they are inappropriate for invasive bacterial diarrhea 1, 2

2. Initiate Empiric Antibiotic Therapy

Azithromycin is the preferred first-line antibiotic for severe travelers' diarrhea with dysentery 1

• Azithromycin has a strong recommendation with moderate-to-high quality evidence for severe travelers' diarrhea 1
• Fluoroquinolones (ciprofloxacin) are an alternative for severe non-dysenteric diarrhea, but have only weak recommendation for dysentery due to increasing resistance patterns, particularly with Campylobacter and Shigella 1
• Rifaximin should be avoided in this case—it carries a caution against use when invasive pathogens are suspected (which bloody stools indicate) 1

3. Obtain Stool Studies Before Starting Antibiotics (If Feasible)

• Collect stool for culture, ova and parasites, and C. difficile testing 1
• Evaluate for Shigella, Campylobacter, Salmonella, and enteroinvasive E. coli 1
• However, do not delay antibiotic therapy while waiting for results in a patient with 10 days of dysentery 1

4. Assess for Complications Requiring Hospitalization

This patient likely needs hospitalization given the following red flags: 1

• 10-day duration without improvement despite attempted treatment 1
• Frank blood in stool 1
• Severe cramping and vomiting suggesting possible dehydration 1
• Symptoms worsening or not improving after 48 hours of initial management 1

In hospital, evaluate for: 1

• Dehydration status (orthostatic vital signs, electrolytes, renal function) 1
• Complete blood count to assess for leukocytosis or anemia from blood loss 1
• Signs of sepsis (fever, tachycardia, hypotension) 1

5. Supportive Care

• Aggressive IV fluid resuscitation if dehydrated 1
• Electrolyte replacement as needed 1
• Dietary modifications: eliminate lactose, alcohol, caffeine, fatty and spicy foods 1
• Maintain adequate oral fluid intake (8-10 glasses daily) if able to tolerate 2

Common Pitfalls to Avoid

• Never use loperamide in bloody diarrhea—this is the most critical error and may have contributed to this patient's prolonged illness 1, 2
• Do not wait for stool culture results before starting antibiotics in a patient with 10 days of dysentery 1
• Do not use single-dose antibiotic regimens in persistent diarrhea lasting >7 days—this requires a full treatment course 1
• Do not assume this is viral gastroenteritis given the blood and duration—bacterial dysentery is the presumptive diagnosis 1

Expected Clinical Course

• With appropriate antibiotic therapy, symptoms should begin improving within 24-48 hours 1
• If no improvement occurs within 48-72 hours of antibiotic therapy, reassess for alternative diagnoses including inflammatory bowel disease, ischemic colitis, or parasitic infections 1, 2
• Consider non-infectious etiologies (IBD, IBS) if symptoms persist beyond 14 days despite treatment 1