What is the treatment for presumed infectious diarrhea?

Treatment for Presumed Infectious Diarrhea

For most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended; instead, focus on oral rehydration as the cornerstone of treatment. 1

Rehydration: The Primary Treatment

Reduced osmolarity oral rehydration solution (ORS) is the first-line therapy for mild to moderate dehydration in all age groups. 1, 2 This approach is lifesaving, less painful, safer, and more cost-effective than intravenous fluids for patients who can tolerate oral intake. 1

Rehydration Algorithm by Severity:

Mild to Moderate Dehydration:

• Administer reduced osmolarity ORS until clinical dehydration is corrected 1, 2
• Continue ORS to replace ongoing stool losses until diarrhea resolves 1, 2
• If oral intake is not tolerated, consider nasogastric administration of ORS in patients with normal mental status 1, 2

Severe Dehydration:

• Immediately start isotonic intravenous fluids (lactated Ringer's or normal saline) for severe dehydration, shock, altered mental status, or ileus 1, 2
• Continue IV rehydration until pulse, perfusion, and mental status normalize 1, 2
• Transition to ORS for remaining deficit replacement once patient is stabilized 1, 2

Nutritional Management During Illness

Resume age-appropriate usual diet during or immediately after rehydration is complete. 1, 2 This is a critical point often missed—withholding food during diarrheal episodes is a common pitfall that should be avoided. 2

• Continue human milk feeding in infants and children throughout the diarrheal episode 1, 2
• Early refeeding prevents bodyweight loss and promotes nutritional recovery 3

When to Use Empiric Antimicrobial Therapy

Empiric antibiotics are indicated only in specific high-risk scenarios:

Adults - Use Empiric Antibiotics For:

1. Febrile dysentery (fever, abdominal pain, bloody diarrhea) presumptively due to Shigella 1
2. Recent international travelers with body temperature ≥38.5°C and/or signs of sepsis 1
3. Suspected enteric fever with clinical features of sepsis (after obtaining blood, stool, and urine cultures) 1
4. Immunocompromised patients with severe illness and bloody diarrhea 1

Empiric antibiotic choice for adults: Ciprofloxacin (a fluoroquinolone) or azithromycin, depending on local susceptibility patterns and travel history 1, 4

Children - Use Empiric Antibiotics For:

1. Ill-appearing young infants 1, 2
2. Infants <3 months with suspected bacterial etiology or neurologic involvement: use third-generation cephalosporin 1, 2
3. Older children with febrile dysentery or recent international travel: use azithromycin, depending on local susceptibility patterns and travel history 1, 2

Critical Exception - Avoid Antibiotics:

Antimicrobial therapy must be avoided in infections attributed to STEC O157 and other STEC that produce Shiga toxin 2 (or if toxin genotype is unknown), as antibiotics increase the risk of hemolytic uremic syndrome. 1, 2 This is a strong recommendation with moderate-quality evidence and represents a dangerous pitfall if missed. 1

Adjunctive Therapies: Use With Caution

Antimotility agents (loperamide):

• Never give to children <18 years with acute diarrhea 2
• May be given to immunocompetent adults with acute watery diarrhea 2, 5
• Must be avoided in inflammatory or febrile diarrhea due to risk of toxic megacolon 2, 5
• Avoid in bloody diarrhea 5

Antiemetic agents:

• May be given to children >4 years and adolescents to facilitate oral rehydration when vomiting is present 2

Probiotics:

• May be offered to reduce symptom severity and duration in immunocompetent patients 2, 5

Modifying Treatment Based on Pathogen Identification

Antimicrobial treatment should be modified or discontinued when a clinically plausible organism is identified. 1, 2 This is a strong recommendation with high-quality evidence, emphasizing the importance of obtaining cultures before starting empiric therapy in appropriate patients. 1

Key Clinical Pitfalls to Avoid

1. Administering antimotility agents to children or in cases of bloody/inflammatory diarrhea 2
2. Using antimicrobials for routine acute watery diarrhea without appropriate indications 1, 2
3. Neglecting rehydration while focusing on antimicrobial therapy 2
4. Withholding food during diarrheal episodes 2
5. Using antimicrobials in STEC infections 1, 2
6. Treating asymptomatic contacts with empiric or preventive therapy (they should only be advised on infection prevention measures) 1

Special Populations

Persistent watery diarrhea (≥14 days):

• Empiric treatment should be avoided 1
• Consider non-infectious causes including inflammatory bowel disease and irritable bowel syndrome 2

Immunocompromised patients:

• Lower threshold for empiric antimicrobial therapy with severe illness and bloody diarrhea 1