What is the recommended treatment for a 15-year-old male with mesenteric adenitis, stool culture positive for enteropathogenic Escherichia coli (E. coli) and Giardia lamblia, presenting with abdominal pain?

Treatment of Mesenteric Adenitis with Enteropathogenic E. coli and Giardia lamblia Infection

For a 15-year-old male with mesenteric adenitis, stool culture positive for enteropathogenic E. coli and Giardia lamblia presenting with abdominal pain, treatment should include metronidazole for Giardia lamblia and supportive care for enteropathogenic E. coli, as antimicrobials are not routinely recommended for enteropathogenic E. coli unless the patient is severely ill.

Diagnostic Considerations

• Mesenteric adenitis presents with abdominal pain that can mimic appendicitis, often accompanied by fever and sometimes diarrhea 1
• The presence of both enteropathogenic E. coli and Giardia lamblia in stool culture indicates a dual infection that requires targeted management 2
• Abdominal pain is a common symptom associated with both pathogens, with Giardia typically causing persistent or chronic diarrhea and enteropathogenic E. coli causing abdominal pain 2

Treatment Approach

For Giardia lamblia:

• Metronidazole 250-750 mg three times daily for 7-10 days is the first-line treatment for Giardia lamblia infection 2
• Giardia infection requires specific antiparasitic therapy to eradicate the organism and prevent persistent infection 2, 3
• Treatment is indicated even in mild cases to prevent complications such as malabsorption and to reduce transmission 4

For Enteropathogenic E. coli:

• For enteropathogenic E. coli, antimicrobial therapy is generally not routinely recommended unless the patient is severely ill 2
• In cases where treatment is deemed necessary, trimethoprim-sulfamethoxazole (if susceptible) or a fluoroquinolone may be considered 2
• For a 15-year-old patient, fluoroquinolones should be used with caution due to potential adverse effects on developing cartilage 2

Supportive Care:

• Maintain adequate hydration with oral rehydration solutions or, if necessary, intravenous fluids for severe dehydration 2
• Monitor for signs of worsening infection or complications such as sepsis 2
• Antipyretics for fever control as needed 2

Monitoring and Follow-up

• Clinical improvement should be expected within 2-3 days after initiating appropriate therapy 1
• Follow-up stool examination may be considered to confirm eradication of Giardia lamblia after completing treatment 2
• If symptoms persist beyond expected timeframes, consider:
  • Antimicrobial resistance (particularly for Giardia) 3
  • Need for alternative treatment regimens 3
  • Possible complications or additional undiagnosed pathogens 2

Special Considerations

• Mesenteric adenitis is often self-limited, but the presence of specific pathogens requires targeted therapy 1
• Unlike Yersinia-associated mesenteric adenitis which is common in Western countries, infections with other pathogens like Salmonella can carry risk for systemic complications 1
• The dual infection with both bacterial and parasitic pathogens may lead to more severe or prolonged symptoms requiring careful management 2

Common Pitfalls to Avoid

• Failing to treat Giardia lamblia infection, which can lead to chronic infection and malabsorption 4
• Unnecessary use of antibiotics for enteropathogenic E. coli in mild cases, which may promote antimicrobial resistance 2
• Not considering potential drug interactions between antiparasitic and other medications the patient may be taking 3
• Inadequate follow-up to ensure resolution of symptoms and clearance of infection 2