What causes diarrhea in Continuous Ambulatory Peritoneal Dialysis (CAPD) peritonitis?

Diarrhea in CAPD Peritonitis: Causes and Mechanisms

Diarrhea in CAPD peritonitis is primarily caused by the inflammatory response in the peritoneum that affects adjacent bowel function through direct extension of inflammation to the intestinal wall. This inflammatory process disrupts normal gastrointestinal motility and absorption, leading to diarrhea as a clinical manifestation.

Pathophysiological Mechanisms

The development of diarrhea in CAPD peritonitis can be explained through several mechanisms:

1. Direct Inflammatory Response:

   • The peritoneal infection triggers an inflammatory cascade that affects the adjacent intestinal wall
   • Inflammatory mediators disrupt normal bowel motility and secretory functions
   • This inflammation can lead to increased intestinal permeability and fluid secretion

2. Microbial Factors:

   • Peritonitis in CAPD patients is commonly caused by various organisms 1:
     • Gram-positive bacteria (especially Staphylococcus species) account for approximately 50% of cases
     • Gram-negative bacteria and fungi account for the remainder
   • Certain bacterial toxins and byproducts can directly stimulate intestinal secretion

3. Bidirectional Relationship:

   • Gastrointestinal symptoms can both predict and result from peritonitis
   • A prospective study demonstrated that patients with higher gastrointestinal symptom scores had significantly higher risk of developing peritonitis 2
   • Specifically, belching and constipation were identified as strong predictors of subsequent peritonitis

Clinical Significance

Understanding the relationship between diarrhea and CAPD peritonitis is important for several reasons:

• Diagnostic Value: Diarrhea may be an early warning sign of developing peritonitis
• Treatment Considerations: Addressing both the infection and gastrointestinal symptoms is important for patient comfort
• Complication Risk: Diarrhea can increase the risk of contamination of the peritoneal catheter exit site, potentially creating a cycle of infection 1

Special Considerations

1. Enteric Organisms and Peritonitis:

   • Inflammatory or ischemic bowel disease increases the risk of transmural contamination by enteric organisms 1
   • Patients with frequent episodes of diverticulitis are at higher risk for peritonitis due to potential bacterial translocation

2. Campylobacter Peritonitis:

   • There is a strong association between acute enterocolitis and subsequent peritonitis in CAPD patients
   • Diarrhea may precede cloudy dialysate by several days in cases of Campylobacter peritonitis 3
   • The spread from gastrointestinal tract to peritoneal cavity likely occurs through bacteremic transfer

Management Implications

When managing CAPD patients with diarrhea and peritonitis:

1. Antibiotic Selection:

   • Initial empiric therapy should cover both gram-positive and gram-negative organisms 4
   • Intraperitoneal cefazolin plus gentamicin is often recommended as first-line therapy
   • Adjust antibiotics based on culture results

2. Preventive Measures:

   • Address gastrointestinal symptoms promptly, as they may predict future peritonitis episodes 2
   • Consider antifungal prophylaxis with oral nystatin during antibiotic treatment to prevent fungal peritonitis 5

3. Monitoring Response:

   • Assess clinical response within 48-72 hours of initiating therapy
   • Consider catheter removal if no improvement after 5 days of appropriate antibiotics

Understanding the connection between diarrhea and peritonitis in CAPD patients helps clinicians recognize early warning signs and implement appropriate preventive and therapeutic measures to reduce morbidity and mortality associated with this common complication.