What are the causes of Spontaneous Bacterial Peritonitis (SBP)?

From the Guidelines

Spontaneous Bacterial Peritonitis (SBP) is primarily caused by bacterial translocation from the intestines into the ascitic fluid in patients with cirrhosis and ascites, with the most common causative organisms being gram-negative enteric bacteria, such as Escherichia coli, and gram-positive bacteria like Streptococcus and Enterococcus 1. The main risk factors for SBP include:

• Advanced liver disease with portal hypertension
• Low protein content in ascitic fluid (below 1.5 g/dL)
• Previous episodes of SBP
• Gastrointestinal bleeding
• Poor liver function (high Child-Pugh or MELD scores) Bacterial translocation occurs due to increased intestinal permeability, intestinal bacterial overgrowth, and impaired local and systemic immune defenses in cirrhotic patients 1. Other contributing factors include:
• Use of proton pump inhibitors (which may promote bacterial overgrowth)
• Malnutrition
• Alcohol use Patients with cirrhosis who develop ascites should be monitored regularly for SBP, especially if they have low ascitic fluid protein levels 1. Prophylactic antibiotics like norfloxacin (400 mg daily) or trimethoprim-sulfamethoxazole are recommended for high-risk patients, such as those with prior SBP episodes, gastrointestinal bleeding, or low ascitic protein 1.

From the Research

Causes of Spontaneous Bacterial Peritonitis (SBP)

The causes of SBP are multifactorial and involve several mechanisms. Some of the key causes include:

• Bacterial translocation from the gut to the mesenteric lymph nodes, which can lead to infection of the ascitic fluid 2
• Depressed reticuloendothelial phagocytic activity, making it harder for the body to clear bacteria from the ascitic fluid 2
• Deficient ascitic fluid antibacterial activity, allowing bacteria to grow and cause infection 2
• Use of proton pump inhibitors (PPIs), which can suppress gastric acid secretion and allow bacterial colonization of the upper gastrointestinal tract, leading to bacterial overgrowth and translocation 3
• Use of beta-adrenergic antagonist therapies, which have been strongly associated with SBP in at-risk individuals 4
• Acid suppressive medication, which can increase the risk of SBP 4

Risk Factors for SBP

Several risk factors have been identified, including:

• Cirrhosis and ascites, which are the primary risk factors for developing SBP 4, 5, 6, 3, 2
• Low ascitic fluid total protein concentration, which can increase the risk of SBP 2
• Gastrointestinal hemorrhage, which can increase the risk of SBP 2
• Hospitalization, which can increase the risk of healthcare-associated and nosocomial SBP infections 4
• Use of certain medications, such as PPIs and beta-adrenergic antagonists, which can increase the risk of SBP 4, 3

Pathogens Involved in SBP

Several pathogens have been identified as causes of SBP, including:

• Gram-negative bacteria, such as Escherichia coli and Streptococcus pneumoniae 5, 6
• Gram-positive bacteria, such as Staphylococcus and Enterococcus 4, 6
• Multi-resistant bacteria, which can make treatment more challenging 4