What is the most common organism causing spontaneous bacterial peritonitis in patients with cirrhotic ascites?

Spontaneous bacterial peritonitis (SBP) is a common and serious complication in patients with cirrhosis and ascites. It occurs when bacteria from the gut or other sources translocate into the peritoneal cavity, leading to infection. The most frequently identified organism in cases of SBP is Escherichia coli.

E. coli is a gram-negative bacillus that is part of the normal intestinal flora, making it readily available for translocation, especially in patients with compromised liver function and altered gut permeability due to cirrhosis. This unique susceptibility among patients with cirrhosis arises from a combination of factors, including potential alterations in gut microbiota, decreased immune response, and changes in the permeability of intestinal barriers.

Other bacteria, such as Klebsiella pneumoniae, while being significant pathogens in various infections, are not as commonly associated with SBP as E. coli. Similarly, Staphylococcus aureus and Pseudomonas aeruginosa, though important pathogens in different clinical settings, are less frequently isolated in cases of SBP.

Understanding the prevalence of E. coli in this context is critical for clinicians, as it guides empirical treatment decisions and informs antibiotic choice when managing SBP in patients