Impact of small intestinal bacterial overgrowth on systemic inflammation, circulatory and renal function, and liver fibrosis in patients with cirrhosis and ascites

Authors Olga Alexiou, Grigorios Despotis, George Kalambokis, Ilias Tsiakas, Maria Christaki, Spiridon Tsiouris, Xanthi Xourgia, Lampros Lakkas, Georgios S. Markopoulos, Georgios Kolios, Damianos Kolios, Stavroula Tsiara, Haralampos Milionis, Dimitrios Christodoulou, Gerasimos Baltayiannis.


Background Small intestinal bacterial overgrowth (SIBO) occurs frequently in patients with cirrhosis, particularly in those with ascites, and promotes the translocation of gut-derived bacterial products into the portal and systemic circulation. We investigated the effects of SIBO on systemic inflammatory activity, circulatory and renal function, and the degree of liver fibrosis in patients with cirrhosis and ascites.

Methods Eighty patients with cirrhosis and ascites were prospectively enrolled. SIBO was determined by lactulose breath test. Serum levels of lipopolysaccharide-binding protein (LBP), tumor necrosis factor-α, and interleukin-6, mean arterial pressure (MAP), cardiac output (CO) by echocardiography, systemic vascular resistance (SVR) as MAP/CO ratio, plasma renin activity (PRA), plasma aldosterone, radioisotope-assessed glomerular filtration rate (GFR), and liver stiffness by shear wave elastography were evaluated.

Results SIBO was detected in 58 patients (72.5%). Compared to patients without SIBO, those diagnosed with SIBO had significantly higher LBP levels (P<0.001), significantly lower MAP (P<0.001) and SVR (P<0.001), and significantly higher CO (P=0.002) and PRA (P<0.001). Patients with SIBO had significantly lower GFR (P=0.02) and higher liver stiffness (P=0.04) compared to those without SIBO. The presence of SIBO was independently associated with LBP (P=0.007) and PRA (P=0.01). Among patients with SIBO, peak breath hydrogen concentration was significantly
correlated with serum LBP (P<0.001), MAP (P<0.001), CO (P=0.008), SVR (P=0.001), PRA (P=0.005), plasma aldosterone (P<0.001), GFR (P<0.001), and liver stiffness (P=0.004).

Conclusion SIBO in patients with cirrhosis and ascites may predispose to greater systemic inflammation, circulatory and renal dysfunction, and more advanced liver fibrosis.

Keywords Small intestinal bacterial overgrowth, systemic inflammation, systemic hemodynamics, renal function, liver fibrosis

Ann Gastroenterol 2024; 37 (3): 348-355

Original Articles