Small-intestinal bacterial overgrowth in cirrhosis is related to the severity of liver disease

Small-intestinal bacterial overgrowth (SIBO) is known to be present in patients with cirrhosis, predisposing to various complications. To determine the frequency of SIBO in cirrhotics and correlate with severity of cirrhosis. Small-intestinal bacterial overgrowth was determined by glucose-hydrogen breath test (GHBT). A basal breath-hydrogen > 20 ppm or a rise by >= 12 ppm above baseline following glucose administration was taken as positive test. Prevalence of SIBO in cirrhotics was compared with healthy controls and correlated with severity of cirrhosis. Of the 53 cirrhotics, 26 (49%) had SIBO, compared to one (8%) control (P = 0.010). The prevalence of SIBO increased with severity of cirrhosis (Child-Pugh A 20%, B 52% and C 73%; P = 0.013). On multivariate analysis, SIBO was independently associated with serum bilirubin and ascites. The best cut-off of serum bilirubin was >= 2 mg/dL [AUROC 0.77 (95% CI 0.64-0.90)] predicting SIBO with sensitivity 65%, specificity 81%, positive predictive value 77%, negative predictive value 71% and accuracy 74%. Patients having combination of ascites and serum bilirubin >= 2 mg/dL had 82% chance, while patients having neither had only 10% chance of having SIBO. Small-intestinal bacterial overgrowth was prevalent in about half of cirrhotics. Its frequency increased with increase in severity of cirrhosis. Ascites and raised serum bilirubin reliably predicted presence of SIBO.