Low-grade small intestinal bacterial overgrowth is common in patients with non-alcoholic steatohepatitis on quantitative jejunal aspirate culture.

Background: Though pathogenesis of non-alcoholic steatohepatitis (NASH) is unclear, association with small intestinal bacterial overgrowth [SIBO] and fecal dysbiosis is suggested. We evaluated SIBO in NASH using quantitative jejunal aspirate culture (conventional criteria: ≥ 10 colony forming unit (CFU)/mL and newer cutoff ≥ 10 CFU/mL) and glucose hydrogen breath test.

Methods: Thirty-eight patients with NASH (age 37.5 years, range 20-54, 9, 24% female), diagnosed by ultrasonography, alanine aminotransferase >1.5 times normal and liver biopsy (in 27/38, 71%) and exclusion of other causes and 12 constipation-predominant irritable bowel syndrome as historical controls (age 39.5-y, 26-44; 3, 25% female) without fatty liver were studied.

Results: Jejunal aspirates, obtained in 35/38 patients, were sterile in 14/35 (40%) and bacteria isolated in 21 (60%) (all aerobic, in one anaerobe also; Gram positive 5, negative 13, both 3). In contrast, bacteria (two Gram negative) were isolated in 3/12 (25%) controls (odds ratio 4.5, 95% CI 1.0-19.5; p = 0.04); colony counts were higher in NASH than controls (median 380 CFU/mL, 0-200,000 vs. 0 CFU/mL, 0-1000; p = 0.02). Gram negative bacteria tended to be commoner in NASH than controls (16/35 vs. 2/12; p = 0.07). Seven out of 35 (20%) patients with NASH (≥ 10 CFU/mL in 5 and 2 other on glucose hydrogen breath test) and no control had SIBO (p = ns); low-grade SIBO (≥10 CFU/mL) was commoner in NASH than controls (14/35, 40%, vs. 1/12, 8.3%; p = 0.04). There was no correlation between bacterial colony count and bacterial type and anthropometric and biochemical parameters.

Conclusion: Low-grade bacterial overgrowth, particularly with Gram negative bacteria, was commoner in NASH than controls.