Small intestine bacterial overgrowth is frequent in cystic fibrosis: combined hydrogen and methane measurements are required for its detection.
OBJECTIVE To investigate the prevalence of carbohydrate malabsorption and bacterial overgrowth in children with cystic fibrosis (CF) and abnormal stool pattern referred for breath hydrogen testing. METHODS Results from 89 tests using lactose, sucrose and lactulose in 54 children with CF were compared with 5430 tests on children with non-CF-related stool abnormalities. RESULTS Children with CF were more frequently unable to ferment lactulose to hydrogen (39% vs. 20%, P<0.03); they had significantly longer oro-caecal transit times (mean 99 vs. 68 min, P<0.0003); they had a higher incidence of bacterial overgrowth (32% vs. 7%, P<0.003) and sucrose malabsorption (47% vs. 14.5%, P<0.004); but they had no increase in lactose malabsorption (40% vs. 31%). Children with bacterial overgrowth in both groups had longer transit times (CF 123 min, non-CF 108 min) compared to the non-CF children without overgrowth (68 min) and reference normal children (69 min). CONCLUSIONS Bacterial overgrowth and carbohydrate malabsorption, particularly of sucrose, should be considered when assessing children with CF and abnormal stool patterns.