Small intestinal bacterial overgrowth in patients post major upper gastrointestinal cancer surgery

A review of patients who underwent a hydrogen breath test (HBT) for small intestinal bacterial overgrowth (SIBO), following an esophagectomy or gastrectomy, was carried out in the GI Function Unit, St. James's Hospital, Dublin. This study aimed to evaluate the incidence of SIBO in this high-risk cohort, to determine possible contributing factors and to create an optimal protocol, for testing and follow up care for HBT in patients after major GI surgery. Consecutive patients undergoing esophagectomy or total gastrectomy were included. Exclusion criteria included complicated major upperGI surgery and surgery performed for nonmalignant diagnoses. Statistical analysis was performed to evaluate the association of specific factors and the development of SIBO. Eighty-seven patients were included, suspected for having malabsorption post major upper GI surgery, with a positive HBT rate of 53%. The proportion of patients testing positive was greatest in the time period of 6 to 12 months postoperatively where the positive rate for patients tested was 87% versus 50% within 6 months of surgery and 50% for patients more than one year after surgery (P = 0.005). Female patients were significantly more likely to have a positive HBT than male patients (74.1% vs. 43.3%, P = 0.011). The median body mass index (BMI) of patients with a positive breath test was 24.86 (range: 17.47-42.75) versus median 29.22 (19.11-40.82) for patients with a negative HBT (P = 0.012). Patients with a BMI of < 25 were more likely to have a positive HBT (75% positive rate) versus those with BMI > 25 (45% positive rate, P = 0.119). Using multivariate regression analysis, both BMI (P = 0.033) and sex (P = 0.044) were significant independent predictors of a positive HBT. In a subgroup of 18 patients who were treated with rifaximin, the impact of GI symptoms on overall quality of life was significantly reduced (median score (5.39 vs. 3.78, P < 0.001) following treatment. In patients with weight loss or symptoms suggestive of malabsorption following radical upper GI surgery, a large proportion of patients test positive for SIBO using the HBT. Low BMI and female sex are relative predictors of a positive HBT.