Asymptomatic gastric bacterial overgrowth after bariatric surgery: are long-term metabolic consequences possible?

Patients with postbariatric bacterial overgrowth were reinvestigated after a follow-up of 15 years. It was hypothesized that systemic associations analogous to those reported for whole gut microbiome would be revealed.

Patients (n = 37, 70.3 % females, 42.4 ± 9.9 years old, preoperative BMI 53.5 ± 10.6 kg/m(2), current BMI 32.8 ± 10.8 kg/m(2)), all submitted to RYGB on account of morbid obesity, were followed during 176.8 ± 25.7 months. Blood tests included fasting blood glucose, HbA1c, liver and pancreatic enzymes, and lipid fractions. Bacterial overgrowth was diagnosed by quantitative culture of gastric fluid in both the excluded remnant and the gastric pouch, with the help of double-balloon enteroscopy. Absolute counts of aerobes and anaerobes in both gastric reservoirs were correlated with nutritional and biochemical measurements, aiming to identify clinically meaningful associations.

Patients denied diarrhea, abdominal pain, weight loss, or other symptoms related to bacterial overgrowth. Biochemical profile including enzymes was also acceptable, indicating a stable condition. Positive correlation of bacterial count in either segment of the stomach was demonstrated for BMI and gamma-glutamyl transferase, whereas negative correlation occurred regarding fasting blood glucose.

An antidiabetic role along with deleterious consequences for weight loss and liver function are possible in such circumstances. Such phenotype is broadly consistent with reported effects for the whole gut microbiome. Prospective controlled studies including molecular analysis of gastrointestinal fluid, and simultaneous profiling of the entire microbiome, are necessary to shed more light on these findings.