Endoscopically Assisted Glucose Breath Test: A Novel Diagnostic Approach for Distal SIBO

Abstract

Introduction: Small intestinal bacterial overgrowth (SIBO) is characterized by excessive amount of bacteria in the small intestine along with abdominal pain, bloating, gas, and diarrhea. Although oral glucose breath test (GBT) and duodenal aspirate/culture are used to assess proximal SIBO, at present, there is no practical method to identify distal SIBO. We aimed to determine whether direct administration of glucose into the distal duodenum/jejunum can identify SIBO. Methods: Patients with unexplained GI symptoms >1 yr, negative endoscopy, colonoscopy and CT underwent standard GBT, and within a week had upper endoscopy, during which distal duodenal juice was aspirated for aerobic/anaerobic culture and 75g glucose dissolved in 250cc water was directly administered into the 4th part of duodenum. Breath samples were collected for hydrogen/methane at baseline and every 15min for 2h. Symptom profiles and results of GBT, endoscopically assisted glucose breath test (EAGBT) and duodenal cultures were analyzed and compared. Results: 9 patients (m/f=6/3), mean age 45y, participated. Bloating, abdominal pain, cramping, nausea, and belching were the main symptoms present in 89% of patients. 7/9 subjects had a GBT and 1/9 had a fructose breath test (diabetic). Overall, 1/8 (12.5%) patients had a positive test suggesting proximal SIBO and 7/8 (87.5%) had a negative test. In contrast, 8/9 (89%) had a positive EAGBT suggesting distal SIBO (Table 1). 7/9 (78%) patients were symptomatic during the EAGBT. 7/9 (78%) patients had positive cultures (>103 CFU/mL); 4 grew S. viridans, 1 grew Veillonella, 2 grew MSSA, 3 grew alpha-hemolytic streptococcus, 1 grew H. parainfluenzae and 1 grew E.Coli. Eight were >103 CFU/mL, 4 were >104 CFU/mL, and 1 was >105 CFU/mL. EAGBT (85%) was more sensitive than GBT (16%) (Table 1). Although baseline hydrogen levels were similar, baseline methane, peak hydrogen and methane levels and AUC were higher in EAGBT vs. GBT (Table 2). Average AUC was higher using EAGBT with nearly 10 fold higher hydrogen levels (p= 0.06) and nearly twice as high methane level measured (Table 2).Table 1: Positive and Negative Diagnostic Agreement between Breath Test and Culture DataTable 2: Baseline and Peak Hydrogen and Methane Levels as well as AUC in Both Glucose Breath TestsConclusion: EAGBT is a novel method of identifying distal SIBO. It appears to be a safe and practical technique for detecting distal SIBO, and, in our cohort, had a similar yield as duodenal aspirate/culture. EAGBT could be an appropriate next step for patients with high index of suspicion for SIBO or in whom an oral glucose breath test is negative.Figure 1