Small Intestinal Bacterial Overgrowth in Children: Clinical Features and Treatment Response

**Background:** Small intestinal bacterial overgrowth (SIBO) is defined as excessive bacteria in the small bowel causing gastrointestinal symptoms. Diagnosis is challenging, especially in pediatrics, where the carbohydrate breath test (BT) is the predominant noninvasive method but has variable sensitivity (60–70%) and specificity (40–80%). Data on antibiotic efficacy for pediatric SIBO are limited, with most studies restricted to small, specific populations. This study aimed to characterize children diagnosed with SIBO via BT, correlate symptoms with breath test findings, and describe treatment outcomes.

**Methods:** This IRB-approved retrospective cohort study included pediatric patients (age 1–21 years) seen at Stanford Children’s Health Gastroenterology Clinics from June 2012 to October 2018 with a positive BT. A positive BT was defined as a baseline hydrogen ≥20 ppm, a rise in hydrogen ≥20 ppm above baseline, or methane ≥10 ppm using either glucose or lactulose substrate. Exclusion criteria were concomitant infectious gastroenteritis or antibiotic/probiotic use within the month before the BT. Data were collected on demographics, comorbidities, risk factors, symptoms, BT results, treatment modality, and symptom resolution. The primary outcome was complete or partial symptom improvement after treatment. Statistical analysis used absolute standardized differences (ASD) and Chi-square tests, conducted in R version 3.6.2.

**Key Results:** Of 98 patients identified, 54 met inclusion criteria (53.7% female; mean age 11.33 years). Lactulose was used in 75.9% of tests, glucose in 24.1%. The most common symptoms were abdominal pain (72.2%), bloating (53.7%), and constipation (50%). Risk factors included prior gastrointestinal infection (18.5%) and PPI use (18.5%). Hydrogen-only elevation occurred in 51.9%, hydrogen and methane in 42.6%, and methane-only in 5.6%. Overall, 72.3% of patients achieved complete or partial symptom resolution. Symptom resolution was 81.2% in patients receiving probiotics with or without antibiotics versus 67.7% with antibiotics alone (P = 0.524). No significant difference was found between metronidazole (63.2%), rifaximin (76.5%), and other antibiotics (77.8%) (P = 0.601). Treatment duration (7–10 days vs. >10 days) also showed no difference in resolution (71.4% vs. 70.8%, P = 1.00). Sixteen patients (29.6%) had a subsequent BT, mostly for persistent symptoms (75%).

**Clinical Implications:** This study found that approximately 72% of children with SIBO experienced symptom relief after treatment, with no clear superiority of one antibiotic regimen over another. The lack of correlation between specific symptoms and breath test analyte elevation underscores the diagnostic complexity of SIBO in pediatrics. The high rate of repeat testing for persistent symptoms (75% of those retested) and the low rate of negative follow-up BTs (18.8%) suggest substantial treatment failure or recurrence. These findings highlight the urgent need for prospective, head-to-head trials comparing antibiotic regimens and for improved diagnostic methods to guide targeted therapy in pediatric SIBO.