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Probiotics in Small Intestinal Bacterial Overgrowth (SIBO)

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Research Glimpse: The results of this phase I trial of a probiotic in treating or reducing complications in patients with SIBO suggests that adding a probiotic to the maintenance regimen may improve GI symptoms and prevent complications from antibiotic treatment. "Evaluating the efficacy of probiotic on treatment in patients with small intestinal bacterial overgrowth (SIBO) - A pilot study"  

The evidence for benefit of probiotic therapy in patients with SIBO is controversial. Probiotics are defined as live microorganisms that can enhance epithelial barrier function, modulate immune function, and prevent dysbiosis by competitive binding and adherence to the intestinal mucosa. Some patients with SIBO report benefit from taking probiotics. 

This Iranian study was conducted on 30 consecutive adults diagnosed with SIBO on hydrogen breath testing (HBT). Following 3 weeks of treatment with broad-spectrum antibiotics, 15 males and 15 females were treated with a monthly maintenance regimen of minocycline 100 mg twice daily for 15 days, and then randomized to receive for 15 additional days either (1) a probiotic (Bacillus coagulans spores and fructo-oligosaccharides) twice daily after meals for 15 days, or (2) no treatment. After 6 months of such treatment, the HBT was repeated. 

Results: At 6 months, all 15 of the patients in the probiotic group reported complete resolution of GI pain, versus only 7 of the 15 controls (p=0/002). There was statistically significant reduction in flatulence, belching, and diarrhea in the treatment group, but non-significant reductions in nausea, vomiting, constipation, and lack of appetite between groups. HBT was negative in 93.3% of those taking probiotic versus 66.7% of controls, although this result did not reach significance. 

Limitations: Numerous limitations of this study raise questions about the clinical significance of the results: small size, no placebo, no measurement of methane gas, no pro-kinetic therapy, and no dietary intervention. Minocycline is not typically used in North America for maintenance treatment of SIBO. The broad-spectrum antibiotics used in the initial phase of treatment were not identified by the authors. Bacillus coagulans was provided in the spore form, and, as such, is not a true probiotic as it is not living. The fructo-oligosaccharides may feed gas- producing bacteria. 

Clinical Conclusion: These results suggest that adding a probiotic (or spore-based microorganism) to the maintenance regimen may improve GI symptoms and prevent complications from antibiotic therapy in patients with SIBO. However, SIBO, as well as GI health in general, are far too complex to support a claim that certain types of bacteria will solve the problem of SIBO when there is interplay between hundreds of different types of bacteria in the GI tract. A study designed to correct the weaknesses described above should be performed to further elucidate the role probiotics may play in the treatment of SIBO. 

Khalighi et al. Indian J Med Res. 2014;140(5):604-608.