A new, innovative characterization of the small-bowel microbiome may lead to new treatments for small intestinal bacterial overgrowth (SIBO). When contrasted to a control group, the bacteria Escherichia and KIebsiella were dominant in the microbiome of SIBO patients. Targeting these bacteria may restore the healthy balance of the microbiome according to this research.
This analysis of SIBO came from an ongoing study, which is utilizing several new methods to sample and sequence the microbiome. Applying computational strategies to characterize the microbial interrelationships have proven to be a “powerful approach to generate meaningful insights in complex biological systems,” said Leopoldo Valiente-Banuet, a researcher with the Medically Associated Science and Technology (MAST) program at Cedars-Sinai Medical Center, in Los Angeles, who contributed to the study.
Mr. Valiente-Banuet and his colleagues analyzed microbiome samples from 34 people with SIBO and 34 control participants who did not have SIBO. Escherichia and Klebsiella were identified as “the most important disrupters of the integrity of the microbiome network,” said Mr. Valiente-Banuet, who performed the work in collaboration with senior author Mark Pimental, MD, the executive director of the MAST program.
The effects are systemic and “are further exemplified by dramatically reduced connectivity at the genus level,” Mr. Valiente-Banuet reported. He pointed to the density of the triangle motifs, which is one method of tracking relationships in complex networks. The triangle motifs were significantly lower in SIBO microbiomes when compared to non-SIBO microbiomes. This change is likely attributed to the dominant growth of Escherichia and Klebsiella. The alterations in taxa were noted at different levels among all phyla.
Scientists have long recognized the importance of a healthy gastrointestinal tract and other body systems. The complexity of pinpointing the signature differences between a healthy microbiome and a microbiome in people with several disease states remains difficult. The difficulty includes discovering whether the change in the microbiome is a cause or result of any specific disease.
The network analysis is promising for tracing the pathogenicity of microbial alterations, according to Mr. Valiente-Banuet. He said the data make it possible to study the impact of the small-bowel microbiome on SIBO. This provides a path to understanding the imbalances that drive this disease and for finding treatments. The same approach may be applicable to interventions for other diseases linked to unhealthy microbiomes.
Although the area of research is promising, translating it into new treatment strategies requires overcoming several obstacles, according to Purna S. Kashyap, MBBS, the co-director of the microbiome program at the Center for Individualized Medicine at Mayo Clinic College of Medicine and Science, in Rochester, Minn.
“We do think that the small intestinal microbial composition is likely to be as or a more important determinant of symptoms than an overgrowth of bacteria alone, but we still need to demonstrate the relationship between specific microbial members and GI symptoms before we can embark on a therapeutic strategy,” Dr. Kashyap said.
Dr. Kashyap pointed to the use of MacConkey agar for the culture medium and suggested using caution. This medium is selective for gram-negative bacteria, so the strong representation of Klebsiella and Escherichia in SIBO-positive patients was “not surprising,” but he agreed that network analysis is an appropriate first step to document the relationship between microbes.
“Such network analyses are important and would be even more relevant when combined with clinical data,” he said, referring to the need to show a correlation between the overgrowth of specific bacteria and SIBO-related symptoms.