Small Intestinal Bacterial Overgrowth in Children: A State-Of-The-Art Review

Abstract

Small intestinal bacterial overgrowth (SIBO) is a heterogenous and poorly understood entity characterised by an excessive growth of select microorganisms within the small intestine. This excessive bacterial biomass, in turn, disrupts host physiology in a myriad of ways, leading to gastrointestinal and non-gastrointestinal symptoms and complications. SIBO is a common cause of non-specific gastrointestinal symptoms in children, such as chronic abdominal pain, abdominal distention, diarrhoea, and flatulence, amongst others. In addition, it has recently been implicated in the pathophysiology of stunting, a disease that affects millions of children worldwide. Risk factors such as acid-suppressive therapies, alterations in gastrointestinal motility and anatomy, as well as impoverished conditions, have been shown to predispose children to SIBO. SIBO can be diagnosed via culture-dependant or culture-independent approaches. SIBO's epidemiology is limited due to the lack of uniformity and consensus of its diagnostic criteria, as well as the paucity of literature available. Antibiotics remain the first-line treatment option for SIBO, although emerging modalities such as probiotics and diet manipulation could also have a role. Herein, we present a state-of-the-art-review which aims to comprehensively outline the most current information on SIBO in children, with particular emphasis on the gut microbiota.

Change of the duodenal mucosa-associated microbiota is related to intestinal metaplasia

“…Consequently, probiotic intake may have a greater influence on the duodenal microbiota than on the distal gut microbiota [22]. Probiotics have also been used for treatment of small intestinal bacterial overgrowth in children [23]. Further studies on modulation of the duodenal microbiota for IM treatment through microbiota-modulating therapies, such as probiotics, are needed.…”

Duodenal microbiome in patients with or without Helicobacter pylori infection

“…This gap of information is probably associated with difficulties to reach and sample this segment of the gastrointestinal tract 6 . However, SI microbiota alterations could lead to gastrointestinal and non‐gastrointestinal symptoms and complications 9 . Although there has been an important progress to understand the structure and function of the gut microbiota, there is still a need to further characterize this new organ, particularly in the SI.…”

Enteroendocrine cells sense bacterial tryptophan catabolites to activate enteric and vagal neuronal pathways

“…IBS is a complicated disease that display comorbidities of both impairment of GI motility and CNS symptoms. The cause of SIBO in IBS is incompletely understood although several studies demonstrated that some of the indole producing bacteria like Escherichia coli exhibit high abundance in the small intestine of SIBO associated IBS patients (Ghoshal et al, 2014, Leite et al, 2020, Avelar Rodriguez et al, 2019. Our findings raise the possibility that SIBO leads to an increase of microbial tryptophan metabolite production in the small intestine, which then activates Trpa1+EECs to increases intestinal motility and modulate CNS activity through the vagal nerve, resulting in the complex comorbidities of intestinal and psychiatric disorders in IBS.…”