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

David Avelar Rodriguez,Paul Macdaragh Ryan,Jaime Alfonso Ramirez Mayans,Erick Manuel Toro Monjaraz,Eamonn Martin Quigley

doi:10.3389/fped.2019.00363

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.

Highlights

Small intestinal bacterial overgrowth (SIBO) is a heterogenous disorder characterised by an excessive growth of select microorganisms within the small intestine
SIBO can negatively impact the host in a range of ways [1, 31, 53,54,55,56,57,58,59,60,61]. These include bacterial carbohydrate fermentation leading to excess gas and water production [1]; bacterial deconjugation of bile acids resulting in poorly absorbed liposoluble vitamins [18]; bacterial macronutrient and micronutrient consumption, leaving the host with less available nutrients for absorption [58]; villous blunting leading to carbohydrate malabsorption [13, 62,63,64]; decreased short
Amongst the SIBO cases, Proteobacteria (Pseudomonas aeruginosa, Klebsiella pneumonia, and Acinetobacter spp.) were the most commonly isolated microorganisms followed by members of the Firmicutes phylum (Streptococcus spp. and Enterococcus faecalis); 20% of cases were due to overgrowth of more than one microorganism. These findings demonstrate that in most cases, SIBO is caused by a single microorganism that belongs to the Proteobacteria phylum [37], coliform bacteria such as E. coli and Klebsiella spp

Summary

INTRODUCTION

Small intestinal bacterial overgrowth (SIBO) is a heterogenous disorder characterised by an excessive growth of select microorganisms within the small intestine. SIBO is a common cause of non-specific gastrointestinal symptoms in children, such as chronic abdominal pain, abdominal distention, diarrhoea, and flatulence, amongst others [2,3,4,5] It has recently been implicated in the pathophysiology of stunting [6], a disease that affects millions of children worldwide. Bacteria from the Actinobacteria (e.g., Bifidobacterium), Firmicutes (e.g., Faecalibacterium, Clostridium, Ruminococcus, Lactobacillus) and Bacteroidetes (e.g., Bacteroides, Prevotella) phyla are largely regarded as commensal microorganisms, while a significant portion of gastrointestinal pathogens belong to the Proteobacteria phylum (e.g., Escherichia, Shigella, Salmonella, Klebsiella, and Helicobacter, amongst others) [36, 37] In addition to this diverse community of bacteria, the human gastrointestinal tract is home to an extensive array of viruses [38], fungi [39], and archaea [40]. These include bacterial carbohydrate fermentation leading to excess gas and water production [1]; bacterial deconjugation of bile acids resulting in poorly absorbed liposoluble vitamins [18]; bacterial macronutrient and micronutrient consumption (bacterial-host nutrient competition), leaving the host with less available nutrients for absorption [58]; villous blunting leading to carbohydrate malabsorption [13, 62,63,64]; decreased short

Study design

Findings

CONCLUSION