Observational Study
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World J Gastroenterol. Mar 14, 2022; 28(10): 1067-1077
Published online Mar 14, 2022. doi: 10.3748/wjg.v28.i10.1067
Gut dysbiosis and small intestinal bacterial overgrowth as independent forms of gut microbiota disorders in cirrhosis
Roman Maslennikov, Vladimir Ivashkin, Irina Efremova, Elena Poluektova, Anna Kudryavtseva, George Krasnov
Roman Maslennikov, Vladimir Ivashkin, Irina Efremova, Elena Poluektova, Department of Internal Medicine, Gastroenterology and Hepatology, Sechenov University, Moscow 119435, Russia
Roman Maslennikov, Vladimir Ivashkin, Elena Poluektova, Anna Kudryavtseva, Scientific Community for Human Microbiome Research, Moscow 119435, Russia
Roman Maslennikov, Department of Internal Medicine 1, Сonsultative and Diagnostic Center 2 of the Moscow City Health Department, Moscow 107564, Russia
Anna Kudryavtseva, George Krasnov, Laboratory of Postgenomic Research, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
Author contributions: Ivashkin V contributed research idea; Ivashkin V and Maslennikov R contributed study design; all authors contributed research and data analysis; Kudryavtseva A performed gut microbiota sequencing; Krasnov G performed bioinfomatics analysis of gut microbiota sequencing data; Maslennikov R contributed draft writing; all authors contributed draft editing; Maslennikov R is the guarantor.
Supported by Biocodex Microbiota Foundation: National Research Grant Russia 2019.
Institutional review board statement: The present study was approved by the Ethics Committee of Sechenov University.
Informed consent statement: The study procedures were explained to potential participants, and written informed consent was obtained before enrollment.
Conflict-of-interest statement: No conflicts of interest.
Data sharing statement: The data can be provided upon request to the corresponding author.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Roman Maslennikov, MD, PhD, Assistant Professor, Professor, Department of Internal Medicine, Gastroenterology and Hepatology, Sechenov University, Pogodinskaya str., 1, bld. 1, Moscow 119435, Russia. mmmm00@yandex.ru
Received: May 15, 2021
Peer-review started: May 15, 2021
First decision: June 27, 2021
Revised: June 29, 2021
Accepted: February 9, 2022
Article in press: February 9, 2022
Published online: March 14, 2022
Processing time: 300 Days and 0.4 Hours
Abstract
BACKGROUND

Gut dysbiosis and small intestinal bacterial overgrowth (SIBO) are commonly observed in patients with cirrhosis. Despite the substantial number of articles describing the relations between disorders of gut microbiota and various manifestations of cirrhosis, dysbiosis and SIBO were always studied separately.

AIM

To study the relationship of gut dysbiosis and SIBO in cirrhosis.

METHODS

This observational study included 47 in-patients with cirrhosis. Stool microbiome was assessed using 16S rRNA gene sequencing. SIBO was assessed using the lactulose hydrogen breath test.

RESULTS

SIBO was found in 24/47 (51.1%) patients. Patients with SIBO had a higher abundance of Firmicutes (P = 0.017) and Fusobacteria (P = 0.011), and a lower abundance of Bacteroidetes (P = 0.013) than patients without SIBO. This increase in the abundance of Firmicutes occurred mainly due to an increase in the abundance of bacteria from the genus Blautia (P = 0.020) of the Lachnospiraceae family (P = 0.047), while the abundance of other major families of this phylum [Ruminococcaceae (P = 0.856), Peptostreptococcaceae (P = 0.066), Clostridiaceae (P = 0.463), Eubacteriaceae (P = 0.463), Lactobacillaceae (P = 0.413), and Veillonellaceae (P = 0.632)] did not differ significantly between the patients with and without SIBO. Reduced level of Bacteroidetes in samples from patients with SIBO was a result of the decrease in bacterial numbers from all the major families of this phylum [Bacteroidaceae (P = 0.014), Porphyromonadaceae (P = 0.002), and Rikenellaceae (P = 0.047)], with the exception of Prevotellaceae (P = 0.941). There were no significant differences in the abundance of taxa that were the main biomarkers of cirrhosis-associated gut dysbiosis [Proteobacteria (P = 0.790), Bacilli (P = 0.573), Enterobacteriaceae (P = 0.632), Streptococcaceae (P = 0.170), Staphylococcaceae (P = 0.450), and Enterococcaceae (P = 0.873)] between patients with and without SIBO.

CONCLUSION

Despite the differences observed in the gut microbiome between patients with and without SIBO, gut dysbiosis and SIBO are most likely independent disorders of gut microbiota in cirrhosis.

Keywords: Dysbiosis; Gut-liver axis; Microbiome; Small intestinal bacterial overgrowth; Cirrhosis; Microbiota

Core Tip: Patients with small intestinal bacterial overgrowth (SIBO) had a higher abundance of Firmicutes and Fusobacteria, and a lower abundance of Bacteroidetes than patients without SIBO. This increase in the abundance of Firmicutes occurred mainly due to an increase in the abundance of bacteria from the genus Blautia of the Lachnospiraceae family. There were no significant differences in the abundance of taxa that were the main biomarkers of cirrhosis-associated gut dysbiosis.