The role of the microbiota in the management of intensive care patients

Abstract

The composition of the gut microbiota is highly dynamic and changes according to various conditions. The gut microbiota mainly includes difficult-to-cultivate anaerobic bacteria, hence knowledge about its composition has significantly arisen from culture-independent methods based on next-generation sequencing (NGS) such as 16S profiling and shotgun metagenomics. The gut microbiota of patients hospitalized in intensive care units (ICU) undergoes many alterations because of critical illness, antibiotics, and other ICU-specific medications. It is then characterized by lower richness and diversity, and dominated by opportunistic pathogens such as Clostridioides difficile and multidrug-resistant bacteria. These alterations are associated with an increased risk of infectious complications or death. Specifically, at the time of writing, it appears possible to identify distinct microbiota patterns associated with severity or infectivity in COVID-19 patients, paving the way for the potential use of dysbiosis markers to predict patient outcomes. Correcting the microbiota disturbances to avoid their consequences is now possible. Fecal microbiota transplantation is recommended in recurrent C. difficile infections and microbiota-protecting treatments such as antibiotic inactivators are currently being developed. The growing interest in the microbiota and microbiota-associated therapies suggests that the control of the dysbiosis could be a key factor in the management of critically ill patients. The present narrative review aims to provide a synthetic overview of microbiota, from healthy individuals to critically ill patients. After an introduction to the different techniques used for studying the microbiota, we review the determinants involved in the alteration of the microbiota in ICU patients and the latter’s consequences. Last, we assess the means to prevent or correct microbiota alteration.

Cerebral Intraparenchymal Hemorrhage Changes Patients’ Gut Bacteria Composition and Function

“…Through Influencing the balance between bacterial anti-inflammatory and pro-inflammatory properties, dysbiosis contributes to inflammation and various disease severity, leading to a worse clinical outcome. ( Tilg et al., 2020 ; Zuo et al., 2020 ; Gou et al., 2021 ; Szychowiak et al., 2022 ). The composition of the gut microbiota is influenced by various factors, including environment, host disease state, host immune response and genetic background ( Wu et al., 2020 ; Gou et al., 2021 ), among which the environment is a critical factor in gut bacterial property transformation.…”

Probiotic Supplementation Prevents the Development of Ventilator-Associated Pneumonia for Mechanically Ventilated ICU Patients: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

“…Furthermore, the gastrointestinal conditions of patients before the treatment could contribute to the heterogeneity of the patients and affect the treatment efficacy. The aforementioned four limitations were common among the studies in this field, which may contribute to the slight heterogeneity ( 13 , 40 , 113 , 114 ). These heterogeneities could not be eliminated by statistical methods.…”

“…The development of VAP involves dysbiosis and failure of host immune response ( 12 ). Gut dysbiosis is common in critically ill patients ( 13 ), especially in invasive mechanically ventilated patients ( 1 ) who are generally subjected to various types of stress, such as shock, trauma, and bleeding ( 14 ). These insults to the gut deteriorate beneficial commensal bacteria and promote the overgrowth of pathogens ( 15 ).…”

Impact of microbiota-immunity axis in pancreatic cancer management

“…Because an estimated 70% of the bacteria in the human body have not been grown yet, studying the human microbiota is a difficult endeavor[ 13 ]. A breakthrough in DNA sequencing occurred in the mid-2000s thanks to next-generation sequencing[ 14 ]. Through gene sequencing, metagenomics, metatranscriptomics, metaproteomics, and metabolomics (the recently introduced “meta-omics” techniques) analysis of strain composition, production of metabolites, and other bacterial activities can be performed[ 15 , 16 ].…”