This review examines how the human microbiome impacts the management of critically ill or injured patients. The authors frame the gastrointestinal microbiome as particularly active and influential for physiologic recovery or failure in critical illness. The review aims to summarize microbiome characterization, mechanisms of derangement in the ICU, and interventions to mitigate harmful shifts and restore homeostasis.
English-language manuscripts were identified through PubMed and OVID searches from database inception through August 2025. The review included studies addressing mammalian microbiomes, microbiome characterization and derangement, microbiome restoration, critical care interventions, the ICU setting, and organ system outcomes tied to the human microbiome. Gray literature was excluded. Data abstracted informed microbiome characterization, derangement, support, manipulation, and the microbiome’s impact on critical care interventions and outcomes.
Humans possess distinct microbiomes across multiple body sites, including the eyes, skin, oropharynx, lung, bladder, and the gastrointestinal tract. The authors emphasize that while many compartments are relevant, the gastrointestinal microbiome is the most identifiable and active outside the lifecycles of resident microbiota and, therefore, most informative for critical care applications.
The gastrointestinal microbiome plays a critical role in maintaining health and regulating host functions that influence recovery. In the context of critical illness, this microbiome is presented as a lens through which microbial actions and host–microbe–regulated functions can be understood. The review highlights the gastrointestinal microbial community’s importance to physiologic processes implicated in recovery or progression to organ dysfunction.
Microbial balance disruption, or dysbiosis, is common among ICU patients. Derangement arises from both the index disease processes prompting admission and from therapeutic or rescue interventions used in the ICU environment. The review synthesizes evidence that illness and common critical care therapies alter microbial communities, producing characteristic dysbiotic patterns relevant to patient outcomes.
Understanding how disease-modulated and therapy-driven microbiome changes occur—and their downstream impact—may reveal strategies to improve critical care outcomes. The authors argue that the microbiome influences interventions and organ-system outcomes, although specifics of causation or quantified effects are reported in the literature cited rather than enumerated in the abstract. Key clinical contexts named as particularly relevant include sepsis, shock, and other critical care conditions identified among the review’s keywords.
The review advises that ICU clinicians will benefit from a practical grounding in microbiome evaluation fundamentals. This includes awareness of the different body-site microbiomes, the methods used to characterize microbial communities, and recognition of how clinical conditions and therapies can alter microbial composition and function. Details of specific diagnostic techniques and protocols are discussed in the full text and referenced studies cited by the authors.
Based on the literature synthesis, the review outlines current and emerging interventions aimed at mitigating pathobiome induction and restoring microbial homeostasis. While the abstract highlights the concept that interventions exist and may improve outcomes, it does not provide a comprehensive list or outcomes data within the abstract. The full article and its 130 references are the source for specific restorative strategies and their evidence bases.
The authors conclude that ICU clinicians should understand three core areas: 1) fundamentals of microbiome evaluation, 2) how disease processes and therapeutics adaptively or maladaptively alter the microbiome, and 3) current and emerging approaches to mitigate pathobiome formation and restore homeostasis to improve outcomes. Emphasis is placed on the gastrointestinal microbiome as a vantage point to interpret microbial and host–microbe functions relevant to critical care.
The review lists disclosures: several authors and their institutions received support from the National Institutes of Health; one author received funding from the Society of Critical Care Medicine; one author received support from Florida State University; an author’s institution received funding from an industry source; and other funding and disclosures were reported. The article appears in Crit Care Med (online ahead of print, 2026 Aug 26). PMID 42644690; DOI 10.1097/CCM.0000000000007327. The paper references a broad bibliography (130 references) supporting the review statements.
(Notes: This rewritten summary preserves the review’s intent and high-level findings as reported in the PubMed abstract. Specific trial results, quantitative effects of interventions, and detailed protocols were not detailed in the abstract and therefore are not reported here.)