Gut barrier dysfunction and multidrug-resistant bacterial translocation in adult critical illness: Mechanistic insights from a systematic review

Table 3 Biomarker and microbiome evidence associated with intestinal barrier dysfunction in critically ill patients

Ref.	Country	Study design	Population	Biomarker/method	Key findings	Clinical implication
Wijnands et al[9], 2015	Netherlands	Review/clinical synthesis	Sepsis patients	Citrulline metabolism	Reduced citrulline associated with enterocyte dysfunction	Marker of intestinal barrier injury
Blaser et al[10], 2019	Europe	Observational clinical study	Critically ill patients	Citrulline, I-FABP	Low citrulline and elevated I-FABP associated with GI dysfunction	Biomarkers of mucosal injury
Padar et al[31], 2021	Estonia	Prospective ICU study	ICU patients	Citrulline, I-FABP	Dynamic changes correlated with enteral nutrition and gut injury	Monitoring intestinal function
Reintam Blaser et al[33], 2021	Multicentre Europe	Prospective multicentre study	Critically ill patients	GI Dysfunction Score	Developed standardized scoring for GI dysfunction	Clinical assessment tool
Garcia et al[13], 2022	Spain	Prospective cohort	ICU patients	Gut microbiome sequencing	Reduced diversity associated with MDR colonization and infection	Dysbiosis associated with increased infection risk
Onuk et al[34], 2023	Turkey	Prospective cohort	ICU patients	Citrulline, I-FABP, gastric ultrasound	Biomarkers correlated with gastrointestinal injury	Early detection of GI dysfunction
Tyszko et al[35], 2023	Poland	Observational cohort	Septic ICU patients	Citrulline, I-FABP	Biomarkers associated with severity of gastrointestinal injury	Prognostic markers
Baek et al[14], 2023	South Korea	Microbiome analysis	ICU patients	Microbiome sequencing	CRE colonization associated with microbiome disruption	Loss of colonization resistance
Yang et al[15], 2025	China	Microbiome study	ICU patients	Microbiome diversity analysis	Preserved microbiome diversity associated with reduced CRKP colonization	Microbiome-mediated resistance

I-FABP: Intestinal fatty acid-binding protein; GI: Gastrointestinal; ICU: Intensive care units; MDR: Multidrug-resistant; CRE: Carbapenem-resistant Enterobacteriaceae; CRKP: Carbapenem-resistant Klebsiella pneumoniae.