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

Table 2 Clinical studies evaluating the association between intestinal colonization and subsequent bloodstream infection in critically ill patients

Ref.	Country	Study design			Population		Pathogen		Colonization site		Progression to infection		Key finding
Thom et al[22], 2010	United States	Observational study			ICU patients		Acinetobacter baumannii		GI tract		Identical strains detected		GI colonization matched bloodstream isolates
Jung et al[20], 2010	South Korea	Cohort			ICU patients		MDR Acinetobacter baumannii		Gastrointestinal tract		Increased risk of bacteraemia		Colonization independently predicted bloodstream infection
Giannella et al[17], 2014	Italy	Prospective multicentre cohort			ICU patients with rectal colonization		CRKP		Rectal		Approximately 20%-40% bacteraemia		Rectal carriage strongly predicted CRKP bloodstream infection
Giacobbe et al[19], 2017	Italy	Multicentre retrospective cohort			Colonized patients		CRKP		Rectal		Increased bacteraemia risk		Previous infections predicted CRKP bacteraemia
Freedberg et al[11], 2018	United States	Prospective observational study			ICU patients		MDR gut pathogens		Gastrointestinal microbiome		Increased infection and mortality risk		GI pathogen colonization at ICU admission predicted adverse outcomes
Amberpet et al[21], 2018	India	Prospective study			Pediatric ICU patients		Vancomycin-resistant enterococci		Intestinal tract		Increased colonization risk		Intestinal colonization facilitated MDR persistence and transmission
Silago et al[29], 2020	Tanzania	Observational cohort			Critical care patients		MDR Gram-negative bacteria		GI/environmental		Transmission linked to bacteraemia		Colonization and cross-transmission contributed to infection
Chu et al[16], 2022	China	Prospective cohort			ICU patients		CRE		Rectal		Approximately 15%-30% progression		Colonization associated with subsequent infection
Mu et al[23], 2022	China	Molecular cohort			Septic ICU patients		Various pathogens		Gut microbiome		High strain concordance		Bloodstream pathogens genetically matched gut strains
Casale et al[40], 2023	Italy	Cohort study			COVID-19 ICU patients		Carbapenem-resistant organisms		Gastrointestinal/respiratory		Increased mortality and infection risk		Colonization associated with superinfection and adverse outcomes
Fang et al[28], 2025	China	Molecular epidemiological study			Hospitalized patients		CRKP		Gastrointestinal tract		Genotypic concordance observed		Colonizing and infecting strains shared homologous resistance plasmids
Lyu et al[27], 2026	China		Prospective cohort	ICU patients		CRE		Rectal		Significant progression observed		Colonizing and infecting isolates showed genotypic concordance
Favier et al[18], 2026	Argentina		Prospective surveillance study	ICU patients		Carbapenem-resistant Enterobacterales		Rectal and extra-rectal		Increased infection risk		Surveillance cultures predicted subsequent CRE infection

ICU: Intensive care units; COVID-19: Coronavirus disease 2019; GI: Gastrointestinal; MDR: Multidrug-resistant; CRKP: Carbapenem-resistant Klebsiella pneumoniae; CRE: Carbapenem-resistant Enterobacteriaceae.