Table 2.

Summary of Contemporary Studies Investigating Heart Failure and Alterations in Microbiota

Author	Sample Groups and Measurements	Results Summary
Sandek et al.29	FISH of mucosal biofilm samples (20 CHF, 22 Ctrl) collected by sigmoidoscopy	Elevated bacterial concentration and increased strain diversity of mucosal biofilm in CHF patients; Increased detection frequency (from 38 FISH probes) of Bacteroides/Prevotella, Eubacterium Rectale, Faecalibacterium Prausnitzii in CHF; Increased gut permeability as measured by lactulose-mannitol test.
Sandek et al.87	FISH of mucosal bacterial film (22 CHF; 20 Ctrl) collected by sigmoidoscopy; Stool samples (21 CHF; 17 Ctrl)	Concentrations and proportions of both anaerobic and aerobic bacteria in the stool were not significantly different; Trend of positive correlation between increased anaerobic juxtamucosal bacteria and decreased intestinal blood flow.
Pasini et al.88	Stable CHF patients with NYHA I-II (n=30), NYHA III-IV, (n=30), and matched healthy control (n=20) had stool samples collected to measure bacteria and Candida species using traditional culture techniques.	The CHF population (NYHA III-IV in particular) had large increases in detected pathogenic bacteria including Campylobacter, Shigella, Salmonella, Yersinia enterolytica, and Candida species; Increased gut permeability as measured by cellobiose sugar test
Mamic et al.89	2012 Healthcare cost and utilization project National Inpatient Sample data	Clostridium difficile infection rates were higher in hospitalizations with discharge diagnosis of HF compared with those without HF after controlling for patient demographics and comorbidities and hospital characteristics.
Luedde et al.90	Bacterial 16S rRNA gene sequencing of fecal samples from 20 patients with heart failure with reduced ejection fraction due to ischemic or dilated cardiomyopathy and matched controls selected from the PopGen study.	Tendency for decreased bacterial diversity in HF with significant differentiation between HF and control patients; Those with HF showed significant decreases in Coriobacteriaceae, Erysipelotrichaceae and Ruminococcaceae on the family level and decreases in Blautia, Collinsella, uncl. Erysipelotrichaceae and uncl. Ruminococcaceae on the genus level.
Cui et al.91	Bacterial 16S rRNA gene sequencing of fecal samples from consecutive recruitment of 53 ischemic and dilated cardiomyopathy CHF patients (94% of NYHA III-IV) and 41 controls.	Significant differentiation between CHF and controls but similar between ischemic and dilated cardiomyopathy patients; Faecalibacterium prausnitzii decrease and Ruminococcus gnavus increase were the essential characteristics identified in this CHF patient cohort.
Kamo et al.92	Bacterial 16S rRNA gene sequencing of fecal samples from 12 HF patients and 12 age-matched controls; 12 HF patients younger than 60 and 10 HF patients 60 or older.	Significant differentiation between HF and controls; Those with HF showed significant decreases in Clostridium and Dorea at the genus level and decreases in Eubacterium Rectale and Dorea longicatena at the species level; Older HF patients had depletion of Faecalibacterium and enriched Lactobacillus genus compared to younger HF patients.
Kummen et al.93	2 independent cohorts of stable HFrEF cohorts (discovery, n = 40; and validation, n = 44; NYHA II–IV) and population-based control subjects (n = 266, randomly allocated to HF cohorts for comparison).	Decreased bacterial diversity in HF even after risk factor adjustments; Increase in genus Prevotella, Hungatella, Succinclasticum; Decrease in multiple genera belonging to Lachnospiraceae family - Anaerostipes, Blautia, Coprococcus (3), Fusicatenibacter, Lachnospiraceae FCS020, NCS2004, ND3007, Pseudobutyrivibrio, Eubacterium Hallii group; Decrease in Rumminococcaceae Faecalibacterium and Bifidobactericeae Bifidobacterium

CHF-Congestive Heart Failure; FISH – fluorescent in situ hybridization; HF – Heart Failure; NYHA – New York Heart Association; Uncl. - unclassified