Among patients treated with DAA, SVR was associated with a considerable reduction in the risk of HCC. We did not find any evidence to suggest that DAAs promote HCC. However, in patients with SVR, the absolute risk of HCC remained high in patients with established cirrhosis. These patients should be considered for ongoing HCC surveillance.

Enterococcus faecalis (EF) is both a common commensal of the human gastrointestinal tract (GI) and a leading cause of hospital acquired infections1. Systemic infections with multi-drug resistant enterococci occur subsequent to GI colonization2. Preventing colonization by multi-drug resistant EF could therefore be a valuable approach to limiting infection. However, little is known about mechanisms EF uses to colonize and compete for stable gastrointestinal niches. Pheromone-responsive, conjugative plasmids encoding bacteriocins are common among enterococcal strains3, and could modulate niche competition among enterococci or between enterococci and the intestinal microbiota. We developed a model of mouse gut colonization with EF without disrupting the microbiota, to evaluate the role of the conjugative plasmid pPD1 expressing bacteriocin 214 on enterococcal colonization. Here we show that EF harboring pPD1 replaces indigenous enterococci and outcompetes EF lacking pPD1. Furthermore, in the intestine, pPD1 is transferred to other EF strains by conjugation, enhancing their survival. Moreover, colonization with an EF strain carrying a conjugation-defective pPD1 mutant resulted in clearance of vancomycin-resistant enterococci, without plasmid transfer. Therefore bacteriocin expression by commensal bacteria can influence niche-competition in the GI tract, and bacteriocins, delivered by commensals that occupy a precise intestinal bacterial niche, may be an effective therapeutic approach to specifically eliminate intestinal colonization by multi-drug resistant bacteria, without profound disruption of the indigenous microbiota.

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Sustained virologic response (SVR) after direct acting antiviral agents (DAAs) holds promise for reducing hepatocellular cancer (HCC). DAAs have recently been available long enough to estimate the long‐term risk. We conducted a retrospective cohort study of hepatitis C virus (HCV) patients who achieved SVR with DAAs from 129 Veterans Health Administration hospitals between January 1, 2015, and December 31, 2015, with follow‐up through September 30, 2018. We calculated the overall and quarterly HCC incidence rates. We examined the effect of demographic, clinical, and behavioral factors and the decline or increase of FIB‐4 and aspartate aminotransferase to platelet ratio index (APRI) on HCC risk. Among the 18,076 patients with SVR, 544 incident cases of HCC were diagnosed during the mean 2.9 years of follow‐up. The cumulative 1, 2, and 3‐year risks of HCC were 1.1%, 1.9% and 2.8%, respectively. Cirrhosis was strongly associated with HCC risk (adjusted hazard ratio = 4.13, 95% confidence interval = 3.34‐5.11). The quarterly incidence rate of HCC remained stable between 1.00 and 1.23/100 person‐years (PY) and 1.5 to 2.3/100 PY in patients with cirrhosis. The risk of HCC was the highest in patients who had persistently high FIB‐4/APRI and both with and without cirrhosis. HCC risk fell in patients with cirrhosis who experienced a decrease of FIB‐4/APRI scores yet remained higher than the accepted threshold for HCC surveillance. HCC risk was also higher in patients with alcohol use, older age, and infection with HCV genotype 3. Most patients treated at an early stage of liver fibrosis had a stable low risk. Conclusion: Patients successfully treated with DAAs and at risk of HCC did not regress after 3.6 years of follow‐up. HCC risk remained above the accepted thresholds for surveillance in patients with cirrhosis. These data have important implications for HCC surveillance in cured HCV patients.