is a well-known human nosocomial pathogen with an arsenal of virulence factors, including capsular polysaccharides (CPS), fimbriae, flagella, and lipopolysaccharides (LPS). Our previous study found that alcohol acted as an essential virulence factor for high-alcohol-producing (HiAlc ). Integration host factor (IHF) is a nucleoid-associated protein that functions as a global virulence regulator in . However, the regulatory role of IHF in remains unknown. In the present study, we found that deletion of or resulted in a slight defect in bacterial growth, a severe absence of biofilm formation and cytotoxicity, and a significant reduction in alcohol production. RNA sequencing differential gene expression analysis showed that compared with the wild-type control, the expression of many virulence factor genes was downregulated in Δ and Δ strains, such as those related to CPS (, , , and ), LPS (), type I and type III fimbriae ( and operon), cellulose ( operon), iron transporter (, , , , , and ), quorum sensing ( operon and ), type II secretion system (T2SS) and type VI secretion system (T6SS) (, , and ). Of these virulence factors, CPS, LPS, fimbriae, and cellulose are involved in biofilm formation. In addition, IHF could affect the alcohol production by regulating genes related to glucose intake (), pyruvate formate-lyase, alcohol dehydrogenase, and the tricarboxylic acid (TCA) cycle. Our data provided new insights into the importance of IHF in regulating the virulence of HiAlc . IMPORTANCE is a well-known human nosocomial pathogen that causes various infectious diseases, including urinary tract infections, hospital-acquired pneumonia, bacteremia, and liver abscesses. Our previous studies demonstrated that HiAlc mediated the development of nonalcoholic fatty liver disease by producing excess endogenous alcohol . However, the regulators regulating the expression of genes related to metabolism, biofilm formation, and virulence of HiAlc remain unclear. In this study, the regulator IHF was found to positively regulate biofilm formation and many virulence factors including CPS, LPS, type I and type III fimbriae, cellulose, iron transporter, AI-2 quorum sensing, T2SS, and T6SS in HiAlc . Furthermore, IHF positively regulated alcohol production in HiAlc . Our results suggested that IHF could be a potential drug target for treating various infectious diseases caused by . Hence, the regulation of different virulence factors by IHF in requires further investigation.