Among patients with cirrhosis, infections caused by Escherichia coli organisms that translocate from the gut are a frequent and severe complication. One hundred ten E. coli isolates from 110 cirrhotic patients with spontaneous bacterial peritonitis and/or spontaneous bacteremia were characterized for their phylogenetic group and virulence genotype (34 extraintestinal virulence factor genes). Genetic relatedness was investigated by enterobacterial repetitive intergenic consensus sequence type 2 (ERIC-2) PCR typing and multilocus sequence typing. Phylogenetic groups A, B1, B2, and D accounted for 24%, 4%, 48%, and 24% of the population, respectively. Overall, 68 distinct ERIC-2 profiles were encountered. Eleven clonal groups, represented by multiple isolates (2 to 11) from the same sequence type (ST) or sequence type complex, were identified. These clonal groups accounted for 54 (49%) isolates overall. Membership in one of these clonal groups was more frequent among B2 isolates than non-B2 isolates (67% versus 32%, P < 0.001). The most frequent sequence types were ST95 (n ‫؍‬ 13) and ST73 (n ‫؍‬ 8), followed by the ST14 and ST10 complexes (n ‫؍‬ 7). ST131 and ST69 were represented by three isolates each. Clonal group-associated isolates exhibited a greater prevalence of 11 virulence genes, including pap elements, than the other isolates. However, no association between clonal groups and host factors, type of infection, or mortality was observed. In conclusion, E. coli isolates causing spontaneous bacterial peritonitis and bacteremia in cirrhotic patients are genetically diverse. However, approximately half of the isolates belong to familiar clonal groups and exhibit extensive virulence profiles that may be associated with greater invasive potential.Infections caused by intestinal bacteria are common complications in patients with cirrhosis (8, 30). Spontaneous bacterial peritonitis (SBP) and bacteremia are the most frequent and severe infections in such patients, with in-hospital mortality rates being 20 to 30% and the survival expectancy at 6 months being Ͻ50% (1, 29, 34). Increasing evidence indicates that these infections result from bacterial translocation (BT) from the intestinal lumen to the mesenteric lymph nodes, combined with failure of host defense mechanisms to clear the translocating organisms (8, 37). BT is also associated with activation of the immune system and hyperdynamic circulatory status in cirrhosis, thereby contributing to the development of ascites and hepatorenal syndrome (37). The presence of bacterial DNA in the blood or ascitic fluid of uninfected patients, considered a surrogate marker of BT, has been shown to predict decreased 1-year survival (38). Given the key role of BT in cirrhosis, it is not surprising that Escherichia coli, which within the intestinal microflora is both the predominant facultative organism and the most adept at translocating to mesenteric lymph nodes (33), is also the most frequent agent of bacteremia and SBP in cirrhotic patients.Most extraintestinal E. coli str...