Different roles of host and bacterial factors in Escherichia coli extra-intestinal infections.

Many host and bacterial factors contribute to the development of different Escherichia coli extra-intestinal infections. The aim of this study was to evaluate the roles of host and bacterial factors in different extra-intestinal E. coli infections. A total of 221 E. coli isolates collected from urine, bile and peritoneal fluid were included in this retrospective study. Four main phylogenetic groups of E. coli, 14 genetic determinants, static biofilm formation and antimicrobial resistance data were assessed, as well as the immunological status of the hosts. Group B2 was the most common phylogenetic group (30%), especially in cases of asymptomatic bacteriuria (ABU), urinary tract infection (UTI), acute appendicitis/gastrointestinal perforation, and spontaneous bacterial peritonitis (SBP), and was associated with elevated prevalence of papG III, fimH, sfa, iha, hlyA, cnf1, ompT and usp. Phylogenetic group A was most common in the isolates from asymptomatic bacteriocholia, biliary tract infection, and peritoneal dialysis (PD)-related peritonitis. There was similarity with respect to both phylogenetic groups and virulence factors in strains from faeces and ABU, and in strains from faeces and SBP/PD-related peritonitis. Host characteristics were important in patients with ABU, UTI, and SBP/PD-related peritonitis. Immunocompetence of hosts was associated with a relatively high prevalence of papG II, afa and iha, and relatively low antimicrobial resistance to fluoroquinolones. This study demonstrates that, in most E. coli extra-intestinal infections, phylogenetic group B2 was predominant and was more virulent than the three other phylogenetic groups in the Taiwanese population studied. The diverse patterns of host and bacterial factors demonstrate that there were different host and bacterial factors dominating in different extra-intestinal E. coli infections.