Molecular characterisation of Escherichia coli isolated from hospitalised children and adults with urinary tract infection.

Urinary tract infection (UTI) is common amongst children and recurs in 10-30 % of cases. The differences between Escherichia coli strains causing UTI among hospitalised children and adults remains to be fully elucidated. Here, we examined the genetic relatedness and virulence gene (VG) profiles of a collection of E. coli causing UTI among hospitalised children and adults. Genetic relatedness among the strains was investigated using random amplified polymorphic DNA (RAPD) analysis and the strains were characterised using a combination of phylogenetic grouping, the ability to form biofilm and the presence of antigen 43 (Ag43) and its five known alleles, as well 20 VGs associated with uropathogenic E. coli (UPEC). RAPD analysis resolved six major clusters, with two clusters (A and B) consisting almost exclusively of E. coli isolated from children. Isolates from children had a higher prevalence of alpha-haemolysin (hlyA, p < 0.05) and group II capsular polysaccharide synthesis genes (kpsMT II, p < 0.01) than adults. In contrast, E. coli strains from adults had a higher prevalence of invasive ibeA (p < 0.05) and Ag43 (agn43) (p < 0.05) genes, and produced significantly (p < 0.001) more biofilm than E. coli from children. Adult isolates also carried significantly (p < 0.05) more agn43 allele RS218 compared to isolates from children, which carried significantly (p < 0.05) more of the agn43 allele bCFT073. Our results suggest that bacterial virulence factors play an important role in UTI among hospitalised children; however, further research will determine whether these findings apply to a larger cohort and other clinical settings for UTI in children and adults.