The aggregate-forming pili (AFP) mediates the aggregative adherence of a hybrid-pathogenic Escherichia coli (UPEC/EAEC) isolated from a urinary tract infection

Schüroff PA, Salvador FA, Abe CM, Wami HT, Carvalho E, Hernandes RT, Dobrindt U, Gomes TAT, Elias WP

Abstract

Abstract EnteroaggregativeEscherichia coli(EAEC) comprises an important diarrheagenic pathotype, while uropathogenicE. coli(UPEC) is the most important agent of urinary tract infection (UTI). Recently, EAEC virulence factors have been detected inE. colistrains causing UTI, showing the importance of these hybrid-pathogenic strains. Previously, we detected anE. colistrain isolated from UTI (UPEC-46) presenting characteristics of EAEC,e.g., the aggregative adherence (AA) pattern and EAEC-associated genes (aatA, aap, andpet). In this current study, we analyzed the whole genomic sequence of UPEC-46 and characterized some phenotypic traits. The AA phenotype was observed in cell lineages of urinary and intestinal origin. The production of curli, cellulose, bacteriocins, and Pet toxin was detected. Additionally, UPEC-46 was not capable of forming biofilm using different culture media and human urine. The genome sequence analysis showed that this strain belongs to serotype O166:H12, ST10, and phylogroup A, harbors thetet, aadA, anddfrA/sulresistance genes, and is phylogenetically more related to EAEC strains isolated from human feces. UPEC-46 harbors three plasmids. Plasmid p46-1 (~135 kb) carries some EAEC marker genes and those encoding the aggregate-forming pili (AFP) and its regulator (afpR). A mutation inafpA(encoding the AFP major pilin) led to the loss of pilin production and assembly, and notably, a strongly reduced adhesion to epithelial cells. In summary, the genetic background and phenotypic traits analyzed suggest that UPEC-46 is a hybrid strain (UPEC/EAEC) and highlights the importance of AFP adhesin in the adherence to colorectal and bladder cell lines.