Iron uptake by Escherichia coli in urinary tract infections and
urosepsis -- genetic and proteomic studies
Abstract
Urinary tract infection caused by Escherichia coli can lead to
urosepsis, and the pathogens’ effectiveness in acquiring iron determines
their virulence. The level of expression of the siderophore genes in
different environments (M9 medium, artificial urine, and M9 supplemented
with blood) was investigated using the CAS assay and qPCR. Aerobactin
was found much more frequently in blood than in urine isolates (P=0.03),
but the expression in artificial urine was 2x higher than in blood
(P=0.03). We observed significant changes in the expression of
entC, iro-2, iucA, and iroB bacterial genes between groups
in artificial urine. The siderophores enterobactin, aerobactin and
yersiniabactin (P=0.016), with the iha and hlyA genes, may
represent markers of increased urosepsis risk. Moreover, proteomic
profiles between groups were significantly different (ferritin-1, iron
uptake system component EfeO, ferrous iron transport protein B,
nitrate/nitrite response regulator protein NarL, protein HemY,
ferrienterobactin receptor FepA, lipopolysaccharide export system
protein LptA and 2Fe-2S ferredoxin). We also observed the positive
association with urosepsis of IL-6, TNF, and CRP proteins between
groups. In conclusion, risk factors for UTI-related sepsis may be
related to the iron uptake system, and genetic and proteomic profiles
may help in their identification.