Urinary tract infection (UTI) is the most common
form of extraintestinal pathogenic Escherichia coli (ExPEC) infection. The ability of
these ExPEC strains to form biofilms is likely to serve as a pathogenic
determinant that allows them to persist in the urinary tract for a prolonged
period and contribute to development of UTIs. The widespread use of antibiotics
to fight against infectious disease has lead to the emergence of many
antibiotic resistant bacteria and the presence of antibiotic resistance genes
in bacteria are suggested to affect their ability to form biofilms. In this
study the effect of the presence of new antibiotic resistance genes on biofilm
formation of UTI associated E. coli strains was examined. Two clinical UTI associated E. coli
(SMC18 and SMC 20) were transformed
with pGEM-T, pGEM-T::KmΔAmp or
pGEM-T::Km to construct ampicillin resistant (KmSAmpR), kanamycin resistant (KmRAmpS) or ampicillin and kanamycin resistant (KmRAmpR) strains. The biofilm forming ability and potential
factors associated with biofilm formation (the presence of virulence factors,
bacterial surface hydrophobicity, auto-aggregation and bacterial attachment) of
these strains were determined. Biofilm formation by E. coli SMC18 was
reduced by the presence of either one or both antibiotic resistance gene(s),
while biofilm formation of E. coli SMC20 was increased by the presence
of the ampicillin resistance gene but not affected by the presence of the kanamycin
resistance gene alone or the presence of both ampicillin and kanamycin
resistance genes together. The results of the study showed that cells
transformed with plasmids carrying
different antibiotic resistance genes had significant influence on
biofilm formation by different E. coli
strains which suggest that the genetic background, in particular the presence
of virulence genes, strongly influences biofilm formation by UTI associated E. coli acquiring antibiotic resistance.