Biofilm Formation and Adherence of

1
Biofilm Formation and Adherence of Uropathogenic
E. coli
Jeffrey Voreis, Steven Nus Adam
Ostendorf Winter 2004, BI 412
Introduction Biofilms are a group of sessile
bacteria attached to a surface. They secrete a
slime matrix which surrounds and protects them.
Chemical signals accumulate and trigger gene
expression which may initialize biofilm
production. Growing these films is difficult in
the laboratory because they form very slowly.
Sessile bacteria secrete antigens and stimulate
antibody production. Biofilms facilitate survival
of bacteria because they protect against
antimicrobial attacks due to the thick layer of
slime and its slow diffusion rate. Furthermore,
limited nutrition leads to a metabolic rate
reduction that also protects the bacteria encased
in a biofilm by reducing their susceptibility to
metabolic attacks. By using a biofilm for
protection, bacteria may infect surrounding
tissues while avoiding attack.
Uropathenogenic Escherichia coli (UPEC) is the
leading cause of urinary tract infections (UTI).
UTIs are extremely common in women, accounting
for over 8 million doctor visits annually.
During a UTI, E. coli coats the surface of
bladder epithelial cells. Type 1-pili expressed
by UPEC are required for stable attachment and
pathogenicity. When type 1-pili are present on
the bacteria, it is able to invade the urothelium
by interacting with uroplakins on the tissue
cell. E. coli has the ability to adhere to
epithelial cells and secrete a biofilm for
protection. Therefore, understanding these
mechanisms and the conditions under which they
are expressed may be the key to reducing the
pathogenicity of this organism. We hypothesize
that the UPEC strains will adhere quicker to the
tissue cells and cause more degradation than the
non-uropathogenic strain.
Materials Methods Note about the strains used
Escherichia coli ATCC 29214 was isolated from a
patient with a UTI. E. coli ATCC 700417 came
from a patient with recurrent UTIs. The third
strain was our control, a nonpathogenic E. coli
strain from Dr. Ventullos microbiology
laboratory. The two ATCC strains are
uropathogenic strains of E. coli. Bladder Cell
Experiment 10?L of bacteria was added to 0.8ml
of RPMI-1640 in a sterile centrifuge tube. (8)
4-well slides containing human bladder epithelial
cells were washed with 0.6mL PBS and rocked for
30 seconds. Then we added 0.8mL of
RPMI-1640/bacteria mixture to a well on each
slide. One well contained only RMPI-1640 as a
control. Slides were placed in airtight jars and
gassed with 5 CO2 for 15 seconds. Jars were
incubated at 37oC. At designated times, media
was removed from each well on 1 slide and the
well was rinsed once with PBS. Wells were then
rinsed twice and rocked with PBS. Then slides
were fixed and stained using DAPI as previously
described. The wells were removed from each
slide. SloFade was added and a coverslip with
fingernail polish sealed the slide. The fixing
and staining procedure was repeated for each time
period.

• Conclusions
• No significant differences of adherence between
  different strains
• UPEC strains appeared to degrade the tissue
  cells at a higher rate than the control strain
• UPEC strains exhibited additional virulence
  factors or more robust metabolic activity which
  may account for the increased degradation of the
  tissue cells