Journal of Biomaterials and Nanobiotechnology, 2012, 3, 533-540 Published Online October 2012 (
Using Atomic Force Microscopy to Measure Anti-Adhesion
Effects on Uropathogenic Bacteria, Observed in Urine
after Cranberry Juice Consumption
Laila Abu-Lail1, Yuanyuan Tao1, Paola A. Pinzón-Arango1, Amy Howell2, Terri A. Camesano1*
1Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, USA; 2School of Environmental and Biological
Sciences, Rutgers University, Newark, USA.
Email: *
Received August 16th, 2012; revised September 18th, 2012; accepted September 30th, 2012
A volunteer was given cranberry juice cocktail (CJC) or water to drink, and urine was collected at 2 and 8 hours after
consumption, in order to quantitatively determine whether adhesion forces were changed for the volunteer after CJC
consumption. Atomic force microscopy (AFM) was used to measure adhesion forces between bacteria and a silicon
nitride tip. Forces between Escherichia coli or Staphylococcus aureus and the AFM tip were lower in the urine after the
volunteer consumed CJC, compared to drinking water. A steric model was applied to the AFM data, in order to quantify
how the urine changed the properties of the bacterial surfaces. There was a small decrease in the equilibrium length of
surface molecules on the bacteria when in the post-CJC urine, compared to the post-water urine. However, these
changes were not statistically significant. We hypothesize that post-CJC urine imparts subtle changes on the molecules
of the bacterial surfaces, and that these changes lead to the reduction in adhesion with the AFM probe.
Keywords: Vacciniumm macrocarpon; Urinary Tract Infections; E. coli; S. aureus; AFM
1. Introduction
Considered to be one of the most common bacterial in-
fections, urinary tract infections will affect almost half of
all women in their lifetime, and nearly 1 in 3 women will
have a UTI requiring antibiotics before age 24 [1]. Al-
ternative therapies for UTIs have drawn increasing inter-
est due to concern of antibiotic resistant bacteria. The
American cranberry (Vacciniumm macrocarpon) is a
potential therapeutic for UTIs, and several clinical stud-
ies have shown that consumption of cranberry can help
prevent UTIs or recurrences of UTIs among elderly peo-
ple [2,3], children [4], and sexually active women with
previous UTIs [5], although it has been difficult to dem-
onstrate longer term benefits of cranberry as a means to
prevent UTI recurrence over long times [6]. Cranberry
products are consumed by many healthy women as a
preventive measure, but further research is needed to
elucidate how oral consumption of cranberry affects the
activity of uropathogenic bacteria, and to better under-
stand the type of cases where cranberry can be effective
for UTI prevention. The timing and dose needed for this
thearapeutic effect are also being investigated [7].
E. coli spp. are by far the most predominant species
that cause UTIs, accounting for 70% - 95% of all UTIs.
In addition, P-fimbriated E. coli strains are the primary
cause for 90% of acute pyelonephitis cases [8]. Remain-
ing UTIs are caused by various organisms, including
staphylococci, proteus organisms, Klebsiella spp., and
Enterococcus faecalis. The incidence of UTIs related to S.
aureus was found to be 3.5%, based on an analysis of
321 patients over a 3-year period [9]. Pathogenic bacteria
have the ability to adhere to inert surfaces, such as a
catheter, which leads to device-associated infections.
Catheter-related UTIs tend to be caused by Gramne-
gative bacilli [10], including pseudomonads [11], fungi,
and Gram-positive cocci, which includes staphylococci
The first step in the initiation of a UTI, or any bacterial
infection, is that bacteria must attach to a surface, such as
a catheter placed inside the body or the epithelial cells
that line the urinary tract. The attachment of bacteria to
abiotic materials is a complicated process that is affected
by various physicochemical properties of both bacterial
cells and substratum surface. Understanding the role of
cranberry juice components on interactions within this
process is critical in developing novel strategies for the
*Corresponding author.
Copyright © 2012 SciRes. JBNB
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
efficient control of bacterial attachment and biofilm for-
Exposure to cranberry juice has been shown to de-
crease bacterial attachment, adhesion, and biofilm forma-
tion. For example, cranberry juice inhibited the attach-
ment of E. coli to human uroepithelial cells, red blood
cells, and resin beads coated with receptors that bind to
P-fimbriae, the molecules on uropathogenic E. coli cell
surfaces that facilitate adhesion to uroepithelial cells
[14-16] In an attempt to gain more quantitative informa-
tion on how cranberry juice affects bacterial adhesion,
adhesion force measurements have been made using
atomic force microscopy (AFM). AFM experiments
demonstrated that P-fimbriated bacteria alter the confor-
mation of their fimbriae in the presence of cranberry
juice cocktail (CJC) [17], and adhesion forces between E.
coli and an AFM silicon nitride tip were reduced when
bacteria were grown in the presence of light CJC or in
proanthocyanidins extracted from the same juice [14]. In
addition to studies with juice, the urine of volunteers who
have consumed CJC has been investigated to determine
if anti-adhesive or anti-biofilm compounds remain in
urine. We previously reported that AFM adhesion force
measurements between uropathogenic E. coli were de-
creased in the presence of urine from a volunteer who
had consumed CJC [18]. In addition, DiMartino et al.
showed that cranberry juice consumption decreased bio-
film development of uropathogenic E. coli in the urine
compared with placebo [19,20].
In recent years, AFM has emerged as a valuable and
powerful tool for understanding the nanoscale properties
of living cells. A major advantage of AFM is that it al-
lows measurements of the forces associated with single
biomolecules in aqueous media. This is ideal for bio-
logical applications, where AFM can be used to investi-
gate the individual bacterial cells in buffer solution,
without the need of fixing, staining, or labeling. AFM
has been extremely useful for providing high-resolution
topographic images of cell surfaces and biomolecules
[21-23]. In addition, quantitative information on bacterial
interaction forces and adhesion can be provided though
analysis of AFM data [24]. Furthermore, in order to
quantify AFM data and use it to interpret behavior of
bacterial surfaces, a steric model can be applied to force
vs. distance profiles [25,26]. This model allows us to
characterize the physicochemical properties of polymers
on a bacterial surface.
In this work, AFM was used to investigate the interact-
tions between bacteria (S. aureus or E. coli) and a model
surface (silicon nitride tip) in the presence of urine sam-
ples containing cranberry juice components. We focused
on representative bacterial pathogens in this study,
namely, two types of clinical E. coli that are associated
with UTIs (strains BF1023 and CFT073, both of which
have P-fimbriae), and S. aureus ATCC43866. While E.
coli is the most common uropathogen, S. aureus is a
pathogen frequently involved in device-centered infec-
tions, has the ability to adhere to catheters and other
medical devices and form biofilm [13], and is a growing
concern due to multi-drug antibiotic resistance. The
steric model was applied so that changes in the bacterial
surfaces due to exposure to the urine of a volunteer who
had consumed CJC could be quantified. To our knowl-
edge this is the first study to characterize the effect of
CJC byproducts in urine on the adhesion properties of
Staphylococcus aureus (S. aureus) using AFM.
2. Materials and Methods
2.1. Urine Samples
De-identified urine samples were sent to Worcester
Polytechnic Institute (WPI) from Rutgers University. An
arbitrary, crossover design was applied, with a single
volunteer. The volunteer was a healthy Caucasian male,
aged 42. He drank 16 oz. (240 mL) of commercial cran-
berry juice cocktail (CJC) or water. After consuming the
single dose, urine was collected at two time intervals (2
and 8 hours). Samples were immediately frozen and
shipped to WPI, where they were stored at –20˚C. Urine
samples were later thawed and filtered though 0.8 μm
(Pall Corp., East Hills, NY) and 0.2 μm (VWR Interna-
tionalTM, West Chester, PA) polyethersulfone syringe
filters, sequentially.
2.2. Bacteria Cultures
Two E. coli clinical strains that cause acute pyelonephitis
(AP) or cystitis, and one S. aureus strain (ATCC 43866)
were selected as model bacteria. All bacteria were pur-
chased from ATCC (Manassas, VA). The two E. coli
strains were; E. coli CFT073 and E. coli BF1023, both
are P-fimbriated strains from different classes. CFT073
expresses P-fimbriae from class II and was isolated from
the blood and urine of a woman with AP, and BF1023
expresses P-fimbria from classes I and III and was iso-
lated from a female patient with cystitis.
E. coli strains were cultured at 37˚C in colonizing fac-
tor antigen (CFA) media. CFA media is composed of 1%
(w/v) casamino acids (BactoTM, Sparks, MD 21152),
0.078% (w/v) yeast extract (BactoTM, Sparks, MD 21152),
0.4 mM MgSO4 (Sigma-Aldrich), 0.04 mM MnCl2
(Sigma-Aldrich) in ultrapure water, and the pH was ad-
justed to 7.4 using sodium hydroxide (Sigma-Aldrich).
For culture plates, 2% agar (BactoTM, Sparks, MD 21152)
was added to the media. S. aureus cultures were grown
overnight in Luria-Bertani (LB) medium at 37˚C. Bacte-
Copyright © 2012 SciRes. JBNB
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
ria were harvested at late exponential phase, when the
absorbance of the culture was 0.9 - 1.1 at a wavelength of
600 nm, measured with a spectrophotometer (Thermo
Spectronic, Rochester, NY).
2.3. Bacterial Cell Preparation for AFM
Bacteria were immobilized to acid-cleaned glass slides
using a cross-linking reaction between amine and car-
boxyl groups [18]. The cleaned glass slides were im-
mersed in 10% 3-aminopropyltrimethoxysilane in metha-
nol for 20 min. Glass slides were rinsed with methanol
and ultrapure water. Bacterial cultures were washed thee
times with ultrapure water by centrifuging at 7000 rpm
for 10 min, removing the supernatant, and resuspending
the bacterial pellets in ultrapure water. A mixture of 300
μl of 100 mM EDC (1-ethyl-3-(3-dimethylaminopropyl)
carbodiimide hydrochloride) and 10 ml of the bacterial
solution was prepared and incubated for 10 minutes at
37˚C with rotation at 18 rpm. After 10 min, a 600 μl ali-
quot of 40 mM NHS (N-hydroxysulfosuccinimide) solu-
tion was added to the bacterial solution and incubated at
37˚C for 10 min with rotation at 18 rpm. The final solu-
tion was then added to the aminosilane-treated glass
slides and agitated at 70 rpm for 4 h to allow bacteria to
bind to the glass slides. Previous work has shown that the
viability and morphology of bacterial cells is not affected
by the binding process [27].
2.4. AFM Force Measurements
AFM interaction forces were measured using an MFP-
3D-BIO AFM (Asylum Research, Santa Barbara, CA).
Silicon nitride cantilevers were used, with an average
spring constant of 0.12 ± 0.02 N/m (DNPS, Veeco Me-
trology) calibrated and estimated from the power spectral
density of the thermal noise fluctuations in air. The nor-
mal photodiode sensitivity was determined in liquid by
measuring the slope of the constant compliance region of
the force curve on a hard surface. Before experiments,
the cantilevers were exposed to ultraviolet light for 1 h to
remove any potential organic contamination. All force
measurements were performed with the bacterial-coated
slides and cantilevers immersed in the urine sample.
During this time, we found that the bacterial cells remain
viable but are not actively growing. For each condition
studied, at least five individual bacterial cells were
probed, and ten force measurements were recorded in the
center of each bacterium.
2.5. Steric Model
The repulsive interactions between the bacterium and
AFM tip were fit using a model for steric interactions.
The steric model describes the forces between interacting
surfaces that have thermally mobile surface groups [28].
A common type of thermally-diffuse surface is a surface
covered with chain molecules that dangle out into the
solution, such as polymers. When another surface is ap-
proaching these dangling chains in a well-defined vol-
ume, a repulsive force known as “steric” force arises.
The steric model originally developed by Alexander [29]
and de Gennes [28] (AdG) to describe the forces between
two flat surfaces with high coverage of grafted or ad-
sorbed polymers. In addition, the AdG model has been
successfully applied to the characterization of bacterial
polymers [24,26] and to quantify interactions between a
polymer-covered surface, such as hyaluronic acid [30],
with model surfaces. Adaption of the AdG model to ac-
count for the spherical AFM probe interacting with a flat
surface was performed [25], where the steric model takes
the following form
FD dLs
where F is the steric repulsive force measured by AFM,
as a function of the separation distance (D), k is the
Boltzmann constant, T is the absolute temperature, R is
the tip radius, s is the average distance between grafting
sites, and Lo is the equilibrium length of the polymer
layer. The separation distance, D, was used as the sum of
the measured distance (d) and the offset distance (δ),
according to the procedure of Chang et al. [30]. Although
modeling has sometimes been done without this parame-
ter, the inclusion of δ offset enables improved fitting be-
cause it provides an estimate for the layer thickness at the
maximal applied force. By fitting the steric model to the
approach portions of the AFM force cycles, the equilib-
rium polymer length, spacing, and offset distance were
calculated. For each bacterium and condition studied,
average values of the equilibrium polymer length and
spacing were reported in plots, but individual values
(with no averaging) of these parameters were statistically
compared. At each time point, the two way ANOVA test
was used to compare the data sets from the two treat-
ments (water or CJC).
2.6. Adhesion Force Analysis
Each AFM force cycle has two parts, the approach of the
AFM tip to the bacterium, and the retraction of the tip
away from the bacterial sample. During the approach
portion of the force cycle, repulsive steric forces are of-
ten observed, as described. However, the retraction por-
tion of the cycle is useful to analyze because this is
where adhesion forces between the AFM tip and mole-
cules protruding from the bacterial surface can be ob-
Copyright © 2012 SciRes. JBNB
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
served. For each experimental condition studied, we col-
lected the data from all adhesion events and calculated an
average adhesion force. Both individual (representa- tive)
retraction force profiles are presented, along with aver-
aged adhesion forces for each experimental condi- tion.
Statistical analyses using SigmaStat® 2.03 (Systat Soft-
ware, San Jose, CA) were also performed The two way
ANOVA test was used to compare the two groups that
were treated with urine samples collected after (2 hours
and 8 hours) of water or CJC consumption.
3. Results and Discussion
3.1. Analysis of Adhesion Forces
The retraction portions of the AFM force cycles were
examined to gain information regarding the adhesion
forces between biomolecules on the bacterial surface and
AFM tip. Individual adhesion forces from 50 retraction
curves were combined and used to calculate an average
adhesion force between the bacterial cell surface and
AFM tip. Figure 1 shows the average adhesion forces for
each bacterial strain in the urine collected after CJC
consumption (post-CJC urine) and after water consump-
tion (post-water urine), at two time intervals (2 and 8 h)
following beverage consumption. In addition, adhesion
forces for different treatments and at different time points
were compared statistically to obtain more reliable re-
sults (Figure 1). Tested data groups were considered
significantly different if the resulting P-value was less
than 0.05. For all bacterial strains, the adhesive forces
between bacterial cells and AFM tip in the post-CJC
urine were significantly less than the adhesive forces
between bacterial cells and AFM in the post-water urine
(Figure 1). E. coli strains demonstrated a significant de-
crease in the adhesive forces with time after CJC con-
sumption and showed no significant changes in the adhe-
sive forces with time after water consumption. Strain
BF1023 showed a greater reduction in the adhesive
forces with time after CJC consumption than CFT073.
For BF1023, the average adhesive forces decreased from
(0.86 ± 0.05 nN) at 2 h to (0.29 ± 0.01 nN) at 8 h fol-
lowing CJC consumption, while CFT073 adhesive forces
decreased from (0.77 ± 0.04 nN) at 2 h to (0.38 ± 0.02
nN) at 8 h following CJC consumption. On the other
hand, adhesion forces between S. aureus and the AFM
tip at 2 h (0.124 ± 0.01 nN) and 8 h (0.115 ± 0.01 nN)
after CJC consumption were not statistically different
from one another. Similarly, the adhesive forces between
S. aureus and the AFM tip at 2 h (0.24 ± 0.03 nN) and 8
h (0.21 ± 0.02 nN) after water consumption were not
statistically different from one another. Comparing all
strains under various conditions, BF1023 had the highest
adhesion forces with the AFM tip and S. aureus had the
Bacterial Strains
BF1023CFT073S. aureus
Average Adhes ion For c e (nN)
2h Post-water
2h Post-CJC
8h Post-water
8h Post-CJC
Figure 1. Average adhesion forces for E. coli BF1023, E. coli
CFT073, and S. aureus after 2 h and 8 h of beverage con-
sumption (water or CJC). Error bar indicates the standard
error of the mean. 5-point black star indicates a statistically
significant difference between two treatments at one time
point. 7-point black star indicates a statistically significant
difference between two times at one treatment condition.
weakest adhesion forces with the AFM tip. For example,
at 2 h after water consumptions, the adhesion forces be-
tween the AFM tip and BF1023, CFT073, and S. aureus
were (1.61 ± 0.09), (0.99 ± 0.07), and (0.24 ± 0.03), re-
spectively. The silicon nitride AFM tip has a weakly
negative electrostatic charge in solution. It is not meant
to represent a catheter or an epithelial cell exactly, but
can be used as a model probe to screen for non-specific
physicochemical interactions between the bacterium and
the probe material. It can also be used to help rank the
strength of different samples or treatments.
In all the strains tested, there was a significant de-
crease in the adhesion forces between bacteria and AFM
tip in the post-CJC urine as compared to the post-water
urine both at 2 and 8 h after beverage consumption.
These results confirm the existence of anti-adhesive
molecules in the urine after oral consumption of CJC.
This trend is also easily visualized by examining repre-
sentative adhesion force profiles for the 8 h conditions
(Figure 2). All 3 bacterial strains tested show an obvious
decrease in the magnitude of the adhesion forces, as well
as the distance at which those force extend, in the pres-
ence of post-CJC urine at 8 h, compared to post-water
urine at 8 h. A similar trend in the data was observed for
the 2 h post condition (data not shown), in which adhe-
sion forces were lower and extended over shorter dis-
tances in post-CJC urine than in post-water urine.
However, the effect of time post-consumption on the
adhesion forces differed among the strains. Within two
hours of drinking CJC, S. aureus had the highest reduce-
tion in the adhesion forces between the post-CJC urine
Copyright © 2012 SciRes. JBNB
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
Copyright © 2012 SciRes. JBNB
BF1023 8h water
Distance (nm)
-50050100 150 200
Force (nN)
BF1023 8h CJC
Distance (nm)
-50050100 150 200
Force (nN)
(a) (b)
CFT073 8h water
Distance (nm)
0100 200 300
Force (nN)
CFT1023 8h CJC
Distance (nm)
0100 200 300
Force (nN )
(c) (d)
S. aureus 8h water
Distance (nm)
0100 200 300
Force (nN)
S. aureus 8h CJC
Distance (nm)
0100 200 300
Force (nN)
(e) (f)
Figure 2. Representative adhesion force data corresponding to 8 hours after consumption of water or CJC for all thee bacte-
rial strains. In all cases, the right panels (b), (d), and (f) show much lower adhesion forces than the left panels (a), (c), and (e),
which correspond to CJC and water, respectively. Similar types of data trends were observed 2 h post-beverage consumption
data not shown). For each condition, 50 force curves were collected. For clarity, only representative plots are displayed. (
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
and post-water urine, followed by E. coli BF1023 and
finally by E. coli CFT 073 (Figure 1). However, after 8
hs of beverage consumption, the scenario was different,
E. coli BF1023 had the highest reduction in the adhesion
forces between the post-CJC urine and post-water urine
followed by E. coli CFT073 and then by S. aureus. By
considering changes in the post-CJC urine data as a func-
tion of time, our results demonstrated that the adhesion
forces for the two E.coli strains after drinking CJC con-
tinued to decrease over the eight hour measurement pe-
riod while the adhesion forces of S. aureus appeared to
reach a plateau 2 hs post-CJC. Furthermore, the adhesive
forces between AFM tip and S. aureus were lower than
the adhesive forces between E. coli strains and the AFM
The differences in how E. coli and S. aureus, and even
among the two E. coli strains, reacted to post-CJC urine
will also depend in part on the nature of the bacterial
surfaces. E. coli CFT073 and BF1023 each exhibit man-
nose resistant hemagglutination. CFT073 expresses P-
fimbriae, while the adhesins on BF1023 have not been
characterized. S. aureus has surface protein adhesins that
are smaller than E. coli fimbriae [31]. There are no pub-
lished reports in which AFM has been used to character-
ize how S. aureus is affected by cranberry juice or its
byproducts. However, a recent study found that cranberry
extracts could inhibit growth and biofilm formation for S.
aureus and other Staphylococcus spp., as well as inhibit-
ing biofilm formation (but not growth), for E. coli [32].
The difference in activity of cranberry extracts against
Gram-negative and Gram-positive bacteria was sug-
gested by LaPlante et al. to be due to the lack of outer-
membrane lipopolysaccharides for the Gram-positive
bacteria, which could then make it easier for cranberry or
other antimicrobial compounds to penetrate the cell
3.2. Bacteria Surface Characterization and
Steric Model Application
Data from all 50 force curves were used to determine the
parameters of the steric model, the equilibrium length,
the spacing between polymer units, and the offset. For
strain S. aureus, the correlation coefficient values ob-
tained by fitting the steric model to 50 approach curves
were higher than 0.98 (R2 > 0.98), while for strains
CFT073 and BF1023, the correlation coefficient values
were (R2 > 0.95) and (R2 > 0.90), respectively.
For each bacterial strain, the two way ANOVA test
was applied to the steric model parameters for two time
intervals (2 and 8 h) and at two treatments (post-water
and post-CJC). A given set of two tested groups was
considered significantly different if the resulting P-value
was less than 0.05. Figure 3 shows the average equilib-
rium length for each given strain as a function of time
and treatment after beverage consumption. For S. aureus,
our statistical analysis demonstrated that there was a sig-
nificant difference between the equilibrium lengths in the
urine collected 2 h after water consumption and the urine
collected 2 h after CJC consumption. The equilibrium
polymer length in the urine 2 h post-CJC consumption
was 60% less than its equivalent value in urine 2 h
post-water consumption. However, the decrease in the
equilibrium length did not continue with time, since the
post-water urine and the post-CJC urine groups showed
no significant difference in their average equilibrium
lengths after 8 h of beverage consumption.
Neither E. coli strains, BF1023 nor CFT073, showed a
significant change in the average equilibrium length be-
tween the post-water urine group and the post-CJC urine
group during the 2 h or the 8 h following beverage con-
sumption. In general, S. aureus average equilibrium
polymer lengths were shorter than the average equilib-
rium polymer lengths of E. coli strains BF1023 and
CFT073. The average equilibrium polymer lengths of
strain S. aureus were in the range of 48 - 116 nm and the
average equilibrium polymer lengths of strains BF1023
and CFT073 were in the range of 119 - 205 nm and 73 -
420 nm, respectively.
Another parameter obtained from fitting the steric
model to the AFM approach curves is the spacing be-
tween polymers sites, which can represent how densely
the bacterial surface is covered with interacting mole-
cules (Figure 4). In all cases, S. aureus had smaller aver-
age spacing (2.0 - 3.1 nm) compared to the average spac-
Bacterial Strains
BF1023CFT073S. aureus
Equilibruim Length (nm)
2h Post-water
2h Post-CJC
8h Post-water
8h Post-CJC
Figure 3. Average equilibrium lengths of E. col i BF1023, E.
coli CFT073, and S. aureus at two time intervals (2 and 8 h)
after beverage consumption (water or CJC). Error bar in-
dicates the standard error of the mean. 5-point black star
indicates a statistically significant difference between two
treatments at one time point.
Copyright © 2012 SciRes. JBNB
Using Atomic Force Microscopy to Measure Anti-Adhesion Effects on Uropathogenic
Bacteria, Observed in Urine after Cranberry Juice Consumption
Bacter ia l S t r ai n s
BF1023CFT073S. aureus
Spacing (nm)
2h Post-water
2h Post-CJC
8h Post-water
8h Post-CJC
Figure 4. Average spacing values of E. coli BF1023, E. coli
CFT073, and S. aureus at two time intervals (2 and 8 h)
after beverage consumption (water or CJC). Error bar in-
dicate the standard error of the mean. 5-point black star
indicates a statistically significant difference between two
treatments at one time point.
ing for BF1023 (4.6 - 10.2 nm) and CFT073 (7.4 - 19.6
nm) (Figure 4). Furthermore, when tested at 2 and 8 hs
following beverage consumption, S. aureus showed a
significant decrease in the spacing between grafting sites
in the post-CJC urine group compared to its equivalent
value in the post-water urine group (Figure 4). This is an
indication that the decrease in the spacing between S.
aureus polymer brushes as a result of drinking CJC
lasted up to 8 hours. However, statistical analysis applied
on the average spacing values for both E. coli strains re-
vealed that there was no significant difference between
the spacing in post-CJC urine and post-water urine for
both strains after 2 and 8 h following beverage con-
4. Conclusion
Exposure to the urine of a volunteer who consumed CJC
imparted changes in bacterial adhesion and in the phys-
icochemical properties of bacterial surface molecules,
which were not observed in post-water urine. The
changes were also dependent on properties of the bacte-
ria. For two E. coli strains, adhesion forces were de-
creased in post-CJC urine, as quantified via AFM. How-
ever, we did observe statistically significant changes in
the conformation of the polymers on the E. coli surface
in post-CJC urine, compared to post-water urine. For S.
aureus, we observed both a decrease in adhesion force in
post-CJC urine, and statistically significant changes in
the conformation of bacterial surface polymers in post-
CJC urine. Since the nature of the surface molecules on E.
coli and S. aureus are very different, these results suggest
that there are multiple mechanisms by which post-CJC
compounds in urine can interact with Gram-negative and
Gram-positive bacteria.
5. Acknowledgements
We are grateful to Ocean Spray for providing cranberry
juice cocktail.
This work was supported in part by grants from the
National Center for Complementary and Alternative
Medicine (NIH R15 AT003385-01A1), the Cranberry
Institute, and the Wisconsin Cranberry Board. Funds for
the atomic force microscope used in this work were pro-
vided in part by a grant from the National Science Foun-
dation (CBET 0922901).
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