A new study from Washington
University School of Medicine in St. Louis indicates that the pH level or
acidity of urine and the presence of small molecules related to diet may affect
susceptibility to Urinary Tract
The research published in The Journal of Biological Chemistry
have implications for treating Urinary Tract
According to a recent analysis, a
strain of bacteria called Escherichia coli or E. coli is responsible for more
than 85% of all UTIs. Medicos have long relied on antibiotics to wipe out these
However, increasing bacterial
resistance to these drugs has caught scientists' attention and also forced them
to work on alternative treatment methods for UTIs.
As part of the mission, Dr. Jeffrey P. Henderson an assistant
professor of Medicine at the
University and his research team analyzed how the body normally fights
The team along with first author
Robin R. Shields-Cutler, cultured E. coli in urine samples from healthy people
and examined main differences in how individual urine samples use the natural
power of siderocalin - a key immune protein, to limit bacterial growth. Past studies
have demonstrated that siderocalin helps the body to fight infections by depriving bacteria an important mineral
necessary for its growth, namely iron.
The researchers divided the urine
samples into two groups based on whether they restricted or permitted bacterial
growth. They found that the urine samples that prevented bacterial growth
supported more activity of siderocalin.
They also noted that more
siderocalin proteins were developed naturally in the samples that prevented the
infection as compared to the samples that permitted bacterial growth.
Researchers found that samples
which were less acidic and closer to the neutral pH of pure water, showed a
higher activity of siderocalin and were comparatively more effective at
reducing bacterial growth than the acidic samples.
"These results are
surprising. The conventional wisdom in medicine favors the concept that acidic
urine can better prevent bacterial growth," said Henderson.
Most importantly, the scientists
showed that they could encourage or discourage bacterial growth in urine simply
by adjusting the pH level.
The scientists also linked
bacterial growth to a person's diet. They examined thousands of compounds in
the urine samples to identify the presence of small metabolites called aromatics
in samples that restricted bacterial growth.
Samples that almost prevented
bacterial growth had more aromatic compounds compared to samples that allowed
The research team says that at
least some of these aromatics are excellent iron binders, helping deprive the
bacteria of iron. The team further commented that these molecules are not
produced by human cells but by an individual's gut microbes as they process
food in the diet.
"Our study suggests that the body's
immune system harnesses dietary plant compounds to prevent bacterial growth. We
identified a list of compounds of interest, and many of these are associated
with specific dietary components and with gut microbes," said Henderson.
The study results implicate cranberries
other possible dietary interventions.
"It's possible that
cranberries may be more effective when paired with treatment to make the urine
less acidic. And even then, maybe cranberries only work in people who have the
right gut microbes," Henderson noted.
The investigators also showed that
enterobactin is good at binding iron in urine. Therefore finding strategies to
block it may help develop antimicrobial drugs that work very differently from