H. pylori. In one study among those randomized placebo, the recurrence rate was over 10 times as gre as among those randomized to antibiotic treatme directed against H. pylori. This research led to a sear
H. pylori. In one study among those randomized placebo, the recurrence rate was over 10 times as gre as among those randomized to antibiotic treatme directed against H. pylori. This research led to a sear
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Describe the negative and positive roles that biological plausibility played in establishing causation.
Transcribed Image Text:►H.pylori and Peptic Ulcers
Duodenal ulcers and benign stomach ulcers are fre-
quently referred to as peptic ulcers. Peptic ulcers are
among the digestive diseases with the highest inci-
dence. Approximately 10% of the population experi-
ence a peptic ulcer at some point in their life, though
a substantial proportion, perhaps a majority, are not
medically diagnosed. Peptic ulcers generally heal even
without prescribed treatment in 4-6 weeks. Approx-
imately 1% of those with peptic ulcers experience
complications, with potentially life-threatening perfo-
ration of the stomach or duodenum being the more
serious complications. The disease often recurs, with a
probability of recurrence in the range of 50%.
For many years, peptic ulcers were believed to be
exclusively the result of excess acid production due
to such factors as alcohol, aspirin, and other anti-
inflammatory medications, spicy foods, and stress.
The stomach and duodenum were known to be highly
acidic, and it was believed that bacteria were unable to
survive in this high-acid environment.
In the early 1980s, investigators observed
a spiral-shaped bacterium, which they named
Helicobacter pylori, or H. pylori, in a number of patho-
logical specimens from patients with disease of the
stomach and duodenum. Most scientists doubted the
relationship to disease, often concluding that the organ-
ism must be a contaminant because of the belief that
bacteria could not grow in highly acidic environments.
After many unsuccessful attempts, Australian
researchers Barry J. Marshall, MD, and J. Robin War-
ren, MD, were able to culture the bacteria from the
stomach and became convinced that the bacteria were
actually the cause of peptic ulcers. They were frus-
trated in their attempts to demonstrate that H. pylori
was the cause of the disease because of the absence of
good animal models.
To attempt to establish causation, Marshall drank
a flask of the cultured bacteria. He became ill and
developed acute ulceration of the stomach. H. pylori
was cultured from his ulcerations. This dramatic effort
brought attention and extensive investigations to
address whether H. pylori is a contributory cause of
duodenal ulcers.
Subsequent studies in the United States and other
countries established that H. pylori is a frequently
occurring organism that increases with increasing
age. Overall, over 20 % of people in the United States
have H. pylori; that is its prevalence is over 20% in the
United States, with a higher prevalence beginning at
an early age in many developing countries, as well as
Japan. In case-control studies, H. pylori was found to
Transcribed Image Text:the time of their diagnosis.
I have a strong association with duodenal ulcer,
over 70% of peptic ulcer patients having H. pylori at
Randomized controlled trials examined the
recurrence rates of duodenal ulcers after treatment
of the bacteria with antibiotics shown to eliminate
H. pylori. In one study among those randomized to
placebo, the recurrence rate was over 10 times as grea
directed against H. pylori. This research led to a search
as among those randomized to antibiotic treatment
for biological mechanisms. Extensive research estab-
lished a greater understanding of the physiology of
peptic ulcers, including identifying the production of
an enzyme by H. pylori that reduces acidity and thus
facilitates its growth in an acid environment.
New tests demonstrated that H. pylori is associ-
ated with the great majority of duodenal ulcers;
with
among
outpatients. Randomized controlled trials and exten-
sive clinical follow-up established the effectiveness
and relative safety of antibiotic treatments of H.pylori.
These investigations led to evidence-based recommen-
dations for routine testing for H. pylori among outpa-
tients diagnosed with peptic ulcers and treatment of
H. pylori with antibiotics when it was detected.
300
In the US diet can.
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