Helicobacter pylori

Helicobacter pylori

The cause of stomach ulcers had long been attributed to stress, spicy foods, smoking, or other lifestyle habits.[1]

Conventional thinking was that no bacterium could live within the acidic environment of the stomach.

It was not until the early 1980's when the bacteria, Helicobacter pylori (H. pylori) was discovered in the stomachs of patients with gastritis and stomach ulcers that conventional thinking began to change...

... Began to change ... as in, the 'H. pylori - ulcer' connection being proposed by Dr. Barry Marshall and Dr. Robin Warren in the early 80's was initially met with strong resistance from colleagues adhering to the accepted theories of the day.

Unable to gain access to suitable test subjects (H. pylori affects only primates), Marshall decided to take matters into his own hands by drinking a solution H. pylori from the gut of an ailing patient. Shortly thereafter, he began to develop symptoms of gastritis, the precursor to an ulcer. Taking a biopsy from his own gut (as one does), he was able to culture H. pylori and show the bacteria to be the underlying cause of ulcers.[16]

In recognition of their discovery, Dr. Barry Marshall and Dr. Robin Warren were awarded the 2005 Nobel Prize in Physiology or Medicine.[12][13][14][15]

• It is estimated that at least half the world's population is infected by the H. pylori bacterium, making it the most widespread infection in the world.[4]

• Considering that statistic, it is indeed fortunate that up to 85% of people infected with H. pylori never experience symptoms or complications.[5]

• On another positive note, the overall frequency of H. pylori infection appears to be on the decline.[2][6]

• Most frequently acquired in early childhood,[2] H. pylori is contagious, although the exact route of transmission is not known.[8][9] 

• It is believed H. pylori may be transmitted person-to-person via the oral-oral or fecal-oral route; oral transmission may also occur through the ingestion of waste-tainted water.[10][11]

COMPLICATIONS ASSOCIATED WITH H. PYLORI INFECTION: 

ULCERS

A benign gastric ulcer of a gastrectomy 
specimen.

A natural mucous barrier exists on the lining of the stomach to protect against its strong digestive acids. 

There is normally a balance between the amount of acid produced by the stomach and the mucous defense barrier.[1][2][3]

H. pylori can damage the protective lining of the stomach and small intestine, and disrupt this balance, allowing stomach acid to create an open sore (ulcer).

Individuals infected with H. pylori have a 10 to 20% lifetime risk of developing peptic ulcers.[2][30][31][34]

INFLAMMATION OF THE STOMACH LINING

By the same action as described above, H. pylori infection can cause inflammation of the stomach lining (gastritis). This may develop into an ulcer.[31]

CANCER

Endoscopic image of gastric ulcer, biopsy proven
to be gastric cancer.

In 1994, the International Agency for Research on Cancer classified H. pylori as a carcinogen, or cancer-causing agent, in humans.[34]

Infection with H. pylori is the primary identified cause of non-cardia gastric cancer (cancer found in all other areas of the stomach other than the top portion).[35-43]

A meta-analysis[33] conducted in 2009 concluded the eradication of H. pylori reduces gastric cancer risk in previously infected individuals. The analysis suggested the continued presence of H. pylori constitutes a relative risk factor of 65% for gastric cancers; in terms of absolute risk, the increase was from 1.1% to 1.7%.[2][31][32]

Although it is not known for certain how H. pylori infection increases the risk of non-cardia gastric cancer, some researchers speculate that the long-term presence of an inflammatory response predisposes cells in the stomach lining to become cancerous.[40][41]

Long-term follow-up of data from a randomized clinical trial carried out in Shandong, China—an area where rates of gastric cancer are very high—found that short-term treatment with antibiotics to eradicate H. pylori reduced the incidence of gastric cancer.

During a nearly 15-year period after treatment, gastric cancer incidence was reduced by almost 40%.[42]

When the results of this trial were pooled with those of several smaller trials examining the effects of H. pylori eradication on incidence of gastric cancer, a similar reduction was seen.[42]

SYMPTOMS   

Acute infection may appear as an acute gastritis (inflammation of the stomach lining) with abdominal pain or nausea.[17]

Where this develops into chronic gastritis, the symptoms may include stomach pains, nausea, bloating, belching, and sometimes vomiting or black stool.[18][19]


DIAGNOSIS[20][21]

H. pylori can be detected via:

• A breath test
• A stool antigen test
• A blood test to detect the presence of H. pylori antibodies 
• If a biopsy sample of the stomach’s lining has been taken during gastroscopy, it can be tested for H. pylori.

Immunohistochemical detection of H. pylori in
gastric biopsy

TREATMENT

• H. pylori infections are usually treated with two varieties of antibiotics at once, to help prevent the bacteria from developing a resistance to one particular antibiotic; as well as an acid-suppressing drug, to help the stomach lining heal.[1]

• Despite efforts to prevent resistance, it is perhaps not entirely surprising to hear that an increasing number of infected individuals are being found to harbor antibiotic-resistant bacteria.[7][22]

• This results in initial treatment failure and requires additional rounds of antibiotic therapy or alternative strategies.[23][24][25] 

• Supplementing diets with yogurt containing Lactobacillus and Bifidobacterium has improved the rates of eradication of H. pylori in humans.[26]

• The substance sulforaphane, which occurs naturally in broccoli and  cauliflower, has also been proposed as a treatment.[27][28][29] 

GENOME

• H. pylori is believed to have migrated out of Africa along with its human hosts around 60,000 years ago.[50][51]

• There is a great deal of diversity among the various strains of H. pylori. The genomes of three have been completely sequenced.[43-47]

A 'PATHOGENICITY ISLAND' IS THE NAME GIVEN TO A COMMON GENE SEQUENCE BELIEVED TO BE RESPONSIBLE FOR PATHOGENESIS

• The Cag PATHOGENICITY ISLAND (cag PAI) is usually absent from H. pylori strains isolated from asymptomatic human carriers of the bacteria.[48]

• About 50–70% of H. pylori strains in Western countries carry the cag PAI.[49]

• Western patients infected with strains carrying the cag PAI have been shown to have a stronger inflammatory response in the stomach and are at a greater risk of developing peptic ulcers or stomach cancer than those infected with strains lacking the island.[2]

***

FIN

REFERENCES:

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IMAGE CREDITS

"EMpylori" by Yutaka Tsutsumi, M.D.Professor Department of PathologyFujita Health University School of Medicine - Yutaka Tsutsumi, M.D.Professor Department of Pathology Fujita Health University School of Medicinehttp://info.fujita-hu.ac.jp/~tsutsumi/photo/photo002-6.htmhttp://info.fujita-hu.ac.jp/~tsutsumi/image/002/2-6.jpg. Licensed under Copyrighted free use via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:EMpylori.jpg#mediaviewer/File:EMpylori.jpg

"Ulcer-causing Bacterium (H.Pylori) Crossing Mucus Layer of Stomach" by Illustration Credit: Zina Deretsky, National Science Foundation - NSF Flickr photostream, http://www.flickr.com/photos/nsf_beta/4822021538/in/set-72157621768317570. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Ulcer-causing_Bacterium_(H.Pylori)_Crossing_Mucus_Layer_of_Stomach.jpg#mediaviewer/File:Ulcer-causing_Bacterium_(H.Pylori)_Crossing_Mucus_Layer_of_Stomach.jpg

"Benign gastric ulcer 1" by Ed Uthman, MD - http://web2.airmail.net/uthman/specimens/index.html. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Benign_gastric_ulcer_1.jpg#mediaviewer/File:Benign_gastric_ulcer_1.jpg

"Gastric ulcer 3" by Original uploader was Samir (The Scope) at en.wikipedia - Originally from en.wikipedia; description page is/was here.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Gastric_ulcer_3.jpg#mediaviewer/File:Gastric_ulcer_3.jpg

"Immunohistochemical detection of Helicobacter (1) histopatholgy" by User:KGH - User:KGH. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Immunohistochemical_detection_of_Helicobacter_(1)_histopatholgy.jpg#mediaviewer/File:Immunohistochemical_detection_of_Helicobacter_(1)_histopatholgy.jpg