What are Helicobacter pylori?
Helicobacter pylori (H. pylori) are bacteria found in the stomach that are responsible for most cases of peptic ulcer. About half of the world's population has the bacteria making it the most common bacterial infection in humans.
H. pylori infection is more common in developing nations. The risk of contracting H. pylori is related to socioeconomic status and poor living conditions such as overcrowding, lack of clean, running water and a higher number of siblings. As a result, most children in developing nations are infected before the age of 10.
In New Zealand, there is a higher prevalence amongst Maori and Polynesians. Studies show that about 5% of European children become infected with H. pylori by the age of 20 years, in contrast to 50% of Polynesian children.
The exact route of infection remains unknown, but person-to-person transmission through oral/oral or faecal/oral exposure is the most likely cause. Activities such as sharing food, cutlery or poor toilet hygiene can result in the transmission of H. pylori to another individual.
What diseases are linked to H. pylori infection?
H. pylori cause direct disease of the stomach. Other conditions are probably related to the body's immune response to the bacteria.
- Chronic gastritis (inflammation of the stomach lining)
- Peptic ulcers
- Stomach cancers
- Certain types of lymphomas (cancers of lymphoid tissue)
What are the symptoms of H. pylori infection?
Most individuals with H. pylori infection have no symptoms. Symptoms arise if infection with H. pylori causes peptic ulcers or gastritis. These symptoms can be non-specific and may include:
- Abdominal pain (usually in the upper abdomen)
- Red or tar-coloured stools (indicating bleeding in the intestine)
- Low blood count (anaemia).
How do H. pylori damage the stomach?
The damage to the lining of the stomach is due to a complex interaction of the bacteria and the host's immune response. H. pylori release several enzymes and microbial products that directly damage the lining of the stomach. The immune system reacts by mounting a florid inflammatory response in an attempt to eradicate the bacteria. As a consequence of this inflammatory response, the stomach lining is unintentionally damaged.
What investigations are there for H. pylori?
There are several tests available to detect the presence of H. pylori in the stomach:
- Blood test – This detects specific antibodies against H. pylori bacterium.
- Breath test – This involves drinking a solution of carbon labelled urea. This solution is broken down by H. pylori, and its breakdown products can be detected in the breath.
- Stool test – This detects H. pylori proteins in the faeces.
- Endoscopic testing – This involves the use of optical instruments for the visual examination of interior parts of the body. A flexible tube is inserted through the mouth into the stomach and upper regions of the small intestine. Small tissue samples can be taken from the stomach wall, which is then tested for H. pylori.
Blood test and breath test are often the first line approach to testing for H. pylori. Endoscopic biopsy is a relatively invasive procedure and is often reserved for patients who require endoscopy for another reason.
Who should be tested?
The American College of Gastroenterology recommends testing in the following situations:
- Patients with active peptic ulcer disease
- A history of documented peptic ulcer
- Gastric MALT (Mucosa Associated Lymphoid Tissue) lymphoma
- Patients who have undergone resection of early gastric cancer.
Testing is not recommended for people who are asymptomatic (no symptoms) or who have no history of peptic ulcer disease. However, certain population groups who are at risk for developing ulcers or stomach cancers may be considered for asymptomatic testing.
What is the treatment?
Treatment of H. pylori infection involves taking several medications for 7 to 14 days ('triple therapy'), for example, a proton-pump inhibitor (inhibitor of stomach acid secretion) such as omeprazole 40mg once daily, amoxicillin 1g twice daily and clarithromycin 500mg twice daily.
Treatment cures up to 90% of individuals.
What is the relationship of H. pylori to diseases of the skin?
H. pylori have been implicated in a variety of diseases that are not related to the gastrointestinal tract. The skin is an example, and several studies have suggested an association with the following conditions:
- Chronic spontaneous urticaria – Several studies have found a link between H. pylori infection and chronic urticaria. It is thought that infection with H. pylori increases the permeability of the stomach lining and thus increases the exposure to allergens (substances that causes an allergy) in the gastrointestinal tract. Also, the immune response to H. pylori produces antibodies that may encourage the release of histamine in the skin.
- Rosacea – H. pylori can increase levels of nitrous oxide in the blood or tissue contributing to the flushing and erythema (redness) of rosacea.
- Psoriasis – H. pylori may be one of the organisms capable of triggering the inflammatory response in psoriasis.
- Sjögren syndrome – H. pylori may induce an autoimmune reaction to the skin and glands causing Sjögren syndrome.
- Henoch-Schönlein purpura
- Alopecia areata
- Sweet disease
- Systemic sclerosis
- Atopic dermatitis
- Behçet disease
- Generalised pruritus (itch)
- Nodular prurigo
- Immune thrombocytopenic purpura
- Lichen planus
- Aphthous ulceration.
Does the treatment of H. pylori affect skin disease?
Several small studies have suggested that eradicating H. pylori has a positive outcome on certain skin diseases such as urticaria, Behçet disease, lichen planus, atopic dermatitis, Sweet syndrome, and systemic sclerosis. Conditions which may not benefit are psoriasis and rosacea.
These studies are not randomised and involve small numbers of patients so no definitive conclusion can be drawn about the eradication of H. pylori in skin diseases at present.