Last Updated December 20th, 2021
Characteristics of an H. pylori Host
The pathogen is generally acquired during the first five years of a person’s life. The percentage of people affected in developing countries is 30-50% in a sample containing only children and reaches as high as 90% in a sample containing only adults.
The percentage of people infected by H. pylori is nearly 90% in developing countries and it is around 40% in the developed world, excluding Japan. The prevalence among children up to the age of ten is only 1.2%-12% in developed countries. In developing countries, however, it is the most isolated bacteria in children in that age bracket. In developed countries, the prevalence of the infection continues to decline, whereas no such change is visible in developing countries.
How H. pylori Enter the Body
H. pylori enter the body through the mouth and then move to the stomach and the upper part of the small intestine. They are transmitted from a person’s mouth to another’s, possibly by kissing or during sexual intercourse. They can also be transmitted by the consumption of food or water that has been contaminated by fecal matter.
Pathogenesis: H. pylori in Action
As stated earlier, H. pylori enter through the mouth and move into the stomach. They have the capability to neutralize stomach acids and survive in the otherwise harsh environment of the stomach. They do this by creating an enzyme which breaks down the urea in the stomach acid to ammonia.
What this means is that they can reduce stomach acid, until they reach the lining of the stomach. Once there, they are protected from being detected by the body’s immune system by mucus on the stomach lining. They affect the stomach lining by invading it and generating a cytotoxin called vacuolating cytotoxin A (Vac-A). With the gastric tissue exposed, the combined action of the stomach acids as well as H. pylori leads to stomach ulcers and perhaps over time even to gastric cancer.
The immune system of the body responds by sending macrophages, neutrophils, and lymphocytes to the gastric tissue to combat the inflammation. But once it reaches the stomach lining, the bacteria have mechanisms that can help them avoid getting killed by phagocytes. They are therefore able to counter-act the phagocytes generated by the immune system of the body and continue multiplying and spreading the damage over the gastric tissue.
Factors that Increase the Risk of Infection
H.pylori are generally contracted by contact with an infected person. There are many factors that increase the risk of infection by H. pylori. Some of them are:
Living in crowded areas increases the chances of contracting an H. pylori infection. This is especially the case if a lot of people are living under the same roof, constantly interacting with each other.
Impure Drinking Water
Living without a source of clean water increases the risk of infection. The spiral, active form of the bacteria can survive in river water for up to a week while the coccoid form is known to survive for up to a year in river water. In many areas of developing countries, insufficiently treated river water forms the main water supply.
Children in countries such as Brazil where the sewage disposal is not properly done or flush toilets are not provided are at a higher risk of infection. It has also been observed that if the garbage collection service is not regular, the accumulation of waste could also increase the risk of infection.
Living with Infected People
If one is living with an infected person, then he/she is at a greater risk of getting the infection since the primary mode of transmission is by contact.
Symptoms of an H. pylori Infection
Immediate Symptoms of an H. pylori infection are:
- Nausea and vomiting
- Abdominal discomfort
Serious symptoms of an H. pylori infection include:
- Abdominal pain
- Vomiting violently and vomiting blood
- Bad breath
- Dark or tarry stools
People with any of the above symptoms must consult a doctor and diagnose the underlying medical condition responsible for it. This is because all of these symptoms are very general and these do not help distinguish infection by H. pylori from other medical conditions. And the sooner the patient receives treatment for the infection, the better it would be for him/her.
Testing for H. pylori
People who exhibit symptoms of ulcer, gastritis or stomach cancer form the test subjects for the presence of H. pylori. It is generally detected by collecting blood, breath and stool samples.
The following methods are used for diagnosing ulcers:
The medical problems experienced by the patient in the past along with the exhibited symptoms are analyzed. If possible, previously suggested treatment procedures and the response of the patient to them can also be considered.
Upper GI Series
Special X-rays are used to view the inside of the stomach. These would help to determine the presence of ulcers on the stomach walls once the patient drinks a chalky white solution of Barium.
In endoscopy, the doctors insert an instrument (called an endoscope) to observe the inside of a cavity or an organ (in this case, the stomach). This is a painless procedure and only very few people have reported a sore throat or another minor discomfort. In endoscopy, the doctor can take images with the camera at the end of the endoscope or can take a piece of tissue to better analyze it.
Once an ulcer is diagnosed, the doctor tests for H. pylori. To test for H. pylori, doctors collect and analyze blood, breath, and stool samples.
A blood test remains the most common non-invasive test for H. pylori infections. Blood samples are analyzed for antibodies. A blood test is useful for detecting active strains of H. pylori as well as understanding whether the patient has suffered from infection by the bacteria in the past.
Urea Breath Test
A urea breath test is the most common test used to detect an active case of H. pylori infection. In this test, the patient drinks a urea solution which contains a carbon atom. If H. pylori are present, then they will reduce the urea, releasing the carbon atom, which will reach the lungs and is exhaled by the patient. This test is 96-98% accurate.
The stool test involves detecting H. pylori in fecal matter. Studies have shown stool tests to be accurate in detecting an active infection.
A tissue test is generally carried out using the tissue sample that is removed during endoscopy. They are more invasive than the tests mentioned earlier, and it is therefore always conducted after the earlier tests.
- The rapid urease test detects the enzyme urease. This enzyme is produced by H. pylori.
- A histology test (or biopsy) allows the doctor to find and examine the actual bacteria.
- A culture test involves allowing H. pylori to grow in the tissue sample.
- Treatment for H. pylori
A note on H. pylori and Antibiotic Resistance
Across the globe, a growing number of bacteria and viruses are becoming resistant to antibiotics. As many as 23,000 people die every year in the United States as a result of antibiotic-resistant infections. An example is the methicillin-resistant Staphylococcus aureus.
A study in the journal Clinical Gastroenterology and Hepatology found that some patients with H. pylori infections in the United States that were resistant to at least two different antibiotics. The American Journal of Gastroenterology reported a large number of H. pylori infections in Latin American countries that were resistant to antibiotics.
Fortunately, H. pylori are still treated by a wide range of antibiotics. Early treatment ensures the successful elimination of ulcers, gastritis, and even stomach cancer.
For the treatment of ulcers resulting from H. pylori, the following methods are used:
- Antibiotics are used to kill H. pylori bacteria. Examples of such antibiotics are metronidazole, tetracycline, clarithromycin, and amoxicillin. Antibiotic regimens for patients will vary across the world depending on the antibiotic resistance of H. pylori in a particular region.
- Drugs that reduce the gastric acid like proton pump inhibitors or histamine receptor (H2) blockers are administered. These are referred to as acid suppressors and suppress the secretion of gastric acid. H2 blockers and proton pump inhibitors have been prescribed for years in the treatment of ulcers. However, by themselves, they cannot be used to eliminate an H. pylori infection.
- Medicines that form a coating over the ulcer and help it to heal like bismuth subsalicylate also help to treat H. pylori infections. They are referred to as stomach protectors. In addition, bismuth subsalicylate also kills H. pylori bacteria.
Treatment generally involves a combination of the use of antibiotics, acid suppressors, and stomach protectors. A two-week course of triple therapy is carried out with a combination of any two antibiotics and an acid suppressor or a stomach protector.
It helps to eliminate the symptoms of an ulcer, kills the bacteria and prevents the recurrence of the ulcer in nearly 90% of those undergoing treatment.
The patients have to take as many as 20 pills a day over the course of two weeks. Also, they cause side effects like vomiting, nausea, diarrhea, metallic taste in the mouth, and dizziness in both men and women and yeast formation in women alone.
A dual therapy that involves the use of an antibiotic and an acid suppressor over the course of two weeks is found to be moderately effective. Quadruple therapy that involves the use of two antibiotics, an acid suppressor and a stomach-lining protector over the course of two weeks looks most promising. This also called bismuth triple therapy.
Prevention of H. pylori
Studies on understanding the exact cause of an H. pylori infection are still inconclusive. Also, there is no vaccine presently that can prevent an H. pylori infection. The testing using both classical and recombinant H. pylori antigens in the immunization of mice has been onerous. However, there are ways to prevent it from happening by maintaining personal hygiene.
- Washing your hands regularly with soap and water, especially after using the toilet can help reduce the risk of infection.
- Ensuring that food that is consumed is cleaned and cooked properly also may reduce the risk of infection.
- Have a drinking water supply that is well treated also prevents the possibility of infection.
Despite the different fool-proof methods by which H. pylori can be detected in the body, there is still no vaccine or no proper understanding of its cause and therefore prevention methods may or may not work. On the bright side, in the treatment of ulcers, if the cause is an H. pylori infection, there are several therapies that work over as short a window as 14 days. The one thing to remember if one is suffering from the serious symptoms described in this article is to never dismiss the possibility of an H. pylori infection.
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