The Microaerophilic Culprit: Exploring Helicobacter pylori and its Role in Chronic Gastritis

The bacterium Helicobacter pylori is spiral in shape and it grows in the digestive tract of the human being. The bacterium (H. pylori) is gram negative, microaerophilic, i.e., it grows in an environment of lower amount of oxygen and is responsible for the condition of chronic gastritis which involves the entire stomach also known as pangastritis. The bacterium is also acutely responsible for several other acute conditions such as peptic ulcer, gastric carcinoma and lymphoma (1). The infection caused by the bacterium Helicobacter pylori is highly prevalent and results in the infection of more than half population of the world. The bacterium causes infection of the stomach in the childhood period of the individuals specifically in the developing countries the frequency of infection among children is quite common. Human being acts as the major reservoir for the bacterium and the transmission of the bacterium from one person to the other occurs via oral, gastric and the faecal route. Moreover, the prevalence of the bacterium H. pyroli is approximately 70- 90% within the population of the developing countries whereas the rate of prevalence of infection is much lower in the developed countries (2). The following risk factors such as the excess consumption of salted food, extreme congestion due to excess population and absence of running water enhances the chances of development of the infection and also contributes to the risk of developing gastric cancer. For those conducting research in this area, biomedical science dissertation help can provide valuable support in navigating the complexities of studying H. pylori and its associated conditions.

The panel of tests that are available for the identification of the bacterium Helicobacter pylori includes the following:

The Non endoscopic tests include the antibody tests, stool antigen tests, urea breath test. The endoscopic tests include biopsy urease tests, histology examination and the culture confirmation.

Serology

The technique Elisa is non invasive in nature and is used to detect the presence of specific IgG antibodies. The techniques is not that much expensive and have the high sensitivity in the range of 90 to 100%, variable specificity within the range of 76 to 96% and accuracy ranging in between 83 to 98%. To confirm the infection, the ELISA test needs to be complimented with another test such as the stool antigen or the urea breath test prior to the treatment (Refer Fig:1).

Urease breath test (UBT):

The urease breath test is used to detect the presence of active H. pylori infection which also confirms the serology test and therefore guides the clinician to conduct the correct treatment of the patient. This particular test has specificity higher than 95% and sensitivity within the range of 88% to 95%. The application of this test is found to be significant before and after the treatment procedures (Refer Fig:2).

Stool antigen assay

The stool antigen assay is an immunoassay which is used to examine the presence of antigen of the bacterium H. pyroli in the stool samples and the sensitivity and specificity of the test is found to be 94% and 97% respectively. The test is used to confirm the diagnosis and eradication process.

Biopsy urease testing

The kits that are available commercially to conduct the test are CLOtest (Rapid urease test), Pylori Tek and Hp- fast. The sample shows positive reaction within one hour of collection its collection when tested with the CLOtest but it is recommended in the guidelines to note the final reading only after 24 hours of the test to avoid false positivity. The test can show false negativity with the possible presence of the recently used drugs PPIs and antibiotics. This particular test is both rapid to diagnose the condition, economical and also shows accuracy for the selected target population as the sensitivity is within the range of 90 -95% and specificity is within 95 -100% (Refer Fig: 3).

Histology

The histological examination of the biopsy sample not only detects the presence of the bacterium H. pylori but also confirms the presence of conditions such as metaplasia of the intestine, dysplasia, neoplasia, adenomas and MALT lymphoma. The test is considered to be the gold standard test for confirming the diagnosis as the sensitivity and specificity are reported to be as high as 95% and 98% respectively. The only requirement to conduct the test is trained personnel who can interpret the results and can perform the test cautiously.

Culture

The bacterium is fastidious in nature which makes it difficult to culture and therefore special culture media is required to grow the bacteria. The technique of culture is recommended by the clinician when the patient is not responding to the ongoing antibiotic treatment due to the suspected presence of antibiotic resistant strain showing the nature of varied sensitivity (3).

The disease listeriosis is caused by the bacterium Listeria monocytogenes (L. monocytogenes). The causative pathogen is Gram positive, facultative in nature, associated with food and responsible for several fatal conditions such as the disease listerosis, meningitis, encephalitis, septicaemia and even miscarriage. The most vulnerable groups for acquiring the infection are the elderly people, the pregnant women and their foetus and individuals with immunocompromised condition revealing a considerable high death rate within the range of 10 – 40%. Moreover, the disease can also affect those people who do not belong to the category of high risk group. The prevalence of the disease listeriosis, caused by this particular bacterium is rare but the rate of infection is comparatively higher of approximately 20% among the pregnant ladies when compared with the general population and is responsible for the associated death rate within the range of 20%-30%.

The pathogen is resistant to the stressful conditions of the food and its linked environment such as it can grow in harsh conditions of high level of salinity (approx 10%), in lower temperature of around 4°C, in an environment having low activity of water of <0.9, within a wide pH range of 4.1–9.6. All these conditions prevail at different stages of food processing and the bacterium is able to survive in that condition. The condition of listeriosis arises due to the intake of foods contaminated with L. monocytogenes.

The bacterium is considered to be unique in nature as it also exhibits an intracellular life cycle; the ability of the bacterium to survive in the intracellular condition explains the crossing of the placental barrier condition. The bacterium is considered to be in the third position among the leading causes of death associated with food poisoning. Moreover, the situation becomes more serious when 90% of the individuals who are infected with this particular bacterium are of 65 years or above them and naturally show a weaker immune system associated with other comorbiditis such as disease of kidney and liver, high blood sugar, HIV/AIDS, pregnant condition with their infants and addiction to alcohol.

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The condition of listeriosis in case of pregnant women can eventually result in abortion spontaneously or giving birth to an acutely ill baby because of the infection of the foetus and even still birth. The disease also affects the new born babies as a result of post natal infection of the mother or from other infected babies. The disease rarely causes an acute condition in the mother as it mainly affects the foetus (BOOK : Listeria). The bacterium L. monocytogenes can be commonly isolated from the processed Ready To Eat (RTE) food, meat stored at cold storage and the dairy food products. This particular bacterium is ubiquitous in nature and is present in the food products such as raw fish, meat, shell fishes, unpasteurised milk and milk products, poultry and vegetables.

As the bacterium is present everywhere it generally contaminates the immediate environment where the food is processed which poses potential threat to the food chain. The ready to eat foods causes more infection because there is no involvement of any sterilization method applying heat treatment or any other step employing any antimicrobial techniques in between production and the consumption steps. Therefore the measures to check the growth of L. monocytogenes are considered to be very important from the public health and industrial point of view.