Digestion, General | December 15, 2015 | Author: The Super Pharmacist
Helicobacter pylori (H. pylori) is a spiral-shaped bacterium that is found in the mucous layer lining of the inner surface of the stomach or first part of the small intestine (“helico-,” means “spiral”). H. pylori is the main cause of ulcers occurring in the lining of the upper part of the small intestine (duodenal ulcers) and in the lining of the stomach (gastric ulcers). Initially, the bacterium causes inflammation (gastritis or duodenitis). Many people may be unaware of this inflammation, and only experience symptoms when an ulcer develops, perhaps years later. Not all people infected with H. pylori will develop an ulcer.1
Currently, about half of the world’s population is infected by H. pylori, with rates in the developed world in the order of 70%.2 H. pylori may be detected in approximately 90% of individuals with peptic ulcer disease; however, less than 15% of infected persons may have peptic ulcer disease.3
The presence of H. pylori in the stomach or small intestine is usually asymptomatic. However, duodenal or gastric ulcers are reported to develop in 1 to 10% of infected patients.4 In 20% of cases, the infection may progress to pre-cancerous changes in the stomach and eventually to gastric cancer in 2% of those persons infected with the organism.5 Gastric lymphoma is an even rarer consequence of H. pylori infection, occurring in fewer than 1% of those who are infected.6
The most common ulcer symptom is gnawing or burning pain in the epigastrium (the upper middle region of the abdomen). This pain typically occurs when the stomach is empty, between meals and in the early morning hours, but it can also occur at other times. It may last from minutes to hours and may be relieved by eating or by taking antacids. Less common ulcer symptoms include nausea, vomiting, and loss of appetite. Bleeding can also occur; prolonged bleeding may cause anemia leading to weakness and fatigue. If bleeding is heavy, bloody vomiting or bloody stools may occur.1
The most common route of H. pylori infection is either oral-to-oral (stomach contents are transmitted from mouth to mouth) or fecal-to-oral (from stool to mouth) contact. Parents and siblings seem to play a primary role in transmission.3 However, it is thought that people infected with the bacterium are only capable of passing it to others for a short period (days or weeks). It may be passed via the fingers through contact with vomit or stools from an infected person. Therefore, good hygiene may decrease the risk of the bacterium being spread. However, it is thought that people living in the U.S. are unlikely to pass it on and do not need to take any special measures to avoid giving it to others.1
The test usually used to diagnose an ulcer is an endoscopy. This is a procedure where a flexible fiber-optic tube, which relays images to a video camera, is passed through the mouth down into the stomach. The oesophagus, stomach, and duodenum can be inspected in this manner and a biopsy can be obtained. This involves taking a sample of cells from the lining of the stomach or duodenum. The cells are then grown in a special culture to test for the presence of H. pylori. If there is growth of H. pylori, different antibiotics can then be tested on this culture to establish which is the most effective in treating the bacterium.1 Noninvasive tests are divided into the urea breath test (UBT), serology and stool antigen test (SAT). For the urea breath test, patients swallow urea labelled with an uncommon isotope, either radioactive carbon-14 or non-radioactive carbon-13. In the subsequent 10–30 minutes, the detection of isotope-labelled carbon dioxide in exhaled breath indicates that the urea was split; this indicates that urease (the enzyme that H. pylori uses to metabolize urea) is present in the stomach, and hence that H. pylori bacteria are present. Urea is an organic chemical compound, and is essentially the waste produced by the body after metabolising protein. Serological tests detect the presence of antibodies to H. pylori. Positive serology indicates current or past infection with H. pylori. A stool antigen test checks to see if substances that trigger the immune system to fight an H. pylori infection are present in the stool.
Standard treatment of an H. pylori infection consists of 3 drugs, the so-called ‘triple therapy’ plan which includes a proton pump inhibitor (PPI) (suppresses gastric acid) and two different antibiotics.
Duration options are as follows (each duration below yields good outcomes of around 80% and is associated with similar risks because of good tolerance):
Standard triple therapy started from eradication rates of more than 90%, and has now decreased to 70–80%.9,10 Treatment of H. pylori infection is challenged by a dramatic fall in eradication rates all over the world. Over the past few decades, the efficacy of the standard first-line triple therapy has experienced a steady decline. There are several reasons for the loss of eradication efficacy, but the far most important is the increasing rate of H. pylori resistance to antibiotics. The resistance to clarithromycin has the highest impact on treatment failure and the rate of resistance to clarithromycin has dramatically risen in many countries. Newer treatment regimens have been introduced including sequential, quadruple therapies. In sequential therapy for H. pylori, more antibiotics are added to the treatment regimen in sequence rather than giving all 4 drugs together. Typically, this involves an initial 5-day therapy with a benign combination (e.g. pantoprazole 40 mg twice daily, with amoxicillin 1 g twice daily) followed by 5 days of 2 further antibiotics plus a proton pump inhibitor (PPI) (e.g. clarithromycin 500 mg twice daily, and tinidazole 500 mg twice daily, plus pantoprazole 40 mg twice daily).11 In a large prospective, controlled study,12 researchers showed a 90% cure rate for this “new” treatment versus 80% for the “old.” Sequential therapy is considered superior to standard triple therapy based on 2 systematic reviews.13,14 The confirmation of cure should be performed by noninvasive tests, except in cases when a follow-up endoscopy is indicated from a clinical perspective (gastric ulcer, preneoplastic lesions, lymphoma). As a noninvasive test, the UBT should be employed, if available.