Medical microbiology - Assignment Example

(ii) The most commonly used stain for the gastric biopsy for the detection of H. pylori is the modified giemsa stain. Sections of the biopsy in a patient with gastritis would show epithelial damage and a generalized decrease in the thickness of the mucus layer. Eroded areas of the stomach lining would also show the presence of white blood cells such as lymphocytes and neutrophils. A haematoxylin and eosin stain of a person with chronic gastritis would show polymorphonuclear leucocytes intruding into the lining of the mucus gland.

Helicobacter pylori resides deep into the lining of the stomach wall, and as the polymorphonuclear cell cannot easily reach the site of infection, they release superoxide radicals which damages the stomach lining. A methylene blue stain of the section would stain the H. pylori bacteria blue and would present as small curve shaped, spiral bacteria in the mucus lining. (iii) 13C urea breath test is a very accurate, non-invasive, simple test that can produce results within 20 minutes. Helicobacter pylori produces urease enzyme which forms the basis of 13C urea breath test.

The patient is given a non-radioactive 13C urea to drink, which is broken down into ammonia and bicarbonate by the urease enzyme in Helicobacter pylori. Bicarbonate ions dissociate into Carbon dioxide and water in the acidic environment of the stomach. The 13C isotope containing carbondioxide is absorbed into the blood stream and taken to the lungs to be expired. Readings are taken of the expired air and the results are sent to the lab for Mass correlation spectrometry to be performed and levels of 13CO2 are determined, which are synonymous with the presence of Helicobacter pylori. (iv) A triple regimen therapy is advised to the patient, which consists of a proton pump inhibitor (e.g. omeprazole) and two antibiotics (e.g. amoxicillin,