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Helicobacter gastritis: Does it cause chronic vomiting? (Proceedings)

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Aug 01, 2010

Helicobacter pylori infection is the most common cause of chronic gastritis and peptic ulceration in humans. It is also associated with an increased risk of gastric lymphoma and adenocarcinoma. Spiral bacteria were described in 1896 in humans and several animal species. They were "rediscovered" in 1983 when they were reported to cause of peptic ulceration in humans. Helicobacter pylori is a microaerophilic curved spiral gram negative organism with 4 flagella. The bacterium lives in gastric mucus, can attach to epithelial cells, and may penetrate intercellular junctions. High bacterial urease concentration cleaves urea to produce ammonia, which helps to neutralize the acid environment surrounding the bacterium. The immune system does not result in removal of the organisms; without treatment infection is life-long. Some studies have shown as many as 90% of people are infected with H. pylori. Luckily, most infections are not associated with clinical signs. Diagnosis can be made with serology, cytology of gastric mucus, culture of biopsies, histopathology of biopsies with H&E or silver stains, C-13 or C-14 labeled urea breath tests, or rapid urease tests. Many treatments have been studied, but the gold standard to which they are all compared to is omeprazole, ampicillin or tetracycline, metronidazole, and bismuth for 2 weeks.

Many species of spiral bacteria have been identified in dogs and cats: H. felis, H. pylori, and H Heilmannii (formerly called Gastrospirillum hominis), H. Salomonis, and H. bizzozeronii are the most common. Experimentally, infection has been established in both dogs and cats and lymphoid follicular gastritis developed. However, in these experimental studies, clinical signs were absent or very mild. Several surveys of laboratory, shelter, and pet populations (with and without GI signs) have shown a very high prevalence rate in dogs and cats, nearing 100% in some studies. Peptic ulceration is very rare in dogs and cats, demonstrating the pathophysiologic difference between H. pylori and the spiral bacteria commonly found in dogs and cats. Little is known about the effects of treatment of dogs and cats with chronic vomiting and Helicobacter spp. infection. At the present time there are many unanswered questions regarding Helicobacter in dogs and cats. Some questions include: 1) What is the relationship between Helicobacter and dogs and cats with chronic gastritis and vomiting? 2) What is the optimal treatment to eradicate the organism? 3) After treatment, is reinfection or recrudescence a common occurrence in dogs and cats? 4) What factors can help predict if a dog or cat with chronic gastritis and Helicobacter would benefit from treatment for Helicobacter? 5) Does Helicobacter have a role in other diseases such as gastric cancer and inflammatory bowel disease?

Because of the potential pathophysiologic relationship between Helicobacter spp. in dogs and cats and chronic gastritis and vomiting, the author has treated clinical cases for Helicobacter. In some cases, treatment has resulted in resolution or improvement in clinical signs. Until additional studies about Helicobacter in dogs and cats are available, it seems prudent to at least determine if spiral bacteria are present in dogs and cats with chronic vomiting, during gastroscopic examination or exploratory celiotomy. Spiral bacteria can be identified in gastric biopsy or brush cytology specimens, or indirectly identified by rapid urease testing of gastric mucosal samples. Obtaining results from histologic evaluation of biopsy samples requires 24-72 hours. Results of rapid urease tests and gastric brush cytology are available much sooner.

The least expensive and most practical diagnostic method of the 3 commonly used tests, that also has the quickest turnaround time, is gastric brush cytology. After completion of the endoscopic examination and collection of biopsy samples from the duodenum and stomach, a brush cytologic specimen can be collected. A guarded cytology brush is passed through the endoscope's biopsy channel into the gastric body along the greater curvature. The cytology brush is extended from the sheath, and gently rubbed along the mucosa from the antrum towards the fundus, along the greater curvature. Hemorrhagic areas associated with previous biopsy sites should be avoided. The brush is retracted into the protective sheath and withdrawn from the endoscope. The brush is extended from the sheath, gently rubbed across several glass microscope slides, which are air died, and stained with a rapid Wright stain.a The slide is examined under 100x oil immersion. Areas with numerous epithelial cells and large amounts of mucus are initially viewed. If present, the spiral bacteria are easily seen. They are usually at least as long as the diameter of a red blood cell and their classic spiral shape is obvious (Figure 3). The author examines at least 10 oil immersion fields on 2 slides before the specimen is considered negative. Unlike diagnostic tests that involve using a single (or several) small biopsy samples, brush cytology gathers surface mucus and epithelial cells from a much larger area, increasing the chances for identification of bacteria. Brush cytology was found to be more sensitive than urease testing or histopathological examination of gastric tissues in identifying Helicobacter organisms in dogs and cats.