Case 4 Answers

1.  Describe the morphologic and microbiologic features of Helicobacter pylori? 

H. pylori are slender, curved, grain-negative bacilli. 

They are slow growing microaerophiles. 

They are oxidase, catalase and ureas positive. 

 Seen with difficulty on grain stain (better on Warthin-Starry silver stain).

2. What is the frequency of infection with H. pylori in the United States? How does the distribution of H. pylori infection differ in populations from underdeveloped countries? 

In U.S. incidence is low in childhood but increases to about 50% in older adults. 

Infection  appears earlier in lower socioeconomic groups and in underdeveloped countries.

3. What phenotypic characteristics of H. pylori are thought to account for its virulence?  Which of  them appear to be most important? 

Motility, Adherence factors, Cytotoxin, Mucinase, and Urease. 

The urease is thought to  be most important because it raises the pH in the area surrounding the organism allowing  survival in the hostile acid environment of the stomach. 

The nasogastric tube aspirate remained blood free and the tube was removed. She was started on an H2 blocker and the pain rapidly subsided.

4.  What further treatment might be helpful?  What long term benefits could she expect if she were to receive the additional treatment? 

 Antibiotics. Either "triple" therapy with bismuth, metronidazole and tetracycline or newer regimens containing omeprazole and either  amoxicillin or clarithromycin.