4.5

Question 1

campylobacter genus

Answer 1

gram negative rods with a spiral morphology
carried by some bird species which cause no disease and may be found in commercial chicken flocks
may also be found in cattle
from animal sources the bacteria may contaminate water sources, particularly in the developing world
chicken, milk, beef may be contaminated

Question 2

species of genus campylobacter

Answer 2

most human disease caused by
C jejuni
C coli

Question 3

campylobacter diseases

Answer 3

common cause of human diarrhoea

may be bloody and associated with nausea, vomiting, abdominal cramps and fever

Question 4

campylobacter infections acquired from

Answer 4

poorly cooked chicken 
other food contaminated by uncooked chicken
milk form infected cows
contaminated natural water sources 
dogs and cats with the infection

Question 5

genus helicobacter

Answer 5

disease causing pathogen is helicobacter pylori
gram negative rod with helical morphology
cause majority of peptic ulcers

Question 6

features posessed by helicobacter pylori allowing it to survive in the acid environment of the stomach and upper duodenum

Answer 6

• flagellar motility, enabling it to penetrate the protective mucous lining of the stomach, gaining protection from the acid
• high level production of the enzyme urease, which breaks down urea in the stomach to produce ammonia, which neutralises acid in the immediate environment

Question 7

how does helicobacter pylori cause damage to the GI epithelial cells

Answer 7

• toxicity produced by ammonia
• damage caused by bacterial enzymes
• inflammatory response of the mucosa caused by exposure to bacterial peptidoglycan
• inflammation causes pyloric astral cells to secrete gastrin into the bloodstream, resulting in greater acid secretion in the stomach

Question 8

result of h pylori bacterial damage to the epithelium

Answer 8

makes the epithelial defences against acid and digestive juices less effective

Question 9

infection with H pylori causes risk of

Answer 9

• symptomatic infected people may have acute or chronic gastritis, gastric ulceration or duodenal ulceration
• places the patient at risk of developing gastric adenocarcinoma, and a rare B cell lymphoma, MALT lymphoma (mucosa-associated lymphoid tissue)