4.5 Flashcards
campylobacter genus
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
species of genus campylobacter
most human disease caused by
C jejuni
C coli
campylobacter diseases
common cause of human diarrhoea
may be bloody and associated with nausea, vomiting, abdominal cramps and fever
campylobacter infections acquired from
poorly cooked chicken other food contaminated by uncooked chicken milk form infected cows contaminated natural water sources dogs and cats with the infection
genus helicobacter
disease causing pathogen is helicobacter pylori
gram negative rod with helical morphology
cause majority of peptic ulcers
features posessed by helicobacter pylori allowing it to survive in the acid environment of the stomach and upper duodenum
- 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
how does helicobacter pylori cause damage to the GI epithelial cells
- 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
result of h pylori bacterial damage to the epithelium
makes the epithelial defences against acid and digestive juices less effective
infection with H pylori causes risk of
- 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)