17 - Campylobacter Campylobacter Among the most widespread...

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Campylobacter Campylobacter
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Campylobacter Among the most widespread cause of infection in the world. Cause both diarrheal and systemic diseases Campylobacter jejuni
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Typical Organisms Gram-negative rods with comma, S, or “gull-wing” shapes. Motive, with a single polar flagellum No spore & no capsule
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Culture An atmosphere with reduced O 2 (5% O 2 ) with added CO 2 (10% CO 2 ) At 42 (for selection) Several selective media can be used (eg, Skirrow’s medium) Two types of colonies: watery and spreading round and convex
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Virulence Factor Lipopolysaccharides (LPS) with endotoxic activity Cytopathic extracellular toxins and enterotoxins have been found
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Pathogenesis The infection by oral route from food, drink, or contact with infected animals or animal products( Milk, meat products ). Susceptible to gastric acid (about 10 4 organisums)
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diarrhea diarrhea malaise malaise fever fever abdominal pain abdominal pain usually self-limiting antibiotics occassionally bacteremia small minority small minority Campylobacter Campylobacter - - symptoms symptoms Incubation: 4-8d Acute enteritis: 1w, stools remain positive for 3 w Acute colitis Acute abdominal pain Bacteremia: <1% C. jejuni Septic abortion Reactive arthritis
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Diagnostic Laboratory Tests Specimens: Diarrheal stools Smears: Gram-stained smears of stool may show the typical “gull-shaped” rods. Culture: (have been described above)
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Control The source of infection may be food (eg, milk, under-cooked fowl) or contract with infected animals or humans and their excreta.
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Curved bacilli – Former name - Campylobacter pylori , H. pylori Helicobacter pylori
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Helicobacter pylori Helicobacter pylori is the prototype organism in this group. It is associated with antral gastritis, gastric ulcers, and gastric carcinoma.
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Microbiology Gram negative rod, curved, Very Motile corkscrew motion Microaerophilic, use amino acids and fatty acids rather than carbohydrates to obtain energy needs 10% CO 2 and 5% O 2 Urease production Catalase production Oxidase positive Growth at 37 0 C, not 25 0 C or 42 0 C
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Virulence factors vacA (vacuolationg associated) cytotoxin, Pathogenicity island: cag, cytotoxin associated gene A+genes related to bacterial secretion Cag + HP is much more associated with peptic ulcer disease than Cag (--) HP.
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Pathogenesis Motility – it moves into the mucus and produces adhesins on gastric epithelial cells (not intestinal epithelial cells) Urease production, breaks down the urea to ammonia which buffers the pH around the bacterium. Persists, escape defense mechanisms – SOD, catalase, Urease. Breack down free radicals
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Pathogenesis H pylori invade the epithelial cell surface to a certain degree Toxins and LPS may damage the mucosal cells NH 3 produced by the urease activity may also damage the cells
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Epidemiology
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Epidemiology Prevalence related to socioeconomic level during childhood.
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17 - Campylobacter Campylobacter Among the most widespread...

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