Helicobacter Flashcards
Helicobacter is a main risk factor for which major diseases?
Gastric & duodenal ulceration
Stomach cancer
Gastric MALT (mucosa-associated lymphoid tissue) lymphoma
List the general characteristics of H.pylori
• Gram negative curved rod
• Microaerophilic: requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere
• Motile
• Produces oxidase,mucinase and urease enzymes
What are the virulence factors of H.pylori?
• Corkscrew motility enables penetration into mucosal layer Adhesins: which help it adhere to epithelial cells
• Mucinase: Degrades gastric mucus; Localized tissue damage
• Urease converts urea into ammonia;neutralize the local acid environment
• Localized tissue damage
Vacuolating cytotoxin (VacA)- apoptosis in eukaryotic cells generating large cytoplasmic vacuoles -epithelial cell damage
Type IV secretion system
Describe pathogenesis of H.pylori
- Attachment – H. pylori binds to mucus-secreting gastric cells.
- Urease Activity – Produces ammonia from urea.
- Acid Neutralization – Ammonia neutralizes stomach HCl.
- Survival & Inflammation – Bacteria survive, triggering inflammation.
- Mucosal Damage – Leads to tissue injury.
- Disease Manifestation – Results in gastritis and peptic ulcers.
Clinical manifestations of H.pylori
Gastric lesions (cancer)
vomiting
Non-invasive diagnostic methods?
Blood antibody test- lgG detection
Stool antigen test- detection of specific antigens in the stools
carbon urea breath test
Invasive methods of diagnosis?
Gastric biopsy
• Urease positive
• Culture on Helicobacter Agar- takes 3-5days
Oxidase, urease positive
State the general characteristics of aeromonas.
Gram-negative
facultatively anaerobic
bacillus resembling members of the Enterobacteriaceae
Motile species have single polar flagellum
Mode of transmission of aeromonas?
Ingestion or exposure to contaminated food and water
State the clinical manifestations of aeromonas.
chronic diarrhoea
wound infections
