Campylobacter & Helicobacter Flashcards
What are the most common species of Campylobacter associated with human infections?
The most common species of Campylobacter associated with human infections are Campylobacter jejuni and Campylobacter coli.
What is the primary habitat of Campylobacter?
The primary habitat of Campylobacter is the intestinal tracts of mammals, birds, cattle, poultry, as well as domestic animals mainly puppies and kittens.
What are the general characteristics of Campylobacter?
• Helical (spiral or curved) gram-negative rods with a ‘Gull-winged’ appearance.
• Motility by amphitrichous (single flagellum at both ends).
• Thermophilic: 42°C-43°C (except C. fetus).
• Microaerophilic: grow best on enriched media in an atmosphere of low oxygen concentration and high CO₂ (capnophilic).
• Not utilizing carbohydrates.
• Hippurate hydrolysis.
• Urease negative.
What are the virulence factors of Campylobacter jejuni?
- Enterotoxin
- Endotoxin
- Adhesins
- Ability to penetrate cells
- Intracellular survival
What are the common symptoms of campylobacteriosis?
• Diarrhea (often bloody)
• Stomach/abdominal pain
• Fever
• Headache
• Nausea
• Vomiting
What are some autoimmune diseases that can follow Campylobacter infection?
- Guillain-Barré syndrome (acute neuromuscular paralysis)
- Reactive arthritis (Painful swelling of joints often the knees and/or ankles)
- Reiter’s syndrome (arthritis, eye inflammation, and urinary problems).
What are the laboratory identification methods for Campylobacter jejuni?
• Specimen: Stool sample or rectal swabs (in semisolid transport medium).
• Microscopy: Gull-wing appearance in gram stain, darting motility in fresh stool.
• Selective media: CampyBAP, Skirrows media, modified charcoal cefoperazone deoxycholate agar (mCCDA), cefoperazone-amphotericin-teicoplanin (CAT) medium.
• Biochemical Tests: Oxidase +ve, Catalase +ve, Hippurate hydrolysis +ve.
What are the general characteristics of Helicobacter pylori?
• Helical or spiral gram-negative bacilli about 3μm long.
• Rapid cork screw motility due to multiple (4-6) polar flagella (lophotrichous).
• Acidophilic organisms.
• Requires microaerophilic atmosphere for cultivation (lower oxygen levels than atmospheric concentration).
• Oxidase +ve, Catalase +ve, Urease +ve.
What are the virulence factors of Helicobacter pylori?
- Flagella: for motility.
- Urease: neutralizes gastric acidity. The resultant ammonia causes gastric mucosal injury.
- Adhesins: outer proteins that adhere to host cells.
- Secretory enzymes (mucinase, protease, lipase): cause gastric mucosal injury.
- Exotoxin(s): Vacuolating cytotoxin A (VacA) causes gastric mucosal injury.
- CagA (cytotoxin-associated gene A product): a highly antigenic protein associated with a prominent inflammatory response in host epithelial cells by eliciting interleukin-8 production.
What are the non-invasive techniques for diagnosing Helicobacter pylori?
• Urea breath test
• Serologic tests (antibody testing)
• Stool antigen test
What is the pathogenesis of Helicobacter pylori?
• Colonization of the gastric mucosal (epithelial) cells in the stomach.
• Release of urease, which splits urea producing ammonia that neutralizes stomach acid around the microbe.
• Ammonia and the H. pylori cytotoxin cause destruction of mucous-producing gastric cells (Goblet cells), exposing the underlying tissues to stomach acid, leading to ulceration.
• It ultimately results in chronic inflammation.
What are the drugs used to treat Helicobacter pylori peptic ulcers?
• Antibiotics: Dual antibiotic therapy (clarithromycin and amoxycillin; metronidazole is used in place of amoxycillin in those allergic to penicillin).
• Acid-suppressing drugs:
1. H2 blockers: block histamine which stimulates acid secretion.
2. Proton pump inhibitors: inhibit and suppress acid production (e.g., omeprazole).
• Mucosal protective agents: Stomach-lining protector (e.g., antacids).
