GBTC 5212 Exam 3 (Campylobacter and Helicobacter)

What shared traits do Campylobacter and Helicobacter have?

• Spiral gram-negative rods

• Microaerophilic (reduced oxygen) conditions

• Unable to ferment or oxidize carbohydrates

What trait is shared between all species of Campylobacter?

Motile rods

What are the clinically important species of Campylobacter?

jejuni, coli, fetus

Where is C. jejuni found?

Jejunum

Where is C. coli found?

Colon

Where is C. fetus found?

Fetal infections

What kind of flagella do Campylobacter species have?

Amphitrichous

What virulence factors are found in C. jejuni?

• Enterotoxin

• Adhesin

• Cytotoxin

What is the pathogenesis of C. jejuni?

• Histological damage to the mucosal surface of the jejunum, ileum, and maybe the colon

• Mucosal surface is: ulcerated, edematous, bloody, crypt abscesses in the epithelial glands, and infiltration of the lamina propria with neutrophils, mononuclear cells and eosinophils

What autoimmune disorder is associated with C. jejuni?

Guillain-Barré Syndrome

What is Guillain-Barré Syndrome?

An autoimmune disorder of the peripheral nervous system

What is the pathogenesis of Guillain-Barré Syndrome?

The host produces antibodies that damage the myelin sheath that surrounds the peripheral nerves

What is the cause of Guillain-Barré Syndrome?

Results from antigen cross-reactivity between oligosaccharides of Campylobacter and glycolipids on the surface of the neural tissues

What are the symptoms of Guillain-Barré Syndrome?

• Rapid onset of numbness

• Weakness, and often paralysis of the legs, arms

• Paralysis may include breathing muscles, and face

• Paralysis is ascending, it travels up the limbs from fingers and toes towards the torso

• Unsteady walking or inability to walk or climb stairs

• Difficulty with eye or facial movements, including speaking, chewing or swallowing

• Difficulty with bladder control or bowel function

What can Guillain-Barré Syndrome be triggered by?

• Most commonly, infection with Campylobacter

• Influenza virus

• Cytomegalovirus

• Mycoplasma pneumonia

• Hepatitis A, B, C and E

• HIV

• Zika virus

What virulence factor is associated with C. fetus?

Protein S

What is Protein S?

Heat stable capsule-like protein

What does Protein S provide?

Serum resistance by inhibiting the binding of complement component C3b; interferes with complement-mediated phagocytosis

What is Protein S responsible for?

• Bacteremia

• Septic thrombophelibitis

• Arthritis

• Septic abortion

• Meningitis

What characterizes zoonotic Campylobacter infections?

Healthy chickens and cattle carry the bacteria and serve as reservoirs

What are C. jejuni outbreaks associated with?

Contaminated food

What are potential causes of C. jejuni outbreaks?

• Contaminated raw chicken

• Unpasteurized milk

• Possibly non-chlorinated water

What species of Helicobacter are clinically important?

pylori

How does H. pylori differ from other Helicobacter species?

• Multiple polar flagella

• Unique composition of the cell wall fatty acids

• Production of urease

Why is H. pylori virulent?

It survives the highly acidic stomach environment

How does H. pylori survive in acidic environments?

• The bacterium is sensitive to low pH (~4.0).

• It both neutralizes and avoids the gastric acidity

How does H. pylori neutralize gastric acid?

• Acid hydrolyzing protein blocks acid secretion from the parietal cells

• Urease hydrolyzes urea into NH₄ and CO₂

How does H. pylori avoid gastric activity?

• Flagella allow the bacteria to burrow through newly secreted mucin to reach the gastric mucosa and to migrate toward areas of higher pH

• Mucinase and phospholipase disrupt gastric mucus

How does H. pylori cause local tissue damage?

• By-products of urease digestion of urea

• Vacuolating cytotoxin (VacA) produces holes in cultured mammalian cells

• Phospholipase

What does H. pylori colonization cause?

Histological evidence of gastritis

What are the symptoms of acute gastritis?

• Feeling full

• Nausea

• Vomiting

• Hypochorhydra (decreased acid secretion in the stomach)

What can acute gastritis evolve into?

Chronic gastritis

What are the symptoms of chronic gastritis?

• Localized to the gastric antrum in individuals with normal acid secretion

• May involve the entire stomach (pan-gastritis) in individuals with suppressed acid secretion

What clinical diseases are associated with H. pylori?

• Gastritis and peptic ulcers

• Associated with gastric cancer (non-cardia gastric cancers)

• Associated with lymphoma of the mucosa-associated lymphoid tissue (MALT) and gastric adenocarcinoma

What H. pylori mechanism is associated with oncogenesis?

• Enhancement in the production of free radicals around the H. pylori infection site

• Increases the mutation rate of the host cells within the area

What does chronic gastritis eventually lead to?

Replacement of normal gastric mucosa with fibrosis

What is gastric fibrosis associated with?

100-fold increased risk of gastric cancer

What is gastric cancer associated with?

• CagA positive H. pylori strains

• Higher levels of IL-1 production

What does H. pylori require for growth?

• Complex medium

• Microaerophilic atmosphere

• Up to 2 weeks

How is H. pylori diagnosed?

Urease test on biopsies of fundus and antrum