1. Gastrointestinal pathogens: Helicobacter pylori
Prof. Alaa Al-Charrakh
Babylon University
Gastrointestinal pathogens: Helicobacter pylori

2. Family Vibrionaceae: Include the genera:
Gastrointestinal pathogens
Family Vibrionaceae: Include the genera:
Vibrio
V. cholerae: cholera
V. parahaemolyticus: gastroenteritis
Aeromonas
A. hydrophila: gastroenteritis; wound infection
Campylobacter
C. jejuni: gastroenteritis
Helicobacter
H. pylori: gastritis; peptic ulcer; gastric cancer, MALToma

3. Helicobacter pylori Morphology and Physiology
Spiral-shaped, gram-negative rod.
Highly motile with polar flagella.
Grow on complex media in microaerophilic (5% O2 and 10% CO2 ) conditions.

4. H. pylori Physiology Grows optimally at a pH of 6.0-7.0.
Able to survive in the stomach because
1. it stays deep in the mucus layer near
the epithelial surface where physiological
pH is present;
2. it produces a potent urease, which catalyzes production
of ammonia that further neutralizes the acid;
3. It produces an acid-inhibitory protein that blocks acid secretion from parietal cells.
Dr. Barry Marshall

5. Pathogenesis and Clinical Diseases
Present on the gastric mucosa of less than 20% of persons under 30
increases in prevalence to 40%-60% of persons age 60.
The prevalence reaches over 80% in developing countries.
H. pylori is associated with gastritis, peptic ulcer, gastric adenocarcinoma, gastric mucosa-associated lymphoid type (MALT) B-cell lymphomas.
Chronic gastritis is a risk factor for gastric carcinoma.

6. Pathogenesis and Clinical Diseases
steps in ulcer formation:
Colonization of the epithelial cells (inhibit gastric acid secretion, neutralization of gastric acid, pass through the gastric mucus, adhere to the epithelial cells)
Localized tissue damage by urease byproducts, enzymes (mucinase, phospholipase etc.), and cytotoxins (vacuolating cytotoxin A)
stimulation of inflammatory response by LPS.

7. Gastric ulcer formation with H. pylori

8. Laboratory diagnosis Treatment, Prevention, and Control
Histological examination of gastric biopsies
Culturing biopsy specimens
Urease test is a rapid methods for detection of H. pylori in biopsy specimens or pure culture.
Urea-breath test
Treatment, Prevention, and Control
Treatment:
Bithmus plus antibiotics
Omeprazole (a proton pump inhibitor), clarithromycin plus ammoxicillin or metronidazole
Humans are the main reservoir.
Mechanism of transmission is most likely oral-fecal, and improved hygienic standards can be helpful for prevention.