GASTROINTESTINAL PATHOGENS
Helicobacter pylori
Dr. Edwin Ginés-Candelaria
Helicobacter pylori
GENUS
Stained in stomach tissue samples obtained from
autopsies many years ago
Uknown dismissed as transient till cultured in 1982
First classified as Campylobacter (cell morphology)
Later reclassified as Helicobacter
GENERAL CHARACTERISTICS
Gram negative S-shaped short spirals
Multiple polar flaggela (sheathed)
Urease positive
RESERVOIR/SOURCE-TRANSMISSION
Resident of surface stomach’s mucosa where mucus
protects from stomach’s acidity
Helicobacter pylori
RESERVOIR/SOURCE-TRANSMISSION
Organism’s prevalence due to production of urease that
neutralize stomach’s acidity —> increasing local pH
Method of transmission
» Not clearly established. Infections appear to be
clustered in families
» One study involving clinical staff obtaining a tissue
biopsy indicate direct contact (w/ stomach contents)
PATHOGENESIS
Peptic Disease Syndrome (gastritis/peptic ulcers)
» Organisms use flagella to penetrate mucose layer,
adhesins (pilus?) to adhere to fucose containing
surface CHOs and blood group antigens on gastric
epithelial cells (specifically in gastric pits)
Helicobacter pylori
PATHOGENESIS
Peptic Disease Syndrome (gastritis/peptic ulcers)
» Mucus production decreases as result of toxic effect
or body’s inflammatory response
» Thining of mucus at infection site —> peptic ulcer of
stomach/duodenum
» Cytotoxin may be involved-cause vacoulation of
gastric epithelial cells (prominent histopathological
feature)
» Symptoms
• Nausea, anorexia, vomiting, epigastric pain, low
stomach’s acidity
• Asymptomatic cases usually occur for decades up
to perforated disesase
PATHOGENESIS OF Helicobacter pylori LEADING TO
ULCERATION OF THE STOMACH
Helicobacter pylori
PATHOGENESIS
Peptic Disease Syndrome (gastritis/peptic ulcers)
» Organism’s urease involved in local pH rise
» 75% gastric ulcer patients (95% have documented
infections w/ H. pylori)
» Correlation between high incidence of H. pylori
infections and increasing risk of stomach cancer
SPECIMEN/DIAGNOSIS
Stomach biopsy (a fiberoptic endoscope is introduced
into stomach through mouth and pinches off small piece
of stomach lining)
Organisms grow after 2-5 days on enriched media under
microarophillic conditions (increasing CO2, humidity)
Helicobacter pylori
SPECIMEN/DIAGNOSIS
Positive Urease test
Cell morphology
Breath Test - Radioactively labeled urea is swallowed
and detection of radioactively labeled CO2 in patient’s
breath w/in 30 min
TREATMENT
Combination of bismuth salts (Bismuth subsalicylate-
Pepto-Bismol)
Antibiotic treatment - metronidazole, tetracycline or
amoxicillin
» Treatments leads to disappearance of peptic ulcer
» Recurrence rate - low