GI bacteria Flashcards
Is Helicobacter pylori gram positive or negative?
Gram negative (stains pink)
What are the 4 effects of H pylori?
1) Decreased somatostatin
2) increased lumen gastric acid due to more gastrin
3) Urease, results in ammonia generation
4) Low HCO3- secretion
How does somatostatin influence gastrin release?
Somatostatin inhibits release of gastrin
So H pylori decreasing somatostatin means gastrin release not inhibited, so excessive gastrin
What can excessive gastrin release cause?
Duodenal ulcers
How can H pylori survive in the acidic stomach?
Produces urease with catalyses the hydrolysis of urea to ammonia which counters the acid to raise the pH
Urea – urease –> CO2 + ammonia
How does H pylori infection cause decreased bicarbonate secretion?
H pylori downregulates activity of 2 key duodenal mucosal epithelial bicarbonate transporters which mediate HCO3 secretion
What are causes of H pylori infection?
Peptic ulcer disease
Gastritis
Gastric carcinomas
How is a H. pylori infection diagnosed?
1st line: Stool antigen test
C-urea breath test
Biopsy
What is treatment for H pylori infection?
Triple therapy (CAP):
Clarithromycin
Amoxicillin
PPI
Is E Coli gram positive or negative?
Gram negative
True or false: all serotypes/ strains of E Coli are very virulent
False
Some are
ETEC, EAEC and EPEC all cause what symptom?
Watery diarrhoea
What symptom does EHEC cause?
Bloody diarrhoea (H for haemorrhagic)
What type of E Coli can cause haemolytic uremic syndrome?
Serotype O157:H7
What can haemolytic uremic syndrome cause?
Condition occurs when small blood vessels become damaged and inflamed leading to clots which can damage the kidneys.
Results in
Haemorrhagic diarrhoea and nephritic syndrome
How are E Coli infections commonly treated?
Often amoxicillin
or trimethoprim
or nitrofurantoin
Is C. difficile a gram positive or gram negative bacteria?
Gram positive (stains purple)
C difficile is a _____-forming bacteria
spore
C difficile is mainly induced with ______
antibiotics
Which antibiotics induce c difficile infection?
Cs:
Cephalosporins
Co-amoxiclav
Clindamycin
Ciprofloxacin
C difficile cause pseudo_____ _____
pseudomembranous colitis
(severe form of colitis, plaques on colon wall)
What kind of diarrhoea does c diff cause?
Very watery severe diarrhoea
What is a big risk of c difficile?
Dehydration due to watery diarrhoea
Is highly infectious
How do you treat c. difficile?
Stop using C’s antibiotics
Give Vancomycin
