Card Set Information
Bacteriology of helicobacter pylori
With 4-6 unipolar flagellae
Microaerophilic (5% O
Strongly urease positive
Prevalence of H. pylori
Global prevalence >50%
developing countries > developed countries
Mode of transmission of H. pylori
Nosocomial due to contaminated endoscopes
Drinking water and food
Risk factors of H. pylori
Poor socio-economical development
Poor hygiene condition in childhood
Absence of sanitary drinking water
Absence of sewage disposal facilities
Pathology of H. pylori
chronic superficial gastritis + atrophy
Foci of infection of H. pylori
Gastric antral epithelium and foci of peptic ulceration
Found in mucus gel layer over gastric epithelium and some may invade intracellularly into the epithelial cells and into lamina propria
Virulence factors of H. pylori
: urease, motility, adherence
: inaccessibility to immune attack
Altered gastric physiology
Vacuolating cytotoxin (vacA gene), cytotoxin-associated gene A protein (cagA gene)
tissue injury and carcinogenesis
4 Diseases in Stomach caused by H. pylori
Chronic superficial gastritis
Gastric adenocarcinoma of body and antrum
Gastric MALT lymphoma (mucosa-associated lymphoid tissue- type low grade B cell lymphoma)
5 types of diagnosis of H. pylori infection
Bacteriological diagnosis ** for antibiotic sensitivity test
Stool antigen detection test
Antibody detection **for epidemiological studies
What is the sample taken for bacteriological diagnosis of H. pylori infection?
Endoscopic gastric mucosal biopsies transported in sterile saline in microaerophilic culture
may give rise to sampling error
What to look for in histopathological diagnosis of H. pylori infection?
Presence of inflammation
Special stain for H. pylori
What are the samples for serology looking for H. pylori infection?
What’s the difference between enzyme immunoassay and immunochromatographic assays in stool antigen detection tests for diagnosis of H. pylori?
: lab-based using monoclonal antibodies + better accuracy
: rapid in office setting + relatively low sensitivity
What are the two types of urease-based tests?
Rapid urease test (using biopsies of gastric mucosa)
urea breath test
What’s the difference between eradication and clearance?
Clearance = absence of detectable organisms immediately after stopping therapy
Eradication = absence of detectable organisms >/= 4 weeks after stopping therapy
What are the Agents used for eradication of H. pylori?
Ranitidine bismuth citrate
Which of the eradication agents of H. pylori has resistance?
Nitroimidazole (e.g. metronidazole)
What are the eradication regimens for H. pylori?
Triple therapy (PPI-based/ bismuth-based)
Ranitidine bismuth citrate-based therapy
Quadruple therapy and second-/third-line treatment
What is triple therapy?
: PPI + Clarithromycin + amoxicillin/ metronidazole (10-14 days)
: bismuth + metronidazole + amoxicillin/ tetracycline
Yet both have low eradication power due to resistance to metronidazole/ clarithromycin
What is ranitidine bismuth citrate-based therapy?
Ranitidine bismuth citrate + clarithromycin + (amoxicillin/ metronidazole)
What is quadruple therapy and second-/third-line treatment of H. pylori infection?
PPI + bismuth + two antibiotics (TM/ AC)
PPI + 3 antibiotics (MAC)
Levofaloxacin- or moxifloxacin-based regimens
What is sequential therapy of H. pylori infection?
5D of PPI + amoxicillin
5D of PPI + C+ M
What are the 4 normal intestinal defence mechanisms?
enteric normal flora -> colonization resistance
What are the normal flora of the stomach?
swallowed oral bacteria
What are the normal flora of the duodenum?
transitory oral bacteria
What are the normal flora of the colon?
4 Control measures of enteric infectios
public health measures
non-specific host factors
Principles of therapy of infectious diarrhoea
Fluid replacement (oral rehydration solution ORS)
Antimotility agents (avoided in invasive infections)
What are the 3 types of toxins and their respective examples?
secretory toxins e.g. Vibrio Colerae, enterotoxigenix E. Coli, Clostridium Perfringens
cytotoxins e.g. Shigella, enterohaemorrhagic E. Coli, Clostrium Difficile
neurotoxins e.g. Clostridium botulinum, Staphylococcus aureus, Bacillus cereus