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Helicobacter spp Flashcards

1
Q

When was Helicobacter spp. first observed?

A

1983

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2
Q

What type of organisms were Helicobacter spp. first identified as in the stomachs of patients?

A

Campylobacter-like organisms

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3
Q

In what year was the genus Helicobacter established?

A

1989

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4
Q

What type of bacteria is Helicobacter spp.?

A

Curved spiral gram negative bacteria

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5
Q

Which specific strain of Helicobacter is a human pathogen with no animal reservoir?

A

Helicobacter pylori

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6
Q

What disease is Helicobacter pylori associated with?

A

Peptic Ulcer Disease

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7
Q

What is the treatment for Helicobacter pylori infections?

A

Antibiotics

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8
Q

What type of malignancies can Helicobacter pylori trigger?

A

MALT Malignancies

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9
Q

What is the global prevalence of Helicobacter pylori?

A

50%

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10
Q

What is the prevalence of Helicobacter pylori in developing countries?

A

80%

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11
Q

What is the first step in the pathogenesis of H. pylori?

A

Mucosal Penetration

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12
Q

How does H. pylori penetrate the mucosal layer?

A

Equipped with multiple flagella

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13
Q

What compounds attract H. pylori to the epithelial surface?

A

Hemin and urea

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14
Q

What enzyme does H. pylori use to neutralize gastric acid?

A

Urease

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15
Q

What does urease hydrolyze to produce ammonia?

A

Urea

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16
Q

What does ammonia help to do in the stomach?

A

Neutralize local gastric acid

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17
Q

What is the consequence of H. pylori triggering an inflammatory response?

A

Chronic gastritis

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18
Q

What do the cytotoxins released by H. pylori damage?

A

Mucous-producing epithelial cells

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19
Q

What can the erosion of the protective barrier by H. pylori lead to?

A

Ulceration and potentially gastric cancer

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20
Q

What is the role of flagella in bacteria?

A

Essential for motility, enabling the bacterium to swim through gastric mucus and reach the epithelial surface.

21
Q

What is urease and its function?

A

A key survival enzyme that breaks down urea into ammonia and carbon dioxide, neutralizing gastric acid in the immediate environment.

22
Q

What are lipopolysaccharides (LPS) and their significance?

A

Present in the bacterial outer membrane, these LPS molecules are less immunogenic than typical gram-negative LPS, helping the bacterium evade immune detection while contributing to chronic inflammation.

23
Q

What does VacA (Vacuolating cytotoxin A) do?

A

Induces vacuole formation in gastric epithelial cells, leading to cell damage and modulates immune responses by inhibiting T cell activation and promoting apoptosis.

24
Q

Name three types of secretory enzymes and their functions.

A
  • Mucinase: Breaks down mucins in the protective mucus layer, facilitating bacterial movement.
  • Protease: Degrades host proteins, including immunoglobulins and extracellular matrix components.
  • Lipase: Hydrolyzes host lipids, potentially altering cell membranes and aiding invasion.
25
What is the Type IV Secretion System (T4SS)?
A needle-like apparatus used to inject bacterial proteins (effector molecules) directly into host cells, encoded by the cag pathogenicity island.
26
What is CagA (Cytotoxin-associated gene A) and its role?
Once delivered into host cells via the T4SS, CagA becomes phosphorylated and interferes with host cell signaling pathways, promoting inflammation, altering cell polarity, and may contribute to carcinogenesis.
27
True or False: Lipopolysaccharides (LPS) are highly immunogenic.
False
28
Fill in the blank: Urease neutralizes gastric acid by breaking down _______ into ammonia and carbon dioxide.
urea
29
What is the function of mucinase?
Breaks down mucins in the protective mucus layer, facilitating bacterial movement.
30
What is the effect of CagA on host cells?
Interferes with host cell signaling pathways, promotes inflammation, alters cell polarity, and may contribute to carcinogenesis.
31
What are the invasive techniques for detecting H. pylori?
Examine gastric biopsies taken at endoscopy
32
What are the non-invasive techniques for detecting H. pylori?
Serology, urea breath tests, faecal antigen tests, rtPCR of faeces
33
Why is proper specimen handling crucial for H. pylori culture?
H. pylori is a highly fastidious and fragile microorganism
34
What type of specimens are preferred for H. pylori culture?
Gastric or duodenal mucosal samples
35
How should biopsy specimens be transported to maintain H. pylori viability?
Immediate transport in a specialized transport medium like Portagerm pylori
36
What factors can rapidly kill H. pylori during specimen transport?
Exposure to oxygen, desiccation, and room temperature
37
What is the purpose of grinding or homogenizing biopsy tissues before culture?
To release bacteria into suspension, enhancing the likelihood of recovery
38
What type of media is typically used for H. pylori culture?
Selective media including enriched agar base and blood supplements
39
What blood supplements are used in the culture media for H. pylori?
Horse or sheep blood
40
What antimicrobials are used in H. pylori culture to suppress competing flora?
Vancomycin, polymyxin B, amphotericin B
41
What are the atmospheric requirements for H. pylori growth?
Microaerophilic (5% O₂) and capnophilic (about 10% CO₂)
42
At what temperature does optimal growth of H. pylori occur?
37°C
43
How long does it typically take for H. pylori colonies to appear?
3–7 days, although some may take longer
44
What is the Gram stain result for H. pylori?
Gram-negative spiral
45
Is H. pylori oxidase positive or negative?
Oxidase positive
46
Is H. pylori catalase positive or negative?
Catalase positive
47
What biochemical test result is positive for H. pylori?
Urease positive
48
What molecular target is used for detecting H. pylori?
cagA
49
What is the standard treatment for H. pylori infection?
Triple therapy of amoxicillin, clarithromycin, and proton pump inhibitor

Medical Microbiology lectures (10 decks)

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