HAI - Clostridium difficile Flashcards

1
Q

What is clostridium difficile?

A

A typically commensal bacteria found in the guts of children, and in low amounts in some adults (asymptomatic carriage)

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2
Q

What are the main toxins that Clostridium difficile produce?

A

ToxA (308 kDa enterotoxin)
ToxB (270 kDa cytotoxin)

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3
Q

What are the steps in toxin mechanism?

A

Attachment
Endocytosis
Acidification of vacuole
Release of enzymatic domain
Action on GTPases

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4
Q

Summarise toxin attachment and endocytosis

A

Toxins bind to specific receptors on host intestinal epithelial cells. Toxins are internalised into the host cell via endocytosis, forming an endocytic vesicle

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5
Q

Summarise acidification of vacuole and release of enzymatic domain

A

Endocytic vesicle undergoes acidification, which is necessary to allow translocation of their enzymatic domain into host cell cytoplasm

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6
Q

Summarise action of toxins on GTPases

A

The enzymatic domains of the toxins glucoslyate small GTPases such as Rac and Rho, resulting in their inactivation. This disrupts various cellular processes, including actin cytoskeleton organisation

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7
Q

What is the result of the disruption of actin cytoskeleton organisation?

A

Damages the absorptive surface of the interstinal epithelium. This impairs nutrient absorption, and contributes to diarrhea

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8
Q

What can occur as a result of the toxins in severe cases?

A

Pseudomembraneous colitis: - Plaques of nectrotic tissue slough from colon - Can be fatal

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9
Q

In what environments does C. difficile thrive?

A

Less diverse microbiota. Therefore use of antibiotics allows it to thrive.

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10
Q

What often happens when antibiotics are used to treat C. difficile?

A

Antibiotics kill them, however the spores produced by C. difficile remain, so when antibiotic treatment ceases, the spores can germinate again, causing another infection

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11
Q

What is ribotype 027?

A

A fluroquinolone resistant type of C. difficile

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