GIT Infection Microbiology: Clostridioides difficile

A set of vocabulary flashcards covering the pathogenesis, risk factors, and toxin mechanisms of Clostridioides difficile infection based on microbiology lecture notes.

Clostridioides difficile

An obligate anaerobic, gram-positive, spore-forming bacillus responsible for pseudomembranous colitis.

Pseudomembranous colitis

A unique colonic disease originating almost exclusively in association with prolonged antimicrobial use.

Toxin A (enterotoxin)

One of two powerful exotoxins secreted by C. difficile; high IgG response to this toxin results in asymptomatic carrying, while inadequate response leads to disease.

Toxin B (cytotoxin)

One of two powerful exotoxins secreted by C. difficile in the intestine that works alongside toxin A to glycosylate GTP binding proteins.

Mechanism of C. difficile Toxins

Toxins A and B glycosylate GTP binding proteins that regulate the cellular actin cytoskeleton, leading to loss of cell shape, adherence, and disruption of the epithelial cell barrier.

Normal Colonic Flora Function (Bile Salts)

Helps in converting primary bile salts to secondary bile salts, which in turn resist the germination of spores.

Risk Factors for C. difficile Infection

Prolonged hospital stay, advanced age ($>65$ years), immunosuppression, cancer chemotherapy, gastric acid suppressant medications, and malignancies.

Antibiotics Implicated in C. difficile

Cephalosporins (e.g., ceftriaxone), clindamycin, ampicillin, and fluoroquinolones (e.g., ciprofloxacin).

Host Immune Response Outcome

The determination of whether a person becomes an asymptomatic carrier (strong IgG response to toxin A) or develops disease (inadequate IgG response to toxin A).