Listeria monocytogenes — Flashcards

Flashcard 1: Which Gram-positive rod grows well at refrigeration temperatures (4°C; cold enrichment)?

Answer: Listeria monocytogenes

Flashcard 2: Tropheryma whipplei is an intracellular, gram _____ organism

Answer: positive

Flashcard 3: Strep pneumonia contains _____, allowing bacteria to adhere and colonize the mucous membranes.

Answer: IgA protease

Flashcard 4: Gas gangrene

Answer: Clostridium perfringens

Extra: alpha toxin causes myonecrosis and hemolysis

Flashcard 5: Gram stain status of Clostridium perfringens

Answer: Gram-positive (+)

Extra: Characteristics: - Morphology: Large, box-car shaped Gram-positive bacilli - Oxygen requirement: Anaerobe - Pathogenesis: Alpha toxin (lecithinase) - Clinical: Gas gangrene (myonecrosis), food poisoning

Flashcard 6: Characteristics of Clostridium botulinum:

Answer: Gram-positive bacilli, anaerobic, spore-forming

Extra: Clinical features: Botulism (descending paralysis), Floppy baby syndrome (infant botulism from honey). Toxin: Botulinum toxin (protease that cleaves SNARE proteins, preventing ACh release).

Flashcard 7: What are the key microbiological characteristics and toxins of Clostridium tetani?

Answer: Gram-positive, anaerobic, spore-forming bacilli (drumstick appearance)

Extra: - Tetanospasmin: Neurotoxin that blocks release of inhibitory neurotransmitters (GABA and glycine) from Renshaw cells in spinal cord. - Clinical features: Trismus (lockjaw), Risus sardonicus (raised brows, open grin), Opisthotonus (back arching). - Spores are found in soil; enter via penetrating wounds.

Flashcard 8: _____, _____, and _____ are important spore-forming Gram-positive bacteria found in soil.

Answer: Bacillus anthracis

Flashcard 9: What is the causative agent of Diphtheria?

Answer: Corynebacterium diphtheriae

Extra: Exotoxin inhibits protein synthesis via ADP-ribosylation of EF-2. Presentation: Pseudomembranous pharyngitis (grayish-white membrane), cervical lymphadenopathy ("bull neck"), myocarditis, arrhythmias, and cranial nerve palsies.

Flashcard 10: Gram stain and morphology of Corynebacterium diphtheriae:

Answer: Gram-positive bacilli (non-spore forming)

Extra: - Morphologically described as club-shaped, V or L shaped (Chinese letter appearance). - Culture: Black colonies on Cystine-Tellurite agar (Tinsdale medium). - Biochemical: Catalase positive. - Key pathogen: Causes Diphtheria (pseudomembranous pharyngitis).