Group B streptococci — Flashcards

Flashcard 1: Streptococcus agalactiae (GBS) is pyrrolidonyl arylamidase (PYR) _____

Answer: negative

Flashcard 2: Group B strep (Streptococcus agalactiae) is part of the natural flora of the GI tract and _____

Answer: vagina

Flashcard 3: Streptococcus agalactiae (GBS) is catalase _____

Answer: negative

Flashcard 4: Streptococcus pyogenes is also known as _____

Answer: group A strep (GAS)

Flashcard 5: Streptococcus agalactiae (GBS) is hippurate _____ (positive or negative)

Answer: positive

Flashcard 6: Group B Strep (S. agalactiae) has a positive _____ test, meaning it enhances the zone of hemolysis when plated with S. aureus.

Answer: CAMP

Flashcard 7: Gas gangrene

Answer: Clostridium perfringens

Extra: alpha toxin causes myonecrosis and hemolysis

Flashcard 8: 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 9: 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 10: 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.