Group A streptococci — Flashcards

Flashcard 1: Streptococcus agalactiae (GBS) is _____-hemolytic

Answer: beta

Flashcard 2: Streptococcus pyogenes (GAS) is pyrrolidonyl arylamidase (PYR) _____

Answer: positive

Flashcard 3: S. pyogenes (GAS) is bacitracin _____

Answer: sensitive (sensitive or resistant)

Flashcard 4: Streptococcus pyogenes contains the enzyme _____,which breaks down connective tissue, allowing for the spread of cellulitis

Answer: hyaluronidase

Flashcard 5: Streptococcus pyogenes results in _____, which is a superficial infection of the skin

Answer: erysipelas

Flashcard 6: Gas gangrene

Answer: Clostridium perfringens

Extra: alpha toxin causes myonecrosis and hemolysis

Flashcard 7: 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 8: 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 9: 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 10: _____, _____, and _____ are important spore-forming Gram-positive bacteria found in soil.

Answer: Bacillus anthracis