Gram-negative US Medical PG Flashcards - Medical Study Cards
Master Gram-negative with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Gram-negative Flashcard Deck - 10 Cards
Flashcard 11: Production of what byproduct differentiates Salmonella from Shigella?
Answer: Salmonella produces hydrogen sulfide
Flashcard 12: What morphologic feature distinguishes Salmonella from Shigella?
Answer: Salmonella has flagella
mnemonic: salmon swim
Flashcard 13: Key characteristics of Shigella spp.?
Answer: Gram-negative, non-motile, non-lactose fermenting bacilli; causative agent of bacillary dysentery.
Extra: Key features of Shigella:
- Gram-negative rods
- Non-motile (distinguishes from Salmonella)
- Non-lactose fermenters (colorless colonies on MacConkey agar)
- Low infectious dose (as few as 10–100 organisms)
- Causes bloody diarrhea (dysentery) via Shiga toxin (S. dysenteriae) and invasion of M cells in Peyer's patches.
Flashcard 14: Key microbiological characteristics of Salmonella enterica?
Answer: Gram-negative bacilli, non-lactose fermenter, motile, H2S producer, causes enteric fever or gastroenteritis
Extra: Salmonella enterica:
- Morphology: Gram-negative bacilli
- Metabolism: Non-lactose fermenter (on MacConkey agar)
- Motility: Motile (flagellated)
- Key trait: Produces H2S (black colonies on TSI/HE agar)
- Transmission: Fecal-oral
- Clinical: Entreic fever (Typhoid), gastroenteritis, osteomyelitis (especially in Sickle Cell disease)
Flashcard 15: Describe the classic appearance of sputum from Klebsiella pneumonia.
Answer: "red currant jelly" sputum
Flashcard 16: What populations are most commonly associated with Klebsiella pneumonia?
Answer: alcoholics, diabetics
Flashcard 17: What are the key characteristics and common clinical presentations of Klebsiella pneumoniae?
Answer: Characteristics: Gram-negative bacilli, mucoid colonies (large capsule), fast lactose fermenter.
Clinical: Lobar pneumonia (alcoholics/diabetics, "currant jelly" sputum), nosocomial UTIs, and liver abscesses.
Extra: Klebsiella is a member of the Enterobacteriaceae family. It is non-motile and urease positive. The 'currant jelly' sputum is due to its thick polysaccharide capsule.
Flashcard 18: Main causative agent of Hemolytic-Uremic Syndrome (HUS)
Answer: EHEC O157:H7 (Shiga toxin-producing E. coli)
Extra: HUS Triad:
1. Microangiopathic hemolytic anemia
2. Thrombocytopenia
3. Acute renal failure (uremia)
Flashcard 19: What test distinguishes EHEC from other E. coli strains?
Answer: EHEC can't ferment sorbitol
Flashcard 20: What are the clinical manifestations of Enterohemorrhagic E. coli (EHEC)?
Answer: Causes Hemolytic-Uremic Syndrome (HUS) and hemorrhagic colitis (bloody diarrhea)
Extra: - Serotype O157:H7 is the most common cause.
- Produces Shiga-like toxin (Verotoxin).
- Does not ferment sorbitol (unlike other E. coli).
- HUS triad: Anemia (MAHA), Thrombocytopenia, Acute Renal Failure.
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