Gram Negative Facultative Anaerobic, Glucose Fermenters

Question 1

Escherichia coli

Answer 1

Acute diarrhea

UTI

Question 2

Escherichia coli O157:H7

Answer 2

Acute diarrhea & colitis

Hemolytic uremic syndrome

Question 3

Salmonella enterica

Answer 3

Acute diarrhea

Question 4

Shigella dysenteriae

Answer 4

Acute diarrhea

Bacillary dysentery

Question 5

Yersinia pestis

Answer 5

Bubonic plague

Septicemic plague

Pneumonic plague

Question 6

Enterics Characteristics

Answer 6

• common residents of mammalian large intestines
• frequent cause of diarrhea and dysentery (esp. Escherichia, Salmonella, Shigella)
• account for significant % of HAIs
• facultative anaerobes; glucose fermenters
• flagella (except Shigella)
• isolated and grown on:
  MacConkey (MAC) agar, Hektoen enteric (HE) agar
  TSI slants
  IMViC tests

Question 7

Antigenic structures and virulence factors of Enterics

Answer 7

• flagellar Ag (H)
• capsule (K)
• cell wall Ag (O)
• exotoxins
• fimbriae

Question 8

Escherichia coli

Answer 8

Tm: fecal-oral route of normal residents
flagella, endotoxin
acute diarrhea, UTIs
Tx: rehydration, abx

Question 9

Escherichia coli O157:H7

Answer 9

Tm: contaminated food and water
flagella, endotoxin, exotoxins, Shiga toxin
acute diarrhea, colitis, dysentery, HUS
Tx: rehydration, Pepto-Bismol

Question 10

Salmonellosis

Answer 10

Tm: contaminated poultry (meat, eggs), milk and dairy products, reptiles
capsule, endotoxin
acute diarrhea, vomiting
Tx: rehydration

Question 11

Shigellosis

Answer 11

Tm: fecal-oral route of contaminated food
spreads easily in crowded settings
enters Peyer’s patches of large intestine
endotoxin, exotoxins, shiga toxin
acute diarrhea, dysentery, nausea,
abdominal cramps
Tx: abx

Question 12

Plague

Answer 12

Tm: flea vectors, respiratory droplets
at risk: veterinarians, woods/forest workers
endotoxin, capsule, coagulase
3 forms

Question 13

Bubonic plague

Answer 13

• most common
• 2-8 day incubation → fever, headache, weakness, buboes (bacterial growth in
  lymph nodes, which become necrotic, swollen and painful)
• buboes may rupture and drain spontaneously
• 50-75% mortality rate

Question 14

Septicemic plague

Answer 14

• bacteria grow in bloodstream
• intravascular coagulation, subcutaneous
  hemorrhaging, internal bleeding, necrosis and
  gangrenous, septic shock

Question 15

Pneumonic plague

Answer 15

• bacteria grow in alveoli, which breakdown and hemorrhage
• highly contagious
• difficulty breathing, bloody and frothy sputum, high heart rate
• toxins spread to left side of heart, causing left-sided heart failure → death
• 100% mortality
  Tx: abx