7 Gram Negative Rods: Enterobacteriaceae (Inefectious Bacterial Agents)

Question 1

Gastrointestinal Gram-negative rods

Answer 1

• Normal Flora
• Found due to fecal contamination
• Disease inside/outside GI tract

Question 2

Escherichia coli

Answer 2

• Gram negative rod
• E. COLI IS THE MOST COMMON CAUSE OF URINARY TRACT INFECTIONS (UPEC)
• Common E. coli strains: ETEC, EPEC, EHEC, EIEC, EAEC

Question 3

ETEC (EnteroToxigenic E. coli)

Answer 3

• Releases HEAT-STABLE (ST) AND HEAT LABILE TOXIN (LT)
• Traveler’s diarrhea
• Transmission: FECAL-ORAL route

Question 4

EPEC (EnteroPathogenic E. coli)

Answer 4

• T3SS leads to PEDESTAL DEVELOPMENT
• Watery Diarrhea in infants w/poor sanitation
• BfpA on pili
• Non-invasive

Question 5

EHEC (EnteroHemorrhagic E. coli)

Answer 5

• HEMOLYTIC UREMIC SYNDROME (HUS) infection
• Antimicrobial treatment can release more toxins and worsen outcome
• Bloody diarrhea

Question 6

EIEC (EnteroInvasive E. coli)

Answer 6

• INVASION OF EPITHELIAL CELLS (IPA)

- Dysentery syndrome w/fever and blood stools

Question 7

EAEC (EnteroAggregative E. coli)

Answer 7

• AGGREGATIVE ADHERENCE FIMBRIAE
• Traveler’s diarrhea
• Shiga-like toxin 2

Question 8

Salmonella

Answer 8

• Gram negative, produce H2S
• Eggs, poultry, pet turtles
• Typhi and Typhimurium
• Typhi in gall bladder
• Invasion of M (microfold) cells
• Clinical significance: Gastroenteritis, Enteric or Typhoid Fever

Question 9

Shigella

Answer 9

• Gram negative rod
• Causes SHIGELLOSIS
• Humans only nature host
• Virulence: Shiga toxin, T3SS
• Clinical Significance: invasion/destruction of large intestine, bloody diarrhea, HUS w/S. dysenteriae

Question 10

Other Enterobacteriaceae

Answer 10

• Enterobacter: nosocomial infections
• Klebsiella: bacteremia in hostpital pts, multi-drug resistant infections
• Serratia: multi-drug resistant

Question 11

Campylobacter Jejuni

Answer 11

• Curved (vibrio), Spiral (spirillum) or S-shaped
• Darting motility, fecal-oral contamination
• Virulence: cytotoxin and enterotoxin
• Clinical significance: Acute enteritis, Guillian-Barre

Question 12

Vibrio

Answer 12

• Short curved Gram (-)
• Rapid motility from single polar flagella, growth media contains NaCl
• Found in aquatic environments

Question 13

Vibrio Cholerae

Answer 13

• Cholera disease
• Consumption of raw/undercooked seafood
• Contaminated water outbreaks
• Virulence: Cholera toxin (AB-toxin) –> RICE WATER STOOLS

Question 14

Helicobacter pylori

Answer 14

-Curved or spiral Gram (-) rods (spirochete)
-Virulence factors: Urease, Cytotoxin
Clinical significance: Acute gastritis, DUODENAL/GASTRIC ULCERS