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Flashcards in Bacterial Infections Deck (18):
1

Tx: C. difficile

Metronidazole

2

Stool samples in the US should routinely be cultured for the presence of ___, ___, and ___

  1. Campylobacter
  2. Salmonella
  3. Shigella

3

Empiric Tx

Ciprofloxacin

4

Tx: Campylobacter jejuni

Azithromycin

5

  • Anaerobic
  • Autoclaving → sterilization; incineration → decontamination
  • Heat-labile enterotoxins A&B → damage epithelial lining 
  • Antibiotic-associated GI infections
    • Diarrhea
    • Pseudomembranous colitis
  • Resistance to certain antibiotics → alters flora
    • Endogenous overgrowth
    • Exogenous acquisition
  • Discontinue antibiotic (mild cases); metronidazole or vancomycin (severe)

Clostridium difficile

6

  • Enteric fever 
    • Dissemination via lymphatics
  • LPS endotoxin affects vascular permeability and nerve tissue 
    • Rash (weakened BV)
    • Fever (compromised thermal reg.)
  • Vaccine available
  • Chemotherapy indicated

Salmonella enterica Typhi

7

  • Oxidase (-); lactose (-)
  • 2500 serotypes
  • Adhesins allow biofilm formation on small or large intestine mucosa → invasion and toxin extrusion (type III) → intracellular replication within phagosomes (unlike EIEC & Shigella)
  • Dairy, poultry, meat
  • Low ID50

Salmonella enterica

8

  • Microaerophilic
  • Most important etiologic agent for gastroenteritis in the US; also causes septicemia
  • Undercooked poultry
  • Dysentery
  • Resolution ~7-10 days

Campylobacter jejuni

9

  • Type III secretion system → injects 4 exotoxins → phagosome lysis → cytoplasmic replication → actin filament → cell-to-cell passage
  • Water diarrhea or (MC) dysentery
  • Toxin possibility causes HUS
  • MC in children <5 y/o
  • Low ID50

Shigella

10

  • Oxidase (-); peritrichous flagella
  • Watery diarrhea (traveler's diarrhea, bacterial gastroenteritis)
  • Strain with plasmid-acquired:
    • Fimbrial edhesin
    • Heat-labile (cAMP)
    • Heat-stable (cGMP)

Enterotoxigenic E. coli (ETEC)

11

Special culture protocols are necessary for ___, ___, and ___

  1. Vibrio
  2. C. difficile
  3. EHEC

12

  • Oxidase (+); polar flagella
  • Acid labile
  • Halophilic
  • Watery diarrhea, vomiting → dehydration, metabolic acidosis, hypovlemic shock
  • Hydration therapy

Vibrio cholera

13

  • Don't cause infection, rather intoxications (enterotoxins)
  • Foodborne gastroenteritis
  • RAPID onset: N/V, diarrhea
  • Chemotherapy not indicated

Staphylococcus aureus

Bacillus cereus

Clostridium perfringens

14

Tx: H. pylori

Triple therapy

  1. PPI
  2. Clarithromycin
  3. Amoxicillin (Pen allergy = metronidazole)

 

15

Tx for all enterics

E. coli

Shigella

Salmonella

Ciprofloxacin

16

  • Dysentery with high fever
  • Plasmid-mediated adhesion → invasion of colonic epithelium → lyse phagocytic vacuoles → cytoplasmic replication → actin tails → infect adjacent cells
  • Small ID50 
  • Generally self-limiting
  • Very similar to Shigellosis

Enteroinvasive E. coli (EIEC)

17

  • Oxidase (+); polar flagella
  • Microaerophilic 
  • Urease byproducts + exotoxins → localized tissue damage
  • Epithelial cytoskeleton destruction mediated by specific exotoxin inctroduced by type VI secretion
  • Growth suppressed by probiotics

H. pylori

18

Tx: Vibrio

Doxycycline

or 

Azithromycin