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Anaerobic Bacteria
Microbiology
8
Biology
Graduate
09/15/2008

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Term

 

 

 

Clostridium tetani

Definition
Disease: Tetanus
Characteristics:
  • Anaerobic gram + spore-forming rods
  • "tennis racket"
Habitat and Transmission: Soil. Infection through breaks in skin
Pathogenesis: 
  • Germination in anaerobic conditions in wound
  • Exotoxin
    • blocks release of inhibitory neurotransmitters
    • excitatory neurtons are unopposed
    • Extreme muscle spasm results
    • Lock jaw and risus sardonicus (grimmace)
    •  opisthotonos (arching of back)
Lab Dx: Clinical Dx
Tx: IV IgG
Prevention: Tetanus toxoid vaccine (conjugated)
 
Term

 

 

 

Clostridium botulinum

Definition
Disease: botulism
Characteristics: 
  • Anaerobic gram + spore-forming rods
Habitat and Transmission: Soil.  Transmitted in improperly preserved food.
Pathogenesis:
  • Botulinum toxin is a protease that results in inhibition of Ach release at myoneural jct.
  • Flaccid Paralysis
  • toxin is heat labile
Lab Dx: Presence of toxin in serum or stool or in food.
Tx: Antitoxin to types A, B, and E
Prevention: Proper cooking.
Term

 

 

 

Clostridium perfringens

Definition
Diseases: Gas gangrene
Characteristics: 
  • Anaerobic gram + spore-forming rods
Habitat and Transmission: Soil. Vegetative cells are members of the normal flora of the colon and vagina.  associated with war wounds, motor vehicle accidents and septic abortions.
Pathogenesis: 
  • Alpha toxin
    • damages cell membranes and leads to hemoysis.
Clinical Findings:
  • Pain, edema, and cellulitis in wound area.
  • Crepitation indicates the presence of gas in tissues.
  • Hemolysis and jaundice
  • Blood-tinged exudates
Lab Dx:
  • Large gram + rods.
  • double zone of hemolysis on blood agar
Tx: Penicillin G
Term

 

 

 

Clostridium perfringens

Definition
Disease: Food Poisoning
Characteristics: See other card
Habitat and Transmission: contaminated food
Pathogenesis: 
  • Member of nrl flora of colon but NOT small intestine
  • enterotoxin acts as a superantigen (like S. aureus)
Clinical Features:
  • 8-16 hr incubation
  • watery diarrhea, cramps and little vomiting
  • resolves in 24 hrs
Lab Dx: None
Tx: Symptomatic treatment
Term

 

 

 

Clostridium difficile

Definition
Disease: Pseudomembranous colitis
Characteristics: 
  • Anaerobic gram + spore-forming rods
Habitat and Transmission: Human colon. Fecal-oral transmission.
Pathogenesis: 
  • Antibiotics suppress the normal flora allowing C. difficile to over grow.
  • Exotoxins A and B inhibit signal transduction and depolymerize actin.
  • Leads to apoptosis and death.
  • pseudomembranes seen in colon are visual result of enterocyte death
Lab Dx: Exotoxin detected in stool by cytopatheic effect on cultured cells.
Tx: Metronidazole. Stop causative antibiotic
Prevention: None
Term

 

 

 

Bacteroides fragilis

Definition
Diseases: Sepsis, peritonitis and abdominal abscess DZ Below the Diaphram
Characteristics: Anaerobic gram-negative rods
Habitat and transmission: colon. Transmission by spread from the colon to the blood or peritoneum.
Pathogenesis: 
  • LPS is different and less potent than typical LPS
  • No exotoxins
  • Antiphagocytic capsule
  • At risk: bowel surgery and abdominal wounds
Lab Dx: 
  • Gram Negatvive and anaerobic culture.
Tx: Metronidazole, clindamycin and cefoxitin.  Drain abcesses
Prevention: Pre-op antibiotics
Term

 

 

 

Prevotella melaninogenica

Definition
Disease: Disease Above the Waist, abscess
Characteristics: BLACK -Melanin
 
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Porphyromonas gingivalis

Definition
Gram Negative rod. Found in mouth. anaerobic. cause periodontal infections like gingivitis and dental abscesses.BLACK
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