Anaerobic Pathogens Flashcards
clostridium sp.
*OBLIGATE ANAEROBIC
*gram POSITIVE rods
*FORM ENDOSPORES
*part of the normal flora
clostridium difficile (C diff) - overview
*gram POS anaerobic rod that freely forms spores
*oxygen is toxic
*infection limited to large intestine
*disease is toxin-mediated (not invasive)
clostridium difficile - virulence factors
- Toxin A (enterotoxin) - causes cell death of intestinal mucosa
- Toxin B (cytotoxin) - causes actin depolymerization
C diff - toxin A (enterotoxin)
*chemotactic for neutrophils; stimulates infiltration of PMNs
*cytopathic effect: disruption of tight cell-to-cell junction
*increased permeability of intestinal wall and subsequent diarrhea
C diff - Toxin B (cytotoxin)
*causes actin to depolymerize, with resultant destruction of cellular cytoskeleton
3 required events to get C diff infection:
hospitalization (usually), followed by:
1) change in normal GI flora (ANTIBIOTICS)
2) acquire C diff spore (usually from environment or another person)
3) inadequate IgG response to toxins A and B
what is the name of the disease caused by C diff infection
pseudomembranous colitis
risk factors for C diff
**recent antibiotic exposure
*hospitalization
*recent GI surgery
*recent chemotherapy
*proton pump inhibitors
what is the highly virulent strain of C diff in North America
BI/NAP1
*more likely to cause death
C diff - clinical manifestation
*acute onset of severe, watery diarrhea
*fever, toxicity, high WBC count
**COMPLICATION = TOXIC MEGACOLON
C diff - treatments
*oral vancomycin (recurrences can occur)
*stool transplant is highly effective for recurrent infections
C diff - diagnosis
*demonstration of Toxin A and B in the stool by ELISA
clostridium perfringens - overview
*gram positive rod
obligate anaerobe
**beta (DOUBLE RING) hemolysis
what is the pathogen characterized by beta double ring hemolysis
clostridium perfringes
clostridium perfringens - virulence factors
*alpha toxin - lyses erythrocytes and other cells; mediates massive hemolysis
*beta toxin - causes intestinal stasis and necrotic lesions
*enterotoxin - alters membrane permeability and causes diarrhea