Anaerobic Bacteria Flashcards
What is the most common cause of anaerobic bacteremia?
Bacteroides fragilis
What are characteristics of C. perfringens when plated?
Few to no spores, decolorization of some bacteria, double zone of hemolysis
What are the four common characteristics of most anaerobic bacterial infections?
Endogenously acquired, polymicrobial, involve abscesses, foul odor & gas
What is the neurotoxin released by C. tetani?
Tetanospasmin
What is the function of C. perfringens epsilon lethal toxin?
Increases vascular permeability of the GI wall
What diseases are associated with C. perfringnes infection?
Cellulitis, fasciitis, myonecrosis, food poisoning (toxin-mediated), enteritis necroticans (toxin-mediated)
What are the common G- anaerobic bacteria?
Bacteroides, Porphyromonas, Prevotella, Fusobacterium
What is the most common Actinomyces spp.?
Actinomyces israelii
What are the common Clostridium spp.?
C. perfringens, C. tetani, C. botulinum, C. difficile
Describe the mechanism of tetanospasmin.
Travels to inhibitory neurons via blood or retrograde transport. Prevents the release of inhibitory GABA, resulting in uncontrolled muscle spasms.
This Clostridium spp. grows in alkaline or neutral foods in anaerobic conditions.
C. botulinum
Fusobacterium is normal flora in what locations?
Mouth, colon, female genital tract
What is the process of myonecrosis by C. perfringens?
Spores enter tissue from the environment. Toxins damage and kill cells. Enzymes facilitate the spread of the organism. Metabolic activity of the organism produces gases. Toxins can lead to shock, renal failure, and death.
What symptoms may be associated with C. perfringens infection?
Enterotoxin-mediated –> food poisoning, watery diarrhea
What is the most common type of C. perfringens? What lethal toxin does it produce?
Type A, alpha toxin
This C. perfringens lethal toxin contains a phospholipase that degrades cell membranes and lyses cells.
Alpha toxin
Trench Mouth/Vincent’s Angina is often a coinfection with what bacteria?
Prevotella, Fusobacterium
What are the symptoms of Trench Mouth/Vincent’s Angina?
Acute necrotizing ulcerative gingivitis, tender, bleeding gums, foul breath, bad taste
Bile-esculin agar is required for growth of which anaerobic bacteria?
Bacteroides fragilis
What are some of the characteristics of Actinomyces?
Aerotolerant or obligate anaerobe, G+, filamentous and branched morphology, normal flora in the mouth, GI tract, and female genital tract
What are the symptoms of Leimerre’s syndrome?
Acute oropharyngeal infection, pharyngitis, fever, lethargy, neck
tenderness & swelling, jugular vein thrombophlebitis, abscess formation in the lung
What are the symptoms of cervicofacial actinomyces?
Chronic, slow-developing infection. Lesions with pus that contain sulfur granules that are yellow in color
What diseases are associated with Fusobacterium infection?
Trench Mouth/Vincent’s Angina & Lemierre’s Syndrome
This Clostridium spp. is a common nosocomial infection. It is often the result of antibiotic use that kills normal flora.
C. difficile
What neurotoxin is released by C. botulinum?
Botulinum toxin
These bacteria have a drumstick-like appearance with spores at the end of the organism.
C. tetani
Where are Bacteroides spp. most often found?
Gut microbiome
What virulence factors are associated with Bacteroides fragilis?
Capsule, beta-lactamase, heat-labile zinc metalloprotease toxin, rearranges actin, induces IL-8 release, Cl- release and water loss
This C. perfringens lethal toxin has necrotizing activity and increases vascular permeability.
Ioda toxin
What C. perfringens lethal toxin has necrotizing activity in the intestinal mucosa?
Beta toxin
Describe the mechanism of the botulinum toxin.
A-B exotoxin. The toxin binds receptors on motor neurons and prevents release of acetylcholine at the neuromuscular junction. This causes spastic paralysis.
What is the mechanism by which C. difficile toxins cause symptoms?
Toxins depolymerize actin, disrupting intercellular junctions. This results in cell apoptosis, hypersecretion of fluids, and inflammation.
What bacteria is the cause of Leimerre’s Syndrome?
Fusobacterium nucleatum
