E2 Anaerobes Flashcards
Where do anaerobes like to live?
Intestinal tract
Commensals!
What is common pathogenic factor among anaerobes?
Toxins!
What are the two classes of anaerobes?
- Obligate = die in O2
2. Aerotolerant = kinda like facultative bacteria but use fermentation
Why do obligate anaerobes die when exposed to O2?
H202 and superoxide are formed
= toxic
= lack enzymes to deal with these chemicals
What are signs of an anaerobic infection (4)?
- Painful tissue necrosis
- Gas in the wound
- Foul odor
- Black discoloration
What are some anaerobic environments in healthy animals?
- Oral cavity between teeth and gums
2. Intestines
How can anaerobic grow in wounds?
Facultative bacteria use up all the O2 first
What is Eh?
Measure of redox potential
Lower Eh = more anaerobic environment
What is a spore forming Gram POSITIVE bacteria that are anaerobic?
Clostridium!
What are the two groups of Clostridium?
- Tissue invasive w/ weak toxins
2. Non-invasive w/ severe toxins
Where do Clostridium live in nature?
Soil!
Can also be normal commensals
What is type A Clostridium?
Has only alpha toxin
Normally present in intestines of healthy animals
What type of toxins do Clostridia have?
Exotoxins
= secreted toxins
What is the most dangerous toxin?
Alpha toxin
What type of diseases are caused by Type A Clostridium?
Necrotizing myositis in horses
Gas gangrene
Yellow lamb disease = enterotoxemia
What toxin is in Type D clostridium?
Alpha & Epsilon toxins
What are some disease caused by Type D clostridium?
Enterotoxemia of sheep & goats
“Pulpy kidney disease”
“Overeating disease”
= Epsilon toxin!
What is Clostridium chauvoei?
Black leg in ruminants 1. Wounds 2. Inhalation 3. Tooth loss = necrotic muscle tissue
What is special about Clostridium chauvoei’s pathogenesis?
Can remain latent until tissue is damaged!
What is Clostridium septicum?
Malignant edema
Ingestion of spores
Rapid death! 1-2 hrs
How is Clostridium septicum different from Clostridium chauvoei (Blackleg)?
C. septicum does NOT produce gas!
What is Clostridium difficile?
Pseudomembranous enterocolitis
What can cause Clostridium difficile infections?
Antibiotics
What are the clinical signs of Clostridium difficile infection?
Bloody diarrhea
How is Clostridium difficile diagnosed?
PCR of feces
What are the 2 non-invasive super toxic Clostridia?
- C. botulinum
2. C. tetani
What is Clostridium tetani?
Causes Tetanus or “Lockjaw”
What species are most susceptible to Clostridium tetani? Least susceptible?
Most = Horses & Humans Least = Cats, Chickens
Of the 3 Clostridium tetani toxins which one is the most pathogenic? What does it do?
Tetanospasmin
Blocks inhibitory NTs at NMJs
How do animals become infected with Clostridium tetani?
Spores enter damaged tissue
Why is the toxin so lethal?
Binding is permanent
Need to wait for protein turnover
What species experience ascending tetanus?
Dogs & cats
= via nerves
What species experience descending tetanus?
Horses & Humans
= via blood stream
What are clinical signs of Clostridium tetani infection?
- Stiffness
- Third eyelid
- Bloat
What do Clostridium tetani look like microscopically?
Drumsticks
What is used for the Clostridium tetani vaccine?
Toxoid
What is special about Clostridium botulinum?
Forms the most potent toxin known
What is common route of Clostridium botulinum poisoning?
Contaminated food
What kind of paralysis is produced by Clostridium botulinum?
Flaccid paralysis
C. tetani = spastic paralysis
What is Clostridium botulinum toxicity in birds called?
“Limberneck”
How is Clostridium botulinum infection diagnosed?
Detection of toxin
How is Clostridium botulinum toxicity treated?
Anti-toxin!
What are some Gram NEGATIVE anaerobic rods?
- Bacteroides
2. Fusobacterium
What is Dichelobacter nodosus?
Obligate parasite of hooves
“Contagious foot rot” in sheep
Secondary invader! after Fusobacterium
FOUL smelling
What is the virulence factor for Dichelobacter nodosus?
Keratin degrading proteases
What is Fusobacterium necrophorum?
Calf diphtheria
Food rot in cattle = “Scald”
Swine = “Bullnose”
What is Prevotella melaninogenicus?
Causes suppurative lesions
Implicated in periodontal disease