Lecture 7: GI 2 Flashcards
(45 cards)
clostridia bacteria are gram ______, and thrive in a _____ envionment, and form _______ that can remain dormant for years. One of the things they are best at which is closely related to their pathogenesis is the production of ______
positive
anaerobic
spores
exotoxins
C. perfringens strains are classified into five toxinotypes (ABCDE), based on …..
the production of four major toxins: alpha, beta, epsilon, and iota (there is also the theta toxin which most strains of C. perfingens produce)
briefly describe what each of the clostridial perfingens toxins do
alpha: a phospholipase acting on cell membranes, cytolytic, hemolytic, dermonecrotic
beta: pore forming activity, hemorrhage, cytolytic, dermonecrotic
epsilon: alteration of cell membrane permeability, causing edema in various organs
iota: cytoskeleton necrosis
theta: a hemolysin, pore forming, cytotoxic, lethal leakage of water and ions by enterocytes, causes diarrhea
type A food poisoning id caused by _______, which produces ______ which causes disease in _______
C. perfringens type A
enterotoxin at the moment of sporulation
humans
clostridium perfringens enterotoxin (CPE) seems to be a bifunctional toxin. describe the two things it does
- pore formation, cytotoxic due to plasma membrane permeability alterations
- interaction with the epithelial tight junctions which alters paracellular permeability
type A C. perfringens causes a disease in poultry called ______. What does this disease look like in poultry? There is a predisposition for this disease, what is it?
necrotic enteritis (NE): results in decreased rates of gain, necrosis in jejunal and ileal mucosa, often short clinical course culminating in death
predisposition: high fiber diet and concurrent coccidiosis
sucking and feeder pigs can get a disease caused by type A C. perfringens called ______
necrotizing enterocolitis (with villous atrophy)
type A C. perfringens causes what disease in horses?
neonatal hemorrhagic diarrhea/hemorrhagic mucosal necrosis
what disease does type A C. perfringens cause in the following species?:
- beef calves
- dairy calves
- adult cattle
beef calves: abomasal ulceration and tympany
dairy calves: necrotic enteritis in newborns
adult cattle: hemorrhagic bowel syndrome
when doing a necropsy on a cow with type A C. perfringens infection, the most impressive finding is _____
‘redgut’ in which large segments of the small intestine are reddish purple anf filled with blood
type D C. perfringens causes _______ which affects calves, goats, horses, and adult cattle, but is most prevelant in _____. This disease is associated with…
enterotoxemia
young lambs
upsets in the gut microbiota, sudden changes in feed to a rich diet, or continuous feeding ofa high ration diet. Notable for its short clinical course and fatal outcome
C. defficile disease (CDAD) is responsible for a high percentage of cases of ______. How do these cases present?
antibiotic-associated disease
C/S: diarrhea, colitis, pseudomembranous colitis or fulminant (severe sudden onset) colitis
CDAD has emerged as the main cause of enteritis in _____
neonatal pigs
clostridium difficile causes neutrophilic diarrhea by producing two toxins. Name these toxins and what they do
- A toxin (TcdA), an enterotoxin
- B toxin (TcdB), a cytotoxin
these toxins inactivate proteins involved in regulation of the actin cytoskeleton. disaggregation of polymerized actin leads to the opening of tight junctions and cell death. they also cause the release of proinflammatory mediators and cytokines and activation of the enteric nervous system leading to polymorphonuclear neutrophil chemotaxsis and fluid secretion.
how do you diagnose C. perfringens and C. difficile?
C. perfringens: clinical signs, gross, microscopic lesions, multiplex PCR for toxins, ELISA for toxins, can culture but it must be anaerobic
C. difficile: culture, toxin detection via neutralization test or ELISA
what is the best way to prevent clostridial infections in cattle?
there is a 7 way vaccine for cattle:
- chauveoi (black leg)
- septicum (malignant edema)
- sordelli (malignant edema)
- novyi (black disease)
- 3 types of perfringens (enterotoxemia)
Tyzzer’s disease in foals is caused by ______. What are some characterisics of this bacteria?
clostridium piliforme
- super oxygen sensitive/strict anaerobe
- gram labile: gram neg but gram + when stained under anaerobic conditions
- obligate intracellular bacterium
- use silver stain or giemsa to see it
- spores can survive up to 1 year in soiled bedding
how is Tyzzer’s disease in foals transmitted? what is the pathogenesis? If a foal has this disease, what is the prognosis? How do you prevent this disease?
- ingestion of spores from environment
- pathogenesis is very poorly understood
- prognosis is poor
- no vaccines available, rely on farm hygiene, well grassed paddocks may help prevent exposure to contaminated soil
Tyzzer’s disease can also happen in cats and dogs. How is it transmitted and what is the pathogenesis? What is the prognosis?
- transmission via ingestion of rodent feces containing spores
- the bacteria locally proliferates in the intestinal epithelial cells. after stress or immunosuppression of the host the bacteria can spread by the portal system to the liver
- the bacteria then colonizes the hepatic parenchyma, resulting in multifocal periportal hepatic necrosis, probably due to a toxin that is not yet identified
- prognosis is bad, usually fatal
what are some gross lesions of Tyzzer’s disease in dogs and cats. What two things together indicate a Tyzzer’s infection in dogs and cats? Can you treat this disease?
- thickening of intestinal mucosa at the terminal ileum and proximal colon, foamy dark brown feces
- multifocal periportal hepatic necrosis and necrotic ileitis or colitis
- treatment is not successful
what is the major risk factor for developing a clostridial infection?
disruption of normal gut flora
C. perfringens primarily affects______, while C. difficile primarily affects_____
- neonatal farm animals (enterotoxemia and bloody diarrhea)
- horses, piglets, humans, lab animals (antibiotic associated diarrhea in adults, usually less bloody)
what stain should you use to view a spirochete bacteria?
silver stain (since spirochetes are gram negative)
swine dysentry is caused by ________.
brachyspira hyodysenteriae (infectious colitis)
