Lecture 7: GI 2 Flashcards
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)
what causes porcine colonic spirochaetosis?
brachyspira pilosicoli
what are some clinical signs of swine dysentry? Even though this disease has a low mortality, why do we care?
emaciation, mucus in feces, dehydration, edema of the walls of the intestine, usually in pigs weaned 6-12 weeks of age
we care because there are huge economic losses
how do you diagnose swine dysentry? How do you treat it?
- on PM
- fluorescent stains on smears
- anaerobic culture
- PCR
treatment: antibiotics such as Tiamulin
what are 3 virulence factors of brachyspira pilosicoli
- the bacteria is highly motile in mucin
- undergoes chemotaxis via mucin to the enterocytes
- serine protease secretion affects tight junction integrity
what are the 5 steps of brachyspira pilosicoli infection pathogenesis ?
- attachment to apical membranes of enterocytes, loss of microvilli
- persistence extracellularly in the lamina propria and intracellularly goblet cells
- beta-haemolysin released
- induction of outpouring of mucus into the lumen
- diarrhea results from colonic malabsroption due to failure of epithelial transport mechanisms
campylobacter species are gram _____ and are commensals of the
negative
intestines and reproductive tract
true or false: campylobacter causes diarrhea in many species invluding small animals
true
if a small animal is infected with a campylobacter species, what does the diarrhea look like?
mucoid, smetimes blood flecked, sometimes with fever
why is it difficult to confirm a campylobacter infection in small animals?
because animals without diarrhea will also test positive for campylobacter as they are normal commensals of the intestines
who is most at risk of developing a campylobacter infection? In dogs specifically, who is at risk?
- young and immunocompromised at risk
- in dogs, campylobacter way worsen effects of other GI pathogens like giardia or helminths
is campylobacter zoonotic?
YES and resistance is becoming a problem in humans
The most important clinical effects of Campylobacter infection are….
infertility in cattle caused by C. fetus subsp venerealis and abortion in ewes caused by either C. fetus subsp fetus or C. jejuni
Helicobacter spp. are common inhabitants of the
canine stomach
Chronic canine gastritis has been associated with
Helicobacter, BUT a causative relationship has not been proven
Although gastric ulcers and gastric cancer are strongly related to H. pylori infection in people…..
a similar relationship between Helicobacter spp. and gastric ulcers or cancer has not been shown in dogs
true or false: there is a relationship between Helicobacter spp and gastric ulcers in dogs
FALSE!
there is no significant relationship between helicobacter spp and gastric ulcers in dogs
Yersina spp are ______ anaerobes
facultative
what are the 3 pathogenic species of yersina?
- pestis
- enterocolitica
- pseudotuberculosis
yersina enterocolitica and pseudotuberculosis cause _____ in farm animals and wildlife, _____ in humans
yersina pestis causes ______ in humans, cats, rodents
enterocolitis and sporadic abotions, gastroenterocolitis
plague
______ is one of the most common and important diseases of farmed deer
enteric yersiniosis (pseudotuberculosis more severe than enterocolitica)
who gets infected with enteric yersiniosis, what are the clinical signs, and when does this disease usually happen?
- young farm animals, esp deer and sheep. can also happen in lab animals
- diarrhea sometimes death
- during cold wet weather
