GI Pathogens 2 Flashcards
What are the general Characteristics of clostridia
- Gram (+)
- Anaerobic
- Make spores
- Exotoxins
What are the 3 relevant types of clostridium
Clostridia (C. perfringens and difficile and piliforme)
What are the 4 toxins produced by C. perfringens
o Alpha: phospholipase (dermonecrotic/hemolytic/cytolytic)
o Beta: pore forming activity/hemorrhagic (dermonecrotic/hemolytic/cytolytic)
o E: alter cell membrane permeability causing edema
o L: cytoskeleton damage = necrosis
o Theta: hemolysin (perfringolysin) - (form pores/cytolytic/osmotic diarrrhea)
- Toxins: alpha toxin, most with theta toxin (cholesterol dependent cytolysin = perfringolysin)
- 5 toxinotypes: A, B, C, D, E – make 4 major toxins
List a histotoxic and enteric clostridia
C. perfringens
What type of toxin does type A C. perfringens have
- Type A: alpha toxin (also theta toxin)
What type of toxin does type B C. perfringens have
- Type B: toxin A, B, e
What type of toxin does type C C. perfringens have
- Type C: toxin A, B
What type of toxin does type D C. perfringens have
- Type D: a, e
mainly produces epsilon toxin - converted to active form in intestine
What type of toxin does type E C. perfringens have
- Type E: A, l
What is the disease manifestation of type A C. perfringens in poultry, pigs, horses, and cows
o Poultry: necrotic enteritis
o Suckling and feeder pigs: necrotizing enterocolitis
o Equine> hemorrhagic mucosal necrosis
o Beef: abomasal ulcer/tympany
o Dairy: necrotic enteritis in calf
o Adult cattle: haemorrhagic bowel syndrome
What is the disease manifestation of type B C. perfringens
o Ovine hemorrhagic enterotoxemia
o Hemorrhagic enteritis
What is the disease manifestation of type C C. perfringens
o Neonatal hemorrhagic or necrotizing enterotoxemia
What is the disease manifestation of type D C. perfringens
o Ovine enterotoxemia
What is the disease manifestation of type E C. perfringens
o Bovine hemorrhagic enteritis
What C. perfringens toxin causes food poisoning
o CPE enterotoxin
Zoonotic/cause food poisoning
Pore forming (cytotoxic) and interfere with tight junctions (alter paracellular permeability)
What are the associated lesions with type A C. perfringens
o Lesions
‘red gut’ – large sections of small intestine or red/purple and full of blood
Sudden death in dairy/feedlot cow (enterotoxemia)
What factors contribute to development of type D C. perfringens infection
o Associated with alteration in GI microbiota: diet change (high concentrate) – overeating disease
o Short course of disease > fatal
What is the general pathogenesis of type A C. perfringens infection
o Pathogenesis
Overgrowth of C. perfringens
Enzymes allow cleavage of mucin on epithelium
Act on TNFa = cause sloughing of epithelium
Activate host proteases to cut off basal epithelium
Phospholipase affect membranes of epithelium and vasculature
= necrosis/hemorrhage/sloughing epithelium
What are the lesions and main species affected by type D C. perfringens infection
o Lesions:
Enterotoxemia
Pulpy kidney
o Species: Calf/goat/horse/mostly lambs
What are the clinical manifestations of C. difficile in pigs and people
C. Difficile: Clostridioides difficile
* Human: antibiotic associated diarrhea
o Diarrhea/pseudomembranous colitis/fulminant colitis
* Pig: neonatal (1-7d) = mesocolonic edema (full of yellow fluid)
What is the main clinical consequence of C. difficile
- Neutrophilic diarrhea
What are the toxins produced by C. difficile and what are their functions
TcdA acts on the apical side = disrupt tight junction = allow TcdB to enter and act on basal side of enterocyte
o Toxins: A (TcdA enterotoxin) + B (TcdB cytotoxin)
Inactivate regulation of actin cytoskeleton = open tight junctions = cell death
Increase proinflammatory cytokines + activate enteric NS = PMN chemotaxis and fluid secretion
Form volcano lesions in intestine (inflame cells leak into lumen)
How do you diagnose C. perfringens infection
- C. perfringens: PE/gross/histo lesions
o Anaerobic culture with double zone of hemolysis
o Multiplex PCR or ELISA = identify toxin
How do you diagnose C. difficile infection
- C. difficile: anaerobic culture
o Neutralization test/ELISA = identify toxin (best way for dx)
How to prevent clostridia in cattle
- 7 way cattle vaccine: C. chauveoi (blackleg) /septicum /sordelli (malignant edema)/novyi (black disease)/perfringens (3 types)
What are the general characteristics of C. piliforme
- Spore forming – can live 1 year in dirty bedding
- Obligate anaerobic + obligate intracellular
- Cause icterus: alter liver function
How to stain C. piliforme
- Gram (-) – but gram (+) under strictly anaerobic conditions
- gram stain depends on the environment
- Stain with silver stain or giemsa stain
What is the disease that C. piliforme causes in horses? How do they get it? Prognosis? Prevention?
- Tyzzers disease: foals
o From ingestion of spores from environment
o Unknown pathogenesis
o Poor prognosis
o No vaccine
o Farm hygiene
What is the disease that C. piliforme causes in dog/cat? How do they get it? Main lesions? Prognosis?
- Tyzzers disease: dog/cat
o Due to ingesting rodent feces with spores
o Higher risk if stress/immunosuppressed
o Lesions: thickened intestine mucosa in distal ileum and proximal colon + foamy dark brown feces
o Poor prognosis = fatal
What is the pathogenesis of tyzzers disease in dogs/cats
o Locally proliferate in enterocytes – spread to liver – colonize hepatocytes = multifocal periportal hepatic necrosis due to toxin
Necrotic ileitis or colitis
What is the main risk factor for clostridium infection
Risk factors: disruption to normal GI microbiota
What is the morphologic characteristic of spirochetes
- Thin/long/flexible bacteria
How to stain spirochetes
- Silver stain (gram (-) but less effective than silver stain)
What are the 4 main genus’s of spirochete GI bacteria
- Genus
o Leptospira
o Borrelia
o Treponema
o Brachyspira
What are the 2 main types of brachyspira causing GI disease
Brachyspira (B. hyodysenteriae and pilosicoli)
What animals does B. Hyodysenteriae infect
- Pigs – 6-12 weeks
What are the general characteristic s of B. Hyodysenteriae? What type of disease does it cause
- Infectious colitis
- Oxygen tolerant anaerobe
- Obligate symbiotic
- Environmentally resistant
What are the clinical and gross signs of B. Hyodysenteriae
o Emaciation
o Lots of mucus-y feces
o Dehydration
o Edema of large intestine walls
o Low mortality but high production loss
How to diagnose B. Hyodysenteriae
- Diagnose: post mortem
o Fluorescent stain
o Anaerobic culture
PCR
What is a main virulence factor of B. pilosicoli
B. pilosicoli
* Virulence factors
o Beta hemolysins (can kill cells)
What is the pathogenesis of B. pilosicoli
o Verry motile in mucin
o Chemotaxis
o Attach to apical membrane of enterocutes = loss of microvilli
o Serine protease secretion = damage tight junctinos = parracytoss
o chronic extracellular infection – in goblet cells and lamina propria
o colonic malabsorption = osmotic diarrhea
What are the general characteristics of campylobacter spp.
- gram (-)
- microaerophilic
- commensal in intestines and repro tract
What are 3 relevant types of campylobacter spp
o C. fetus fetus and C. fetus venerealis = abortion
o C. jejuni = enteritis
What are the main risk factors and clinical signs of C. jejuni? What else should be considered
- Zoonotic
- Risk: young/immunocompromised
- Clinically: self limiting diarrhea (+/- mucoid/blood)
o Fever
How is diagnosis and treatment of C. jejuni complicated?
- Diagnosis: difficult to confirm in animals without diarrhea
o Can worsen the effects of other GI pathogens - Treat: resistance is more common (resistant to fluoroquinolones)
What are the main types of helicobacter
- Types:
o H. felis, bizzozeronii, heilmanni
o H. pylori
What type of disease is helicobacter associated with
- Associated with chronic gastritis in dogs
What are the general characteristics of yersinia spp
- Family: Enterobacteriaceae (also salmonella/e. coli)
- Gram (-)
- Facultative anaerobe
What are the 3 main types of yersinia
o Y. pseudotuberculosis and enterocolitis
o Y. pestis
Plague
Human/cat/rodent
What is the clinical manifestation of Y. pseudotuberculosis and enterocolitis and what species does it affect? How to prevent
Enterocolitis/sporadic abortion – diarrhea
Farm animal/wildlife/humans – deer (common)/sheep
Vaccine available
What is the clinical manifestation of Y. pestis and what species does it affect
Plague
Human/cat/rodent
What 4 pathogens cause enteric disease in cattle
Johnes dz
Salmonella
Clostridia
Neonatal diarrhea - ETEC
What 4 pathogens cause enteric disease in horse
Salmonella
Potomac horse fever
Clostridium associated enterocolitis
Lawsonia intracellularis
What 2 disease complexes and the associated pathogens cause enteric disease in foals
Bacterial enterocolitis in neonaatal foals
- kleibsiella
- salmonella
- e. coli
- clostridia
haemorrrhagic diarrhea in foals
- C. perfringens
- Bacteroides fragilis
- rhodococcuss equi
What 6 pathogens cause enteric disease in pigs
Salmonella
C. difficile/perfringens (type C)
ETEC
Brachyspira hyodysenteriae (dysentery) or pilosicoli (spirochetosis)
Lawsonia intracellularis
What 6 pathogens cause enteric disease in cat/dogs
Salmonella
Campylobacter
Helicobacter
Shiegllosis
Tyzzer’s disease
C. perfringens
