Lecture 31 - Hepatobiliary bacteria Flashcards
what bacteria are specific to the liver
- fusobacterium necrophorum
- clostridium spp.
describe fusobacterium
gram - rod
anaerobe (tolerant)
grows at physiologic pH
ferments lactate
habitat of fusobacterium
- GI tract
- oral cavity
- genitourinary tract
- soil contaminant
what are fusobacterium virulence factors
- hemolysin
- hemagglutinin
- adhesins
- dermonecrotic toxin
- platelet aggregation factor
the endotoxin LPS does what
has necrotic effect on tissue to induce DIC and create an anaerobic environment
how does leukotoxin work
protects the bacteria against phagocytosis from lymphoid cells
describe how a liver abscess forms due to F. necrophorum
grain feeding and mucosal trauma allow for colonization nd spread via portal vein
necrobacillosis
suppurative and necrotic with foul-smelling pus
high morbidity; low mortality
fusobacterium in calves
calf diphtheria
damage to mucosa from feed, virus, or allergen and subsequent production of leukotoxin creates lesions in pharynx, larynx, oral cavity
fusobacterium in cattle
hepatic necrobacillosis (liver abscess)
economically significant
how is fusobacterium diagnosed
- clinical signs
- liver abscess at slaughter
- anaerobic culture
T/F: liver function tests are a good indicator of fusobacterium presence
FALSE
in humans, fusobacterium is called
lemierre’s syndrome
pharynx and tonsils to jugular vein and abscesses
how is fusobacterium treated and prevented
- abx therapy
- feedlot management
describe clostridium spp.
gram + rods that form endospores and are motile anaerobes
what is the habitat of clostridium species
- GI tract
- soil, freshwater, sediments
what are endospores? what is their significance?
resistant, asexual spores that develop in a bacterial cell that survive conditions the cell would not normally
what are the histotoxic clostridium
- C. novyi
- C. septicum
T/F: histotoxic clostridium affect primarily grazing animals
TRUE
infectious necrotic hepatitis
C. novyi type B
sheep
spores migrate to liver and are activated by liver damage (e.g. flukes)
acute death, no signs
braxy
C. septicum
sheep
necrotizing abomastitis characterized by anorexia, depression, and fever
how to diagnose histotoxic clostridium
- cytology
- anaerobic culture
- fluorescent antibody staining
- PCR (alpha-toxin)
T/F: treatment for histotoxic clostridium is usually ineffective
TRUE
while vaccination is available for histotoxic clostridium, what additional prevention measures should be taken for C. novyi
fluke control
describe enteropathogenic/toxemic clostridium
species that replicate and produce elaborate toxins in the GI tract that are encapsulated to protect against phagocytosis
what are the two important enteropathogenic/toxemic clostridium
- C. perfringens
- C. difficile
Clostridium perfringens pathogenesis
requires the presence of intestinal clostridia AND altered enteric microenvironment
hemorrhagic enteritis
C. perfringens in pigs
type C = newborns, death
type A = feeders/>2 weeks, chronic D+ and anorexia
Lamb dysentery
C. perfringens type B
first week of life
abdominal distention, pain, and blood-stained feces
Hemorrhagic enterocolitis
C. perfringens type C
neonatal calves, foals, piglets, and lambs
beta toxin susceptible to trypsin (low levels in newborns)
C. perfringens diagnostics
- sudden death in unvaxxed
- post-mortem exam
- samples
- anaerobic culture
- toxin detection
why is it important to collect samples promptly
to avoid invasion of clostridium species from intestine to tissues
treatment and control for C. perfringens
- hyperimmune serum
- vaccination
- avoid sudden dietary changes
what is a significant clostridial pathogen in human medicine
C. difficile
what toxins are produced by C. difficile
A = enterotoxin
B = cytoxin
T/F: more hosts are colonized with C. dfficile than those that show clinical signs
TRUE
T/F: C. difficile causes only hemorrhagic necrotizing enterocolitis
FALSE - range from enterocolitis to pseudomembranous
what does C. difficile cause in dogs and horses
dog = chronic D+
foals = hemorrhagic enterocolitis
what is an atypical clostridial organism
C. piliforme
Tyzzer’s Disease
C. piliforme
foals 1-4 weeks old
causes focal liver necrosis, acute fatal disease after brief illness
match the scientific bacterial name to the common disease
a. C. novyi
b. C. piliforme
c. C. septicum
d. C. perfringens type B
e. C. difficile
- lamb dysentery
- chronic D+ in dogs
- infectious necrotic hepatitis
- tyzzer’s
- braxy
a. 3
b. 4
c. 5
d. 1
e. 2
