Lecture 32 - Food Borne Disease Flashcards
describe Yersinia
Gram - rod mostly motile with bipolar staining (closed safety pin)
T/F: Yersinia is zoonotic
TRUE
T/F: all yersinia cause enterocolitis
FALSE - Y. pestis causes the plague
Yersinia pseudotuberculosis pathogenesis
adhere to M cells and the basolateral surface of ilium to migrate to lymphoid cells
T/F: Y. pseudotuberculosis has tropism for respiratory cells
FALSE - tropism for lymphoid cells
what is the overall pathogenesis of yersinia in 5 steps
- adhere and type 3 secretion systems
- invasion into phagocytic cells
- intracellular survival in macrophages
- replication in lymph nodes
- extracellular spread
what are the clinical signs of Y. pseudotuberculosis
V+, D+/constipation, weight loss, depression
what are the clinical diseases of Y. pseudotuberculosis
acute gastroenteritis
mesenteric lymphadenitis
septicemia
mastitis/abortion in ruminants
describe Y. enterocolitica
facultative intracellular and extracellular has yops protein that interferes with phagocytosis
grows well at low temperatures
what is the most common Yersinia spp.
Y. enterocolitica
what species is most commonly infected with Y. enterocolitica
pigs
as an important foodborne pathogen, what is the reservoir for human illness and what is it commonly confused with
reservoir = pigs
differential = appendicitis
how are Yersinia spp. diagnosed
- giemsa stains
- cold culture
- PCR
how is Yersinia treated
antibiotics because resistance is uncommon
how does prevention differ for Y. pseudotuberculosis and Y. enterocolitica
pseudotuberculosis focuses on wildlife control whereas enterocolitica focuses on safe food handling
describe vibro spp.
gram - rod that is motile and a facultative anaerobe
what is the general pathogenesis of vibrio spp.
- adherence and invasion of enterocytes
- T3SS
- enterotoxins
Vibrio vulnificus
gastroenteritis
liver disease in immunocompromised
would/soft tissue infections
many require hospitalization
Vibrio parahaemolyticus
gastroenteritis with watery D+
self limiting after 3 days
higher concentration in summer
how is vibrio diagnosed
- sample
- culture - gold standard
- PCR
what is the treatment for vibrio
fluid and elyte therapy
severe require antibiotics
wound cleaning and debridement
how can you prevent vibrio
- do not consume raw shellfish
- avoid cross-contamination
- avoid going into the water with cuts
Describe Listeria spp.
gram + coccobacillus is a motile and facultative anaerobe that replicates in the environment
tolerate wide temp and refrigeration, prefers neutral pH
what is the most common listeria spp.? what species is most commonly affected?
listeria monocytogenes; ruminants
how is listeria transmitted among animals
- grazing
- contaminated food products
- fecal-oral
describe the pathogenesis of listeria
- adheres
- internalized into enterocytes
- further invades phagocytic cells
- spreads further via lymph and blood
*transplacental in pregnant animals
internalins (a)
gets into enterocytes
listerolysin (c)
lysis of phagolysosome
actin-polymerizing protein (ActA/D)
direct formation of tail-like structures to propel bacteria through cell
pseudopod projection (e)
taken up into adjacent cells
how is listeria diagnosed
- clinical signs and hx of feeding silage
- histology
- cold culture
- PCR
how do humans get listeriosis
consumption of contaminated food (dairy and deli products)
how is listeria treated and controlled
tx: abx
control: avoid feeding poor quality silage and vaccines
