Salmonella Flashcards
What are the 2 species of salmonella?
-S. enterica
-S. bongori
What types of animals does S. bongori infect?
cold blooded, reptiles
Does salmonellosis cause enteric or systemic disease?
both
Enteric disease is found:
in the GI tract
Systemic disease is found:
it can reach the bloodstream
How many subspecies does S. enterica have?
6
How many serovars does S. enterica have?
2000
Are S. enterica and S. bongori gram (-) or (+)?
gram (-)
What type of animals does S. enterica infect?
warm blooded animals
Is salmonella aerobic or anaerobic?
anaerobic (can live with or without oxygen)
When a horse has diarrhea there is always a risk of what?
laminitis
Host-adaptive
-it causes specific symptoms
-serovars produce systemic infections (not diarrhea)
-abortus-equi
Is salmonella host or non-host adaptive?
both
Typhoidal
-diarrhea
-typhoid fever
-paratyphoid fever
Non-typhoidal
diarrhea
Non-host adapted
-typhoidal or non-typhoidal
-typically produces colitis and diarrhea
-can produce systemic disease in neonates
What host-adapted Salmonella serovar causes abortion and hemorrhagic foal death?
abortus-equi
Where is abortus-equi rare?
in the US
Source of infection
-difficult to identify
-possibly feed already consumed
-infected animals
Route of infection
fecal oral –> water, feed, feces, worker contaminated hands, etc.
Where are outbreaks of salmonella most common?
in hospitalized animals
Who can shed the bacteria and infect other horses?
horses, cattle, and hogs
How is salmonella often passed from cattle to horses?
from neighboring farms with shared streams
Where should horses not drink from?
ponds and streams
When do horses shed salmonella more?
in the summer more than the winter
How long can salmonella persist in fecal matter?
months to years
Good manufacturing procedures (GMP)
all commercial equine feeds are manufactured using GMP, but none are certified salmonella free
What in the feed making process can destroy salmonella?
pelleting
Up to what % of concentrate is positive for salmonella?
40%
What can kill salmonella?
heat
Where should fresh manure not be spread?
in pastures (should be composted first, the heat will kill the salmonella)
What can contaminate feed?
rodent and bird feces
bodies of insects
What are sources of pasture contamination?
-organic fertilizers or bone meals
-runoff from neighboring farms
-contaminated water is used in irrigation or sprinkling
Do horses shedding salmonella bacteria always show symptoms?
no
What animal sheds a lot of salmonella?
chickens
Of horses presenting with diarrhea, what % were positive for salmonella?
18%
What makes horses more resistant to salmonella?
-normal intestinal flora
-parastasis motility
What are risk factors of salmonella infection?
-foals (young age)
-deworming
-high environment temps (summer)
Stress from:
-transportation
-surgery
-change in feed (change in flora)
-colic (diminished motility)
How is salmonella transmitted?
fecal-oral route
What does the infection depend on?
bacterial load
What cells does salmonella invade?
the intestinal epithelial cells
What is the response to salmonella in the cells?
large inflammatory response:
-neutrophils release inflammatory mediators
-is responsible for epithelial cell destruction and loss of epithelial barrier functions
What does the inflammation and epithelial necrosis result in?
loss of serum protein into the lumen which leads to hypoproteinemia
What can salmonella cause?
-endotoxemia
-septicemia
How does salmonella cause endotoxemia?
it releases endotoxins which effects cardiac function, causes fever, leukopenia, coagulopathies, hypotension
Clinical signs
-silent carriers
-mild infection: fever, decreased feed intake, loose stools (may or may not shed, but can and will get sick)
-severe acute diarrhea: fever, colic, anorexia, fluid and electrolyte losses, dehydration, can lead to liver and kidney damage and laminitis
-septicemia
-abortion
-death
When can you give antibiotics for salmonella?
if the infection is mild enough
How can salmonella be diagnosed?
-fecal cultures - they are difficult
-bacterial isolation
-false (+) and false (-) are possible
How is salmonella treated?
-antibiotics (controversial)
-fluids
-banamine
-corticosteroids are contra-indicated
-nursing care
What does treatment prevent?
endotoxemia and laminitis
When should antibiotics be used?
only in animals at risk for septicemia or persistent fever
What antibiotic should be given to adult horses
fluoroquinolones (IM)
What antibiotic should be given to foals?
cephalosporines
How many negative tests are needed to rule out salmonella?
3
How to prevent salmonella:
-cleanliness/good husbandry
-quarantine new arrivals (especially those coming back from the hospital)
-avoid overcrowding of pastures (creates stress, fighting, more manure)
-pelleted feeds
-control insect, rodent, and bird access in horse housing
Is there a vaccine for salmonella?
no
What is a big source of salmonella in humans?
-eggs and raw chicken (usually from the juice)
-ground beef
Is salmonella zoonotic
yes
