Gram negative rods Seo Flashcards
Salmonella 2 species
Salmonella bongori
and
Salmonella enterica
Members of subspecies I (enterica are associated with…
99% of Salmonella infections in human and warm blooded animals
Other subspecies are found in cold blooded animals and he environment except for…
Salmonella arizonae (subspecies IIIa)
Where was S. enterica arizonae originally found
in reptiles,
also occurs in fowls and other domestic animals
Host for S. Typhi S. Choleraesuis S. Dublin S. Pullorum S. Gallinarum
humans pigs cattle poultry poultry
Common mode of transmission for people
are animals and their products, especially meat and poultry, milk, and pet turtles
Since 1975 the FDA has banned what
the sale and distribution of turtles with a shell length of less than 4 inches in size as pets because they are links to Salmonella infections
Salmonella disease two major forms
enteritis and septicemia (typhoid)
Major signs of enteritis
fever, anorexia, depression, and foul smelling, watery diarrhea that often contain fibrin, mucus, and blood
Septicemia may lead to
pneumonia, meningitis, and polyarthritis in the young and agalactia and abortion in adults
disease in horses
S. Typhimurium most common, S. Anatum also common
Clinical signs: acute colitis and profuse diarrhea, sometimes abdominal pain, febrile, highly contagious, adults susceptible, colic, GI surgery, and antimicrobial therapy predispose, in neonates septicemia can occur
disease in humans
Enteritis: Typhimurium, Enteritidis and Newport
Systemic disease: Typhi
Disease in cattle
Typhimurium, Dublin, and Newport
Clinical signs:
4-6 week old calve most common, causes diarrhea with blood and fever, Sometimes septicemia can occur. Septicemia caused by Dublin can cause pneumonia in calves
disease in pigs
Typhimurium (enterocolitis) and Choleraesuis (septicemia)
Most common in weaned pigs less than 5 months old
disease in chickens
a. Parathyroid-motile Salmonella (anything but Pullorum or Gallinarum)
b. Pullorum disease-S. Pullorum
c. Fowl typhoid-S. Gallinarium
S. Typhimurium, and S. Enteritidis infect….
a wide range of animals (poultry, cattle, pigs) and humans, usually causing self-limited enteritis
Host adapted S. Typhi causes…
systemic illness in humans (typhoid)
Salmonella carriers
are a major source of infections
Virulence factors
Type III secretion systems and effector proteins
Capsule-not antiphagocytic, but protect from complement
Pathogenesis
a. Oral route to the intestines
b. associated with enterocytes-mediated by fimbriae, M cells are the primary target
c. Invasion of enterocytes by receptor mediated endocytosis. Type III secretion system (needle like projection)
d. Bacterial proteins disrupt enterocyte function and cause release of cytokines (IL 8), which recruits neutrophils that invade and transcytose to intestinal lumen.
e. Neutrophils release prostaglandins causing adenylate cyclase activity in intestinal cells, increased cAMP, disrupts sodium chloride pumpls
f. Diarrhea is secretory and exudative WITHOUT enterotoxin production (similar to EHEC).
g. Some bacteria can transcytose to lamina propria and persist there or be phagocytosed by professional phagocytes and persist there to set up latent carrier state
Pathogenesis of systemic infection
Salmonella that persist in professional phagocytes are protected from antibody and can spread to cause systemic infection, particularly with host adapted serovars ( s. typhi in humans- typhoid fever)
-Survives in special Salmonella modified vacuoles that fail to fuse with lysosomes
Vaccines and antibiotic treatment
Live vaccines provide the best protection against challenge
-stimulate CMI
Controversy on antibiotic treatment
Lab Diagnosis
Most and non-lactose fermenters (exception is S. arizonae group)
Salmonella enterica arizonae
- rare in animals except reptiles, chicks, and turkey poults
- Causes an acute septicemic disease of young turkey poults known as arizonosis
Klebsiella
- Pneumonia and pyosepticemia in foals
- mastitis in cows (coliform mastitis)
Enterobacter-Serratia
(often lumped with Klebsiella as KES group
-Mastitis in cows (coliform)
