Salmonella Flashcards

1
Q

Is salmonella part of the normal flora?

A

No, but colonizes animals without causing clinical disease

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2
Q

What are the 2 species of salmonella

A
  • S. bongori: benign

- S. enterica

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3
Q

Subspecies 1 (enterica)

A

Associated with 99% of salmonella infections in human and warm-blooded animals

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4
Q

S. arizonae

A

Subspecies IIIa

- only other subspecies that is found in warm-blooded animals

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5
Q

S. enterica arizonae

A

Originally found in reptiles, also occurs in fowl and other domestic animals

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6
Q

Most salmonella are not _______

A

Host adapted

- S. typhimurium is most frequent cause of disease

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7
Q

Classes of salmonella that are host-adapted and may or may not cause disease in other hosts

A
  • S. typhi: humans
  • S. choleraesuis: pigs
  • S. dublin: cattle
  • S. pullorum and S. gallinarum: poultry
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8
Q

_________ are innately resistant to salmonellosis

A

Healthy adult carnivores

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9
Q

Habitat of salmonella

A

Intestinal tract of verberates

  • excretion contaminates food, water, and environment
  • fertilizers and feeds made from animal products and milk products are frequently contaminated
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10
Q

Most common sources of transmission for people

A

Animals and animal products!!!

- especially meat, poultry, milk, and pet turtles

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11
Q

Pet turtles

A

Since 1975, FDA has banned sale of turtles with shell length less than 4 inches in size as pets due to salmonella infections in young children

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12
Q

What are the 2 major forms of salmonella?

A

Enteritis and septicemia (typhoid)

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13
Q

Enteritis

A

Fever, anorexia, depression, foul-smelling watery feces that contains fibrin, mucus, and blood
- death due to dehydration, electrolyte loss, and acid base imbalance

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14
Q

Septicemia

A

Pneumonia, meningitis, polyarthritis in young and agalactica and abortion in adults

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15
Q

Horses

A

S. typhimurium and S. anatum

  • acute colitis with profuse diarrhea, abdominal pain
  • febrile!
  • highly contagious and adult horses are susceptible
  • colic, GI surgery, antimicrobial therapy predispose
  • septicemia in neonates
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16
Q

What are the 3 species that cause enteritis in humans?

A
  • typhimurium
  • enteritidis
  • newport
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17
Q

What are the 3 species that cause enteritis in cattle?

A

Typhimurium, dublin, and newport

  • 4-6 week old calves most commonly affected
  • bloody diarrhea, fever
  • sometimes causes septicemia –> septicemia caused by dublin leads to pneumonia in calves
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18
Q

Species specific to swine

A

Typhimurium, choleraesuis

  • common in weaned pigs less than 5 months old
  • stress induced
  • typhimurium causes enterocolitis
  • choleraesuis causes septicemia
19
Q

What are the 3 diseases in chickens?

A
  • paratyphoid
  • pullorum
  • fowl typhoid
20
Q

Paratyphoid

A

Motile salmonella (anything but pullorum or gallinarum)

  • serovars that cause paratyphoid include: enteritidis, infantis, typhimurium
  • highest loss due to septicemia in <2 weeks old
21
Q

Pullorum disease

A

S. pullorum

  • vertically transmitted with septicemia at 2-3 weeks
  • rare in US, only 2 backyard cases in 2001-2002
  • carriers detected by agglutination titiers
22
Q

Fowl typhoid

A

S. gallinarum

  • vertically transmitted
  • septicemia in young and adult birds
  • rare in US
  • diagnose via culture from liver or spleen by agglutination titers
23
Q

S. typhimurium and S. enteritidis infects ______

A

Wide range of animals (poultry, pigs, cattle) and humans

  • usually causes self-limited enteritis
  • host adapted S. typhi causes systemic illness in humans (typhoid)
24
Q

What is the major source of infection?

A

The carrier state

- can still survive for long periods in the environment

25
Q

Excretion increases or disease reactivation occurs in carriers due to ______

A

Stress

26
Q

Mary Mallon

A

Typhoid Mary

- first person in US to be identified as a healthy carrier of typhoid fever

27
Q

Virulence factors

A

Type 3 secretion system and effector proteins are main factors

  • fimbriae to mediate attachement
  • LPS to stimulate host inflammatory response
28
Q

Capsule

A

Vi antigen

  • not antiphagocytic!!! –> phagocytosis contributes to pathogenesis
  • protects from complement
29
Q

Oral route to intestine pathogenesis

A

Occurs with normal flora imbalance to absence

  • association with enterocytes mediated by fimbriae –> M cells are target
  • invasion of enterocytes by receptor-mediated endocytosis –> type 3 secretion system
30
Q

Bacterial proteins disrupt ______ function

A

Enterocyte

  • causes release of cytokines (IL8), recruiting neutrophils to invade and transcytose to intestinal lumen
  • -> neutrophils release prostaglandins, causing adenylate cyclase activity in intestinal cells, increased cAMP = distruption of Na/Cl pumps
31
Q

What specifically causes diarrhea?

A

Disruption of Na/Cl pumps

- secretory diarrhea

32
Q

Does salmonella produce enterotoxins?

A

No!

- similar to EHEC

33
Q

Where are bacteria found in a latent carrier state?

A

Some are transcytosed to lamina propria, or are phagocytosed by professional phagocytes and persist there

34
Q

How does salmonella cause systemic infection?

A

Persists in professional phagocytes and are protected from antibodies
- cause systemic infection with host-adapted serovars

35
Q

How does salmonella survive?

A

Survives in special salmonella modified vacuoles that fail to fuse with lysosomes

36
Q

Resistance is related to _____ and ______

A

Age of animal and serovar of salmonella

- both humoral and cell mediated immunity are important in resistance

37
Q

________ provide the best protection against challenge

A

Live vaccines

  • stimulates CMI
  • may vaccinate poultry
38
Q

Antibiotic treatment

A

Controversial

  • alters the intestinal microflora that prolongs shedding of the organism
  • if you have to treat use doxycycline
39
Q

Media growth

A

Most are non-lactose fermenters, except S. arizonae group

40
Q

Salmonella enterica arizonae is rare in ________

A

Warm blooded animals

- exception: reptiles, chicks, and turkey poults

41
Q

S. enterica arizonae disease

A

Causes acute septicemic disease of young turkey poults known as arizonosis

  • clinically indistinguishable from other salmonellosis
  • diarrhea, pasting of the down around the vent, blindness, nervous system signs
42
Q

Klebsiella

A

K. pneumoniae
- foals: pneumonia and pyosepticemia
- cows: coliform mastitis
opportunists!

43
Q

Enterobacter-serratia

A

Causes coliform mastitis in cows

- opportunistic in mixed infections

44
Q

Proteus

A

UTI and otitis externa in dogs

- hypermotile “swarming on plates”