E.coli, Salmonella, Shigella

Front 1

Name 7 presentations of pathogenic E.coli

Back 1

1. enterotoxigenic diarrhea
2. enteropathogenic
3. enteroinvasive
4. enterohemorrhagic
5. enteroaggregative
6. edema dz (swine)
7. colibacillosis (fowl)

Front 2

Enterotoxigenic diarrhea occurs in

Back 2

neonatal pigs, calves, lambs
weanling pigs
reported in dog/horse

Front 3

What does E.coli need to produce to cause enterotoxigenic diarrhea?

Back 3

1. adhesins (to jejunum/ileum, LI unaffected)
2. enterotoxins (ST and/or LT)

Front 4

Describe the appearance of enterotoxigenic diarrhea from E.coli

Back 4

watery, non-bloody
minimal to no inflammatory changes
bacteria coating villi of SI

Front 5

Enteropathogenic E.coli causes ______ and occurs in ______

Back 5

watery, mucoid, non-bloody diarrhea
all animals

Front 6

Describe the lesions of enteropathogenic E.coli and what mediates cell attachment

Back 6

Effacing: collapsed microvilli in distal SI and upper LI

mediated by adhesin (cell targeting) and intimin

Front 7

T/F enteropathogenic E.coli produces no endotoxins (secreted toxins targeting intestine)

Back 7

T (but produce enterohemolysins which kills cell from inside)

Front 8

Describe the lesions of enterohemorrhagic (EHEC) E.coli

Back 8

effacement of LI, hemorrhagic diarrhea

Front 9

What toxins are responsible for EHEC pathogenesis? The toxins are under the control of what?

Back 9

Shiga-like toxins (SLTs)

bacteriophages

Front 10

What EHEC serovar is responsible for dz in humans (mostly children)/calves, commonly found in fecal contaminated ground beef/pork? What dz in humans?

Back 10

E. coli O157:H7 ZOONOTIC!!

EH diarrhea, kidney failure
hemolytic uremic syndrome -> thrombocytopenia, anemia, uremia

Front 11

Shiga-like toxins (SLTs) damage what cells locally and systemically?

Back 11

locally: endothelium
systemically: endothelium -> kidney, brain

Front 12

What causes susceptibility regarding Invasive EHEC strains? What are points of entry?

Back 12

insufficient colostrum/quality

ingestion, conjunctiva, inadequately treated umbilicus

Front 13

When do invasive EHEC repress expression of adhesins? What must they express to survive nutritionally?

Back 13

upon entry into blood and lymphatics to avoid phagocytosis and complement (also have sialic acid in capsule)

siderophores (many also expr hemolysins)

Front 14

What internal tissues and organs experience inflammation and hemorrhage with extraintestinal EHEC?

Back 14

inflammation: liver, spleen, joints, meninges

hemorrhage: pericardium, serosal linings, adrenal cortex

Front 15

Describe appearance of enteroaggregative diarrhea?

Back 15

watery, can have blood and leukocytes

histo: sheets of bact entrapped in SI mucous

Front 16

enteroaggregative diarrhea is seen in

Back 16

weaned pigs and calves

persistent diarrhea in humans living in dirty environment

Front 17

Name 3 virulence factors in enteroaggregative diarrhea

Back 17

AAF adhesins (SI cell adhesion)
agg gene (biofilm formation)
EAST1 (cause diarrhea)

Front 18

Edema dzs in weaned pigs are triggered by

Back 18

nutritional/social/physical stress

Front 19

Edema dzs caused by EHEC-like bacteria causes acute often fatal enterotoxemia. Upon necropsy the SI appears

Back 19

dilated, flaccid or hyperemic

Front 20

What toxin causes extensive generalized edema in "edema dz" and how?

Back 20

SLT (Shiga-like)

destroys endothelium

Front 21

Colibacillosis of fowl is economically important and can express its pathogenesis in many ways such as

Back 21

acute or chronic respiratory or septicemic dz
cellulitis (skin)
synovitis
pericarditis
salpingitis
panopthalmitis (all tissues of eye)

Front 22

Why is it imperative that the dam is exposed naturally or artificially to the microorganisms and its virulence factors before parturition?

Back 22

for Abs against adhesins and enterotoxins to be made and secreted into milk/colostrum

Front 23

What subspecies of salmonella affects mammals and birds?

Back 23

S. enterica

Front 24

Adhesins on the fimbria/pili of Salmonella allows adherence to what cells?

Back 24

SI epithelium, M cells

Front 25

How many Salmonella pathogenicity islands exist?

Back 25

at least 6, secreting effectors via type 3 and 6 secr systems

Front 26

What are some functions of salmonella effector proteins?

Back 26

mediate uptake (via ruffle formation in host cell)
interference with MØ
survival inside MØ
killing of activated MØ

Front 27

Where are reservoirs of salmonella found?

What animals are important in dissemination?

Back 27

ubiquitous: GI tract of endothermic and ectothermic animals

wild birds and rodents (lizards, snakes asymptomatic)

Front 28

Which individuals are especially susceptible to salmonella?

Back 28

neonates
stressed adults
-parturient cows
-surgical PTs
-colics
-co-infected (virus)
-antibiotic mediated

Front 29

What conditions are associated with Salmonella?

Back 29

diarrhea -> hemorrhagic inflamm of distal SI and colon, superficial necrosis

septicemia
-> inflammation
--->liver, spleen, intestine
->hemorrhages
--->pericardium, serosal surfaces, adrenal cortex

Front 30

Which salmonella serotypes can infect humans? List 4 sources of salmonella?

Back 30

All of them

eggs - S. enteriditis
milk - S. dublin
pork - S. cholerae-suis
beef - S. typhimurium

Front 31

What Salmonella serotypes infect ruminants and what are the presentations?
Where is this likely to occur?

Back 31

cattle: typhimurium, dublin, newport
sheep: typhimurium

intestinal and septic -> abortions and pneumonia

feedlots

Front 32

What Salmonella serotypes infect swine and what are the presentations?
Where is this likely to occur?

Back 32

S. typhimurium, S. cholerae-suis

chronic intestinal
acute fullblown septicemia

feeder pigs

Front 33

What Salmonella serotypes infect horses and what are the presentations?
Where is this likely to occur?

Back 33

S. typhimurium, S. anatum

diarrhea, occasionally septicemia

Front 34

When can Salmonella outbreaks occur in dogs/cats?

Back 34

treats (dried pigs ear) distributed widely

mainly cause septicemia

Front 35

What are 4 types of salmonellosis in poulty?

Back 35

Paratyphoid
Pullorum dz
Fowl typhoid
Avian arizonosis

Front 36

Describe paratyphoid in poultry

Back 36

high septicemic death rate first 2 weeks of life
survivors become asymptomatic shedders
nodular lesions in intestine

Front 37

Describe pullorum dzs

Back 37

Reportable! (uncommon in north america, common elsewhere)

infect ova of turkeys/chickens, hatchlings infect other young nearby

septicemic death for ages 2-3 wk, nodules in heart

Front 38

Describe fowl typhoid

Back 38

S. gallinarium
reportable! (rare in USA)

acute septicemia and chronic dz in domesticated chickens

discolored, enlarged liver
mottled, brittle spleen

Front 39

Describe avian arizonosis

Back 39

S. enterica subsp. arizonae and diarizoniae

vertical and horizontal transmission

Front 40

What selective media can be used for Salmonella? Why?

Back 40

MacConkey: majority are non-lactose fermenters, can deposit H2S under alkaline conditions (black centers)

HE agar (for enterobactericaea)

Front 41

How is a selective medium such as tetrathionate enrichment broth coupled with IFA good for diagnosing Salmonella?

Back 41

Broth contains bile salts -> inhibits G+, salmonella has tetrathionate reductase -> grow uninhibited

Front 42

Why is salmonella antimicrobial treatment controversial?

Back 42

antibiotic needs to penetrate host cells (fac intracellular)

lots of resistance

need susceptibility testing

Front 43

How can salmonella be controlled and prevented?

Back 43

carriers are hard to diagnose

live attenuated vaccines - difficult: strong cellular immune response

Front 44

Name 3 species of Shigella affecting non-human primates and 4 affecting humans!

Back 44

Primate:
S. flexneri
S. boydii
S. sonnei

Human:
S. dysenteriae
S. flexneri
S. boydii
S. sonnei

Front 45

Bacillary dysentery by Shigella can be caused by

Back 45

captivity stress, immunocompromised

Front 46

IpaD mediates Shigella adhesion to

What are the three Shigella toxins?

Back 46

M cells, LI cells

Shiga toxin (S. dysenteriae)
SigA (IgA protease)
Pic (digests mucous)

Front 47

What shigella proteins mediate ruffle formation and lysis of phagocytes?

Intracellular spread?

Back 47

IpaB, IpaC

IcsA, IcsB

Front 48

What do the regulatory genes Fur and rpoS regulate?

Back 48

Fur - iron acquisition: sense levels, express siderophores, shiga toxin, and aerobactin

rpoS - acid tolerance in stomach

Front 49

What pathogenesis is associated with Shigella?

Back 49

hemorrhagic watery diarrhea

endothelial destruction systemically by shiga toxin -> hemolytic uremic syndrome

Front 50

selective media for shigella

Back 50

macconkey, hektoen, XLD

some are lactose ferm, others not