Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Infectious Agents > E. Coli Enteric Diseases > Flashcards

E. Coli Enteric Diseases Flashcards

1
Q

ETEC is primarily a disease of ______ and ______

A

Calves; pigs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

ETEC has _____ fimbrial types

A

5

- F4, F5, F6, F18, F41

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

F4

A

Genes on a plasmid

  • expressed on swine ETEC
  • associated with O groups
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

F5

A

Found on cattle, sheep, swine

  • plasmid-encoded “O” groups
  • often have capsules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

F6

A

Associated with swine ETEC, sometimes cattle

  • “O” groups
  • plasmid-encoded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

F18

A

Common fimbrial adhesion associated with swine ETEC

  • 2 closely related antigenic variants F18ab (edema disease) and F18ac (ETEC)
  • plasmid encoded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

F41

A

Cattle ETEC, sometimes swine

  • some F5 strains also have F41
  • chromosome encoded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Intestinal epithelial receptors for fimbriae are responsible for ________

A

Age susceptibility

  • calves: receptors are transiently expressed in the 1st week of life
  • swine: F4 and F5 receptors decrease with age, F4 receptors are abundant in newborns and remain thru postweaning
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

You need to have both _____ and _____ to cause disease

A

Fimbriae; enterotoxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Diarrhea results from action of _________

A

Enterotoxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

LT

A

Heat-labile produced by human and porcine strains

  • large protein made up of A and B subunits
  • similar to cholera toxin in chemical structure and function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

LT/B vs LT/A

A
  • LT/B: binds to specific ganglioside receptors on enterocytes
  • LT/A: penetrates the cell membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Action of LT

A

Causes dysregulation of adenylate cyclase, leading to overproduction of cAMP
- induces loss of water and electrolytes into small intestinal lumen
= diarrhea, hypovolemia, metabolic acidosis, hyperkalemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 types of LT?

A
  • LT1: plasmid encoded, neutralized by anti-cholera toxin antibodies
  • LT2: chromosomally encoded and NOT neutralized by anti-cholera toxin antibodies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ST

A

Heat stable

- low MW proteins with a lipoprotein binding portion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

STa

A

Activates guanylate cyclase and causes overproduction of cGMP

  • results in enhanced chloride and water secretion and inhibition of Na absorption in the SI
  • encoded on a transposon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

STb

A

Stimulates GTP-binding regulatory protein

  • results in influx of Ca in enterocytes, activating protein kinase C
  • protein kinase C phosphorylates Cl channel proteins, = loss of Cl and water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the difference between porcine and bovine ETEC ST production?

A
  • porcine: STa and/or STb is produced

- cattle: STa is the only type produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

EAST1

A

Enteroaggregative E. coli heat-stable enterotoxin 1

- similar to STa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Pathogenesis of ETEC

A

Adheres to enterocytes in SI, multiply, and secrete enterotoxin

  • fluid and electrolytes accumulate in lumen
  • watery diarrhea, with no blood
  • SI has minimal inflammatory changes, but bacteria can be histologically observed
  • multiply to 10^8-10^9 per ml of luminal content
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Host factors affecting disease

A
  • age (presence of fimbrial receptors)
  • gastric pH
  • specific antibodies against fimbriae and toxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Susceptiblity of calves

A

Most commonly less than 1 week of age, but up to 2-3 weeks

  • 1 day old most susceptible
  • most strains are F5 isolates
  • older calves have mixed infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Susceptiblity of pigs

A

Birth to 12 weeks of age

  • suckling pigs it may or may not be complicated by rotavirus
  • disease is complex in post-weaning diarrhea, but ETEC is majorly responsible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

ETEC also causes diarrhea in young ____, _____, ____, and ______

A

Dogs, cats, horses, rabbits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Diagnosis
Culture and serotype, or demonstrate fimbriae by ELISA or agglutination - culture/demonstrate ST and/or LT by ELISA - DNA probes or PCR for fimbriae or enterotoxins (directly from feces) - quantitative culturing from SI - fluorescent labeled antibodie demonstrates E. coli adhered to intestinal epithelium
26
High number of E. coli in the ______ is suggestive of ETEC
Jejunum
27
Treatment of ETEC
Fluid therapy, oral antibiotics | - cannot use vaccines due to young age of infection!!
28
Prevention of ETEC
Depend on transfer of colostral immunity, does not protect against post weaning diarrhea - good husbandry - vaccines administered parenterally to sows/cows - bacterins: one or more serogroups of ETEC prevalent in area containing O, K, and fimbrial antigens - fimbrial subunit vaccines - monoclonal anti-fimbrial antibodies administered orally to piglets
29
Pathogenesis of EAEC
Adhere to intestine in an aggregative, stacked-brick pattern - aggregative adherence is mediated by aggregative adherence fimbriae - some express EAST1 toxin - contain large set of virulence genes regulated by AggR transcription activator
30
Diagnosis of EAEC
Gold standard: aggregative adherence to tissue culture cells - histopath: presence of bacterial sheets on intestinal eptihelium - demonstration of EAST1 and/or AAF genes in isolated E. coli
31
Disease of EAEC
- humans: persistent diarrhea in children and adults | - E. coli with EAST1 or AAF can be isolated from weaned pigs and calves with diarrhea (may or may not have)
32
Do pigs and calves with EAEC have the same virulence factors as human isolates?
No | - role of EAEC in pigs/calves is not clear, causation is not established
33
Pathogenesis of EPEC
Human EPEC expresses fimbriae called bundle forming pili (Bfp) --> important for initial binding to intestinal cells and bacteria-bacteria interactions = formation of microcolonies of attached bacteria
34
EPEC in animals
Only a small fraction of EPEC causing infection in pigs, calves, dogs, and cats produce Bfp
35
Intimin
Outer membrane protein that mediates intimate adherence to pedestals
36
EPEC uses a ________ to inject effector proteins into intestinal cells
Type 3 secretion system - Tir: inserts in the membrane of enterocytes and binds intimin - reorganize actin cytoskeleton in enterocytes to form attaching and effacing lesions - microvilli are lost (effacing) - pedestal structures are formed that bacteria are attached to - some proteins dysregulate Cl transport and Na transport = reduced water absorption
37
EPEC disease
Watery diarrhea due to loss of absorptive surface (AE lesions) and disruption of electrolyte balance - causes diarrhea in all animal species and humans - major cause of diarrhea in young rabbits
38
EPEC diagnosis
Biopsy and detection of AE lesions | - detection of genes for intimin (eae) from isolated E. coli
39
_____ is similar to EPEC in what aspect?
EHEC - both produce attaching and effacing lesions in the intestine by the same mechanism - target large intestine cells
40
How is EHEC different from EPEC?
EHEC produces Shiga toxin - AB toxin - B: binding - A: cleaves adenine residue from 28S rRNA of 60S subunit of ribosomes = shuts down protein translation!!!!
41
Stx1
Identical to Stx of Sigella dysenteriae | - Stx1 and Stx1c
42
Stx2
More distantly related to Stx of Shigella | - Stx2, Stx2c, Stx2d, Stx2e, Stx2f
43
Stx1 and Stx2 are carried by ________
Lysogenic bacteriophage
44
How does Stx have both local and systemic effects?
- local: damages endothelial cells directly underneath enterocytes = hemorrhage - systemic: endothelial cells in kidney and brain - -> humans: HUS, hemolytic-uremic syndrome
45
EHEC virulence plasmid
Encodes an enterohemolysin and other virulence genes
46
EHEC diarreha
Caused by same mechanism as EPEC, and damage to endothelial cells = causes additional fluid and tissue leakage
47
EHEC disease in cattle
Intestinal disease in newborn to 12 wk calves - 1-8 wk olds, peaks at 4-5 wks - low mortality rate, but reinfection is possible - dehydration and weakness cause decreased growth rate - localized and diffuse hemorrhages in LI - no systemic effects
48
Adulterants in beef
``` O157:57 O26 O45 O103 O111 O121 O145 ```
49
AIEC
Associated with Crohn's disease in humans - etiologic role in dogs with histiocytic ulcerative colitis - -> young boxers, with chronic bloody diarrhea, mucoid diarrhea, tenesmus, weight loss
50
AIEC target cells
Adhere to and invade enterocytes - invade macrophages under epithelial layer and multiply in vacoules - infected macrophages release TNF-alpha = inflammation and tissue damage
51
Edema disease
Weaned pigs caused by STEC - subq and subserosal edema caused by damage to endothelial cells - caused by Stx2e - express F18ab fimbriae
52
Edema disease characteristics
Damage to endothelium causes vascular leakage, thromboses = edema and infarcts - neurologic signs, edema of subcutis of forehead and eyelids, subserosal edema of stomach - sudden death
53
Diagnosis of STEC
Detection of Stx genes | - demonstration of toxic activity on cell culture
54
ExPEC
Extraintestinal pathogenic E. coli - cattle, swine, horses (primarily neonates due to inadequate colostrum) - invasion thru ingestion, improperly treated umbilicus, conjunctivae
55
ExPEC pathogenesis
Intestinal adherence mediated by fimbrial adhesin (CS31A) and by F17c - after intestinal invasion, multiplication occurs in lymphatics and blood - endotoxemia, and death
56
ExPEC virulence factors
- Vir plasmid: carries genes for F17c and siderophore aerobactin - capsule: K1 with sialic acid, outer membrane proteins to mediate serum resistance and escape from phagocytosis - alpha hemolysin
57
ExPEC clinical signs
- fever - depression - sometimes polyarthritis - meningitis - bronchopneumonia
58
UPEC
Uropathogenic E. coli - urethritis, cystitis, ureteritis, prostatitis, pyelonephritis - transient members of normal intestinal flora - ascending infection from urethra to the bladder - P fimbriae bind receptors in bladder epithelium
59
_____ is the most frequent cause of UTI in dogs, cats, people
E. coli
60
APEC
Avian pathogenic E. coli - aerosacculitis, polyserositis, septicemia in chickens, turkeys, etc - found in intestinal microflora of healthy birds, most diseases are secondary to other factors - eggs can be infected thru shell invasion = embryonic death
61
Is APEC similar to human ExPEC?
Yes | - poultry serve as reservoir for zoonotic infections
62
Virulence factors that are similar between APEC and ExPEC
- F1 (respiratory) and P (organs of chicks) fimbriae - aerobactin or enterobactin iron sequestering system - K1 capsule - hemin uptake system - resistance to bactericidal effects of serum and phagocytosis
63
APEC disease
Air-exchange regions of lung and airsacs are important sites of entry into bloodstream during initial infection - causes septicemia = multiple organ lesions and sudden death - chronic disease with debilitation, diarrhea, respiratory distress
64
Pyometra
Adherence to endometrium associated with F1 fimbriae - similarity to ExPEC and APEC - E. coli most common cause
65
What 3 bacteria cause coliform mastitis?
- enterobacter - klebsiella - E. coli
66
Coliform mastitis
Fatal, peracute form of mastitis - occurs due to effects of endotoxin absorbed from udder of infected cows/sows - gangrenous mastitis in cows and agalactica in sows
67
Laboratory diagnosis
- culture/identification for septicemia, mastitis, pyometra, UTI - quantitative culture for UTI if urine collected by voiding or catheter - pathogenic and nonpathogenic strains must be distinguished

Infectious Agents (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions