E coli Flashcards Preview

Bacteriology > E coli > Flashcards

Flashcards in E coli Deck (68)
Loading flashcards...
1
Q

some characteristics of enterobacteriacae

A
  • gram neg
  • facultatively anaerobic
  • rod-shaped
2
Q

how do enterobacteriacae metabolise?

A

-ferment glucose to acid and gas

3
Q

is enterobacteriacae oxidase pos or neg

A

oxidase neg

4
Q

do enterobacteriacae ferment lactose?

A

some do and some dont

5
Q

what is the habitat of enterobacteriacae

A

GI tract, soil, water

6
Q

what is the mode of infection of enterobacteriacae

A

by ingestion

7
Q

which enterobacteriacae ferment lactose?

A
  • escherichia
  • enterobacter
  • klebsiella
8
Q

what enterobacteriacae do not ferment lactose

A
  • morganella
  • proteus
  • salmonella
  • serratia
  • yersinia
9
Q

MacConkey Agar is selective for what?

A
  • selects gram neg

- gram pos are inhibited

10
Q

how do you tell lactose pos or neg on a MacConkey agar plate?

A
  • lactose neg - golden

- lactose pos - pink

11
Q

what is the metabolism of Escherichia coli

A

-facultative anaerobe
-lactose fermenter
(pink colonies on macconkey agar)

12
Q

true/false: some strains of Escherichia coli are hemolytic

A

true

13
Q

Escherichia coli is a normal inhabitnat where?

A
  • soil and water

- lower intestinal tract

14
Q

where are H antigens on Escherichia coli

A

flagella

-heat labile, protein

15
Q

where are O antigens on Escherichia coli

A

cell wall

-LSP, heat stable

16
Q

where at K antigens on Escherichia coli

A

capsule

-CHO or protein

17
Q

where are F antigens on Escherichia coli

A

pilus

-protein (plasma coded)

18
Q

what is serotyping

A

classification of bacteria within a species based on antigenic structure

19
Q

what does the O antigen designate?

A

somatic

20
Q

what are Escherichia coli broadly classified into?

A
  • intestinal pathogenic E. coli (IPAC)

- extraintestinal pathogenic E. coli (ExPAC)

21
Q

what is virotyping (pathotying)

A

classification based on virulence factors

22
Q

what are the 5 categories of pathogenic E. coli based on?

A
  • patterns of attachment on host cells (sinlgy or aggregates)
  • effects of attachment on host cells (none or destruction)
  • production of toxins
  • invasiveness
23
Q

enteropathogenic (EPEC)

A
  • attachment is pili mediated
  • loss of microvilli (effacement)
  • invasion and structural changes
  • prodce cytotoxin
  • cause diarrhea in humans, rarely in animals
24
Q

Attaching and Effacing or Enterohemorrhagic (AEEC, EHEC, STEC, VTEC)

A
  • attachment is mediated by a protein, Intimin (NO PILI)
  • loss of microvilli (effacement)
  • invasion and structural changes
  • ***produces Shiga toxin (Stx)
25
Q

characteristics of Shiga Toxins

A
  • biologially and structually resemble the cytotoxin of Shigella dystenteriae
  • heat labile
  • lethal to vero cells (hence verotoxin, VTEC)
26
Q

what are the two types of shiga toxin

A
  • Stx1

- Stx2

27
Q

*know about Stx2e

A

it is involved in edema disease in swine

28
Q

where are the genes Stx1 and Stx2 located?

A

on a temperate bacteriophage

29
Q

how do shiga toxins work?

A

they inhibit protein synthesis

30
Q

what are shiga toxins a concern

A

-cytotoxic to enterocytes and vascular endothelial cells

31
Q

what is the most common serotype of Escherichia coli

A

E. coli O157:H7

32
Q

characteristics of enteroinvasive (EIEC)

A
  • multiply inside the cell (salmonella-like)
  • invasion and cellular destruction
  • cause bacterimia or septicemia
  • mostly seen in poultry
33
Q

characteristics of enterotoxigenic (ETEC)

A
  • ‘cholera-like’
  • attach (pili mediated)
  • produce enterotoxins
    • heat labile
    • heat stable (100C for 30 min)
34
Q

what doe LT stand for?

A

cholera-like

35
Q

enterotoxin LT

A
  • has 2 polypeptide chains and B (A-B toxin)

- B subunit binds to the intestinal epithelium

36
Q

enterotoxin ST

A

-small proteins
-Sta (methanol soluble)
Stb (methanol insoluble)

37
Q

what does STa cause?

A

induce fluid accumulation in the instestine of suckling mice

38
Q

what does Stb do?

A

does not cause fluid accumulation in the intestine of suckling mice

39
Q

characteristics of enteroaggregative (EAbbEC)

A
  • form aggregates
  • do not invade
  • produce ST-like (heat stable) called EAST and hemolysin-like toxins
40
Q

what is cytotoxin necrotizing factor producing E. coli (CNF-PEC)

A
  • attach but do not invade the cells
  • produce a toxin that causes necrosis
  • reported to cause diarrhea in calves pigs and humans
41
Q

what does extraintestinal pathogenic E. coli (ExPEC) cause

A

-strains cause septicemia mastitis, infections of the uterus, urinary tract or air sacs (poultry)

42
Q

what are the three forms of colibacillosis?

A
  • diarrheal: mild to severe, with or without blood
  • septicemic: colisepticemia
  • localized: suppurative
43
Q

what are the two locations of collibacillosis?

A
  • intestinal

- extraintestinal

44
Q

what is the mode of infection of E. coli

A
  • ingestion
  • inhalation
  • direct infection
45
Q

what are the three forms of colibacillosis in SWINE?

A
  • neonatal enteritis
  • weanling enteritis (post weanling diarrhea)
  • edema disease
46
Q

what strain causes weanling enteritis?

A

-caused by hemolytic strains (EPEC)

47
Q

what strain causes edema disease?

A

caused by AEEC (EHEC)

-Stx (Stx2e) is the major virulence factor

48
Q

whawt are predisposing factors to edema disease?

A
  • age 7-10 days after weaning
  • change of feed
  • rapid growth
  • diarrhea
49
Q

what are the clinical signs of edema disease?

A

edema: eyelids, facial area, stomach, mesenteric lymph nodes, colon, gall bladder, larynx etc

50
Q

how do you prevent edema disease?

A
  • separation of sick pigs

- antibiotics in the feed (enrofloxacin

51
Q

what are clinical signs of colibacillosis in calves?

A
  • diarrhea “white scour” during the first week of life

- feces full of gas bubbles

52
Q

what is the virulence factor of colibacillosis in calves?

A

enterotoxins (STa)

53
Q

what is the septicemic form of colibacillosis in cattle?

A
  • in calves deprived of colostrum
  • virulence factor: endotoxin
  • endotoxic shock and death
54
Q

what is a common E. coli infection of cows in adult cows?

A

mastitis

55
Q

what are clinical signs of mastitis?

A

swelling of udder, discolored milk, blood clots, loss of milk production

56
Q

pagenesis of mastitis in cows

A
entry through teat
adherence to mammary cells
release of endotoxin
absorption of endotoxin
release of cytotoxin
57
Q

what happens to adult horses with colibacillosis?

A

mares- abortion; acute mastitis

58
Q

what are the clinical signs of colibacillosis in fouals?

A

fever, rapid pulse, dullness and weakness

-(no enteritis!)

59
Q

how do you see colibacillosis in dogs and cats?

A

diarrhea is not common

  • commonly isolated from genital and urinary tract infections
  • females - cystitis and pyometra
  • males - prostitis
60
Q

what are the virulence

A
  • pili - adherence
  • hemolysin
  • cytotoxin necrotizing factor
  • protease enzyme
61
Q

colibacillosis in poultry

A
  • diarrheal disease is rare
  • localized or systemic
  • avian pathogenic E. coli
62
Q

do avian strains of colibacillosis cause diseases in other animals?

A

no

63
Q

what is coli-granuloma (hjarre’s disease) in poultry

A

chronic form of bacillosis with granulomatious lesions in the walls of the intestinal tract, liver and lungs

64
Q

what does colibacillosis cause as a respiratory disease in poultry?

A

air-sacculitis

65
Q

what is cellutitis?

A

infection of the subcutis

66
Q

what can celluitis cause in poultry?

A

swollen head syndrome

67
Q

when making a presumptive diagnosis, what do you look at?

A
  • age of the animal (neonate)

- clinical signs (diarrhea with or without blood)

68
Q

is E. coli present in all fecals?

A

yes! need to know if it is a pathogenic strain or not