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BACTERIOLOGY > ENTEROBACTERIACEAE > Flashcards

ENTEROBACTERIACEAE Flashcards

1
Q

Characteristics of ENTEROBACTERIACEAE

A
  • Non acid fast gram (-) baccili
  • Commonly present in large intestine
  • Non-spore forming gram – rods
  • all are glucose fermenters, reduces nitrates to nitrites, oxidase (-)
  • grows on bile containing agar
  • motile except Shigella & Klebsiella
  • non-capsulated except Kelbsiella
  • non sporeforming
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2
Q

Cell wall -outer membrane of

ENTEROBACTERIACEAE

A

LPS (heat stable)
– O polysaccharide
– Core polysaccharide
– Lipid A

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3
Q

Lipid A

A

outer wall coponent responsible for producing fever and shock; inflammatory effect

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4
Q

Serological Identification of ENTEROBACTERIACEAE

A

– O polysaccharide
– K antigen
– H proteins

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5
Q

Virulence Factors of ENTEROBACTERIACEAE

A

O antigen, or somatic antigen- heat stable
H antigen, or flagellar antigen- heat labile
K antigen, or capsular antigen - heat labile
LPS (Lipid A)

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6
Q

Porins

A

Found on the outer membrane of cell wall that acts as sieve, allowing water-soluble mol. to enter cell

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7
Q

Lactose Fermenters Enterobacteriaceae

A

E.coli & Escherichia, Klebsiella

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8
Q

Late Lactose Fermenters Enterobacteriaceae

A

Shigella sonnei

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9
Q

Non-Lactose Fermenters Enterobacteriaceae

A

Salmonella & Shigella

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10
Q

MacConkey Agar

A
  • bile containing agar
  • selective and differential culture medium for bacteria
  • designed to selectively isolate some Gram-positive and enteric
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11
Q

Lactose fermenters:
morphology

E. COLI

A
  • appear in single or pairs
  • motile by petrichate flagella
  • 1-3 x 0.4-0.7 microns
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12
Q

Lactose fermenters: E.COLI

Culture characteristic

A
  • grows between 10-40 c optimal at 37
  • grown in simple medium
  • large grayish, thick-white moist smooth opaque colonies
  • may sometimes contain capsule
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13
Q

Lactose Fermenters in MacConkey Agar

A
  • Briight Pink colonies
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14
Q

Non- Lactose Fermenters in MacConkey Agar

A

Colorless colonies

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15
Q

Lactose fermenters: E.COLI

on Blood Agar

A
  • many strains are haemolytic on blood agar
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16
Q

Lactose fermenters: E.COLI

Biochemical Characteristics

A
  • Glucose, lactose, mannitol, and lactose fermenters
  • Citrate/ urease not produced
  • A/G indole + methyl red + voges Proskauer
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17
Q

Lactose fermenters: E.COLI

Antigenic structure

A

K - capsular 100
H - flagellar 75
O - somatic 170
Virulence factors

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18
Q

Antigen of Enterobacteriaceae that protects the bacteria from phagocytosis

A

K antigen (capsular)

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19
Q

Antigen of Enterobacteriaceae that is important in cases of UTI

A

H antigen (flagellar spcifically fimbriae)

  • absent in Shigella spp.
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20
Q

Antigen of Enterobacteriaceae that promotes endotoxic activity

A

O antigen (somatic)

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21
Q

Antigen of Enterobacteriaceae that is absent in shigella spp.

A

H antigen

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22
Q

Antigen of Enterobacteriaceae that present in extraintestinal infections caused by E. coli?

A

K antigen (capsular)

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23
Q

An isolated organism shows a negative lactose fermentation and negative in motility test. Which among the choices is the presumptive organism?

Salmonella spp.
Shigella spp.
Escherichia spp.

A

Shigella spp

  • non lactose and non-motile

Escherichia is lactose fermenter
Salmonella is non-lactose fermenter but it is motile.

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24
Q

Virulence factor of E.coli that is present in large numbers and can cause mannose sensitive haemagglutination

A

Fimbriae

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25
Q

What strain of E.coli produce enterotoxin

A

Enterotoxigenic strains (ETEC)

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26
Q

E.coli produces these toxins which causes a movement of water and ions from the tissues to the bowel resulting in watery diarrhea

A

Enterotoxin

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27
Q

Types of E.coli involved in different types of gastroenteritis

A 
Shiga toxin-producing E. coli (STEC)—STEC may also be referred to as Verocytotoxin-producing E. coli (VTEC) or enterohemorrhagic E. (EHEC)
Enterotoxigenic E. coli (ETEC)
Enteropathogenic E. coli (EPEC)
Enteroaggregative E. coli (EAEC)
Enteroinvasive E. coli (EIEC)
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28
Q

Types of E.coli:

Enteropathogenic EPEC

A
  • EPEC 026/011
  • produce Verocytotoxin
  • frequent in summer months
  • brush border of intestine is lost
  • Intimacin (EPEC adhesion factor)
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29
Q

Types of E.coli: Identification

Enteropathogenic EPEC

A
  • serotyping for B and o ags.
  • routine culture for isolation
  • fails to ferment sorbitol
30
Q

Types of E.coli: Lab diagnosis

Enteropathogenic EPEC

A
  • Confirm (Polyvalent sera)
  • test sero groups w/ polyvalent and monovalent sera
  • HEp2 adherence
31
Q

Enteropathogenic EPEC adhesion factor

A

Intimacin

32
Q

Enterotoxigenic ETEC adhesion factos

A

Fimbriae specific receptors

CFA mortality in children

33
Q

Types of E.coli:

Enterotoxigenic ETEC

A
  • produce heat stable/ heat labile toxins
  • HL like cholera toxin
  • causes accumulation of fluids
  • adheres to epithelium of sm
34
Q

Types of E.coli: Lab diagnosis

Enterotoxigenic ETEC

A
  • Demonstration of Enterotoxin LT nd ST in tissue culture test
  • Passive agglutination test
  • Animal experiments in rabbit ileal loop test
35
Q

Types of E.coli:

Enteroinvasive (EIEC)

A
  • resembles shigella
  • non lactose fermenter & non-motile
  • penetrate HeLa cells
36
Q

Types of E.coli: Lab diagnosis

Enteroinvasive (EIEC)

A
  • Sereny test positive animal rabbit

- ELISA

37
Q

Type of E.coli that is non lactose fermenter and non-motile

A

ENTEROINVASIVE E. COLI (EIEC)

38
Q

Types of E.coli:

Enterohemorrhagic (EHEC)

A
  • produce verocytotoxin or shiga like toxin
  • hemorrhagic complication with 0157; H7
  • present in human and animal feces
  • disease may manifest as food poisoning
39
Q

Type of E.coli that produces verocytotoxin

A

Enteropathogenic EPEC

Enterohemorrhagic (EHEC)

40
Q

Types of E.coli: Lab diagnosis

Enterohemorrhagic (EHEC)

A
  • DNA detection method
  • ctotoxic effects on vero cells
  • Detection w/ monovalent sera 0157/ h7
41
Q

Type of diarrhea associated with EIEC

A
  • mild diarrhea to frank dysentery
42
Q

Type of diarrhea associated with ETEC

A
  • travelers diarrhea

- present with nausea, vomiting and lose stool

43
Q

Type of diarrhea associated with EPEC

A
  • diarrheal disease in children

- infantile enteritis

44
Q

Type of diarrhea associated with EHEC

A
  • mild diarrhea; can be fatal hemorrhagic colitis and uremic syndrome
45
Q

Type of diarrhea associated with EAEC

A
  • persistent diarrheal
46
Q

Types of E.coli:

Enteroaggresive EAEC

A
  • appear aggregated in S stacked brick formation hep-2 cell

- produce weight heat stable enterotoxin called as low molecular heat stable enterotoxin

47
Q

Types of E.coli: Lab diagnosis

Enteroaggresive EAEC

A
  • Stool culture

- Detection of Enterotoxin

48
Q

Leading cause of urinary tract infection which can lead to acute cystitis (bladder infection) and pyelonephritis (kidnet infection)

A

E. coli infections

49
Q

Specimen used for Culturing of E.coli

A
  • Mid stream sample of urine
  • culture by standard loop method
  • Antibiotic sensitivity tested
50
Q

Which of the following choices grows on SMAC (MacConkey)

Blood culture for EHEC
Urine culture for EIEC
Stool culture for EHEC
Urine culture for EHEC

A

Stool culture for EHEC

51
Q

Most commonly islated spp of Klebsiella

A

K. pneumoniae

52
Q

Small cracks in the medium with black precipitates
Which E coli strains causes infantile diarrhea?

EHEC
EPEC
ETEC
EAEC

A

EPEC

53
Q

Which member of Enterobacterales has a positive result on Neufeld Quellung test? *

Escherichia coli
Proteus vulgaris
Klebsiella pneumoniae
Shigella dysenteriae
Salmonella enteritidis
A

Klebsiella pneumoniae

54
Q

Lactose fermenters: Klebsiella

morphology

A
  • has polysaccharide capsule
  • has distinctive “yeasty” odor
  • non motile
  • has moist and mucoid in its colonies
55
Q

Enterobactericiae spp that is the frequent cause of nosomical pneumonia, speticemia, and meningitis

A

Klebsiella spp

56
Q

Lactose fermenters: Klebsiella

Virulence factors

A
  • capsule
  • adhesions
  • iron capturing ability
57
Q

Lactose fermenters: Klebsiella

Significant biochemical reactions

A
  • lactose positive
  • Citrate (+)
  • non motile
  • urease (+)
  • has both O and K antigens
  • LIA K/K
58
Q

Slow lactose fermenters:

Serratia spp

A
  • 7 spp. but S.marcescnes is the only clinically important
  • produce pink pigment esp. when cultures are left at room temp.
  • fairly resistant to antibiotics
59
Q

Non-lactose fermenters:

Hafnia spp

A
  • H.alvei is the only specie
  • occasionally isolated from stools
  • delayed citrate reaction is major characteristic
60
Q

pathogens of Enterobacteriaceae family that are part of normal intestinal flora—- also called as opporunistic pathogen

A

Proteus, Morganella, and Providencia spp.

  • they deaminate phenylalanine
61
Q

Non-lactose fermenters

Enterobacteriaceae

A
  • Hafnia spp
  • Proteus
  • Morganella
  • ## Providencia
62
Q

Non-lactose fermenters:

Proteus spp.

P. mirabilis
P. vulgaris

A
  • isolated from urine, wounds, and ear
  • both produces swarming colonies on non-selective media
  • distinctive “burned chocolate” odor
  • both urease (+)
  • both are phenylalanine deaminase (+)
63
Q

Widely recognized Proteus spp human pathogens

A

P. mirabilis

P. vulgaris

64
Q

Non-lactose fermenters: Proteus spp.

Biochemical characteristic

A

A- exhibits “swarming”

B shows urease (+) on right

65
Q

Non-lactose fermenters:

Morganella spp.

A
  • Morganella morganii is the only specie
  • urease (+)
  • phenylalanine deaminase (+)
  • isolated from other anatomical sites
66
Q

Non-lactose fermenters:

Providencia rettgeri

A
  • pathogen of urinary tract and has caused nosomical outbreaks
  • phenylalanine deaminase (+)
67
Q

Non-lactose fermenters:

Providencia stuartii

A
  • can cause nosomical outbreaks in BURN units nad has been isolated from urine
  • phenylalanine deaminase (+)
68
Q

Late lactose fermenters:

Citrobacter spp.

A
  • C. freundii
  • resembles salmonell spp.
  • hydrolyze urea slowly
  • differentiated by their ability to convert tryptophan to indole
69
Q

A magenta color develops after incubating inoculated bacteria throughout the medium for urea utilization. Which species would give such a result? *

Providencia spp.
Pasteurella spp.
Hemophilus spp.
Pseudomonas spp.
Proteus spp.
A

Proteus spp.

70
Q

Links:

A

https: //www.austincc.edu/microbugz/negative_stain.php
https: //drive.google.com/file/d/1MsBlYPVAYmg87vapD5WkkPl2wJHAipPA/view

BACTERIOLOGY (15 decks)

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