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Enterobacteriaceae Overview Flashcards

1
Q

What organism is this?

(Blood Agar)

A

Proteus mirabilis

Swarming on blood agar

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2
Q

What are the general characteristics of Enterobacteriaceae?

A

Gram-negative rod shaped organisms

Ability to reduce nitrates to nitrites (NO3->NO2)

Inability to produce the respiratory enzyme oxidase (oxidase negative)

Facultative anaerobic metabolism (prefers oxygen reduced environment)

Fermentation of glucose (glucose positive)

Growth on MacConkey agar

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3
Q

What tests are part of IMViC?

What is a positive result?

A

Used to identify an organism in the coliform group (a gram negative aerobic/non-aerobic lactose producing rod)

I: Indole- tests organism for indole production

POSITIVE: a pink/red layering forming on the top of the liquid

M: Methyl Red- detects fermentation of glucose based on acids produced

POSITIVE: red color change

V: VP- tests to see if bacteria can produce acetoin from fermenting glucose

POSITIVE: red color change

C: Citrate: determines if an organism can use citrate for it’s sole carbon source

POSITIVE: blue color change

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4
Q

Which Enterobacteriaceae are lactose positive?

A
  • Escherichia*
  • Klebciella*
  • Enterobacter*
  • Citrobacter*
  • Serratia marcescens*
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5
Q

Which Enterobacteriaceae are lactose negative?

A
  • Proteus*
  • Providentia*
  • Salmonella*
  • Shigella*
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6
Q

What is the most common clinical isolate?

A

Eschericha coli

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7
Q

Which Enterobacteriaceae are non-motile?

How would you differentiate these two organisms?

A
  • Klebsiella* (lactose positive)
  • Shigella* (lactose negative)
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8
Q

Which organism is a lactose positive H2S producer?

A

Citrobacter

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9
Q

Are Pseudomonas and Vibro enterobacteriaceae?

A

NO

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10
Q

Serratia an Yersinia are _________ (common/rare) clinical isolates.

A

rare

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11
Q

Which lactose positive organism is indole postitive?

A

E. coli

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12
Q

Which lactose positive organisms are citrate and VP positive?

How would you differentiate between the two?

A

Klebsiella (non-motile)
Enterobacter (motile)

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13
Q

Describe the Lysine Iron Agar slant test

A

Tests for glucose fermentation, lysine decarboxylation, lysine deamination, and H2S production.

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14
Q

LIA Slant- interpret slant number 3

A

purple slant/ purple butt

Alkaline slant/ Alkaline butt

K/K

Lysine decarboxylation

No glucose fermentation

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15
Q

LIA slant- interpret tube #1

A

Purple slant/ yellow butt

Alkaline slant/ Acid butt

K/A

Glucose fermentation

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16
Q

LIA slant- interpret slant # 2

A

Red slant/ yellow butt

Red slant/ alkaline butt

R/A

Lysine Deamination

Glucose fermentation

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17
Q

LIA slant- interpret slant #4

A

H2S production

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18
Q

Describe the Triple Sugar Iron Agar slant

A

Tests and organisms abilty to ferment glucose, lactose, sucrose and tests for gas production and H2S.

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19
Q

TSI slant- interpret slant number 2

A

Red slant/ Yellow Butt

Alkaline slant/ acid butt

K/A

Glucose positive (glucose only)

20
Q

TSI slant- interpret slant #4

A

Yellow slant/ yellow butt

Acid slant/ Acid butt

A/A

Glucose + Lactose/Sucrose positive

*** this also shows gas production

21
Q

TSI slant- interpret slant #1

A

Red slant/ red butt

alkaline slant/ alkaline butt

K/K

No fermentation

22
Q

TSI slant- interpret slant #3

A

H2S production

23
Q

Describe the urea hydrolysis test (Christiansen’s).

What is a positive result?

A

Tests an organisms ability to produce the enzyme urease.

POS: magenta

NEG: light orange

24
Q

E. coli is normal flora in which part of the body?

25
Most lactose positive gram negative rods will be E. coli if they are also...
Indole + VP - Citrate -
26
Which are the atigenic determinants of E. coli? What are they associated with?
_O antigens_- associated with cell wall, heat stable (0157) _K antigens_- associated with capsule around cell wall, responsible for inhibition of agglutination by specific antibody _H antigens_- associated with flagella (H7)
27
Pathogenic E. coli is most commonly associated with...
UTI (uropathogenic E. coli) Neonatal meningitis Intestinal disease (gastroenteritis)\*\*\* 5 classes (or virotypes) now recognized Nosocomial Infections
28
E. coli 0157:H7 or EHEC
Gastrointestinal E. coli most life threatening (O and H antigens) Selective media: MacConkey Sorbitol (SOR -) Shiga-toxin producer
29
Enterohemorrhagic E. coil (EHEC)
Gastrointestinal E. coli Produces bloody diarrhea often associated with Hemolytic Uremic Syndrom
30
Enteroaggregative E. coli (EAEC)
Gastrointestinal E. coli Recovered from children with chronic diarrhea
31
Enterotoxigenis E. coli (ETEC)
Gastrointestinal E. coli Produces heat stable (ST) and heat labile (LT) toxins Traveler's diarrhea
32
Enteroinvasive E. coli (EIEC)
Gastrointestinal E. coli Produces a dysentery-like disease in poor nations
33
Enteropathogenic E. coli (EPEC)
Gastrointestinal E. coli Produces a profound diarrhea in infants in poor nations
34
Klebsiella pneumoniae has ____ and ____ antigens which may be typed.
O and K antigens
35
Klebsiella pneumonia specimens of choice
urine (UTI) deep cough (pneumonia)
36
Citrobacter freundii is normal flora in....... It causes infrequent cases of.......
human gastrointestinal tract UTI and RTI
37
Proteus mirabilis is found in...
manure sewage soil
38
Proteus mirabilis is responsible for...
Antibiotic diarrhea (multiple drug resistance) UTI Promotes kidney stones Abscesses, pyelonphritis, cystis, infant diarrhea
39
What are the 3 categories of Salmonella?
Gastroenteritis and diarrhea Bacteremia/ extraintestinal infection Enteric Fever (typhoid fever)
40
How does the Kauffman-White scheme of serotyping identify diffrent groups of Salmonell?
heat stable O antigen heat-liable H antigen heat-liable Vi antigen
41
Where is Salmonella commonly found? What dieseses are associated with it?
Animals- reptiles, pet turtles, fowls Food- eggs, meat, mayo Food poisoning Paratyphoid fever Bacteremia Salmonellosis \* Mistaken as Fever of Unknown Origin (FUO)
42
How long does it take for symptoms to present with Salmonella food poisoning? Staphylococcal food poisoning?
Salmonella: 10-28 hours Staphylococcus: 2-6 hours
43
Shigella are identified ________ with \_\_\_\_\_antigens.
serologically, O
44
Shigella sonnei Host? Infections?
Humans Watery diarrhea (crowding and unsanitary conditions) Shigellosis (from fecally contaminated water or food) \*\* Produce potent toxins, no bacteremias
45
Yersinia enterocolitica Reservoir? Infections?
Dogs, cats, rodents, pigs, cattle Food/Drink vehicle Infection mimics appendicitis
46
Agar? Organism? Colony Appearance?
CIN Yersinia Dark-red bullseye colonies

Microbiology (11 decks)

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