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Microbiology Exam 3 > Enterobacteriaceae Overview > Flashcards

Enterobacteriaceae Overview Flashcards

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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?

A

The gut

25
Q

Most lactose positive gram negative rods will be E. coli if they are also…

A

Indole +

VP -

Citrate -

26
Q

Which are the atigenic determinants of E. coli?

What are they associated with?

A

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
Q

Pathogenic E. coli is most commonly associated with…

A

UTI (uropathogenic E. coli)

Neonatal meningitis

Intestinal disease (gastroenteritis)*** 5 classes (or virotypes) now recognized

Nosocomial Infections

28
Q

E. coli 0157:H7 or EHEC

A

Gastrointestinal E. coli

most life threatening (O and H antigens)

Selective media: MacConkey Sorbitol (SOR -)

Shiga-toxin producer

29
Q

Enterohemorrhagic E. coil (EHEC)

A

Gastrointestinal E. coli

Produces bloody diarrhea often associated with Hemolytic Uremic Syndrom

30
Q

Enteroaggregative E. coli (EAEC)

A

Gastrointestinal E. coli

Recovered from children with chronic diarrhea

31
Q

Enterotoxigenis E. coli (ETEC)

A

Gastrointestinal E. coli

Produces heat stable (ST) and heat labile (LT) toxins

Traveler’s diarrhea

32
Q

Enteroinvasive E. coli (EIEC)

A

Gastrointestinal E. coli

Produces a dysentery-like disease in poor nations

33
Q

Enteropathogenic E. coli (EPEC)

A

Gastrointestinal E. coli

Produces a profound diarrhea in infants in poor nations

34
Q

Klebsiella pneumoniae has ____ and ____ antigens which may be typed.

A

O and K antigens

35
Q

Klebsiella pneumonia specimens of choice

A

urine (UTI)

deep cough (pneumonia)

36
Q

Citrobacter freundii is normal flora in…….

It causes infrequent cases of…….

A

human gastrointestinal tract

UTI and RTI

37
Q

Proteus mirabilis is found in…

A

manure

sewage

soil

38
Q

Proteus mirabilis is responsible for…

A

Antibiotic diarrhea (multiple drug resistance)

UTI

Promotes kidney stones

Abscesses, pyelonphritis, cystis, infant diarrhea

39
Q

What are the 3 categories of Salmonella?

A

Gastroenteritis and diarrhea

Bacteremia/ extraintestinal infection

Enteric Fever (typhoid fever)

40
Q

How does the Kauffman-White scheme of serotyping identify diffrent groups of Salmonell?

A

heat stable O antigen

heat-liable H antigen

heat-liable Vi antigen

41
Q

Where is Salmonella commonly found?

What dieseses are associated with it?

A

Animals- reptiles, pet turtles, fowls

Food- eggs, meat, mayo

Food poisoning

Paratyphoid fever

Bacteremia

Salmonellosis

* Mistaken as Fever of Unknown Origin (FUO)

42
Q

How long does it take for symptoms to present with Salmonella food poisoning?

Staphylococcal food poisoning?

A

Salmonella: 10-28 hours

Staphylococcus: 2-6 hours

43
Q

Shigella are identified ________ with _____antigens.

A

serologically, O

44
Q

Shigella sonnei

Host?

Infections?

A

Humans

Watery diarrhea (crowding and unsanitary conditions)

Shigellosis (from fecally contaminated water or food)

** Produce potent toxins, no bacteremias

45
Q

Yersinia enterocolitica

Reservoir?

Infections?

A

Dogs, cats, rodents, pigs, cattle

Food/Drink vehicle

Infection mimics appendicitis

46
Q

Agar?

Organism?

Colony Appearance?

A

CIN

Yersinia

Dark-red bullseye colonies

Microbiology Exam 3 (5 decks)

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