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Micro 425 > Exam 2 - Enterobacteriaceae > Flashcards

Exam 2 - Enterobacteriaceae Flashcards

1
Q

Which pathogen is the most common cause of nosocomial infections:

A

E. coli

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2
Q

Describe the colony appearance of Entero on SBAP and CAP:

A

large, gray, smooth colonies

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3
Q

Entero are all oxidase ____::

A

negative

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4
Q

Most entero are catalase____, the exception is _____ ______:

A

most are catalase+

Shigella dysenteriae is catalase-

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5
Q

List the 11 opportunistic EB pathogens:

Hint: CCEEEEHKMPS

A 
Citrobacter
Cronobacter
Edwardsiella
Enterobacter
Escherichia coli
Ewingella
Hafnia
Klebsiella
Morganella
Proteus
Serratia
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6
Q

List the 3 EB intestinal pathogens:

A

Salmonella
Shigella
Yersinia

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7
Q

List the 5 EB that ferment lactose:

Hint: CEEEK

A 
Citrobacter
E. coli
Enterobacter aerogenes
Enterobacter cloacae
Klebsiella pneumoniae
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8
Q

List the 5 EB that do NOT ferment lactose:

Hint: PSSSY

A 
Proteus 
Salmonella
Shigella
Serratia marcescens
Yersinia enterolitica
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9
Q

Which Shigella species does contain beta-galactosidase but not permease, and is therefor a LATE fermenter:

A

Shigella sonnei

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10
Q

List the two enzymes required to ferment lactose and what they do:

A

1) permease (allows lactose to penetrate bacterial cell wall)
2) Beta-galactosidase (hydrolyzes lactose to glucose + galactose)

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11
Q

These are defined as non-pathogenic strains of microorganisms, commonly used as bacterial indicators of food/water sanitation:

A

coliforms

Citrobacter, Enterobacter, Escherichia, Klebsiella, Serratia

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12
Q

T/F

Coliforms are rod shaped, Gram-, non-spore forming bacteria which can ferment lactose with production of acid and gas:

A

True

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13
Q

T/F

An example of horizontal transmission of disease would be nosocomial infections:

A

True.

person to person

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14
Q

What type of infection is caused when normal flora get into normally sterile body sites:

A

Endogenous

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15
Q

Is food poisoning from Salmonella or Shigella considered endogenous infections:

A

No.

S and S are not normal flora.

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16
Q

95% of all EB isolated are which 3 species:

A

1) E. coli
2) Klebsiella pneumoniae
3) Proteus mirabilis

(>99% of all isolates belong to 23 species)

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17
Q

List the 3 EB that are non- motile:

Hint: KSY

A
  • Klebsiella
  • Shigella
  • Yersinia
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18
Q

EB all grow well on ___ and ____:

A

SBAP

CAP

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19
Q

T/F

Enterics from sterile body sites are not significant.

A

False. They are highly significant.

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20
Q

MacConkey agar is selective for ______ and differential for _____:

A

Selective for Gram- rods (inhibits Gram+)

Differential for lactose fermentation

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21
Q

What are the two additives in MacConkey besides lactose:

A

Bile salts

Crystal violet

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22
Q

If you see H2S concentrated between slant/butt, think this:

A

Salmonella typhae

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23
Q

What differentiates both Proteus species:

A

P. mirabilis: Indole-

P. vulgaris: Indole+

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24
Q

What is used to differentiate E. coli O157:H7 from other E. coli species:

A

O157:H7 does not ferment sorbitol (which would create clear colonies) on MacConkey w/ Sorbitol media)

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25
Q

How can EHEC be differentiated from dysentery caused by Shigella:

A

EHEC stool does NOT contain leukocytes

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26
Q

Treatment of ETEC, EIEC, EPEC, EHEC, and EAEC commonly involves _____, and use of of antibiotics is sometimes _____:

A

rehydration

Antibiotic use may be contraindicated due to acquired resistance

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27
Q

What is a similar infection to EHEC:

A

-STEC
Shiga like toxin producing E. coli
(the cytotoxin is similar to Shigella dysenteriae)

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28
Q

How is EHEC identified:

A

Serotyping O and H antigens

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29
Q

UTI’s account for ___% of nosocomial infections:

A

35%

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30
Q

Urine should be plated on ____ and ___ within _____ or refrigerated:

A

SBAP
MacConkey
30 minutes

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31
Q

The presence of 3+ different colonies on urine culture plate=

A

contamination, not worked up

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32
Q

What type of plate would be used to detect E. coli and Enterococcus in urine:

A

CHROMagar Orientation plates

allows for distinct colony morphologies, do not need additional testing

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33
Q

T/F

Suprapubic and cytoscopy urine speciments should be sterile:

A

True.

Any organism growing should be worked up.

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34
Q

Is it acceptable for clean-catch midstream and catheterized urine specimens to contain contaminants in low numbers:

A

Yes

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35
Q

What are the two species of Salmonella:

A

S. enterica (human)

S. bongori (animal)

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36
Q

Salmonella has more than 2500 _____:

A

serotypes

reflects the extensive diversity of the O and H antigens Salmonella posesses

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37
Q

List the 3 very important serotypes of the Salmonella subspecies enterica:

A
  • Typhimurium (Group B)
  • Enteriditis (Group D)
  • Typhi
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38
Q 
List the results of the following for Salmonella on TSI:
Slant:
Butt:
Gas:
H2S:
A

K/A Gas+ H2S+

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39
Q

What is thought to blame for the 1985 salmonellosis outbreak in Illinois:

A

contaminated milk

antimicrobials in the cows may have led to the resistant strains

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40
Q

Which two serotypes of Salmonella are associated with food poisoning:

A
  • Typhimurium

* Enteriditis (most common in US)

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41
Q

T/F Salmonella type enteriditis can only infect the shell of an egg:

A

False. It can infect chicken ovaries and get inside egg before it is formed.

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42
Q

This Salmonella serotype only lives in humans, but is not normal flora, is spread via human feces/contamination, and can spread to vasculature:

A

Salmonella typhi

Typhoid Fever

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43
Q 
List the results of the following tests for Salmonella serotype Typhi:
H2S:
Citrate:
Ornithine decarboxylase:
Gas from glucose:
A

H2S: Trace amounts at butt/slant interface
Citrate-
Ornithine decarboxylase-
Gas-

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44
Q

T/F
Death rates of Typhoid Fever are 12-30% w/out treatment, and people can become carriers for 2-3 months, but vaccinations are available:

A

True

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45
Q

T/F A large quantity of Shigella organisms is required to cause dysentary infection:

A

FALSE.

As little as 10 organisms is sufficient to cause infection..

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46
Q

This is the most fastidious of the EB, and grows well on MacConkey’s, HE, XLD agar:

A

Shigella

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47
Q

How many subgroups of Shigella are there:

A 
4
*S. dysentariae
*S. flexneri
*S. boydii
*S. sonnei
Each has additional serotypes based on the O antigen
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48
Q

Shigella species have serotypes based on which antigen:

A

O antigen

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49
Q

TSI slant agar has more ___ and ____ than ____:

A

10x more lactose and sucrose than glucose

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50
Q

What results in the TSI slant with Salmonella and Shigella:

A

Initially converts to yelllow, but reverts back to red (alkaline) when read in 18-24 hours.

51
Q

Why do Shigella and Salmonella turn TSI yellow, and then back to red:

A

Ferments glucose to yellow- when glucose is used up, oxidation of peptones occurs, forming amines, which are basic.

52
Q

What color is the TSI butt with Salmonella/Shigella and why:

A

It remains yellow, because no O2 to oxidize peptones.

S/S can ferment glucose, but not lactose or sucrose. (there is much less glucose in TSA)

53
Q

How do you inoculate TSI:

A

Stab to bottom and streak slant surface

54
Q

Can TSI be used for definitive ID:

A

No. Additional biochemical tests must be performed.

55
Q

How do you report TSI results:

A

slant/butt/gas/H2S

56
Q

What are the incubation requirements for EB:

A

35 degrees in ambient air or increased CO2

57
Q

Do most labs perform Gram stains of stool specimens: why:

A

No, because non-pathogenic intestinal flora look similar to enteric pathogens.
(Though presence of WBC/s could indicate invasive pathogen)

58
Q

What is the ONPG good for:

A

Distinguishing late lactose fermenters from non-fermenters.

59
Q

Green colony w/ black center on HE:

A

Salmonella

60
Q

What is the media of choice for Yersinia:

A

CIN agar

61
Q

Presumptive ID of E. coli strains is based on what characteristic:

A

Spot indole +

62
Q

What 3 pathogens should labs always screen for in stool:

A

Campylobacter
Salmonella
Shigella

63
Q

What makes plasmids a virulence factor:

A

They contain DNA distinct from chromosomal DNA, which may mediate antibiotic resistance

64
Q

List the 3 virulence antigens and their location:

A

O (somatic, cell wall)
H (flagellar)
K (capsular)

65
Q

Which antigens are heat labile, which are heat stable:

A

O –> heat stable
H–> heat labile
K–> heat labile

66
Q

H antigens can be used to for ___ and ___:

A

E. coli

Salmonella

67
Q

O antigens can be used for ___, ____, and ___:

A

E. coli
Salmonella
Shigella

68
Q

K antigen is used to type ____, ____, etc:

A

Klebsiella pneumoniae

K1 antigen of E. coli

69
Q 
Presumptive ID for E. coli includes:
Gram\_\_\_ \_\_\_
Oxidase
Indole
Growth on \_\_\_\_
Definitive includes:
\_\_\_\_ hemolysis OR
Lactose\_\_\_   AND PYR\_\_\_\_\_
A

Gram- rods
Oxidase-
Indole+
Growth on MacConkey

Beta hemolytic
Lactose+
PYR-

70
Q

Describe the morphology of E. coli:

A

dry, pink (lactose+) colony with surrounding pink are on MacConkey

71
Q 
List the TSA slant results of E. coli:
Indole
Methyl red
Simmons citrate 
Voges-Proskauer
A 
A/A Gas+  H2S-
Indole+
Methyl red+
Simmons citrate -
Voges-Proskauer-
72
Q

What differentiates the KIA from TIA:

A

KIA: glucose, lactose
TIA: glucose, lactose, sucrose

73
Q

Which sugar in TIA is in the least amount:

A

glucose

74
Q

What has a safety pin appearance on Gram stain, and from what group:

A

Yersinia spp.

EB group

75
Q

Growth of this on CIN yields bullseye colonies, dark red center with surrounding clear halo:

A

Yersinia enterocolitica

EB group

76
Q

This is a slow lactose fermenter, opportunistic organism from the EB group that can cause nosocomial acquired UTI, resp infection, neonatal meningitis:

A

Citrobacter spp.

77
Q

Bile salts enhance the growth of this:

A

Yersinia spp.

78
Q

Which species of Proteus is more antibiotic resistant, and known to be nosocomial:

A

Proteus vulgaris

79
Q

Citrobacter can use _____ as its sole carbon source:

A

Citrate

80
Q

This organism is DNAase+ and ONPG+ and has variable lactose fermentation, is also associated with contaminated catheters:

A

Serratia spp.

81
Q

This organism produces red, water soluble pigment at room temp, but rarely at 35 C:

A

Serratia marcescens

82
Q

This genus has mucoid colonies, and is associated with nosocomial infections with medical devices:

A

Enterobacter spp.

83
Q

This organism is also known as ‘Friendlander’s bacillus’:

A

Klebsiella pneumoniae

84
Q

Klebsiella pneumoniae has which antigens associated with it:

A

O

K

85
Q

This organism has large, mucoid, stringy colonies, and antigens O and K associated with it:

A

Klebsiella pneumoniae

86
Q

This organism causes an STD that causes genital nodules and scarring, it is seen in phagocytes from scrapings–> called Donovan bodies:

A

Klebsiella granulomatis

87
Q

Which organism is the most fastidious of the EB group, and which media does it grow well on:

A

Shigella

*MacConkey’s, HE, XLD

88
Q

Shigella spp. is catalase variable, S. dysenteriae is catalase ___:

A

Catalase+

89
Q

Which antigens are associated with Salmonella:

A

O

H

90
Q

T/F

Salmonella has endotoxins:

A

True. They enhance intracellular survival.

91
Q

This subtype has the K antigen, is capsular, and will be H2S+ between butt/slant:

A

Salmonella (Typhi)

92
Q

Which antigens are associated with E. coli:

A

O

H

93
Q

This organism is uncommon in humans, but can cause diarrhea, wound infections, and bacteremia, and is associated with snakes and turtles:

A

Edwardsiella tarda

94
Q

Which microbes can cause Traveler’s diarrhea:

A
  • E. coli
  • Salmonella spp.
  • Salmonella
  • Shigella
95
Q

T/F

Specimens for Yersinia pestis (plague) include blood cultures, sputum, lymph node aspirates:

A

True

96
Q

What is the most serious form of Plague:

A

pneumonic

90% fatal w/out treatment

97
Q

This type of Plague causes painful buboes, and can invade blood vessels if untreated–>75% fatality rate:

A

Bubonic Plague

98
Q

Where is the H antigen located:

A

Flagella

99
Q

Describe results of the following on HE media:
Fermentation:
S/S growth:
Salmonella with H2S+

A

Lactose/sucrose ferment= yellow colonies
S/S = blue/green
Salmonella w/ H2S+ produces blue green colonies with black centers

100
Q

This selective and differential media is especially good for isolating S & S:

A

XLD

101
Q

How is XLD selective and differential:

A

Selective: inhibits Gram+
Differential: xylose fermentation

102
Q

What is the ingredient in XLD that inhibits Gram+:

A

Sodium deoxycholate

103
Q

In XLD, fermenting xylose means lysine-decarboxylase ____, so won’t ferment lactose/sucrose, and will cause ____ color colonies:

A

LD negative

yellow colonies

104
Q

What does Lysine-decarboxylase do:

A

Reverts the pH back to alkaline

105
Q

XLD with ______ is used to inhibit Proteus spp.: (in order to not get a false pos of Proteus)

A

Novobiocin

106
Q

This is used as a control organism in autoclave effectiveness:

A

Bacillus stearothermophilus

107
Q

List the TSI results of Proteus mirabilis:

A

K/A Gas+ H2S+

108
Q

List the TSI results of Proteus vulgaris:

A

A/A Gas+ H2S+

109
Q

List the TSI results of Citrobacter:

A

A/A Gas+ H2S+

110
Q

Hafnia alvei is
Lactose__
Citrate___

A

Lactose-

Citrate-

111
Q

List the TSI results of Serratia spp:

A

A/A or K/A Gas+ H2S-

112
Q

List the TSI results of Enterobacter:

A

A/A Gas+ H2S-

113
Q

Enterobacter is Lactose__, VP__, and Indole___:

A

Lactose+
VP+
Indole-

114
Q

List the TSI results for Klebsiella pneumoniae:

A

A/A Gas+ H2S-

115
Q 
List the results for Klebsiella pneumoniae:
Lactose
Antigens
Urease
Indole
MR
VP
Citrate
A 
Lactose+
Antigens:  O, K
Urease   weak+
Indole-
MR  variable
VP+
Citrate+
116
Q

Donovan bodies are associated with this:

A

Klebsiella granulomatis

117
Q

List the TSI results for Shigella:

A

K/A Gas- H2S-

118
Q

List the TSI results for Salmonella:

A

K/A Gas+ H2S+

119
Q

Which produces gas and H2S on TSI, Shigella or Salmonella:

A

Salmonella

120
Q

Do Salmonella and Shigella produce spores:

A

NO

121
Q

List the TSI results for E. coli:

A

A/A Gas+ H2S-

122
Q 
List the following results for E. coli:
Oxidase
Indole
Lactose
PYR
Methyl red
Simmons Citrate
VP
A 
Oxidase-
Indole+
Lactose+
PYR-
Methyl red+
Simmons Citrate-
VP-
123
Q

List the TSI results of Edwardsiella tarda:

A

K/A Gas+/- H2S+

Micro 425 (12 decks)

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