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
How can EHEC be differentiated from dysentery caused by Shigella:
EHEC stool does NOT contain leukocytes
26
Treatment of ETEC, EIEC, EPEC, EHEC, and EAEC commonly involves _____, and use of of antibiotics is sometimes _____:
rehydration | Antibiotic use may be contraindicated due to acquired resistance
27
What is a similar infection to EHEC:
-STEC Shiga like toxin producing E. coli (the cytotoxin is similar to Shigella dysenteriae)
28
How is EHEC identified:
Serotyping O and H antigens
29
UTI's account for ___% of nosocomial infections:
35%
30
Urine should be plated on ____ and ___ within _____ or refrigerated:
SBAP MacConkey 30 minutes
31
The presence of 3+ different colonies on urine culture plate=
contamination, not worked up
32
What type of plate would be used to detect E. coli and Enterococcus in urine:
CHROMagar Orientation plates | allows for distinct colony morphologies, do not need additional testing
33
T/F | Suprapubic and cytoscopy urine speciments should be sterile:
True. | Any organism growing should be worked up.
34
Is it acceptable for clean-catch midstream and catheterized urine specimens to contain contaminants in low numbers:
Yes
35
What are the two species of Salmonella:
S. enterica (human) | S. bongori (animal)
36
Salmonella has more than 2500 _____:
serotypes | reflects the extensive diversity of the O and H antigens Salmonella posesses
37
List the 3 very important serotypes of the Salmonella subspecies enterica:
* Typhimurium (Group B) * Enteriditis (Group D) * Typhi
38
``` List the results of the following for Salmonella on TSI: Slant: Butt: Gas: H2S: ```
K/A Gas+ H2S+
39
What is thought to blame for the 1985 salmonellosis outbreak in Illinois:
contaminated milk | antimicrobials in the cows may have led to the resistant strains
40
Which two serotypes of Salmonella are associated with food poisoning:
* Typhimurium | * Enteriditis (most common in US)
41
T/F Salmonella type enteriditis can only infect the shell of an egg:
False. It can infect chicken ovaries and get inside egg before it is formed.
42
This Salmonella serotype only lives in humans, but is not normal flora, is spread via human feces/contamination, and can spread to vasculature:
Salmonella typhi | Typhoid Fever
43
``` List the results of the following tests for Salmonella serotype Typhi: H2S: Citrate: Ornithine decarboxylase: Gas from glucose: ```
H2S: Trace amounts at butt/slant interface Citrate- Ornithine decarboxylase- Gas-
44
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:
True
45
T/F A large quantity of Shigella organisms is required to cause dysentary infection:
FALSE. | As little as 10 organisms is sufficient to cause infection..
46
This is the most fastidious of the EB, and grows well on MacConkey's, HE, XLD agar:
Shigella
47
How many subgroups of Shigella are there:
``` 4 *S. dysentariae *S. flexneri *S. boydii *S. sonnei Each has additional serotypes based on the O antigen ```
48
Shigella species have serotypes based on which antigen:
O antigen
49
TSI slant agar has more ___ and ____ than ____:
10x more lactose and sucrose than glucose
50
What results in the TSI slant with Salmonella and Shigella:
Initially converts to yelllow, but reverts back to red (alkaline) when read in 18-24 hours.
51
Why do Shigella and Salmonella turn TSI yellow, and then back to red:
Ferments glucose to yellow- when glucose is used up, oxidation of peptones occurs, forming amines, which are basic.
52
What color is the TSI butt with Salmonella/Shigella and why:
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
How do you inoculate TSI:
Stab to bottom and streak slant surface
54
Can TSI be used for definitive ID:
No. Additional biochemical tests must be performed.
55
How do you report TSI results:
slant/butt/gas/H2S
56
What are the incubation requirements for EB:
35 degrees in ambient air or increased CO2
57
Do most labs perform Gram stains of stool specimens: why:
No, because non-pathogenic intestinal flora look similar to enteric pathogens. (Though presence of WBC/s could indicate invasive pathogen)
58
What is the ONPG good for:
Distinguishing late lactose fermenters from non-fermenters.
59
Green colony w/ black center on HE:
Salmonella
60
What is the media of choice for Yersinia:
CIN agar
61
Presumptive ID of E. coli strains is based on what characteristic:
Spot indole +
62
What 3 pathogens should labs always screen for in stool:
Campylobacter Salmonella Shigella
63
What makes plasmids a virulence factor:
They contain DNA distinct from chromosomal DNA, which may mediate antibiotic resistance
64
List the 3 virulence antigens and their location:
O (somatic, cell wall) H (flagellar) K (capsular)
65
Which antigens are heat labile, which are heat stable:
O --> heat stable H--> heat labile K--> heat labile
66
H antigens can be used to for ___ and ___:
E. coli | Salmonella
67
O antigens can be used for ___, ____, and ___:
E. coli Salmonella Shigella
68
K antigen is used to type ____, ____, etc:
Klebsiella pneumoniae | K1 antigen of E. coli
69
``` Presumptive ID for E. coli includes: Gram___ ___ Oxidase Indole Growth on ____ Definitive includes: ____ hemolysis OR Lactose___ AND PYR_____ ```
Gram- rods Oxidase- Indole+ Growth on MacConkey Beta hemolytic Lactose+ PYR-
70
Describe the morphology of E. coli:
dry, pink (lactose+) colony with surrounding pink are on MacConkey
71
``` List the TSA slant results of E. coli: Indole Methyl red Simmons citrate Voges-Proskauer ```
``` A/A Gas+ H2S- Indole+ Methyl red+ Simmons citrate - Voges-Proskauer- ```
72
What differentiates the KIA from TIA:
KIA: glucose, lactose TIA: glucose, lactose, sucrose
73
Which sugar in TIA is in the least amount:
glucose
74
What has a safety pin appearance on Gram stain, and from what group:
Yersinia spp. | EB group
75
Growth of this on CIN yields bullseye colonies, dark red center with surrounding clear halo:
Yersinia enterocolitica | EB group
76
This is a slow lactose fermenter, opportunistic organism from the EB group that can cause nosocomial acquired UTI, resp infection, neonatal meningitis:
Citrobacter spp.
77
Bile salts enhance the growth of this:
Yersinia spp.
78
Which species of Proteus is more antibiotic resistant, and known to be nosocomial:
Proteus vulgaris
79
Citrobacter can use _____ as its sole carbon source:
Citrate
80
This organism is DNAase+ and ONPG+ and has variable lactose fermentation, is also associated with contaminated catheters:
Serratia spp.
81
This organism produces red, water soluble pigment at room temp, but rarely at 35 C:
Serratia marcescens
82
This genus has mucoid colonies, and is associated with nosocomial infections with medical devices:
Enterobacter spp.
83
This organism is also known as 'Friendlander's bacillus':
Klebsiella pneumoniae
84
Klebsiella pneumoniae has which antigens associated with it:
O | K
85
This organism has large, mucoid, stringy colonies, and antigens O and K associated with it:
Klebsiella pneumoniae
86
This organism causes an STD that causes genital nodules and scarring, it is seen in phagocytes from scrapings--> called Donovan bodies:
Klebsiella granulomatis
87
Which organism is the most fastidious of the EB group, and which media does it grow well on:
Shigella | *MacConkey's, HE, XLD
88
Shigella spp. is catalase variable, S. dysenteriae is catalase ___:
Catalase+
89
Which antigens are associated with Salmonella:
O | H
90
T/F | Salmonella has endotoxins:
True. They enhance intracellular survival.
91
This subtype has the K antigen, is capsular, and will be H2S+ between butt/slant:
Salmonella (Typhi)
92
Which antigens are associated with E. coli:
O | H
93
This organism is uncommon in humans, but can cause diarrhea, wound infections, and bacteremia, and is associated with snakes and turtles:
Edwardsiella tarda
94
Which microbes can cause Traveler's diarrhea:
* E. coli * Salmonella spp. * Salmonella * Shigella
95
T/F | Specimens for Yersinia pestis (plague) include blood cultures, sputum, lymph node aspirates:
True
96
What is the most serious form of Plague:
pneumonic | 90% fatal w/out treatment
97
This type of Plague causes painful buboes, and can invade blood vessels if untreated-->75% fatality rate:
Bubonic Plague
98
Where is the H antigen located:
Flagella
99
Describe results of the following on HE media: Fermentation: S/S growth: Salmonella with H2S+
Lactose/sucrose ferment= yellow colonies S/S = blue/green Salmonella w/ H2S+ produces blue green colonies with black centers
100
This selective and differential media is especially good for isolating S & S:
XLD
101
How is XLD selective and differential:
Selective: inhibits Gram+ Differential: xylose fermentation
102
What is the ingredient in XLD that inhibits Gram+:
Sodium deoxycholate
103
In XLD, fermenting xylose means lysine-decarboxylase ____, so won't ferment lactose/sucrose, and will cause ____ color colonies:
LD negative | yellow colonies
104
What does Lysine-decarboxylase do:
Reverts the pH back to alkaline
105
XLD with ______ is used to inhibit Proteus spp.: (in order to not get a false pos of Proteus)
Novobiocin
106
This is used as a control organism in autoclave effectiveness:
Bacillus stearothermophilus
107
List the TSI results of Proteus mirabilis:
K/A Gas+ H2S+
108
List the TSI results of Proteus vulgaris:
A/A Gas+ H2S+
109
List the TSI results of Citrobacter:
A/A Gas+ H2S+
110
Hafnia alvei is Lactose__ Citrate___
Lactose- | Citrate-
111
List the TSI results of Serratia spp:
A/A or K/A Gas+ H2S-
112
List the TSI results of Enterobacter:
A/A Gas+ H2S-
113
Enterobacter is Lactose__, VP__, and Indole___:
Lactose+ VP+ Indole-
114
List the TSI results for Klebsiella pneumoniae:
A/A Gas+ H2S-
115
``` List the results for Klebsiella pneumoniae: Lactose Antigens Urease Indole MR VP Citrate ```
``` Lactose+ Antigens: O, K Urease weak+ Indole- MR variable VP+ Citrate+ ```
116
Donovan bodies are associated with this:
Klebsiella granulomatis
117
List the TSI results for Shigella:
K/A Gas- H2S-
118
List the TSI results for Salmonella:
K/A Gas+ H2S+
119
Which produces gas and H2S on TSI, Shigella or Salmonella:
Salmonella
120
Do Salmonella and Shigella produce spores:
NO
121
List the TSI results for E. coli:
A/A Gas+ H2S-
122
``` List the following results for E. coli: Oxidase Indole Lactose PYR Methyl red Simmons Citrate VP ```
``` Oxidase- Indole+ Lactose+ PYR- Methyl red+ Simmons Citrate- VP- ```
123
List the TSI results of Edwardsiella tarda:
K/A Gas+/- H2S+