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Bacteriology Exam 5 (Enterobacterales) Flashcards

1
Q

What is the only oxidase positive GNR?

A

Plesiomonas

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2
Q

What are the lactose positive GNR?

A

E. coli, Citrobacter, Klebsiella, Enterobacter

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3
Q

What GNR is non-motile at 37 degrees C?

A

Yersinia

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4
Q

What are the two non-motile GNR?

A

Klebsiella and Shigella

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5
Q

How do you differentiate between Klebsiella oxytoca and Klebsiella pneumoniae/granulomatis?

A

Klebsiella oxytoca is indole positive
Klebsiella pneumoniae/granulomatis are indole negative

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6
Q

How do you differentiate between Proteus vulgaris and Proteus mirabilis?

A

P. vulgaris is indole positive
P. mirabilis is indole negative

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7
Q

Which Enterobacterales is spread by fleas (bubonic plague)?

A

Yersinia pestis

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8
Q

What are the common characteristics of Enterobacterales?

A

All reduce nitrate to nitrite
All ferment glucose
All except one are oxidase negative (Pleseomonas is positive)
Referred to as Enterics
All members are facultative anaerobes
GNR
All are motile except for Kleb and Shigella

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9
Q

What are the primary pathogens of interest if a routine stool culture is ordered? What are they the causative agents of?

A

Salmonella and Shigella; they are the causative agents of typhoid fever and dysentery.

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10
Q

What are the primary pathogens of Enterobacterales?

A

E. coli
Salmonella sp.
Shigella sp.
Yersinia sp.
P. shigelloides

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11
Q

What Enterobacterales is the most common cause of UTI/Kidney infection?

A

E. coli

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12
Q

What color is E. coli on EMB?

A

Shiny green metallic color

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13
Q

What color would E. coli (or normal flora) be on XLD agar?

A

Bright yellow colonies

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14
Q

What color would Salmonella sp. be on XLD agar?

A

Black

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15
Q

Where is E. coli O157:H7 found as normal flora?

A

Cows

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16
Q

What meat can you consume and risk acquiring E. coli O157:H7

A

Beef (normal flora in cows)

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17
Q

What is the enterohemorrhagic E. coli (EHEC)? What can it cause?

A

E. coli O157:H7; may cause hemorrhagic colitis causing watery/bloody diarrhea and severe cramps due to consuming bad beef, can cause HUS (hemolytic uremic syndrome)

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18
Q

Does E. coli O157:H7 (EHEC) have a low or a high ID50? What does this mean?

A

Low; it means only a small amount of the bacteria is needed to cause disease

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19
Q

How do you test for E. coli O157:H7? What would it look like?

A

MacConkey Sorbitol Agar, O157:H7 would be clear on this plate

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20
Q

What do EHEC cause?

A

hemorrhagic colitis

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21
Q

What do ETEC cause?

A

“Travelers diarrhea” - toxins not related to EHEC; special toxins (LT and ST) cause lining of intestine to secrete excess fluid

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22
Q

What do EPEC cause?

A

Pediatric diarrhea with large amounts of mucus but no blood - often outbreaks in nurseries and daycares

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23
Q

EIEC

A

rare in U.S/less common worldwide; produces dysentery similar to shigella; EIEC E. coli are lactose negative and non-motile

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24
Q

What does EAEC cause? What group does it mostly affect?

A

Diarrhea by adhering to mucosal surface of intestine; watery diarrhea, vomiting, dehydration, abdominal pain; mostly affects infants and AIDS PATIENTS

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25
Which members of Enterobacterales swarm the BAP?
Proteus spp.
26
What are the phenylalanine positive Enterobacterales?
Proteus, Morganella, Providencia
27
What members of Enterobacterales are H2S positive?
Salmonella, Proteus, Citrobacter
28
What members of Enterobacterales are indole positive?
Edwardsiella, Providencia, Morganella, P. vulgaris, E. coli, Citrobacter, K. oxytoca
29
What is the commonly recovered species from infections involving aquatic environmental wounds, contamination, or ingestion of contaminated water or fish?
Edwardsiella tarda
30
What Is the most common infection caused by Enterobacter spp.?
HAIs via catheterization
31
What citrobacter sp. is associated with nursery outbreaks of neonatal meningitis and brain abscesses?
C. koseri
32
Most common Citrobacter spp. infections:
UTI
33
Which species is slowly urea positive, and may be mistaken for Salmonella in stool cultures because it is H2S positive on HE/XLD?
Citrobacter species
34
Where are Klebsiella species found?
GI tract of animals and humans, soil, water, plants
35
What species has very mucoid colony morphology?
Klebsiella; also Enterobacter
36
What does Klebsiella oxytoca most commonly cause?
UTIs
37
What is a Donovan body?
Klebsiella granulomatis found intracellular (inside endothelial cells)
38
What is the most commonly recovered Enterobacter spp.?
E. cloacae
39
What is the main pathogen of Serratia spp? What do they most likely cause?
Serratia marcescens; infections in medical devices
40
What organism is DNase positive?
Serratia
41
What organism produces a unique red pigment?
Serratia marcescens
42
What are the two main Proteus species of interest?
P. vulgaris/P. mirabilis
43
Nearly all Proteus spp infections are associted with ____, _____, _____, and _____.
urine, ears, wounds, blood
44
What organism can cause a dog's paws to smell like fritos?
Proteus spp.
45
Morganella epidemiology
Ubiquitous through environment and normal flora of the GI tract. Emerging pathogen for skin, soft tissue, and UTIs as HAI
46
Motile, GNR that lives in freshwater environments and causes infections through ingestion or direct contact through wounds in humans/animals (Considered an emerging pathogen for food and waterborne illnesses)
Plesiomonas shigelloides
47
How to differentiate Aeromonas spp. and Plesiomonas spp. (since they are both oxidase POS)
Aeromonas spp. is DNase-positive Plesiomonas spp. is DNase negative
48
What may cross react with Shigella antisera? What is the difference between these two?
Plesiomonas shigelloides; but it is much less virulence than Shigella
49
What organism will grow well on CIN agar?
Yersinia spp.
50
What organism grows best at room temperature, but grows at 37 C and shows no motility at this temp?
Yersinia spp
51
What organism has a safety pin appearance gram stain?
Yersinia spp.
52
What organism can survive cold temperatures, contaminating blood products, and causes appendicitis-like signs/symptoms?
Yersinia enterocolitica
53
Is Yersinia enterocolitica a part of normal GI flora?
No
54
What does Yersinia enterocolitica grow like on CIN agar?
Red bulls-eye colonies
55
What is the H antigen?
Flagellar
56
What is the O antigen?
Somatic
57
What is the normal habitat of S. enterica? Cold or warm blooded environments?
Warm-blooded animals (humans!)
58
Where are Salmonella species normally found?
GI tract of cold blooded animals and birds
59
Where does a human acquire Salmonella?
undercooked poultry, milk, eggs, and dairy products
60
Vi/K antigen
Capsular antigen
61
How can MLS manipulate samples to access the O antigen of Salmonella?
Boil sample to destroy heat labile Vi/K antigens and then retype to access heat stable O antigen
62
How do you ID Salmonella for routine stool culture?
XLD agar, HE agar, Selenite broth, Positive motility
63
Salmonella ID50
Salmonella is highly sensitive to gastric acid so a large ID50 is required --> need a lot of Salmonella to cause disease
64
What bacteria causes a BLOODY diarrhea and destruction of GI tissue through VERTICAL INVASION of colonic epithelial cells?
Salmonella
65
Non-typhoidal vs Typhoidal Salmonella
Typhoidal: systemic disease (Refers to S. typhi and S. paratyphia) can become bloodstream infections Non-typhoidal: acute gastroenteritis (all serotypes of Salmonella enterica except above)
66
Is non-typhoidal or typhoidal salmonella more common? Which is more virulent?
Non-typhoidal is more common, Typhoidal is more virulent
67
When do GI symptoms start after ingestion of Salmonella?
8-36 hours and is self-limiting and resolves within 7 days (non-typhoidal)
68
Are antibiotics recommended with Salmonella? Why?
No; it can cause a carrier state and relapse in non-typhoid species of Salmonella
69
How is Shigella spread? Is it normal flora?
Shigella is NEVER normal flora; it is spread person to person by poor hygiene
70
Clear colony on XLD/HE
Shigella
71
4 Major O antigen groups of Shigella (Group A, Group B, Group C, Group D)
A - S. dysenteriae B - S. flexneri C - S. boydii D - S. sonnei
72
What is the most predominant group of Shigella worldwide?
Group B - S. flexneri
73
What is the most severe/high death rate Shigella group?
Group A - S. dysenteriae
74
What is the most predominant in industrialized countries and in the US Shigells group?
Group D - S. sonnei
75
Is the ID50 for Shigella low or high?
Low ID50 - can withstand gastric acid and is very contagious
76
What organism causes Notorious tissue invasion as an intracellular pathogen and multiplies/spreads to adjacent/HORIZONTAL epithelial cells?
Shigella
77
Does Shigella invade the bloodstream?
Rarely
78
When do symptoms appear after ingestion of Shigella?
2-4 days after ingestion, self-limiting, antibiotics useful in severe cases
79
How long can stool samples be held?
48 hours
80
What is the routine media for Enterobacterale?
BAP/CHOC/MAC XLD/HE for Salmonella & Shigella
81
When is WellColex performed?
AFter API20E
82
Citrate and VP positive organisms? How can they be further narrowed down?
- Enterobacter --> motile and LF - Klebsiella --> non-motile and LF - Serratia --> motile and NLF
83
E. cloacae vs E. aerogenes
E. cloacae is arginine and ornithine positive E. aerogenes is lysine and ornithine positive
84
E. coli hemolysis
Beta hemolytic
85
E. coli citrate and VP
negative
86
E. coli IMViC reactions
++-- (indole, methyl red, BP, citrate)
87
K. pneumoniae IMViC reactions
--++ (indole, methyl red, VP, citrate)
88
What enzyme do CPEs produce? What is CPE?
AmpC; Carbapenem resistant enterbacteriaceae

Microbiology (24 decks)

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