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CLS 753 > Micro - Gram Negative Rods (Non-Enterics) > Flashcards

Micro - Gram Negative Rods (Non-Enterics) Flashcards

1
Q

If a TSI tube was sealed tightly so air cannot get in, any K/A reaction would look like this instead…

A

A/A

-K/A is due to deamination reaction happening with oxygen

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2
Q

Name the 3 bioterror agents in Group I. Which ones can grow on blood agar and which ones can grow only on chocolate agar?

A

Yersinia pestis = blood, chocolate

Brucella spp = chocolate only

Francisella tularensis = chocolate only

-Burkholderia spp also bioterror

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3
Q

In the US, Brucella is transmitted through…

A

Consumption of unpasteurized dairy products

-common lab acquired infection

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4
Q

How long does it take to culture Brucella?

A

4 weeks on blood agar

-very slow growers

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5
Q

When gram stained, Brucella look like this… Why?

A

Gram positive

  • look like tiny gram positive rods
  • however, gram positive rods are fast growers

Hard to decolorize

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6
Q

Francisella tularensis - additional growth requirement…

A

Cysteine

-very slow growers

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7
Q

Francisella tularensis - selective media (2)

A

Thayer-Martin

  • similar to chocolate agar
  • poor growth on blood agar

BCYE (buffered charcoal yeast extract)

  • has cysteine, preferred medium
  • also preferred media for Legionella culture
  • mnemonic - Francisella rhymes with Legionella
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8
Q

Group II organisms like Aeromonas hydrophila, Plesiomonas shigelloides and Vibrio spp colonies and gram stain look similar to this other group of organisms… However, the oxidase test is opposite and the result for this group is ___

A

Enterobacteriaceae

Positive

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9
Q

Aeromonas hydrophila, Plesiomonas shigelloides and Vibrio spp are transmitted via…

A

Contaminated seafood, marine life, open wound swimming in the ocean

  • habitat = aquatic environment
  • causes gastroenteritis, wound infections
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10
Q

Aeromonas hydrophila can be optimally recovered by supplementing stool culture media with these antibiotics… What do the colonies look like?

A

CIN (cefsulodin-irgasan-novobiocin)
-similar to Yersinia

Red bull’s eye

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11
Q

Aeromonas hydrophila, Plesiomonas shigelloides and Vibrio spp - which one can grow in high salt (6% NaCl)?

A

Vibrio

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12
Q

Plesiomonas causes infections similar to… What biochemical tests makes Plesiomonas unique?

A

Aeromonas

Positive for all 3 decarboxylase tests:
Lysine, ornithine, arginine

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13
Q

Which species of Vibrio is associated with infections during natural disasters? Which species of Vibrio is associated with infections eating oysters? Which species of Vibrio is associated with infections eating raw fish or shellfish?

A

Vibrio cholerae

Vibrio vulnificus
-wound infections, septicemia

Vibrio parahaemolyticus
-50-70% of cases in Japan, gastroenteritis

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14
Q

Which Vibrio species can grow WITHOUT salt?

A

Vibrio cholerae

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15
Q

The selective media for Vibrio spp is… It contains this sugar… What color is a positive and negative result?

A

TCBS (thiosulfate-citrate-bile salts-sucrose) agar

Sucrose

Positive = yellow
Negative = green
-V. cholerae, alginolyticus, fluviales = yellow
-V. parahaemolyticus, vulnificus = green

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16
Q

Vibrio cholerae can be identified using this test… How is the test performed?

A

String test

Put bile salt on a slide with some Vibrio culture. Lift the loop to form a fine string

  • cells lysed in bile salt
  • string material = DNA, sticky
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17
Q

Who are the members of Group III - the non-fermenters (glucose oxidizers), gram-negative rods (3)?

A

Pseudomonas

Acinetobacter

Burkholderia

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18
Q

Pseudomonas aeruginosa are known for this appearance on blood agar…

A

Metallic sheen with serrated edges

-flat

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19
Q

Does P. aeruginosa show bipolar gram staining? The organism produces this distinct odor…

A

No
-thin gram negative rods

Aromatic

  • esters, good smelling
  • grapes, corn taco shells
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20
Q

Pseudomonas aeruginosa TSI result looks like this and what it means…

A

K/no change = non-fermenter

-red/red

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21
Q

Unlike other species of Pseudomonas, aeruginosa can grow at…

A

42C

-similar requirement for Campylobacter

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22
Q

When we suspect P. aeruginosa infection, we should always perform this test… Why?

A

AST

Organism is highly antimicrobial resistant

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23
Q

The mucoid strain of Pseudomonas are associated with infections in patients with this condition…

A

Cystic fibrosis

-take mucoid isolates

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24
Q

Pseudomonas aeruginosa - oxidase result…

A

Strongly positive

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25
Q

The only 3 species of Pseudomonas that are fluorescent are…

A

P. aeruginosa

P. fluorescens

P. putida

  • fluorescens/putida have fluorescent pigment = pyoverdin
  • fluorescens/putida have no distinct colony morphology or odor
  • fluorescens/putida cannot grow at 42C
26
Q

What 2 tests and test results can we do to differentiate Pseudomonas from Acinetobacter?

A

Pseudomonas = beta hemolytic, oxidase positive

Acinetobacter = non hemolytic, oxidase negative

27
Q

Two important Burkholderia species

A

B. cepacia

B. pseudomallei

28
Q

Burkholderia cepacia is significant for this reason…

A

Bioterror agent

  • highly drug-resistant
  • B. pseudomallei is potential bioterror agent
29
Q

The selective agar plate for Burkholderia cepacia is…

A

BCSA (Burkholderia cepacia selective agar)

-smooth, raised colonies

30
Q

Burholderia cepacia has this odor…

A

Earth-like, musty

31
Q

Burkholderia pseudomallei causes this condition…

A

Melioidosis

  • contaminated water/soil
  • rice paddy fields
32
Q

List the gram negative rods that are fastidious/difficult to culture and identify (8)

A

Bartonella

Pasteurella

Campylobacter

Helicobacter pylori

Bordetella pertussis

Legionella

Haemophilus

HACEK group

33
Q

Cat scratch fever and trench fever are caused by this genus…

A

Bartonella

  • B. quintana = trench fever
  • B. henselae = cat scratch fever. Enlarged lymph
34
Q

Bartonella require these conditions for culture (2)

A

Chocolate agar

Increased CO2 (capnophilic)

35
Q

The most common species of Pasteurella is… How is it transmitted?

A

P. multocida

Dog or cat bite/scratch

36
Q

The most common bacterial cause of diarrhea in the US is caused by…

A

Campylobacter

-normally do not differentiate species

37
Q

Campylobacter has this peculiar shape on a gram stain called…

A

Gull-wings

-commas, spirals, s-shaped, coccoid forms

38
Q

Campylobacter is considered fastidious and require these conditions for culturing (2)

A

Microaerophilic

42C

  • does NOT grow well at 37C
  • slow grower
  • similar temp as P. aeruginosa
39
Q

Campylobacter is faintly gram stained compared to other gram negative rods. This counterstain, ___, is a better stain to use than safranin

A

Kinyoun’s carbol fuchsin

40
Q

The 3 media used for Campylobacter isolation from stool samples…

A

Skirrow’s agar (no longer used)

Campy blood agar

CVA (cefoperazone, vancomycin, amphotericin)

41
Q

Helicobacter pylori can survive in the ___ due to the actions of the enzyme ___

A

Stomach

Urease
-neutralizes acids around them

42
Q

Best ways to diagnose an H. pylori infection (2)

A

Endoscopy

Stomach biopsy - place on urea media, will turn pink

43
Q

Bordetella produces this condition called…

A

Whooping cough

-B. pertussis

44
Q

Bordetella pertussis specimen sample should be taken from a ___ and cultured immediately because the organisms are fastidious. The two selective isolation media are…

A

Nasopharyngeal swab

Bordet Gengou
Regan-Lowe (horse blood with charcoal)

45
Q

Legionella pneumophila causes these two diseases

A

Legionnaire’s disease
-pneumoniae

Pontiac fever
-flu-like syndrome, milder

46
Q

Legionella selective media. What amino acid does it require?

A

BCYE (buffered charcoal yeast extract)

  • similar to Francisella tularensis
  • mnemonic - Francisella rhymes with Legionella

Cysteine

47
Q

Which Haemophilus species is the most virulent and what is the type?

A

H. influenzae type B

-HiB vaccine

48
Q

Haemophilius require these factors…

A

X = hemin

V = NAD

49
Q

Haemophilius can be screened for using this test…

A

Satellite test

-blood agar co-culture with S. aureus

50
Q

Haemophilus X and V testing has these additional culturing requirements (2)…

A

CO2

Humidity

51
Q

Which Haemophilus species require factor V? Which Haemophilus species require both X and V?

A

V = parainfluenzae

X and V = influenzae

52
Q

Members of HACEK commonly cause this condition… They are all normal flora of the…

A

Endocarditis
-likes to attach to heart valves

Oral cavity

53
Q

HACEK members cause odor that smells like…

A

Bleach

54
Q

What 2 bacteria require growth at 42C?

A

Pseudomonas aeruginosa

Campylobacter

55
Q

What genera are part of the Group II organisms?

A

Aeromonas

Plesiomonas

Vibrio

-all cause gastroenteritis

56
Q

Group II organisms have these similar traits: they can ferment the sugar, ____, they have this test result on MacConkey’s, and they are oxidase ___

A

Glucose

Growth without lactose fermentation

Positive

57
Q

What type of MacConkey result can we expect from Group IV organisms?

A

No/poor growth on MacConkey’s

-fastidious organisms

58
Q

Group III organisms share this similar MacConkey’s result…

A

Growth without lactose fermentation

-some spp oxidize lactose

59
Q

Group I - which members are oxidase positive and which are oxidase negative?

A

Positive = Brucella

Negative = Francisella tularensis, Yersinia pestis

60
Q

Group III - which members are oxidase positive and which are oxidase negative?

A

Positive = Pseudomonas, Burholderia (cepacia, pseudomallei)

Negative = Acinetobacter

61
Q

Pseudomonas F tubes will fluoresce greenish-yellow due to this pigment… Pseudomonas P tubes will display a blue-green pigment called…

A

Pyoverdin
-F tube = fluorescent

Pyocyanin
-P tube = pigment

CLS 753 (12 decks)

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