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MLS Microbiology > Aerobic Gram Positive Bacilli (Exam 4) > Flashcards

Aerobic Gram Positive Bacilli (Exam 4) Flashcards

1
Q

Which of these organisms is spore forming?

A

Bacillus sp. (anthracis and cereus)

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2
Q

What does a positive test for lecithinase look like? What is the test done on? What is the end biochemical product?

A

A white, opaque zone around colonies on egg yolk agar; Insoluble diglyceride

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3
Q

What is the habitat or reservoir for B. anthracis?

A

Herbivorous animals and spores from soil

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4
Q

What is the habitat or reservoir for B. cereus?

A

Soil, straw, and rice (especially rice that has been cooked in large quantities and left out for too long)

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5
Q

Which of these organisms is a possible bioterrorism agent?

A

B. anthracis

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6
Q

Are bacillus species catalase positive or negative?

A

Positive

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7
Q

Are corynebacterium species catalase positive or negative?

A

Positive

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8
Q

Is listeria monocytogenes catalase positive or negative?

A

Positive

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9
Q

Is Rhodococcus catalase negative or positive?

A

Positive

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10
Q

Is Arcanobacterium catalase negative or positive?

A

Negative

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11
Q

Is Erysipelothrix catalase negative or positive?

A

Negative

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12
Q

Is lactobacillus catalase negative or positive?

A

Negative

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13
Q

Is gardnerella vaginalis catalase negative or positive?

A

Negative

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14
Q

What is Woolsorter’s disease?

A

The pulmonary form of anthrax caused by inhaling spores

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15
Q

What is the most common form of anthrax in humans? How deadly is it?

A

Cutaneous anthrax. It is the least deadly form with a 1% mortality rate.

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16
Q

How is the gastrointestinal form of anthrax transmitted? Does it have a high mortality rate?

A

By consuming spores or vegetative bacilli through undercooked food (usually meat); YES

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17
Q

Which form of anthrax has a 80-90% mortality rate?

A

Pulmonary anthrax

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18
Q

What are the three B. anthracis toxins?

A

Protective antigen (PA), Lethal factor (LF), and Edema factor (EF)

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19
Q

What is the colony morphology for B. anthracis?

A

Non-hemolytic with “medusa head” or “egg white” or “ground glass” colonies

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20
Q

What is the gram stain for B. anthracis?

A

Large GPB boxcars, may contain spores

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21
Q

How can you differentiate B. anthracis and B. cereus? What are the results?

A

Motility (Anthracis = Cereus +), hemolysis (Anthracis = Cereus - Beta), and growth on PEA agar (Anthracis = Cereus +)

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22
Q

How quickly do symptoms of B. cereus appear?

A

Within 1-16 hours

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23
Q

What is the main symptom or disease state caused by B. cereus?

A

Food poisoning

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24
Q

What is the colony morphology or B. cereus?

A

Beta hemolytic, green, feathery and spready

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25
Q

What is the gram stain of B. cereus?

A

Large GPB boxcars, may contain spores

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26
Q

What are the distinguishing characteristics of Listeria monocytogenes?

A

Growth at 4C (fridge temp), umbrella pattern in motility agar at RT, BE +, Sodium hippurate +, and block shape in CAMP test

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27
Q

What are the two organisms that are positive for hippurate hydrolysis?

A

Listeria monocytogenes and Gardnerella vaginalis

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28
Q

When hippurate is hydrolyzed, what are the products?

A

Glycine and benzoic acid

29
Q

How is Listeria transmitted?

A

Through contaminated food products, specifically unpasteurized cheese and milk

30
Q

Does Listeria produce a biofilm?

A

Yes, grows best at cold temps

31
Q

When is a Listeria infection most common for pregnant women?

A

3rd trimester

32
Q

What is the mortality rate of neonates who have contracted Listeria?

A

50% if they are born alive (usually stillborn)

33
Q

What does an early onset Listeria infection in neonates usually result in?

A

Systemic infection manifesting as sepsis; in utero infection often causes stillbirth or spontaneous abortion

34
Q

What does a late onset Listeria infection in neonates usually result in?

A

Bacterial meningitis

35
Q

What does the Listeria gram stain look like?

A

GPB, or short, plump coccobacilli

36
Q

What is the colony morphology of Listeria?

A

tight zone of Beta hemolysis

37
Q

What is the habitat of Corynebacterium?

A

Normal flora of skin and respiratory tract

38
Q

What are the distinguishing tests/differential media for C. diptheriae?

A

Elek test , Loeffler media, and Tinsdale/cystine tellurite blood agar

39
Q

Which media is used to stimulate metachromic granules in C. diptheriae to determine gram stain morphology?

A

Loeffler media

40
Q

Which media is selective for recovering C. diptheriae?

A

Tinsdale/cystine tellurite blood agar

41
Q

What is it called when necrotic tissue covers the tonsils, pharynx, larynx, and posterior nasal passages?

A

Diptheritic pseudomembrane

42
Q

How is the diptheriae toxin transmitted?

A

Thru direct contact , sneezing, and coughing

43
Q

What is ecthyma diptheriticum?

A

A C. dipthriae cutaneous infection caused by the toxin absorbed systemically

44
Q

What do the gram stains for Corynebacterium look like?

A

Palisading GPB, sometimes with a club-like appearance

45
Q

Why do Corynebacterium grow better on blood agar than chocolate?

A

They are lipophilic

46
Q

Which Corynebacterium species reduces nitrate?

A

C. diptheriae

47
Q

Which Corynebacterium species is urease positive?

A

C. urealyticum

48
Q

Which species of Corynebacterium ferments glucose and mannitol?

A

C. diptheriae

49
Q

Which species of Corynebacterium may be an MDRO and is resistant to Penicillin?

A

C. jeikeium

50
Q

What is the clinical significance of C. jeikeium?

A

Colonization of the skin of hospitalized patients

51
Q

What is the colony morphology of C. jeikeium?

A

Grey, white, non-hemolytic

52
Q

What is the colony morphology of C. urealyticum

A

White, pinpoint, non-hemolytic

53
Q

Which species of Corynebacterium is a urinary pathogen?

A

C. urealyticum

54
Q

A fisherman has a red rash on his hand because he cut his finger while working, bandaged it, and then kept working. What organism is the cause of this infection? What is the rash called?

A

Erysipelothrix rhusiopathiae; erysipeloid rash

55
Q

What are the two main distinguishing tests for Erysipelothrix rhusiopathiae?

A

H2S (+) and motility (non-motile, but with a distinct pipe cleaner appearance in motility media)

56
Q

What is the colony morphology of Erysipelothrix rhusiopathiae?

A

Small on BAP, with a greenish discoloration

57
Q

What is the gram stain of Erysipelothrix rhusiopathiae?

A

Slender GPB, may be filamentous

58
Q

What is the colony morphology or Lactobacillus?

A

Alpha hemolytic (the only alpha hemolytic organism of this section)

59
Q

What is the gram stain of Lactobacillus?

A

Long, slender GPB

60
Q

What is the colony morphology of Gardnerella vaginalis? What is the media used?

A

Pinpoint, non-hemolytic and slow growing on BAP. Growth on V agar (split plate of HBT and starch hydrolysis plate) shows hemolysis of human blood and starch hydrolysis (purple to yellow +)

61
Q

What is the gram stain of Gardnerella vaginalis?

A

Gram variable

62
Q

What are the two most distinguishing factors of Gardnerella vaginalis?

A

It grows better with CO2 and is positive for hippurate hydrolysis

63
Q

What is the clinical significance of Arcanobacterium haemolyticieum?

A

Acute pharyngitis similar to Group A strep and a rash in 50% of patients

64
Q

What is the colony morphology of Arcanobacterium haemolyticieum?

A

Small, beta-hemolytic colonies

65
Q

What are the two most distinguishing tests for Arcanobacterium haemolyticieum?

A

Positive lecithinase test and reverse CAMP test

66
Q

What is the colony morphology of Rhodococcus spp.?

A

Non-hemolytic, round, sometimes mucoid colonies that often turn red, orange or pink after a few days

67
Q

What is the gram stain of Rhodococcus spp.?

A

Diptheroid-like gram stain

68
Q

What is a distinguishing characteristic of Rhodococcus spp.?

A

It’s partially acid-fast and a very diverse group

MLS Microbiology (15 decks)

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