Aerobic Gram Positive Bacilli (Exam 4)

Question 1

Which of these organisms is spore forming?

Answer 1

Bacillus sp. (anthracis and cereus)

Question 2

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

Answer 2

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

Question 3

What is the habitat or reservoir for B. anthracis?

Answer 3

Herbivorous animals and spores from soil

Question 4

What is the habitat or reservoir for B. cereus?

Answer 4

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

Question 5

Which of these organisms is a possible bioterrorism agent?

Answer 5

B. anthracis

Question 6

Are bacillus species catalase positive or negative?

Answer 6

Positive

Question 7

Are corynebacterium species catalase positive or negative?

Answer 7

Positive

Question 8

Is listeria monocytogenes catalase positive or negative?

Answer 8

Positive

Question 9

Is Rhodococcus catalase negative or positive?

Answer 9

Positive

Question 10

Is Arcanobacterium catalase negative or positive?

Answer 10

Negative

Question 11

Is Erysipelothrix catalase negative or positive?

Answer 11

Negative

Question 12

Is lactobacillus catalase negative or positive?

Answer 12

Negative

Question 13

Is gardnerella vaginalis catalase negative or positive?

Answer 13

Negative

Question 14

What is Woolsorter’s disease?

Answer 14

The pulmonary form of anthrax caused by inhaling spores

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Pulmonary anthrax

Question 18

What are the three B. anthracis toxins?

Answer 18

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

Question 19

What is the colony morphology for B. anthracis?

Answer 19

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

Question 20

What is the gram stain for B. anthracis?

Answer 20

Large GPB boxcars, may contain spores

Question 21

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

Answer 21

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

Question 22

How quickly do symptoms of B. cereus appear?

Answer 22

Within 1-16 hours

Question 23

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

Answer 23

Food poisoning

Question 24

What is the colony morphology or B. cereus?

Answer 24

Beta hemolytic, green, feathery and spready

Question 25

What is the gram stain of B. cereus?

Answer 25

Large GPB boxcars, may contain spores

Question 26

What are the distinguishing characteristics of Listeria monocytogenes?

Answer 26

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

Question 27

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

Answer 27

Listeria monocytogenes and Gardnerella vaginalis

Question 28

When hippurate is hydrolyzed, what are the products?

Answer 28

Glycine and benzoic acid

Question 29

How is Listeria transmitted?

Answer 29

Through contaminated food products, specifically unpasteurized cheese and milk

Question 30

Does Listeria produce a biofilm?

Answer 30

Yes, grows best at cold temps

Question 31

When is a Listeria infection most common for pregnant women?

Answer 31

3rd trimester

Question 32

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

Answer 32

50% if they are born alive (usually stillborn)

Question 33

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

Answer 33

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

Question 34

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

Answer 34

Bacterial meningitis

Question 35

What does the Listeria gram stain look like?

Answer 35

GPB, or short, plump coccobacilli

Question 36

What is the colony morphology of Listeria?

Answer 36

tight zone of Beta hemolysis

Question 37

What is the habitat of Corynebacterium?

Answer 37

Normal flora of skin and respiratory tract

Question 38

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

Answer 38

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

Question 39

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

Answer 39

Loeffler media

Question 40

Which media is selective for recovering C. diptheriae?

Answer 40

Tinsdale/cystine tellurite blood agar

Question 41

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

Answer 41

Diptheritic pseudomembrane

Question 42

How is the diptheriae toxin transmitted?

Answer 42

Thru direct contact , sneezing, and coughing

Question 43

What is ecthyma diptheriticum?

Answer 43

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

Question 44

What do the gram stains for Corynebacterium look like?

Answer 44

Palisading GPB, sometimes with a club-like appearance

Question 45

Why do Corynebacterium grow better on blood agar than chocolate?

Answer 45

They are lipophilic

Question 46

Which Corynebacterium species reduces nitrate?

Answer 46

C. diptheriae

Question 47

Which Corynebacterium species is urease positive?

Answer 47

C. urealyticum

Question 48

Which species of Corynebacterium ferments glucose and mannitol?

Answer 48

C. diptheriae

Question 49

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

Answer 49

C. jeikeium

Question 50

What is the clinical significance of C. jeikeium?

Answer 50

Colonization of the skin of hospitalized patients

Question 51

What is the colony morphology of C. jeikeium?

Answer 51

Grey, white, non-hemolytic

Question 52

What is the colony morphology of C. urealyticum

Answer 52

White, pinpoint, non-hemolytic

Question 53

Which species of Corynebacterium is a urinary pathogen?

Answer 53

C. urealyticum

Question 54

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?

Answer 54

Erysipelothrix rhusiopathiae; erysipeloid rash

Question 55

What are the two main distinguishing tests for Erysipelothrix rhusiopathiae?

Answer 55

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

Question 56

What is the colony morphology of Erysipelothrix rhusiopathiae?

Answer 56

Small on BAP, with a greenish discoloration

Question 57

What is the gram stain of Erysipelothrix rhusiopathiae?

Answer 57

Slender GPB, may be filamentous

Question 58

What is the colony morphology or Lactobacillus?

Answer 58

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

Question 59

What is the gram stain of Lactobacillus?

Answer 59

Long, slender GPB

Question 60

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

Answer 60

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 +)

Question 61

What is the gram stain of Gardnerella vaginalis?

Answer 61

Gram variable

Question 62

What are the two most distinguishing factors of Gardnerella vaginalis?

Answer 62

It grows better with CO2 and is positive for hippurate hydrolysis

Question 63

What is the clinical significance of Arcanobacterium haemolyticieum?

Answer 63

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

Question 64

What is the colony morphology of Arcanobacterium haemolyticieum?

Answer 64

Small, beta-hemolytic colonies

Question 65

What are the two most distinguishing tests for Arcanobacterium haemolyticieum?

Answer 65

Positive lecithinase test and reverse CAMP test

Question 66

What is the colony morphology of Rhodococcus spp.?

Answer 66

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

Question 67

What is the gram stain of Rhodococcus spp.?

Answer 67

Diptheroid-like gram stain

Question 68

What is a distinguishing characteristic of Rhodococcus spp.?

Answer 68

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