Gram Pos Bacilli Exam 2

Question 1

What organisms are of interest in this section?

Answer 1

Bacillus, Corynebacterium, and Listeria

Question 2

Which Bacillus species are not considered normal flora?

Answer 2

B. cereus, B. circulans, B. licheniformis, B. subtilis

Question 3

Bacillus spp. characteristics?

Answer 3

Large, Gram + Rods
Produces spores
Most are motile, ferment glucose, catalase +

Question 4

Bacillus anthracis general characteristics?

Answer 4

Gamma hemolysis 
Non-motile 
Encapsulated (inhibits phagocytosis) 
Produces endospores 
Disease of livestock 
**Causative agent of anthrax in humans**

Question 5

ID for Bacillus anthracis?

Answer 5

Colonies- large, opaque, green-gray to white, tenacious

Ground glass appearance MEDUSSA HEAD

Question 6

What is the BS level done on Bacillus anthracis for preliminary testing?

Answer 6

Level 2

Confirmative ID at reference labs are Level 3

Question 7

What are the 3 human forms of anthrax?

Answer 7

Cutaneous-malignant pustule, typically not fatal.
Pulmonary or Woolsorter’s disease- inhale spores (rare-usually fatal).
Gastrointestinal- ingestion of contaminated meat (rarest form, fatal 25-60% of the time).

Question 8

Anthrax is contagious or not contagious?

Answer 8

Not contagious from person to person

Question 9

What is the treatment of anthrax?

Answer 9

Ciprofloxacin, Doxycycline

Resistant to penicillin

Question 10

What is associated with Bacillus cereus? What is the preferred specimen?

Answer 10

Food poisoning

The food itself

Question 11

ID for Bacillus cereus?

Answer 11

Lavender colonies with slight green tinge on SBAP

Beta hemolytic, catalase +, motile

Question 12

Bacillus stearothermophilus is used for?

Answer 12

Control organism in autoclave effectiveness

Question 13

List and describe the agents of bioterrorism.

Answer 13

Category A- highest risk to public health (Clostridium botulinum, Bacillus anthracis, Yersinia pestis).
Category B- have moderate to low mortality rates (Brucella spp.).
Category C- emerging pathogens.

Question 14

What is Listeria and Corynebacterium characteristics?

Answer 14

Gram pos rods 
Catalase + 
Non-acid fast
Non-spore forming 
Both are facultative anaerobes

Question 15

What is the transportation of Listeria monocytogenes?

Answer 15

Ingestion of raw vegetables, contaminated dairy and food products.
Has been documented to cross the placenta from mother to the developing fetus.

Question 16

What are the virulence factors of Listeria monocytogenes?

Answer 16

Listeriolysin O- pore forming capabilities. Has hemolytic and cytotoxic capabilities.
Internalin- induces phagocytosis (gets in cells).
Act A- induces cellular extensions on phagocytic cells that are infected with microbe. Helps spread microbe.

Question 17

What are Listeria monocytogenes characteristics?

Answer 17

Beta hemolysis. White, smooth translucent. Bile esculin+

Gram pos rods to coccobacilli in pairs or chains. Don’t confuse with Group A or B beta-hemolytic Streptococci.

Question 18

What is the incubation of Listeria monocytogenes?

Answer 18

30-35 degrees C

Question 19

What is the treatment for Listeria monocytogenes?

Answer 19

Ampicillin

Question 20

What is the presumptive ID for Listeria monocytogenes?

Answer 20

End over end tumbling motility.
Umbrella shaped motility pattern via stab in semi-solid agar.
If isolate small gram positive rod, catalase pos, with narrow zone of beta hemolysis, suspect L. monocytogenes.

Question 21

How can L. monocytogenes can be differentiated from other Listeria spp.?

Answer 21

A positive CAMP test or Hippurate test

Question 22

How to prevent Listeria monocytogenes spread?

Answer 22

Wash raw produce, don’t cut raw meats on wood cutting board with veggies, wash your hands, and keep fridge at 40 degrees F or lower.

Question 23

General characteristics of Corynebacterium spp.?

Answer 23

Non-motile, non-acid fast, and pleomorphic

Resemble Chinese letters

Question 24

Which Corynebacterium spp. is not considered normal flora?

Answer 24

C. diphtheriae

Question 25

True/false? Diphtheriods are often considered normal flora and include C. diphtheriae.

Answer 25

False. Normal flora, but does NOT include C. diphtheriae

Question 26

What does the “Chinese letters” appearance come from?

Answer 26

Irregular snapping during cell division

Question 27

What is selective media that can be used for Corynebacterium spp.?

Answer 27

Loeffler’s Media
Cystine tellurite media- brown halo
Tinsdale agar- gray-brown halo

Question 28

Which biotype is the most severe and virulent in Corynebacterium spp.?

Answer 28

Gravis type

Question 29

Which organism has metachromatic granules?

Answer 29

Corynebacterium spp.

Methylene Blue stain allows for visualization.

Question 30

What is the presumptive ID for C. diphtheriae?

Answer 30

Urease -, halo on Tinsdale agar, and non-motile

Question 31

What vaccination can be used for the C. diphtheriae?

Answer 31

DTaP-children

Tdap-adolescents and adults

Question 32

What organism is associated with struvite stone formation and a strong urease activity?

Answer 32

C. urealyticum

Question 33

Which organism has the biggest risk factors for infection associated with catheters and prosthetic heart valves.

Answer 33

C. jeikeium

Question 34

What is C. jeikeium resistant to? Drug of choice?

Answer 34

Resistant: penicillin and cephalosporins

Drug of choice: Vancomycin

Question 35

Which organism is associated with localized red skin lesions (erysipeloid) and veterinary and meat handlers are most at risk?

Answer 35

Erysipelothrix rhusiopathiae

Question 36

General characteristics for Erysipelothrix rhusiopathiae?

Answer 36

Gram positive, alpha to gamma hemolysis
Thread-like rods
Catalase -, non-spore forming, produces H2S on slant.

Question 37

True/false? Lactobacillus spp. are normal flora of mouth, GI, and vagina.

Answer 37

True.

Usually contaminant

Question 38

Which organism is the causative agent of clue cell formation (epithelial cells covered with adherent bacteria observed in vaginal smears)?

Answer 38

Gardnerella vaginalis