Basics

Question 1

What is the chemical composition of spores

Answer 1

• Keratin-like coat
• Dipicolinic acid
• peptidoglycan
• DNA

Question 2

What do you find beta lactamases

Answer 2

periplasmic space of gram negatives

Question 3

What is specific to Gram + and extend from membrane to exterior

Answer 3

Lipoteichoic acids

Question 4

What does lipoteichoic acid induce

Answer 4

• TNF

- IL-1

Question 5

What does PAS stain for

Answer 5

Glycogen

Question 6

Ziehl-Neelsen Stain stains Acid fast bacteria by staining mycolic acid in cell wall, What is another name for this stain?
What is a cheaper alternative that is more sensitive and less specific?

Answer 6

• Carbol Fuchsin stain

- Auramine-Rhodamine stain

Question 7

What type of media favors the growth of particular organism while preventing growth of others?
Give an example

Answer 7

• Selective media
• Thayer-Martin agar contains antibiotics that allow the selective growth of Neisseria by inhibiting the growth of other sensitive organisms

Question 8

What type of media yields a color change in response to the metabolism of certain organism?
Give an example?

Answer 8

• Indicator (differential) media
• MacConkey agar contains a pH indicator; a lactose fermenter like E coli will convert lactose to acidic metabolites —-> color change

Question 9

Describe the Thayer-Martin Agar used to grow Neisseria

Answer 9

• Selectively favors growth of Neisseria by inhibiting growth of gram + organisms with Vancomycin, gram - organisms except Neisseria with Trimethoprim and Colistin and Fungi with Nystatin
• “Very Typically Cultures Neisseria”

Question 10

What bug does Bordet-Gengou agar isolate?

What media contents does it contain?

Answer 10

• Bordetella pertussis

- Potato

Question 11

What bug does Regan-Lowe medium isolate?

What is in the media?

Answer 11

• Bordetella pertussis

- Charcoal, blood, and antibiotic

Question 12

What bug is Eosin-Methylene blue (EMB) agar used for?

Describe the appearance

Answer 12

• E coli

- Colonies with green metallic sheen

Question 13

Sabouraud agar

Answer 13

Fungi

Question 14

Describe the virulence factor protein A and which bacteria express it

Answer 14

• binds Fc region of IgG which prevents opsonization and phagocytosis
• S. aureus

Question 15

Describe the type III secretion system and which bacteria use this?

Answer 15

• also known as “injectisome”
• Needle-like protein appendage facilitating direct delivery of toxins from certain gram - bacteria to eukaryotic host cell
• Pseudomonas, Salmonella, Shigella, E coli

Question 16

Describe Bacterial transformation

Answer 16

• Ability to take up naked DNA (ie, from cell lysis) from environment (also known as “competence”)
• A feature of many bacteria, especially S pneumoniae, H influenza type B, and Neisseria (SHiN)
• Any DNA can be used
• Adding deoxyribonuclease to environment will degrade naked DNA in medium —> no transformation seen

Question 17

What is the location for genes encoding exotoxins?

Endotoxins?

Answer 17

• Plasmid or bacteriophage

- Bacterial chromosome

Question 18

What is the exotoxin in Pseudomonas that inactivates elongation factor 2

Answer 18

Exotoxin A