Culturing Bacteria

Question 1

Thayer-Martin agar

Answer 1

For isolating Neisseria spp.

Contains the following antibiotics to inhibit growth of other organisms:
Vancomycin: inhibits growth of gram‑positive bacteria
Trimethoprim and colistin: inhibit growth of other gram‑negative bacteria
Nystatin: inhibits growth of fungi

Question 2

For isolating Lactose fermenters (e.g., E. coli)

Answer 2

MacConkey agar

Question 3

For isolating Bordetella pertussis

Answer 3

Bordet-Gengou agar (Contains potato extract, sheep blood, and glycerol)

Regan-Lowe medium (Contains blood, charcoal, and antibiotics)

Question 4

For isolating Haemophilus influenzae

Answer 4

Chocolate agar

Contains X factor (hematin) and V factor (NAD+) to promote growth of fastidious organisms (organisms with complex or stringent nutritional requirements that are difficult to culture and only grow with specific nutritional supplementation and precise environmental control)

Question 5

For isolating mycoplasma

Answer 5

Eaton agar, “Fried egg” appearance

Question 6

For isolating Corynebacterium diphtheriae

Answer 6

Cystine-tellurite agar, Löffler medium (note Dark-blue metachromatic granules can be visualized with methylene blue stain)

Question 7

Colonies with green metallic sheen on Eosin methylene blue agar

Answer 7

E. coli

Question 8

Charcoal yeast extract agar, this can isolate…

Answer 8

Contains charcoal and yeast, buffered with cysteine and iron. Isolates:
legionella
pasteurella
brucella
francisella

Question 9

Löwenstein-Jensen agar

Answer 9

Mycobacterium tuberculosis

Question 10

Mannitol salt agar

Answer 10

Gram-positive bacteria, specifically Staphylococcus species

Question 11

Catalase: an enzyme that visibly breaks down hydrogen peroxide into water and oxygen , preventing its breakdown into microbiocidal substances (e.g., ROS) via myeloperoxidase
Catalase-positive organisms include:

Answer 11

Staphylococci, E. coli, Nocardia, Serratia, Listeria, Pseudomonas, Burkholderia cepacia, H. pylori, Bordetella pertussis, Candida, Aspergillus

Question 12

Recurrent infections with Staphylococci, E. coli, Nocardia, Serratia, Listeria, Pseudomonas, Burkholderia cepacia, H. pylori, Bordetella pertussis, Candida, Aspergillus is common in ….

Answer 12

chronic granulomatous disease, these organims are all catalse positive

Question 13

What microbes would turn the colorless phenylenediamine reagent turns dark blue or purple?

Answer 13

Microbes that produce oxidase include Campylobacter, Vibrio, Pseudomonas, Brucella

Question 14

an enzyme that hydrolyzes urea to ammonia and carbon dioxide, which increases the pH

Answer 14

urease

Question 15

Urease-producing organisms

Answer 15

Proteus, H. pylori, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus, Cryptococcus