Staining

Question 1

Gram stain procedure

Answer 1

Crystal violet - grams iodine - decolorizer - safarin

Question 2

Gram variability (cause)

Answer 2

In old cultures peptidoglycan layer shrinks (clostridium / some bacillus) - bacillus endospore also appear gram neg due to capsule In some species cells wall can break off during division to give a false negative because no peptidoglycan remains (propionibacterium / corynebacterium)

Question 3

Catalase

Answer 3

Identify staphylococcus

Question 4

Coagulase

Answer 4

Differentiate Staph aureus and other staph species

Question 5

MALDI-TOF (stands for)

Answer 5

Matrix assisted laser desorption/ionizations - time of flight aka time of flight mass spec identification Time of flight is the measurement procedure for the ionization caused by the lazer

Question 6

MaConkey’s Agar growing….

Answer 6

E. coli (or any lactose fermentor)

Question 7

MaConkey’s Agar growing…

Answer 7

Non lactose fermentor

Question 8

Cetrimide agar growing…

Answer 8

Pseudomonas aeruginosa

Question 9

m-Endo growing..

Answer 9

Coliforms (metallic sheen)

Question 10

Mannitol salt growing…

A) Yellow

B) White

Answer 10

A) Staph aureus - ferments the mannitol -> ph changes phenol red

B) Staph epidermidis