ROUTINE PRIMARY MEDIA FOR AEROBES AND FACULTATIVE ANAEROBES

Question 1

Enriched medium that will grow most non fastidious bacteria.

Answer 1

Blood agar (sheep)

Question 2

Blood agar contains:

Answer 2

Tryptic soy agar with 5% sheep blood added. Allows differentiation of hemolysis.

Question 3

Enriched medium for Haemophilus and Neisseria. Supplies X and V factors. Incubate in increased CO2

Answer 3

Chocolate agar

Question 4

Selective medium for gram-positive microorganisms

Answer 4

Columbia colistin nalidixic acid agar (CNA)

Question 5

Actions of colistin and nalidixic acid in CNA

Answer 5

Colistin and nalidixic acid suppress most Gram-negative bacteria.

Question 6

Selective medium for gram-positive cocci and anaerobic gram-negative rods

Answer 6

Phenylethyl alcohol agar (PEA)

Question 7

Selective medium for S. pyogenes and S. agalactiae

Answer 7

Streptococcal selective agar (SSA)

Question 8

Selective differential medium for isolation of enteric gram-negative rods (Enterobacteriaceae)

Answer 8

Eosin-Methylene Blue (EMB)
MacConkey agar (MAC)

Question 9

The action of Eosin and methylene blue in EMB agar:

Answer 9

Eosin and methylene blue inhibit GRAM-POSITIVES

Question 10

Lactose fermenters in EMB:

Answer 10

green-black or purple colonies

Question 11

E. coli in EMB:

Answer 11

E. coli produces green metallic sheen

Question 12

Non-lactose fermenters in EMB:

Answer 12

Colorless

Question 13

A component in MAC that inhibit most gram-positives

Answer 13

Bile salts and crystal violet

Question 14

Lactose fermenters in MAC:

Answer 14

lactose fermenters in MAC are PINK

Question 15

Non-lactose fermenters in MAC:

Answer 15

Colorless

Question 16

Selective medium for E. coli O157-H7

Answer 16

MacConkey sorbitol agar (SMAC)

Question 17

E. coli O157-H7 in SMAC:

Answer 17

E. coli O157-H7 does not ferment sorbitol.
colonies are colorless

Question 18

Inhibitors present in Hektoen Enteric Agar (HE) that inhibit normal GI flora

Answer 18

Bile salts
Bromthymolblue
Acid fuchsin

Question 19

Nonpathogens in HE are:

Answer 19

Orange to salmon pink

Question 20

Non-lactose fermenters in HE:

Answer 20

Green to blue-green

Question 21

H2S positive colonies in HE:

Answer 21

Have BLACK PRECIPITATE

Salmonella is H2S positive
In HE, Salmonella is green to blue-green (non-lactose fermenter) colored colonies with black precipitate

Question 22

Selective, differential medium for isolation of Salmonella and Shigella in stool

Answer 22

Xylose Lysin Deoxycholate (XLD)

Question 23

Inhibitor present in XLD

Answer 23

Deoxycholate

Deoxycholate inhibits many gram-negative rods and gram-positives

Question 24

Yellow colonies in XLD:

Answer 24

E. coli

Question 25

Yellow with black centers in XLD:

Answer 25

Some proteus spp.

Question 26

Colorless or red colonies in XLD:

Answer 26

Shigella

Question 27

Red colonies with black centers in XLD:

Answer 27

Salmonella (H2S positive+)

Question 28

Selective medium for Salmonella and Shigella

Answer 28

Salmonella-Shigella Agar (SSA)

Question 29

Inhibitors present in SSA (Salmonella-Shigella Agar) that inhibits coliforms:

Answer 29

Brilliant green Bile salts

Question 30

Colonies of Salmonella and Shigella in SSA:

Answer 30

Salmonella and Shigella DO NOT FERMENT LACTOSE - Colonies are colorless Salmonella is H2S positive - Black center

Question 31

Selective enrichment medium for isolation of Salmonella and Shigella from stools and rectal swabs

Answer 31

Gram-negative broth (GN)

Question 32

Enrichment broth used for recovery of Salmonella from stool:

Answer 32

Selenite broth Tetrathionate broth

Question 33

Selective enrichment medium for isolation of Campylobacter from stool:

Answer 33

Campylobacter Blood Agar (Campy BAP)

Question 34

Incubation requirements of Campy BAP:

Answer 34

Incubate plates in increased CO2 at 42 deg. celsius (5% O2; 10% CO2)

Question 35

Organisms that grow at 42 deg. celsius:

Answer 35

1. Campylobacter 2. P. aeruginosa