Plating Media for Routine Bacteriology (Components)

Question 1

Nutrient agar base with ferric citrate. Hydrolysis of
esculin by group D streptococci imparts a brown
color to medium; sodium deoxycholate inhibits
many bacteria.

Answer 1

Bile esculin agar (BEA)

Question 2

Contains azide to inhibit gram-negative bacteria,
vancomycin to select for resistant gram-positive
bacteria, and bile esculin to differentiate enterococci
from other vancomycin-resistant bacteria
that may grow

Answer 2

Bile esculin azide agar with vancomycin

Question 3

Trypticase soy agar, Brucella agar, or beef heart
infusion with 5% sheep blood

Answer 3

Blood agar (BA)

Question 4

Potato-glycerol–based medium enriched with 15%-
20% defibrinated blood; contaminants inhibited by
methicillin (final concentration of 2.5 μm/mL)

Answer 4

Bordet-Gengou agar

Question 5

Dextrose, pork brain, and heart dehydrated infusions

Answer 5

Brain-heart infusion agar or broth

Question 6

Yeast extract, agar, charcoal, and salts supplemented
with L-cysteine HCl, ferric pyrophosphate, ACES
buffer, and alpha-ketoglutarate

Answer 6

Buffered charcoal–yeast extract agar (BCYE)

Question 7

BCYE supplemented with polymyxin B, vancomycin,
and ansamycin to inhibit gram-negative bacteria,
gram-positive bacteria, and yeast, respectively

Answer 7

Buffered charcoal–yeast extract (BCYE) agar with antibiotics

Question 8

Bile salts, gentamicin, ticarcillin, polymyxin B,
peptone, yeast extract

Answer 8

Burkholderia cepacia selective agar

Question 9

Contains vancomycin (10 mg/L), trimethoprim
(5 mg/L), polymyxin B (2500 U/L), amphotericin B
(2 mg/L), and cephalothin (15 mg/L) in a Brucella
agar base with sheep blood

Answer 9

Campy-blood agar

Question 10

Thioglycollate broth supplemented with increased
agar concentration and antibiotics

Answer 10

Campylobacter thioglycollate broth

Question 11

Tryptic soy broth with phenyl-ethyl alcohol, 5% sheep
blood, and added nutrients

Answer 11

CDC* anaerobe 5% sheep blood agar

Question 12

Blood-supplemented enrichment medium containing
cefoperazone, vancomycin, and amphotericin to
inhibit growth of most gram-negative bacteria,
gram-positive bacteria, and yeast, respectively

Answer 12

Cefoperazone, vancomycin, amphotericin (CVA) medium

Question 13

Peptone base with yeast extract, mannitol, and bile
salts; supplemented with cefsulodin, irgasan, and
novobiocin; neutral red and crystal violet indicators

Answer 13

Cefsulodin-irgasan-novobiocin (CIN) agar

Question 14

Peptone base, enriched with solution of 2% hemoglobin
or IsoVitaleX (BD BBLTM Becton Dickenson, Sparks MD)

Answer 14

Chocolate agar

Question 15

Organism-specific nutrient base, selective supplements,
and chromogenic substrate

Answer 15

Chromogenic media

Question 16

Columbia agar base with 10 mg colistin per liter,
15 mg nalidixic acid per liter, and 5% sheep
blood

Answer 16

Columbia colistin-nalidixic acid (CNA) agar

Question 17

Infusion agar base with 5% sheep blood; reduction of
potassium tellurite by Corynebacterium diphtheriae
produces black colonies

Answer 17

Cystine-tellurite blood agar

Question 18

Peptone base containing lactose; eosin Y and
methylene blue as indicators

Answer 18

Eosin methylene blue (EMB) agar (Levine)

Question 19

Peptone-base broth with glucose and mannitol;
sodium citrate and sodium deoxycholate act as
inhibitory agents

Answer 19

Gram-negative broth (GN)

Question 20

Peptone-base agar with bile salts, lactose, sucrose,
salicin, and ferric ammonium citrate; indicators
include bromthymol blue and acid fuchsin

Answer 20

Hektoen enteric (HE) agar

Question 21

Animal tissue (heart muscle), dextrose, egg-and-beef
serum, and sodium chloride

Answer 21

Loeffler medium

Question 22

Peptone base with lactose; gram-positive organisms
inhibited by crystal violet and bile salts; neutral red
as indicator

Answer 22

MacConkey agar

Question 23

A modification of MacConkey agar in which lactose
has been replaced with D-sorbitol as the primary
carbohydrate

Answer 23

MacConkey sorbitol agar

Question 24

Peptone base, mannitol, and phenol red indicator;
salt concentration of 7.5% inhibits most bacteria

Answer 24

Mannitol salt agar

Question 25

Peptone agar base with cornstarch, supplemented
with yeast dialysate, 3% hemoglobin, and horse
plasma; antibiotic supplement includes vancomycin
(2 μg/mL), colistin (5.5 μg/mL), amphotericin B
(1.2 μg/mL), and trimethoprim (3 μg/mL)

Answer 25

New York City (NYC) agar

Question 26

Nutrient agar base; phenylethyl alcohol inhibits
growth of gram-negative organisms

Answer 26

Phenylethyl alcohol (PEA) agar

Question 27

Charcoal agar supplemented with horse blood,
cephalexin, and amphotericin B

Answer 27

Regan Lowe

Question 28

Peptone base with lactose, ferric citrate, and sodium
citrate; neutral red as indicator; inhibition of
coliforms by brilliant green and bile salts

Answer 28

Salmonella-Shigella (SS) agar

Question 29

Peptone and soy protein base agar with yeast
extract, dextrose, and buffers; addition of hemin,
L-cysteine, and 5% blood enriches for anaerobes

Answer 29

Schaedler agar

Question 30

Peptone-base broth; sodium selenite toxic for most
Enterobacteriaceae

Answer 30

Selenite broth

Question 31

Peptone and soy protein–base agar with lysed horse
blood; vancomycin inhibits gram-positive organisms;
polymyxin B and trimethoprim inhibit most
gram-negative organisms

Answer 31

Skirrow agar

Question 32

Contains crystal violet, colistin, and trimethoprim-sulfamethoxazole in 5% sheep blood agar base

Answer 32

Streptococcal selective agar (SSA)

Question 33

Peptone-base broth; iodine and potassium iodide,
bile salts, and sodium thiosulfate inhibit grampositive
organisms and Enterobacteriaceae

Answer 33

Tetrathionate broth

Question 34

Blood agar base enriched with hemoglobin and
supplement B; contaminating organisms inhibited
by colistin, nystatin, vancomycin, and trimethoprim

Answer 34

Thayer-Martin agar (TM)
(modified Thayer Martin [MTM])

Question 35

Pancreatic digest of casein, soy broth, and glucose
enrich growth of most microorganisms; includes
reducing agents thioglycollate, cystine, and
sodium sulfite; semisolid medium with a low
concentration of agar reducing oxygen diffusion
in the medium

Answer 35

Thioglycollate broth

Question 36

Peptone base agar with yeast extract, bile salts,
citrate, sucrose, ferric citrate, and sodium
thiosulfate; bromthymol blue acts as indicator

Answer 36

Thiosulfate citrate–bile salts (TCBS) agar

Question 37

Supplemented with nalidixic acid and gentamicin or
colistin for greater selectivity; thioglycollate and
agar reduce redox potential

Answer 37

Todd-Hewitt broth supplemented with antibiotics (LIM)

Question 38

All-purpose enrichment broth that can support the
growth of many fastidious and nonfastidious
bacteria

Answer 38

Trypticase soy broth (TSB)

Question 39

Yeast extract agar with lysine, xylose, lactose,
sucrose, and ferric ammonium citrate; sodium
deoxycholate inhibits gram-positive organisms;
phenol red as indicator

Answer 39

Xylose lysine deoxycholate (XLD) agar