Additional Info For Culture Media

Question 1

EKE (rapid lactose fermenters)

Answer 1

• Escherichia
• Klebsiella
• Enterobacter

Question 2

is characterized by a clear, colorless zone around the bacterial colony due to complete lysis of red blood cells.

Answer 2

Beta-hemolysis

Question 3

Common bacteria that show beta-hemolysis include

Answer 3

Streptococcus pyogenes (Group A Streptococcus)

Streptococcus agalactiae (Group B Streptococcus).

Question 4

results in a greenish zone around the colonies, caused by the partial reduction of hemoglobin to methemoglobin.

Answer 4

Alpha-hemolysis

Question 5

Examples of alpha-hemolytic bacteria include

Answer 5

Streptococcus pneumoniae

various species of viridans streptococci like Streptococcus mutans.

Question 6

shows no visible hemolysis around the colonies, indicating no lysis of red blood cells.

Answer 6

Gamma-hemolysis (or non-hemolysis)

Question 7

Bacteria like______display gamma-hemolysis

Answer 7

Enterococcus faecalis

Question 8

McCoy’s Cells

Use

Answer 8

Primarily used for the isolation and culture of Chlamydia trachomatis and other related bacteria.

Question 9

• Isolates: Selective for Gram-negative bacteria, particularly members of the family Enterobacteriaceae.

Answer 9

MacConkey Agar (MAC)

Question 10

It differentiates lactose fermenters (e.g., Escherichia coli) which appear pink, from non-lactose fermenters (e.g., Salmonella, Shigella) which appear colorless.

Answer 10

MacConkey

Question 11

• Isolates: Selective for Gram-positive bacteria, specifically Staphylococcus species.

Answer 11

Mannitol Salt Agar (MSA)

Question 12

It differentiates Staphylococcus aureus (which ferments mannitol and turns the medium yellow) from other staphylococci which do not ferment mannitol and leave the medium red.

Answer 12

Mannitol Salt Agar (MSA):

Question 13

• Isolates: Selective for Gram-negative enteric pathogens.

Answer 13

Hektoen Enteric Agar (HEA)

Question 14

It differentiates Salmonella (which produces black colonies due to hydrogen sulfide production) from Shigella (which produces green colonies).

Answer 14

Hektoen Enteric Agar (HEA)

Question 15

• Isolates: Selective for Gram-negative enteric pathogens, particularly Salmonella and Shigella.

Answer 15

Xylose Lysine Deoxycholate Agar (XLD)

Question 16

Salmonella* appears with black centers, while Shigella appears red without black centers.

Answer 16

Xylose Lysine Deoxycholate Agar (XLD):

Question 17

• Isolates: Selective for Neisseria gonorrhoeae and Neisseria meningitidis.

Answer 17

Thayer-Martin Agar:

Question 18

It contains antibiotics to inhibit the growth of contaminating organisms like Gram-positive bacteria and yeast.

Answer 18

Thayer-Martin Agar

Question 19

• Isolates: Selective for Pseudomonas aeruginosa, which produces characteristic green or blue-green colonies due to pyocyanin production.

Answer 19

Cetrimide Agar

Question 20

• Isolates: Selective for Mycobacterium species, especially Mycobacterium tuberculosis.

Answer 20

Lowenstein-Jensen Medium

Question 21

It contains malachite green to inhibit the growth of contaminants.

Answer 21

Lowenstein-Jensen Medium:

Question 22

• Isolates: Selective for fungi, including yeasts and molds. The acidic pH of the medium inhibits bacterial growth, favoring fungal growth.

Answer 22

Sabouraud Dextrose Agar (SDA)

Question 23

• Isolates: Selective for Gram-negative bacteria. It differentiates between lactose fermenters like E. coli (which produces metallic green colonies) and non-lactose fermenters (which produce colorless or pink colonies)

Answer 23

Eosin Methylene Blue (EMB) Agar

Question 24

are those that require specific nutrients or environmental conditions to grow, often needing enriched or enrichment media.

Answer 24

Fastidious bacteria

Question 25

Fastidious bacteria

Answer 25

Neisseria gonorrhoeae and Neisseria meningitidis Haemophilus influenzae Streptococcus pneumoniae Legionella pneumophila Mycobacterium tuberculosis

Question 26

- Media Required: Thayer-Martin agar or Chocolate agar. - Reason: These bacteria require enriched media with added nutrients like hemoglobin, vitamins, and coenzymes to grow.

Answer 26

Neisseria gonorrhoeae and Neisseria meningitidis

Question 27

- Media Required: Chocolate agar or Levinthal agar. - Reason: Requires factors X (hemin) and V (NAD) that are present in lysed red blood cells found in chocolate agar.

Answer 27

Haemophilus influenzae

Question 28

- Media Required: Blood agar with added carbon dioxide. - Reason: This organism is fastidious and grows better in an environment with enriched nutrients and elevated CO2.

Answer 28

Streptococcus pneumoniae

Question 29

- Media Required: Buffered Charcoal Yeast Extract (BCYE) agar. - Reason: Requires L-cysteine and iron salts, which are provided by BCYE agar.

Answer 29

Legionella pneumophila

Question 30

- Media Required: Lowenstein-Jensen medium or Middlebrook agar. - Reason: Requires enriched media with malachite green to inhibit contaminants and provide essential nutrients for growth

Answer 30

Mycobacterium tuberculosis

Question 31

Enrichment and isolation of Salmonella spp. Peptone-base broth; sodium selenite toxic for most Enterobacterales

Answer 31

Selenite broth

Question 32

Contains crystal violet, colistin, and trimethoprim-sulfamethoxazole in 5% sheep blood agar base Selective for Streptococcus pyogenes and Streptococcus agalactiae

Answer 32

Streptococcal selective agar (SSA)

Question 33

Selective for N. gonorrhoeae and N. meningitidis. Supports the growth of Francisella and Brucella spp. Blood agar base enriched with hemoglobin and supplement B; contaminating organisms inhibited by colistin, nystatin, vancomycin, and trimethoprim

Answer 33

Thayer Martin

Question 34

Supports growth of anaerobes, aerobes, micro-aerophilic, and fastidious microorganisms

Answer 34

Thioglycollate broth

Question 35

Selective and differential for Vibrio cholerae and Vibrio parahaemolyticus

Answer 35

Thiosulfate citrate-bile salts (TCBS) agar

Question 36

Basal back-up broth or enrichment broth used for subculturing various bacteria from primary agar plates All-purpose basal broth that can support the growth of many nonfastidious organisms or when supplemented with additional nutrients, it is used to cultivate fastidious microorganisms.

Answer 36

Trypticase soy broth (TSB)

Question 37

Cultivation of fastidious microorganisms such as Haemophilus spp., Brucella spp., and pathogenic Neisseria spp.

Answer 37

Chocolate agar

Question 38

Isolation of Corynebacterium diphtheriae

Answer 38

Cystine-tellurite blood agar

Question 39

Isolation and differentiation of lactose-fermenting and non-lactose-fermenting enteric bacilli Peptone base containing lactose; eosin Y and methylene blue as indicators

Answer 39

Eosin methylene blue (EMB) agar (Levine)

Question 40

Selective (enrichment) liguid medium for enteric pathogens Salmonella and Shigella spp. Peptone-base broth with glucose and mannitol; sodium citrate and sodium deoxycholate act as inhibitory agents

Answer 40

Gram-negative broth (GN)

Question 41

Differential, selective medium for the isolation and differentiation of Salmonella and Shigella spp. from other GN enteric bacilli Peptone-base agar with bile salts, lactose, sucrose, salicin, and ferric ammonium citrate; indicators include bromothymol blue and acid fuchsin

Answer 41

Hektoen enteric (HE) agar

Question 42

Isolation and differentiation of lactose fermenting and non-lactose-fermenting enteric bacilli Peptone base with lactose; gram-positive organisms inhibited by crystal violet and bile salts; neutral red as indicator

Answer 42

MacConkey agar

Question 43

Inverted Umbrella/Christmas Tree appearance of _______on SIM.

Answer 43

Listeria monocytogenes

Question 44

Test Tube Brush appearance of _______on SIM.

Answer 44

Erysipelothrix rhusiopathiae