Selective Media Flashcards
What is selective media?
Selective media is a type of growth medium designed to favor the growth of specific microorganisms while inhibiting others.
True or False: Selective media can be used for both gram-positive and gram-negative bacteria.
True
What type of bacteria does mannitol salt agar primarily select for?
Mannitol salt agar primarily selects for gram-positive bacteria, particularly Staphylococcus species.
Fill in the blank: MacConkey agar is selective for __________ bacteria.
gram-negative
What is the primary use of eosin methylene blue (EMB) agar?
EMB agar is used to isolate gram-negative bacteria, particularly coliforms.
Which selective media is used for isolating Salmonella and Shigella?
XLD (Xylose Lysine Deoxycholate) agar.
True or False: Blood agar is a selective medium.
False
What does the term ‘differential media’ refer to?
Differential media allows for the distinction between different types of bacteria based on their biochemical characteristics.
Which selective medium contains bile salts to inhibit the growth of gram-positive bacteria?
MacConkey agar.
What color do lactose fermenters turn on MacConkey agar?
Pink.
What is the role of sodium chloride in mannitol salt agar?
Sodium chloride helps to create a high-salt environment that inhibits most bacteria except for staphylococci.
Fill in the blank: Cetrimide agar is selective for __________ bacteria.
Pseudomonas aeruginosa.
Which medium is used to isolate enteric gram-negative bacteria?
XLD agar.
True or False: Selective media can help in identifying specific bacterial pathogens.
True
What type of bacteria does phenylethyl alcohol agar (PEA) select for?
Gram-positive bacteria.
What is the indicator used in EMB agar?
Dyes eosin Y and methylene blue.
Which selective agar is known to inhibit the growth of gram-negative bacteria while allowing gram-positive bacteria to grow?
Columbia CNA agar.
Fill in the blank: Hektoen enteric agar is used to isolate __________.
Salmonella and Shigella.
What is the primary component that differentiates gram-positive from gram-negative bacteria?
Cell wall structure.
Which selective medium contains lactose and is used to differentiate between lactose fermenters and non-fermenters?
MacConkey agar.
True or False: All selective media are also differential media.
False
What is the function of the bile salts in MacConkey agar?
To inhibit the growth of gram-positive organisms.
What color indicates a positive result for lactose fermentation on EMB agar?
Metallic green.
Which agar is specifically designed for the isolation of Clostridium species?
Egg yolk agar.
What characteristic do most gram-negative bacteria share that allows them to grow on MacConkey agar?
The ability to ferment lactose.
