Additional Info For Culture Media Flashcards
EKE (rapid lactose fermenters)
- Escherichia
- Klebsiella
- Enterobacter
is characterized by a clear, colorless zone around the bacterial colony due to complete lysis of red blood cells.
Beta-hemolysis
Common bacteria that show beta-hemolysis include
Streptococcus pyogenes (Group A Streptococcus)
Streptococcus agalactiae (Group B Streptococcus).
results in a greenish zone around the colonies, caused by the partial reduction of hemoglobin to methemoglobin.
Alpha-hemolysis
Examples of alpha-hemolytic bacteria include
Streptococcus pneumoniae
various species of viridans streptococci like Streptococcus mutans.
shows no visible hemolysis around the colonies, indicating no lysis of red blood cells.
Gamma-hemolysis (or non-hemolysis)
Bacteria like______display gamma-hemolysis
Enterococcus faecalis
McCoy’s Cells
Use
Primarily used for the isolation and culture of Chlamydia trachomatis and other related bacteria.
- Isolates: Selective for Gram-negative bacteria, particularly members of the family Enterobacteriaceae.
MacConkey Agar (MAC)
It differentiates lactose fermenters (e.g., Escherichia coli) which appear pink, from non-lactose fermenters (e.g., Salmonella, Shigella) which appear colorless.
MacConkey
- Isolates: Selective for Gram-positive bacteria, specifically Staphylococcus species.
Mannitol Salt Agar (MSA)
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.
Mannitol Salt Agar (MSA):
- Isolates: Selective for Gram-negative enteric pathogens.
Hektoen Enteric Agar (HEA)
It differentiates Salmonella (which produces black colonies due to hydrogen sulfide production) from Shigella (which produces green colonies).
Hektoen Enteric Agar (HEA)
- Isolates: Selective for Gram-negative enteric pathogens, particularly Salmonella and Shigella.
Xylose Lysine Deoxycholate Agar (XLD)
Salmonella* appears with black centers, while Shigella appears red without black centers.
Xylose Lysine Deoxycholate Agar (XLD):
- Isolates: Selective for Neisseria gonorrhoeae and Neisseria meningitidis.
Thayer-Martin Agar: