Table of Contents
- 1 Does Staphylococcus aureus grow on MSA?
- 2 What does a positive MSA plate look like for Staphylococcus aureus?
- 3 What organisms are inhibited from growing on MSA?
- 4 Can Salmonella grow on MSA?
- 5 What ingredient makes MSA selective?
- 6 What ingredient in MSA makes it selective?
- 7 What kind of bacteria can grow on MSA?
- 8 How is MSA used for the isolation of Staphylococcus aureus?
Does Staphylococcus aureus grow on MSA?
Mannitol Salt Agar is differential due to the presence of mannitol and the pH indicator Phenol Red. aureus grow on Mannitol Salt Agar. About 8 % to 12 % of Staph. aureus strains will not ferment mannitol.
What does a positive MSA plate look like for Staphylococcus aureus?
Results. Yellow colonies with yellow zones. Colorless or Red colonies with red zones. No growth to trace growth.
How does Staphylococcus aureus appear on MSA?
MSA also contains the sugar mannitol and the pH indicator phenol red. If an organism can ferment mannitol, an acidic byproduct is formed that will cause the phenol red in the agar to turn yellow. The Staphylococcus aureus ferments mannitol and turns the medium yellow.
Can Streptococcus grow on MSA?
MSA contains a high concentration of salt (NaCl), and therefore, selects for the growth of microbes that can tolerate high salt concentrations. Staphylococcus species are halotolerant, whereas Streptococcus species and many other organisms are inhibited by high concentrations of NaCl.
What organisms are inhibited from growing on MSA?
It contains a high concentration (about 7.5–10%) of salt (NaCl) which is inhibitory to most bacteria – making MSA selective against most Gram-negative and selective for some Gram-positive bacteria (Staphylococcus, Enterococcus and Micrococcaceae) that tolerate high salt concentrations.
Can Salmonella grow on MSA?
Bile salts and crystal violet inhibits the growth of most Gram positive, non-enteric bacteria. Gram negative enteric bacilli will grow; E. coli will produce pink colonies, Salmonella and Shigella spp. cereus does not ferment mannitol and colonies are deep red.
What media does Staphylococcus aureus grow on?
Staph. aureus will grow on general culture media such as Blood Agar and chocolated Blood Agar and therefore can be isolated from direct plating of clinical specimens. More specialised media, such as Staph/Strep Selective Medium contain antimicrobials.
Can salmonella grow on MSA?
What ingredient makes MSA selective?
Mannitol salt agar is selective due to the presence of 7.5% sodium chloride (NaCl).
What ingredient in MSA makes it selective?
Does Bacillus grow on MSA?
Some group D enterococci may exhibit growth with mannitol fermentation; however, catalase test and gram morphology should distinguish between enterococci and staphylococci. Prolonged incubation (≥ 48 hours) may also allow growth of Micrococcus, Bacillus, and some species of Serratia.
What is the selective agent found in MSA?
Mannitol Salt Agar (MSA) This is a medium that is both selective and differential. The high salt concentration (7.5%) is the selective ingredient. Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below).
What kind of bacteria can grow on MSA?
Psuedomonas aeruginosa (Gram negative) – no growth Mannitol Salt Agar (MSA) is used to determine if the bacteria is halophilic (salt loving) and if the bacteria can ferment mannitol. If the bacteria is able to grow then it is a halophilic bacteria, due to it’s ability to grow in a high salt environment.
How is MSA used for the isolation of Staphylococcus aureus?
Mannitol Salt Agar for the isolation of Staphylococcus aureus. Mannitol Salt Agar (MSA) is used as a selective and differential medium for the isolation and identification of Staphylococcus aureus from clinical and non-clinical specimens. It encourages the growth of a group of certain bacteria while inhibiting the growth of others.
What kind of bacteria ferments mannitol in MSA?
Staphylococcus saprophyticus (coagulse-negative Staphylococc i) may ferment mannitol, producing yellow halo around colonies in MSA thus resembling S. aureus. Staphylococcus aureus: Yellow colonies; may have a yellow halo around colonies.
Why is MSA a differential medium for mannitol salt?
But if coagulase-negative staphylococci (CONS) grows, they cant ferment mannitol, so the color of the media around the bacterial colony does not change to yellow, it appears pink. So, MSA is also a differential medium. Remember that in the neutral pH (6.9 to 8.4) the color of phenol red is red; while above pH 8.4, the color of phenol red is pink.