Does Staph grow on MSA?
Mannitol Salt Agar (MSA) is a selective and differential medium. The high concentration of salt (7.5%) selects for members of the genus Staphylococcus, since they can tolerate high saline levels. Organisms from other genera may grow, but they typically grow very weakly.
Does Staphylococcus Saprophyticus Grow on mannitol salt agar?
pH of medium: This should be within the range of pH 7.3 to 7.7 at room temperature. Staphylococcus saprophyticus (coagulse-negative Staphylococci) may ferment mannitol, producing yellow halo around colonies in MSA thus resembling S. aureus.
What bacteria can grow on mannitol salt agar?
Result Interpretation on Mannitol Salt Agar
| Organisms | Results |
|---|---|
| Staphylococcus aureus | Yellow colonies with yellow zones. |
| Staphylococci other than S. aureus (e.g. Staphylococcus epidermidis ) | Colorless or Red colonies with red zones. |
| Streptococci | No growth to trace growth. |
| Micrococci | Large white to orange. |
Does Staphylococcus epidermidis ferment mannitol?
Staphylococcus epidermidis grows on MSA, but does not ferment mannitol (media remains light pink in color, colonies are colorless).
What will turn MSA yellow?
The differential ingredient in MSA is the sugar mannitol. Organisms capable of using mannitol as a food source will produce acidic byproducts of fermentation that will lower the pH of the media. The acidity of the media will cause the pH indicator, phenol red, to turn yellow.
Can E coli grow on MSA?
The MSA agar will retain its initial red color and will not change to yellow. Gram-negative bacteria like E. coli and P. aeriginosa are not tolerant to salt (not halophilic) and will not grow colonies on MSA (see quadrants II and IV).
Why does mannitol salt agar turn yellow?
Organisms capable of using mannitol as a food source will produce acidic byproducts of fermentation that will lower the pH of the media. The acidity of the media will cause the pH indicator, phenol red, to turn yellow.
What bacteria Cannot grow on MSA agar?
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 E coli grow on MSA plate?
Why does MSA plate turn yellow?
What can grow on MSA plate?
Mannitol Salt Agar (MSA) Staphylococcus species, which commonly inhabit human skin, can grow on this high salt concentration (left plate in picture below). This is in contrast to Streptococcus species, whose growth is selected against by this high salt agar (plate on the right in the picture below).
What kind of infections does Staphylococcus saprophyticus cause?
Staphylococcus Saprophyticus plays a role primarily as an agent of acute uncomplicated urinary tract infections in young women. In this group, S. saprophyticus is the second most common pathogen in all organisms after Escherichia coli, with a content of 5-20%.
Are there any commercial systems for identifying Staphylococcus?
Various commercial systems for staphylococcus identification have been developed over the past few years as an alternative to the classic identification protocols proposed by Bannerman (2003), which are laborious and time consuming for routine laboratory use.
Where can I find mannitol salt agar matrix?
3 Department of Clinical Microbiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: [email protected].