Inoculate the medium and incubate for 36 hours at 35 ºC or for 3 days at 32 ºC.
Staphylococcus aureus ATCC 6538: good growth, yellow colonies surrounded by
Staphylococcus aureus ATCC 25923: good growth, yellow colonies surrounded by
Staphylococcus epidermidis ATCC 12228: no colour change, growth is usually poorer.
Escherichia coli ATCC 8739: no growth.
Proteose peptone 10 g, Beef extract 1 g, NaCl 75 g, D-Manite 10 g, Phenol red 0.025 g,
Agar 15 g, Distilled water ad 1000ml; adjust pH to 7.4
Sterilize by autoclaving at 121 ºC for 15 minutes.
Medium is used for the isolation of presumptive mannitol-positive staphylococci from milk, food and pathologic materials. Most other
bacteria are inhibited by the bile salts, the crystal violet and the high level of NaCl, with the exception of halophilic species. Medium is
also used for microbial contamination testing.
The correlation between pathogenicity and mannitol degradation to acid is not widely accepted.
|Mannitol Salt Agar
(MSA / Chapman agar)
(c) Costin Stoica