Staphylococcus Agar Nº 110 1032 Condalab

Staphylococcus Agar Nº 110 is a selective medium used to isolate pathogenic staphylococci from clinical and non-clinical samples based on mannitol fermentation, pigment formation and gelatinase activity. Staphylococci can be responsible for cases of pneumonia, meningitis, furunculosis, urethritis, vaginitis, etc. The medium can also be used for isolation staphylococci that can contaminate a wide variety of foods that can cause food poisoning.

Casein peptone provides nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly the B-group. Lactose and D-mannitol are the fermentable carbohydrates as energy sources; Dipotassium phosphate is the buffer; Sodium chloride supplies essential electrolytes for transport and osmotic balance and, in high concentration, inhibits most bacteria except staphylococci. Gelatin is included to test liquefaction and bacteriological agar is the solidifying agent.

Pathogenic staphylococci (coagulase-positive staphylococci) resist the high NaCl concentration and form golden yellow colonial pigments. Mannitol fermentation, producing acid, is detected by adding a few drops of Bromothymol blue to a plate and looking for a yellow halo around the colonies. Staphylococci liquefy gelatin, producing clearing zones around the colonies. One plate can be filled with 5 ml of a saturated solution of ammonium sulphate, or with a drop of 20% sulfosalicylic acid and incubated for 12 minutes to observe the hydrolysis of the gelatin: a clearing around the colony constitutes a positive hydrolysis (Stone’s Reaction).