Moeller KCN Broth Base

The medium facilitates the recognition and identification of enteric bacilli similar to Citrobacter freundii, especially those that are slow to ferment but develop rapidly in the presence of cyanide. Also, this medium is very useful in differentiating Salmonella (including the Arizona group).

Peptone mixture provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Sodium phosphate and potassium phosphate provide minerals and ions and act as a buffer system.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 14 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into tubes and sterilize in autoclave at 121 °C for 15 minutes. Cool to 45-50 °C and aseptically add 15 mL of a 0.5% potassium cyanide solution (0.5 g per 100 mL of sterile distilled water) to each tube containing 10 mL of medium and close tightly.

Instructions for use

Inoculate the medium lightly so that the inoculum cannot be misinterpreted as growth when cultures are examined. This may be accomplished by using a 3 mm loopful of an overnight (24 hours) broth culture, or by transferring a light inoculum from an agar slant culture with a straight wire. Inoculate and incubate at 35 ± 2 °C for 24-48 hours.

• Moeller. Acta Path. and Microbiol. Scand., 134:115. 1954.
• Gershmand Cn. J. Microbiol, 1. 1960.
• Edwards and Ewing, Identification of Enterobacteriaceae. Burgess Publ. Co., Minneapolis, Minn., 1972.