SIM Medium

SIM Medium

SKU: KM0159 Category:

For in vitro diagnostic use.

KM0159 SIM Medium is a multi-purpose medium for the differentiation of Enterobacteriaceae.

This is best described as a multi-purpose medium for the differentiation of Enterobacteriaceae that combines three individual tests into a single medium (hydrogen sulphide production, indole formation and motility).

The presence of motility is apparent by the organism tracking out from the line of inoculation and often turning the medium turbid. Non-motile organisms generally grow within the stab line leaving the surrounding medium clear.

H₂S positive organisms turn the medium black due to the formation of hydrogen sulphide in the presence of the sodium thiosulfate and ferric ammonium citrate often making it difficult to determine the other parameters.

Indole production is tested for by layering a small amount of Indole Reagent (Kovac’s) onto the surface of the medium. A positive result is indicated by the formation of a pink colour at the interface of the reagent and the medium. The enzymatic digest of casein and enzymatic digest of animal tissue provide the required carbon, nitrogen, and vitamins in this medium. Ferric ammonium citrate and sodium thiosulfate are used to detect hydrogen sulphide production. The low concentration of agar allows for a semisolid media which is used for motility detection.

Additional Information

Shelf Life (days)

Storage Temp (°C)

Dehydrated Medium Appearance

Dehydrated Medium Colour

Prepared Medium Appearance

Prepared Medium Colour

Dehydrated PH

Prepared PH

Recommended Incubation

Incubate aerobically at 35 ± 2°C for 18-24 hours

Product Description

Organisms Ref. No Result
S. flexneri ATCC 12022 Motility = -ve. Indole = -ve. H2S production = -ve
E. coli NCTC 12241 Motility = +ve. Indole = +ve. H2S production = -ve
S. typhimurium NCTC 12023 Motility = +ve. Indole = -ve. H2S production = +ve
S. sonnei NCTC 8574 Motility = -ve. Indole = -ve. H2S production = -ve
S. enteritidis NCTC 12694 Motility = +ve. Indole = -ve. H2S production = +ve

Recommended incubation: 35 ± 2°C aerobically for 18-24 hours.

Formula*

g/L
Enzymatic digest of casein 20.0
Enzymatic digest of animal tissue 6.1
Ferric ammonium citrate 0.2
Sodium thiosulphate 0.2
Agar 3.5

 

*Adjusted/supplemented as required to meet performance requirements

Preparation

Suspend 30.0g/L of of dehydrated culture medium in 1 litre of deionised/purified water and allow to soak whilst mixing for 10 minutes.
Autoclave to sterilise at 121°C for 15 minutes before cooling in a water bath to 45-50°C.
Aseptically dispense the specified volume into appropriate sterile containers and allow to cool.
Prepared media may be kept at between 2 and 8°C for up to 14 days away from direct sunlight