Deskripsi

Himedia M181-500G SIM Medium

Himedia M181-500G SIM Medium

Intended use
Recommended for determination of hydrogen sulphide production, indole formation and motility of enteric bacilli from
clinical and non-clinical samples.

Composition**

Ingredients Gms / Litre
HM Peptone B# 3.000
Peptone 30.000
Peptonized iron 0.200
Sodium thiosulphate 0.025
Agar 3.000
Final pH ( at 25°C) 7.3±0.2

Directions
Suspend 36.23 grams in 1000 ml purified/ distilled water. Heat to boiling to dissolve the medium completely. Dispense in
tubes. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Allow the tubes to cool in an upright position.

Principle And Interpretation

SIM Medium is used to differentiate enteric bacilli particularly Salmonella and Shigella on the basis of sulphide production,
indole formation and motility (1,5). Jordan and Victorson (3) reported that Salmonella Paratyphi A and Paratyphi B can be
ddistinguished on the basis of H2S production using lead acetate. Sulkin and Willett (7) used Triple Sugar Iron Agar with 1%
agar for motility along with H2S production and carbohydrate fermentation. Sosa (6) described a peptone medium with low
agar for motility and indole determination.
SIM Medium enables determination of three characteristics by which enteric bacteria can be ddifferentiated. Peptonized iron
and sodium thiosulphate are the indicators of H2S production. This H2S reacts with peptonized iron to form black precipitate
of ferrous sulphide (6,7). Motile organisms intensify the H2S reaction. Motile organisms grow away from line of inoculation
showing ddiffused growth while non-motile organisms grow along the stab line.

Motility detection is possible due to
the semisolid nature of the medium. Growth radiating out from the central stab line indicates that the test organism is
motile. Peptone and HM peptone B provides nitrogenous and carbonaceous compounds, long chain amino acids, vitamins
and other essential nutrients. Tryptophan from peptone, is degraded by specific bacteria to produce indole (1). The indole is
detected by the addition of chemical reagents following the incubation period.
Inoculate fresh culture with a single stab using straight needle through the center of the medium. Following incubation,
observe for motility (ddiffuse growth outward from the stab line or turbidity throughout the medium) and for H2S
production (blackening of the medium). To detect indole production, add three or four drops of Kovacs reagent (1) and
observe for development of red color (positive reaction). Determine motility and H2S production prior to
determination of indole production.