lab069 specification

MMv1 09/06 Simmons Citrate Agar LAB 69 Description A medium devised by Simmons in 1926 to help in the differentiation of enteric bacteria and in the isolation of fungi. Certain Enterobacteriacae have the ability to utilize citrate as the sole source of carbon and utilize inorganic ammonium salts as the sole source of nitrogen resulting in an increase in alkalinity. Bromothymol Blue is used as a pH indicator. Formula g/litre Magnesium sulphate 0.2 Ammonium dihydrogen phosphate 1.0 Dipotassium phosphate 1.0 Sodium citrate 2.0 Sodium chloride 5.0 Bromothymol blue 0.08 Agar No. 2 15.0 Method for reconstitution Weigh 24 grams of powder, disperse in 1 litre of deionised water. Allow to soak for 10 minutes, swirl to mix then heat to dissolve the agar and solids. Dispense into tubes or bottles then sterilise by autoclaving at 121°C for 15 minutes. Allow to set as slopes. Appearance: Green, opalescent. pH: 6.9 ± 0.2 Minimum Q.C. organisms: E. coli NCIMB 50034 C. freundii NCTC 9750 Storage of Prepared Medium: Capped containers – up to 3 months at 15-20°C in the dark. Inoculation: Streak on surface and stab into the butt. Incubation: 37°C aerobically for 24-48 hours, with loose caps to allow gaseous exchange. Interpretation: Utilisation of citrate and ammonium salts results in growth and a change in colour of the medium from green to blue. Growth Characteristics organism growth colour of medium (most) Salmonella spp yes blue S. typhi no green S. cholerasuis no green S. gallinarum no green S. paratyphi A no green Serratia spp. yes blue Shigella spp. no green Yersinia spp. no green Klebsiella spp. yes blue Proteus mirabilis yes blue P. vulgaris yes blue Providencia rettgeri no green P. providenciae no green E. coli no green C. freundii yes blue References Simmons, J.S. (1926). A Culture medium for differentiating organisms of typhoid - colon aerogenes groups and for isolation of certain fungi. J.Inf. Dis. 39: 209-215. Koser, S.A. (1923). Utilisation of the salts of organic Acids by the Colon-aerogenes group. J. Bact. 8: 493-520. MacFaddin, J.F. (1983). Biochemical Tests for Identification of Medical Bacteria. Williams and Wilkins.

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MMv1 09/06

Simmons Citrate Agar LAB 69

Description A medium devised by Simmons in 1926 to help in the differentiation of enteric bacteria and in the isolation of fungi. Certain Enterobacteriacae have the ability to utilize citrate as the sole source of carbon and utilize inorganic ammonium salts as the sole source of nitrogen resulting in an increase in alkalinity. Bromothymol Blue is used as a pH indicator.

Formula g/litre Magnesium sulphate 0.2 Ammonium dihydrogen phosphate 1.0 Dipotassium phosphate 1.0 Sodium citrate 2.0 Sodium chloride 5.0 Bromothymol blue 0.08 Agar No. 2 15.0

Method for reconstitution Weigh 24 grams of powder, disperse in 1 litre of deionised water. Allow to soak for 10 minutes, swirl to mix then heat to dissolve the agar and solids. Dispense into tubes or bottles then sterilise by autoclaving at 121C for 15 minutes. Allow to set as slopes.

Appearance: Green, opalescent.

pH: 6.9 0.2

Minimum Q.C. organisms: E. coli NCIMB 50034 C. freundii NCTC 9750

Storage of Prepared Medium: Capped containers up to 3 months at 15-20C in the dark.

Inoculation: Streak on surface and stab into the butt.

Incubation: 37C aerobically for 24-48 hours, with loose caps to allow gaseous exchange.

Interpretation: Utilisation of citrate and ammonium salts results in growth and a change in colour of the medium from green to blue.

Growth Characteristics organism growth colour of medium (most) Salmonella spp yes blue S. typhi no green S. cholerasuis no green S. gallinarum no green S. paratyphi A no green Serratia spp. yes blue Shigella spp. no green Yersinia spp. no green Klebsiella spp. yes blue Proteus mirabilis yes blue P. vulgaris yes blue Providencia rettgeri no green P. providenciae no green E. coli no green C. freundii yes blue References Simmons, J.S. (1926). A Culture medium for differentiating organisms of typhoid - colon aerogenes groups and for isolation of certain fungi. J.Inf. Dis. 39: 209-215.

Koser, S.A. (1923). Utilisation of the salts of organic Acids by the Colon-aerogenes group. J. Bact. 8: 493-520.

MacFaddin, J.F. (1983). Biochemical Tests for Identification of Medical Bacteria. Williams and Wilkins.