Fluid Thioglycollate Medium (U.S.P. )

LAB 25

Description

A medium for sterility tests, prepared according to the specification of the United States Pharmacopeia. Aerobic and anaerobic organisms grow well in this medium even from small inocula. In appropriate tubes or bottles the thioglycollate ensures adequate anaerobic conditions. The low level of agar reduces oxygen diffusion into the medium. The thioglycollate will also serve to inactivate any mercurial compounds used as preservatives.

Method for reconstitution

Weigh 29.75 grams, disperse in 1 litre of deionised water. Soak for 10 minutes, swirl to mix, then bring to the boil to dissolve and dispense 15ml into 6mm x 150mm tubes. Sterilise by autoclaving for 15 minutes at 121˚C. Store at ambient temperature in the dark, but not in the refrigerator. If more than 30% of the medium turns pink (oxidised) the Eh may be restored (once only) by heating in a boiling water bath or by free-steaming.

Appearance: Pale straw colour, clear. Surface may be pink/blue due to oxidation of Resazurin.

pH: 7.1 ± 0.2

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

Incubation: 30-35˚C aerobically for 14 days.

Growth indicators: Turbidity, colonies in medium.

References

The Pharmacopeia of the United States of America. 21st End. (1985).

References

King, E.O., Ward, M.K. and Raney, D.E. (1954). 2 simple media demonstration of pyocyanin and fluorescein, J. Lab. Clin M 44: 301-307.

Brown, V.I. and Lowbury, E.J.L. (1965). Use of an impro cetrimide agar medium and other culture methods for Pseudomo aeruginosa. J. Clin. Path. 18: 752-756.