Sterility Testing Medium B

Composition

Final pH (at 25°C): 7.1±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 26 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

Principle And Interpretation

Sterility Testing Medium B is used for checking the presence of anaerobic microorganisms in pharmacopeial articles (1). The medium contains peptic digest of animal tissue and meat extract which provides carbonaceous, nitrogenous compounds and essential growth nutrients for the growth of organisms. Sodium chloride maintains the osmotic balance. Sodium thioglycollate acts as a reducing agent and maintains a low oxygen tension in the medium. Resazurin acts as an pH indicator.

Quality Control

Appearance: Cream to yellow coloured homogeneous free flowing powder

Colour and Clarity of prepared medium: Light amber coloured clear to slightly opalescent solution with upper 10% or less medium pink on standing.

Reaction: Reaction of 2.6% w/v aqueous solution at 25°C. pH : 7.1±0.2

pH: 6.90-7.30

Cultural Response

M018: Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours, under anaerobic conditions.

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2-8°C. Use before the expiry date on the label.

Reference

1. The Indian Pharmacopeia, 3rd Ed., 1985, New Delhi, India.