Semisolid Liver Meat Medium (Revised as Semisolid LM Medium)

Intended Use:

For cultivation of fastidious anaerobes.

Composition**

Final pH (at 25°C): 7.6±0.2

**Formula adjusted, standardized to suit performance parameters # Equivalent to Liver meat base

Directions

Suspend 38.0 grams in 1000 ml purified/distilled water. Soak for 15 minutes with occasional stirring. Heat to boiling to dissolve the medium completely. Dispense in tubes or flasks as desired. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

Principle And Interpretation

Anaerobic bacteria live in an oxygen-free environment. Some anaerobic bacteria actually die if oxygen is present, while others fail to grow and multiply (1). Semisolid LM Medium is used for the cultivation of fastidious anaerobes in the respiratory tract, especially anaerobes from deep tissue sites. The medium contains HML Base, which provides amino acids and other nutrients and reducing substances for the growth of fastidious anaerobes. Semisolid nature of the medium favours growth of anaerobic microorganisms. Glucose is the source of fermentable carbohydrates.

Type of specimen

Clinical samples - Throat swab

Specimen Collection and Handling:

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (2,3). After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions :

In Vitro diagnostic use only. For professional use only. Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling clinical specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations :

1. Further biochemical and serological tests must be carried out for further identification.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance Light yellow to brown homogeneous free flowing powder

Gelling Semisolid, comparable with 0.6% Agar gel.

Colour and Clarity of prepared medium Medium amber coloured clear to slightly opalescent gel in tubes

Reaction Reaction of 3.8% w/v aqueous solution at 25°C. pH : 7.6±0.2

pH 7.40-7.80

Cultural Response

Cultural characteristics observed after an incubation at 35-37°C for 24-48 hours.

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 15-30°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly after use. Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques (2,3).

Reference

1. Alcamo E. I., 2001, Fundamentals of Microbiology, 6th Ed., Jones and Bartlett Publishers.
2. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
3. Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1.