Littman Oxgall Agar Base (Revised as Littman Bile Agar Base)

Intended Use

Recommended for primary isolation of pathogenic fungi.

Composition**

Final pH (at 25°C): 7.0±0.2

**Formula adjusted, standardized to suit performance parameters

#Equivalent to Oxgall

Directions

Suspend 55.01 grams in 1000 ml purified/distilled water. Heat to boiling, to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C and aseptically add sterile Streptomycin to a final concentration of 30 µg/ml of medium. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Littman Bile Agar Base was formulated by Littman (1,2). Littman Oxgall Agar is used for the primary isolation of pathogenic selective isolation of pathogenic skin fungi (dermatophytes) and saprophytic fungi from various clinical specimens. It provides effective isolation even when the test samples are heavily contaminated with bacterial flora. Littman Bile Agar Base media are also used for the enumeration of fungal populations of air, soil, foodstuffs and other materials of sanitary significance (3). Crystal violet and Streptomycin has inhibitory effect on most of the bacteria. Bile restricts spreading of fungal colonies. The neutral pH favours the growth of many pathogenic fungi. Littman (2) reported the isolation of fungi on this medium three times more than isolated on Sabouraud Dextrose Agar.

For inoculation, skin or nail scraping or infected hair is directly placed on the surface of agar while sputum, faeces etc. are spread over the surface with sterile swab or the specimen are first enriched in broth and then cultured on agar medium. The incubation should be carried out for upto 8 days. Whenever Nocardia asteroides, Streptomyces or any Streptomycin sensitive microorganisms are to be cultured, use the medium without Streptomycin (3).

Type of specimen

Clinical samples - skin or nail scraping or infected hair etc

Specimen Collection and Handling

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (4,5). After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

In Vitro diagnostic Use. 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. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. Each lot of the medium has been tested for the organisms specified on the COA. It is recommended to users to validate the medium for any specific microorganism other than mentioned in the COA based on the user’s unique requirement.
3. Do not use the media for Nocardia asteroids, Streptomyces or other organisms sensitive to streptomycin.
4. Further serological / biochemical tests are to be carried out on pure colonies for complete 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: Cream to yellow may have green tinge homogeneous free flowing powder

Gelling: Firm, comparable with 2.0% agar gel.

Colour and Clarity of prepared medium: Blue coloured clear to slightly opalescent gel forms in Petri plates

Reaction: Reaction of 5.5% w/v aqueous solution at 25°C. pH : 7.0±0.2

pH: 6.80-7.20

Cultural Response: Cultural characteristics observed after an incubation at 25-30°C for 48-72 hours.

Key : (*) - Corresponding WDCM numbers.

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°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 (4,5).

Reference

1. Littman M. L., 1947, Science, 106:109.
2. Littman M. L., 1948, Am. J. Clin. pathol., 18:409.
3. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol.1, Williams and Wilkins, Baltimore.
4. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
5. 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.