Pagano Levin Base

Intended Use

Recommended for isolating and differentiating Candida species.

Composition

Final pH (at 25°C): 6.0±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 33.0 grams in 490 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. Aseptically add 5 ml of TTC solution 1% (FD057). Mix well. Then add 5 ml of rehydrated contents of one vial of Neo Selective Supplement (FD174). Mix well and pour into sterile Petri plates.

Principle And Interpretation

Pagano Levin Base prepared as per the formulation of Pagano, Levin and Trejo (1) is used for the isolation and differentiation of Candida species. Differentiation is based on the ability of Candida species to reduce TTC (2,3,5-Triphenyl Tetrazolium Chloride). TTC is a redox indicator which is colourless in the oxidized form and when reduced forms an insoluble red triphenyl formazan compound which appears as red coloured colonies (2). Pagano Levin Base is superior to Sabouraud Dextrose Agar in detecting yeast species (3).

Peptone provides carbon and nitrogen source required for good growth of Candida species. Yeast extract provides vitamins and cofactors. Dextrose is an energy source. TTC Solution 1%, added to the basal medium, facilitates the differentiation of yeast colonies based on the color change that occurs when Candida reduces TTC. Neomycin helps to inhibit growth of most of the accompanying bacteria.

Type of specimen

Clinical samples

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 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 wet mount examination of infected material should be done.

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 homogeneous free flowing powder

Gelling

Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium

Light amber coloured slightly opalescent gel forms in Petri plates

Reaction

Reaction of 6.6% w/v aqueous solution at 25°C. pH: 6.0±0.2

pH

5.80-6.20

Cultural Response

Cultural characteristics observed with added TTC solution 1% (FD057) and Neo Supplement (FD174), after an incubation at 35-37°C for 18-48 hours.

Key: *Corresponding WDCM numbers. # - Formerly known as Candida krusei

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. Pagano J., Levin J. V. and Trejo W., 1958, Antibiot. Annu. 1957-1958:137.
2. MacFaddin J.F, 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore
3. Samaranayake L.P., MacFarlane T.W. and Williamson M.I., 1987, J. Clin. Microbiol. 25:162.
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.