Veillonella Agar Base

Intended Use

For selective isolation of Veillonella species.

Composition**

Final pH (at 25°C) 7.5±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 23.75 grams in 1000 ml purified/distilled water containing 21 ml of 60% sodium lactate. If desired, 1.0 gm of Tween 80 may be added. 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 vancomycin to a final concentration of 7.5 mcg/ml medium. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Veillonella are gram-negative cocci that are the anaerobic counterpart of Neisseria. These non-motile diplococci are part of the normal flora of the mouth and have been encountered in patients with oral bite wound, head, neck, and miscellaneous soft tissue infections (1,2). The most common species isolated from humans is Veillonella parvula. Veillonella species are negative for the routine biochemical test, employed in bacterial identification with the exception of an occasional strain being positive for catalase. Veillonella Agar was first developed by Rogosa (3) and later modified by Rogosa et al (4). It is used as a selective medium for the isolation of Veillonella. Veillonella species are isolated from the gastrointestinal tract and oral cavity specimens. Few streptococci and diphtheroids can also grow on this medium.

Tryptone and yeast extract provide nitrogenous compounds, vitamin B complex and other growth nutrients. Sodium lactate also serves as a nutritional source. Sodium thioglycollate reduces the Eh potential. Initially streptomycin was added to the medium to suppress the growth of other organisms without hampering the growth of Veillonella. However later studies showed that vancomycin is superior to streptomycin as a selective agent (5).

Type of specimen

Clinical samples - oral mucosal swab

Specimen Collection and Handling:

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (6,7).

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 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 homogeneous free flowing powder

Gelling Firm, comparable with 1.5% Agar gel.

Colour and Clarity of prepared medium Light pink coloured opalescent gel forms in Petri plates.

Reaction Reaction of 2.37% w/v aqueous solution at 25°C. pH: 7.5±0.2

pH 7.30-7.70

Cultural Response Cultural characteristics observed in an anaerobic atmosphere with added 60% v/v Sodium lactate and Vancomycin 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 20-30°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 (6,7).

Reference

1. Murray P. R., Baron J. H., Pfaller M. A., Jorgensen J. H. and Yolken R. H., (Eds.), 2003, Manual of Clinical Microbiology, 8th Ed., American Society for Microbiology, Washington, D.C.
2. Summanen P., Baron E. J., Citron D. M., Strong C., Wexler H. M., and Finegold S. M., 1993, Wadsworth Anaerobic Bacteriology Manual, 5th Ed., Star Publishing Co., Belmont, California.
3. Rogosa M., 1955, J. Dent. Res., 34:721.
4. Rogosa M., 1956, J. Bacteriol., 72:533.
5. Rogosa M., Fitzgerald R. J., Mackintosh M. E. and Beaman A. J., 1958, J. Bacteriol. 76:455-456.
6. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition
7. 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.