Vaginalis Agar Base

Intended Use

Recommended for qualitative isolation and differentiation of Gardnerella vaginalis from clinical specimens.

Composition**

Final pH (at 25°C): 7.4±0.2

**Formula adjusted, standardized to suit performance parameters

# - Equivalent to Beef extract

Directions

Suspend 52.5 grams in 950 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Dispense in 95 ml amount and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to around 45-50°C and aseptically add 5 ml of sterile anticoagulated human blood to every 95 ml sterile basal medium. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Gardnerella vaginalis is a facultatively anaerobic gram-variable rod. It has been demonstrated to cause a wide variety of infections; however, it is most commonly recognized for its role as one of the organisms responsible for bacterial vaginosis (BV). BV is the most common cause of vaginitis and the most common infection encountered in the outpatient gynaecological setting. Originally Ellner et al (1) developed a blood agar namely Columbia Agar for rapid growth of the haemolytic organisms with improved pigmentation and defined haemolytic reactions. Greenwood et al (2) further modified this medium by increasing the peptone concentration and used human blood instead of sheep blood for the isolation and differentiation of G. vaginalis based on beta haemolysis (3,4). Vaginalis Agar Base is used for the isolation of G. vaginalis from vaginal discharges (5).

Peptone, tryptone, yeast extract and HM peptone B provide nitrogenous compounds, carbon, sulphur, vitamin B complex and trace ingredients required for growth. Corn starch serves as the energy source. Blood supplies additional nutrients and also aids in identification.

Typical colonies of G. vaginalis appear small and white coloured. This medium is recommended for determination of haemolytic reaction of G. vaginalis and not for other microorganisms. If the specimen is suspected to contain streptococci or other haemolytic microorganisms, then a Soyabean Casein Digest Agar (with 5% v/v sheep blood) plate should be inoculated parallel to this medium to ensure the haemolytic reaction.

Type of specimen

Clinical samples - Vaginal secretions

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. If the specimen is suspected to contain streptococci or other haemolytic microorganisms, then a Soyabean Casein Digest Agar (with 5% v/v sheep blood) plate should be inoculated parallel to this medium to ensure the haemolytic reaction.

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 1.35% Agar gel.

Colour and Clarity of prepared medium Basal medium: Yellow coloured clear to slightly opalescent gel. After addition of 5% v/v sterile anticoagulated human blood, cherry red coloured, opaque gel forms in Petri plates.

Reaction Reaction of 5.25% w/v aqueous solution at 25°C. pH: 7.4±0.2

pH 7.20-7.60

Cultural Response

Cultural characteristics observed in an aerobic atmosphere containing 3-10% CO2 with added 5% v/v sterile anticoagulated human blood after an incubation at 35-37°C for 48 hours.

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 (6,7).

Reference

1. Ellner P. D., Stoessel C. J., Drakeford E., Vasi F., 1966, Am. J. Clin. Pathol., 45 : 502.
2. Greenwood J. R., Martin M. J., Mack E. G., 1977, Health Lab. Sci., 14: 102.
3. Greenwood J. R. and Pickett M. J., 1980, Int. J. Syst. Bacteriol., 30: 170.
4. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore
5. Piot P., Van Dyek E., Goodfellow M., Falkow S., 1980, J. Gen. Microbiol., 119: 373.
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.