Chocolate Agar Base
Intended use
Recommended for the isolation of Neisseria gonorrhoeae from chronic and acute cases of gonococcal infections.
Composition**
Ingredients Gms / Litre
Proteose peptone 20.000
Dextrose (Glucose) 0.500
Sodium chloride 5.000
Disodium hydrogen phosphate 5.000
Agar 15.000
Final pH ( at 25°C) 7.3±0.2
**Formula adjusted, standardized to suit performance parameters
Directions
Suspend 45.5 grams in 495 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 equal amount (495 ml)of sterile FO
Growth Supplement (FD022). Also add the contents or one vial of Yeast Autolysate Supplement (FD027) or Vitamino
Growth Supplement (FD025) reconstituted as directed. Mix well and pour into sterile Petri plates. When single
strength medium is desired, suspend 45.5 grams in 1000 ml distilled water.
Principle And Interpretation
Neisseria gonorrhoeae is a gram-negative bacteria and the causative agent of gonorrhea, however it is also
occasionally found in the throat. The cultivation medium for gonococci should ideally be a rich nutrients base with blood,
either partially lysed or completely lysed. The diagnosis and control of gonorrhea have been greatly facilitated by
improved laboratory methods for detecting, isolating and studying N. gonorrhoeae.
Chocolate Agar Base, with the addition of supplements, gives excellent growth of the gonococcus without overgrowth by
contaminating organisms. G.C. Agar (M434) can also be used in place of Chocolate Agar Base, which gives slightly better
results than Chocolate Agar (1). The diagnosis and control of gonorrhea have been greatly facilitated by improved laboratory
methods for detecting, isolating and studying N. gonorrhoea. Interest in the cultural procedure for the diagnosis of
gonococcal infection was stimulated by Ruys and Jens, Mcleod and co-workers (2), Thompson (3), Leahy and
Carpenter (4), Carpenter, Leahy and Wilson (5) and Carpenter (6), who clearly demonstrated the superiority of this
method over the microscopic technique. Chocolate Agar Base with addition of supplement not only supports the
growth of the gonococcus in pure culture but also permits its development from the mixed flora encountered in
chronic gonococcal infections. Carpenter (7) reported that this medium and Haemoglobin (FD022) is useful for
cultural detection of the Gonococcus.
Type of specimen
Clinical samples - urethral swabs, urine samples.
Specimen Collection and Handling:
For clinical samples follow appropriate techniques for handling specimens as per established guidelines (5,6).
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
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. 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
Basal medium: Light amber coloured clear to slightly opalescent gel. After addition of haemoglobin : Chocolate brown
coloured opaque gel forms in Petri plates.
Reaction
Reaction of 4.5% w/v aqueous solution at 25°C. pH : 7.3±0.2
pH
7.10-7.50
Cultural Response
Cultural characteristics observed with added FO Growth Supplement (FD022), Yeast autolysate Supplement (FD027) or
Vitamino Growth Supplement(FD025), after an incubation at 35-37°C for 40-48 hours.
- Organism Inoculum
(CFU)
Growth Recovery
Neisseria gonorrhoeae
ATCC 19424
50-100 luxuriant =70%
Neisseria meningitidis
ATCC 13090
50-100 luxuriant =70%
Streptococcus pneumoniae
ATCC 6303
50-100 luxuriant =70%
Streptococcus pyogenes
ATCC 19615
50-100 luxuriant =70%
Haemophilus influenzae
ATCC 19418
50-100 luxuriant =70%
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
Basal medium: Light amber coloured clear to slightly opalescent gel. After addition of haemoglobin : Chocolate brown
coloured opaque gel forms in Petri plates.
Reaction
Reaction of 4.5% w/v aqueous solution at 25°C. pH : 7.3±0.2
pH
7.10-7.50
Cultural Response
Cultural characteristics observed with added FO Growth Supplement (FD022), Yeast autolysate Supplement (FD027) or
Vitamino Growth Supplement(FD025), after an incubation at 35-37°C for 40-48 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 (9,10).
