NEOMYCIN ANAEROBIC BLOOD AGAR

Cat. no. A62 Neomycin Anaerobic Blood Agar, 15x100mm Plate, 17ml 10 plates/bag

INTENDED USE

Hardy Diagnostics Neomycin Anaerobic Agar is recommended for use in the primary isolation of fastidious anaerobic microorganisms.

SUMMARY

The formulation for Neomycin Anaerobic Blood Agar was developed by Dowell and Hawkins at the Centers for Disease Control (CDC) in Atlanta, Georgia. (4)

The basal medium is composed of tryptic soy agar supplemented with yeast extract, vitamin K, hemin, cystine and 5% sheep blood. Digests of soybean meal and casein, components of tryptic soy agar, provide amino acids and other nitrogenous compounds. Sodium chloride is added to maintain osmotic equilibrium. Yeast extract is rich in vitamins and enhances the growth of fastidious microorganisms. Vitamin K produces enhanced growth of pigmented Bacteroides spp. Sheep blood, hemin and cystine provide additional growth factors required by certain anaerobic microorganisms. The medium is made selective by the incorporation of neomycin which inhibits gram-negative Enterobacteriaceae.

FORMULA

Ingredients per liter of deionized water:*

Pancreatic Digest of Casein 15.0gm
Peptic Digest of Soybean Meal 5.0gm
Sodium Chloride 5.0gm
Yeast Extract 5.0gm
L-Cystine Dihydrochloride 0.4gm
Neomycin Sulfate 0.1gm
Vitamin K 10.0mg
Hemin 5.0mg
Sheep Blood 50.0ml
Agar 15.0gm

Final pH 7.2 +/- 0.3 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), hemolysis, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

PRECAUTIONS

PROCEDURE

Specimen Collection: Consult listed references for information on specimen collection. (1,2,5) It is not recommended that a swab be used for specimen collection. Swabs are prone to drying and may be easily exposed to ambient air. The preferred means of anaerobic specimen collection is aspiration with needle and syringe. The specimen should be transferred to an anaerobic transport system in order to protect it from oxygen exposure. Infectious material should be submitted directly to the laboratory without delay and protected from excessive heat and cold.

Method of Use: Allow the plates to warm to room temperature, and the agar surface to dry before inoculating. Inoculate and streak the specimen as soon as possible after collection. Streak for isolation with a sterile loop. Incubate plates in an anaerobic atmosphere at 35-37ºC. for at least 48 hours and up to seven days. Examine for typical colonial morphology and characteristics.

INTERPRETATION OF RESULTS

Consult listed references for the identification of colony morphology and further biochemical tests required for identification. (1-3,5)

LIMITATIONS

Recovery of some anaerobic microorganisms may necessitate prereduction of the medium by placing it in an oxygen-free holding jar just prior to inoculation.

Many anaerobes are more sensitive to oxygen during the log phase of growth; therefore, it may be necessary to incubate inoculated media for a full 48 hours prior to examination and exposure of the culture to ambient air.

Large numbers of anaerobic bacteria are normally present in the following sites: throat, gingiva, sputum, gastric contents, small bowel, feces, rectal swabs, surfaces of decubitus ulcers, encrusted walls of abscesses, mucosal lining, eschar, voided urine, vagina or cervix, skin and adjacent mucous. Specimens for anaerobic culture, therefore, should not be collected from these sites.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, other culture media, swabs, applicator sticks, incinerators, and incubators, anaerobic holding jars, anaerobic incubation systems, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Clostridium perfringens
ATCC ® 13124
A 24-48hr 35°C Anaerobic Growth
Bacteroides fragilis
ATCC ® 25285
A 24-48hr 35°C Anaerobic Growth
Escherichia coli
ATCC ® 25922
B 24hr 35°C Aerobic Inhibition

User Quality Control

PHYSICAL APPEARANCE

Neomycin Anaerobic Blood Agar should appear opaque, and red in color.

B. fragilis growing on Neomycin Anaerobic Blood Agar

Bacteroides fragilis (ATCC ® 25285) colonies growing on Neomycin Anaerobic Blood Agar (Cat. no. A62). Incubated anaerobically for 48 hours at 35ºC.

E. coli inhibited on Neomycin Anaerobic Blood Agar

Escherichia coli (ATCC ® 25922) inhibited on Neomycin Anaerobic Blood Agar (Cat. no. A62). Incubated aerobically for 24 hours at 35ºC.

REFERENCES

1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

3. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

4. Dowell, V.R. and Hawkins, T.M. CDC Laboratory Manual, Jan. 1974.

5. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

6. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

7. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.


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