ETA with Antibiotics

Cat. no. G265 ETA with Antibiotics, 15x100mm Plate, 18ml 10 plates/bag

INTENDED USE

Hardy Diagnostics ETA with Antibiotics is recommended for the isolation of fungi from clinical and non-clinical specimens.

SUMMARY

ETA with Antibiotics is a selective mycological medium for the isolation of yeast and mold. The medium contains chloramphenicol and gentamicin to inhibit the growth of contaminating bacteria. Chloramphenicol is a broad-spectrum antibiotic used to inhibit a wide range of gram-positive and gram-negative bacteria. Gentamicin inhibits most gram-negative bacteria, including Pseudomonas spp. Sodium sulfite is the salt of sulphurous acid and is also added to the medium to inhibit the growth of unwanted bacterial flora.

Media containing dyes are not commonly used for the primary isolation of fungi. However, ETA with Antibiotics contains trypan blue, which can be used to differentiate colonies of fungi from bacteria. Trypan blue is a nontoxic dye, staining yeast and mold colonies blue to enhance their visibility. Historically, trypan blue has been incorporated into chlamydospore agar for the identification of Candida species; it has also been used to differentiate Cryptococcus species from other microorganisms. (6)

ETA with Antibiotics also contains peptones, L-cystine, and dextrose to provide a rich source of nitrogen, trace elements, vitamins, amino acids, and carbon to promote fungal growth. Sodium chloride is added to maintain osmotic equilibrium. Agar is the solidifying agent.

FORMULA

Ingredients per liter of deionized water:*

Casein Peptone 15.0gm
Soy Peptone 5.0gm
Dextrose 5.5gm
Sodium Chloride 4.0gm
L-Cystine 0.7gm
Sodium Sulfite 0.2gm
Trypan Blue 0.1gm
Chloramphenicol 0.05gm
Gentamicin 0.05gm
Agar 15.0gm

Final pH 6.9 +/- 0.2 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), contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

PRECAUTIONS

PROCEDURE

Specimens should be protected from excessive heat and cold and delivered to the laboratory without delay. The specimen should be collected prior to initiation of therapy for proper identification. However, if the specimen is collected after the onset of therapy, alert laboratory personnel. Consult references for additional information on the appropriate techniques for specimen collection and transport. (2-4,6)

Inoculate the specimen directly onto the medium without delay. Incubate one plate at 35 to 37ºC. and one plate at room temperature. Examine plates within 3 to 5 days for growth. Room temperature plates should be kept for 4 to 6 weeks before discarding as negative. To avoid excessive drying of the medium during prolonged incubation, MycoSeal™ (Cat. no. SS9225) can be used to seal in moisture.

INTERPRETATION OF RESULTS

Examine plates for growth of pigmented colonies. Yeast colonies appear blue and molds appear as blue-gray. If no blue or blue-gray colonies are present, then interpret the test as negative for the presence of yeast and mold.

LIMITATIONS

Antimicrobial agents incorporated into the medium to inhibit the growth of bacteria may also inhibit certain strains of pathogenic fungi. It is recommended that a non-selective fungal medium be used in parallel with selective media when isolating fungi.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, MycoSeal™ (Cat. no. SS9225), other culture media, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Tricophyton mentagrophytes
ATCC ® 9533**
A 3-5 day 30°C Aerobic Growth; blue-gray colonies
Candida albicans
ATCC ® 60193
A 24-48hr 35°C Aerobic Growth; blue colonies
Escherichia coli
ATCC ® 25922**
B 24hr 35°C Aerobic Inhibited
Pseudomonas aeruginosa
ATCC ® 27853
B 24hr 35°C Aerobic Inhibited

** Recommended QC strains for User Quality Control according to the CLSI document M22 when applicable.

USER QUALITY CONTROL

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

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

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

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

6. Vickers, R.M., J.J. McElligott, Jr., J.D. Rihs, and B. Postic. 1974. Medium containing trypan blue and antibiotics for the detection of Cryptococcus neoformans in clinical samples. Appl. Microbio.; 27(1):38-42.


ATCC is a registered trademark of the American Type Culture Collection.

022316gr