Sulpha Sensitivity Test Agar

Intended Use

Recommended for testing the sensitivity of common pathogens to Sulphonamides.

Composition**

Final pH ( at 25°C) 7.3±0.2

**Formula adjusted, standardized to suit performance parameters

# Equivalent to Beef extract

Directions

Suspend 36.0 grams in 1000 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. Mix well and pour in sterile Petri plates.

Principle And Interpretation

Trimethoprim/sulfamethoxazole or co-trimoxazole is a sulfonamide antibiotic. Combination of trimethoprim and sulfamethoxazole, in the ratio of 1 to 5, used in the treatment of a variety of bacterial infections (1). Mueller Hinton Agar is recommended for the diffusion of antimicrobial agents impregnated on paper disc through an agar gel as described in CLSI Approved Standard (2). Sulpha Sensitivity Test Agar is used for determination of susceptibility of microorganisms to sulphonamides (3).

Tryptone and HM peptone B provide nitrogenous compounds, carbon, sulphur and other essential nutrients. Disodium phosphate and monopotassium phosphate buffer the medium well.

Type of specimen

Isolated Microorganism from clinical samples

Specimen Collection and Handling

A standardized suspension of the organisms is swabbed over the entire surface of the medium. Paper discs impregnated with certain amount of specific antibiotics are placed on the surface of the medium. The plates are incubated and the zones of inhibition around each disc are measured.

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. Well isolated colonies must be used.

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 Light yellow coloured homogeneous free flowing powder

Gelling Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium Light amber coloured clear gel forms in Petri plates

Reaction Reaction of 3.6% w/v aqueous solution at 25°C. pH : 7.3±0.2

pH 7.10-7.50

Cultural Response Cultural characteristics observed after an incubation at 35-37°C for 18-24 hours.

Key : *Corresponding WDCM numbers.

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 (4,5).

Reference

1. Brumfitt W, Hamilton-Miller JM (December 1993). Reassessment of the rationale for the combinations of sulphonamides with diaminopyrimidines". J. Chemother 5 (6):465-9. PMID 8195839
2. NCCLS Approved Standard: ASM-2, 1979, Performance Standards for Antimicrobic disc Susceptibility Tests, 2nd Ed., National Committee for Clin. Lab. Standards.
3. McCoy and Pelczar 1961, Antimicrobial Agents and Chemotherapy, ASM., Detroit, Michigan.
4. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
5. Jorgensen,A 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.