Hi-Sensitivity™ Test Broth

Intended Use:

Recommended for antimicrobial susceptibility tests.

Composition**

Ingredients

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 23.4 grams in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Dispense into tubes or flasks or as desired. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

Principle And Interpretation

The goal of an antimicrobial susceptibility test is to predict through an in vitro assessment the likelihood of successfully treating an infection with a particular antimicrobial agent. There are several continual or novel methods for performing antibacterial susceptibility testing. These include the disk diffusion test, broth microdilution, agar gradient and rapid automated instrument methods (1). Hi-Sensitivity™ Test Broth, which is used for antimicrobial susceptibility tests, is a semi-defined medium in which the mineral contents have been stabilized to give reproducible results. The thiamine and thymidine content is very low thus making it most suitable for testing antimicrobial activity of sulphonamides. However Some mutant strains which are totally dependent on thiamine and thymidine for their growth, will not grow in Hi- Sensitivity™ Test Broth, due to very low levels of these compound in the media as they are the naturally occurring antagonist of trimethoprim. These strains should be carefully recognized (2,3,4). Hi-Sensitivity™ Test Broth has been so designed to overcome the problems occurring in Mueller-Hinton Media that are as follows (5-11).

1. Mueller Hinton Agar and Mueller Hinton Broth give different MIC values.
2. Mueller Hinton Agar shows antagonistic effect towards tetracycline.

3. High levels of sulphonamide and trimethoprim antagonists.

4. Media prepared using peptone of different manufacturers give poor reproducibility.

5. Poor growth supporting ability for Streptococci and variable growth rates with gram-positive organisms.

6. Some pathogenic organisms are nutritionally dependent due to their intrinsic demands for special growth factors. Tryptone, Peptone, dextrose, and vitamins provides nitrogen, carbon compounds and other essential growth nutrients.

Type of specimen

Isolated Microorganism from Clinical samples.

Specimen Collection and Handling:

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (12,13). 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. Some mutant strains which are totally dependent on thiamine and thymidine for their growth, will not grow in Hi- Sensitivity™™ Test Broth, due to very low levels of these compound.

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

Colour and Clarity of prepared medium

Basal medium: Light yellow coloured clear to slightly opalescent solution.; After addition of 5%v/v laked blood : Red to chocolate coloured opalescent solution in tubes

Reaction

Reaction of 2.34% w/v aqueous solution at 25°C. pH: 7.4±0.2

pH

7.20-7.60

Cultural Response

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

Key: *Corresponding WDCM numbers.
**Formerly known as Bacillus subtilis subsp. spizizenii * Formerly known as Bacteroides vulgatus

Storage and Shelf Life

Store dehydrated medium at 2-8°C and use freshly prepared medium. 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 (12,13).

Reference

1. Murray P. R., Baron J. H., Pfaller M. A., Jorgensen J. H. and Yolken R. H., (Ed.). 2003, Manual of Clinical Microbiology, 8th Ed., American Society for Microbiology, Washington, D.C.
2. Barker J., Healing D., and Hutchinson J. G. P., 1972, J. Clin. Path., 25:1086
3. Tanner E. I. and Bullin C. H., 1974, J. Clin. Path., 27:565.
4. Thomas M. and Bond L., 1973, Med. Lab. Technol., 30:277.
5. Bridson E.Y., 1976, Arztl. Lab., 22:373.
6. Duncan I. B. R., 1974, Antimicrob. Agents Chemother., 5:9.
7. Ericsson H. M. and Sherris J. C., 1971, Acta. Pathol. Microbiol Scand Suppl., 217:1.
8. Garrod L. P. and Waterworth P. M., 1971, J. Clin. Path., 24:779.
9. Neussil H., 1976, Chemother., Vol. 2: 33.
10. Reller L. B., Schoenknecbt F. D., Kenny M. A. and Sherris J. C., 1974, J. Infect. Dis., 130:454.
11. Yourassowsky E., Vanderlinden M. P. and Schoutens E., 1974, J. Clin. Path., 27:897.
12. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
13. 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.