INHIBITORY SUBSTANCES MEDIUM
CAT Nº: 1367
For the test of different antibiotics
FORMULA IN g/l
Sodium Chloride
10.00
Beef Extract
3.75
Peptone
6.25
Dipotassium Phosphate
1.00
Glucose
4.00
Bacteriological Agar
13.00
Final pH 7.2 ± 0.2 at 25ºC
PREPARATION
Suspend 38 grams of medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil
for one minute until complete dissolution. Sterilize in autoclave at 121ºC for 15 minutes. Cool to 45-50ºC, mix well and
dispense into plates. The prepared medium should be stored at 2-8°C. The color of the prepared medium is clear amber,
slightly opalescent amber, slightly opalescent.
The dehydrated medium should be homogeneous, free-flowing and beige in color. If there are any physical changes,
discard the medium.
USES
INHIBITORY SUBSTANCES MEDIUM is recommended for the test of different antibiotics.
Peptone and Beef extract provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is
source of vitamins, particularly the B-group. Sodium chloride supplies essential electrolytes for transport and osmotic
balance. Dextrose is the fermentable carbohydrate providing carbon and energy. Dipotassium Phosphate act as a buffer
system. Bacteriological Agar is the solidifying agent.
The potency of an antibiotic can be demonstrated under appropriate conditions by its inhibitory effect on
microorganisms. This method is based on the diffusion of an antibiotic solution from a cylinder placed on the surface of
an inoculated agar medium. The diameter of an inhibition zone after incubation depends, in part, on the concentration or
activity of the antibiotic.
Incubate at 30-32ºC and observe after 24 hours.
MICROBIOLOGICAL TEST
The following results were obtained from type cultures in the performance of the medium after incubation at a
temperature of 30-32°C, and observed after 24 hours.
Growth
Inhibition Zone
Micrococcus luteus ATCC 9341
Good
Ampicillin
Eritromycin
Bacillus cereus ATCC 11778
Good
Tetracycline
Bacillus subtilis ATCC 6633
Good
Gentamycin
Streptomycin
Microorganisms
BIBLIOGRAPHY
Federal Register. 1992. Tests and methods of assay of Antibiotics and Antibiotic-Containing Drugs. Fed. Regist. 21:436.100-436-106
1
LABORATORIOS CONDA, S.A.
www.condalab.com
STORAGE
25ºC
Once opened keep powdered medium closed to avoid hydration.
2ºC
2
LABORATORIOS CONDA, S.A.
www.condalab.com