Antibiotic agar no. 11

Antibiotic agar no. 11 is recommended for the microbiological assay of antibiotics in pharmaceutical preparations, body fluids, animal feed preparations, and other materials. The sample material can be tested by dilution and diffusion methods. The most common method is the agar diffusion test which can be performed as a cylinder, punched-hole, or paper-disc test. The culture medium is inoculated with the relevant test strain and poured into plates. Defined quantities of the antibiotic under examination and an antibiotic standard are applied as spots (cylinder, punched hole, paper discs). On incubation, inhibition zones develop around the site of application. There is no microbial growth within these zones, and their diameter is a measure of the activity of the antibiotic being tested. The activity of the antibiotic under test is determined by comparing the diameter of its inhibition zone with that of the antibiotic standard.Carbohydrate and potato infusion promote the growth of yeasts and molds, while the low pH partially inhibits the accompanying bacterial flora. If the medium is to be used for fungal growth, the pH should be adjusted to approximately 3.5. Fungi grow on this medium to develop typical morphology.

Antibiotic agar no. 11 is used for the microbiological assay of antibiotics in pharmaceutical preparations, body fluids, animal feed preparations, and other materials.

Appearance (clearness): clear
Appearance (colour): yellowish-brown
Solidification behaviour (2 hrs., 40 °C): liquid
pH-value (25 °C): 8.2 - 8.4
Growth (Kocuria rhizophila ATCC 9341): fair to good
Inhibition zone diameter/Ampicillin 10 µg (Kocuria rhizophila ATCC 9341):
Inhibition zone diameter/Erythromycin 15 µg (Kocuria rhizophila ATCC 9341):
Growth (Staphylococcus aureus ATCC 6538-P (WDCM 00033)): good to very good
Inhibition zone diameter/Kanamycin 30 µg (Staphylococcus aureus ATCC 6538-P (WDCM 00033)):
Inhibition zone diameter/Neomycin 30 µg (Staphylococcus aureus ATCC 6538-P (WDCM 00033)):
Growth (Staphylococcus epidermidis ATCC 12228 (WDCM 00036)): good to very good
Inhibition zone diameter/Oleandomycin 15 µg (Staphylococcus epidermidis ATCC 12228 (WDCM 00036)):
Inhibition zone diameter/Neomycin 30 µg (Staphylococcus epidermidis ATCC 12228 (WDCM 00036)):

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany

We offer two media types: the superior granulated GranuCult^® and the cost-efficient powdered NutriSelect^® culture media, depending on your needs. The designations basic, plus, or prime are added to indicate the quality control level, from basic quality control to standard QC plus to prime for full regulatory compliance.