Agar Well Diffusion Method

General purpose media are used for the agar well diffusion method, such as a nutrient agar medium for bacteria and a PDA medium for fungi. 

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The thiophene polyine ( )-2[5-hept-5-en-l,3-diynyl)-thien-2-yl]-ethan-1,2-diol isolated from an ethanolic extract of the underground parts of Leuzea carthamoides DC. demonstrated significant antifungal activity [247], while the dichloromethane extract of the air-dried leaves of Chrysanthemum coronarium afforded N-isobutyl-6-(2-thiophenyl)-2,4-hexadienamide. Fig. (46) [248]. Antimicrobial tests by the agar well diffusion method indicated that it has low activity against Bacillus subtilis. Pseudomonas aeruginosa and Candida albicans, and is inactive against Staphylococcus aureus and Escherichia coli at a concentration of 20 pg/ml. 

Antimicrobial activity of the medication was determined by the agar diffusion method [4, 5]. A wide spectrum of pyogenic microflora (Table 16.1) as well as Candida spp. and Helicobacter pylori were studied as test cultures. 

A comparison of the G.L.C. and microbiological (agar-diffusion) assays has been reported by Tsuji et al239 who showed the neomycin content of neomycin sulphate powders determined by the G.L.C. method, to correlate well with values obtained by the microbiological assay when it is assumed neomycin C has 35% of the biological activity of neomycin B. 

The simplest method uses a standard Petri dish filled with agar in sahne (2 to 4g/dL) to a depth of about 3 mm. Holes are cut in the agar plate with a punch or a sharp cork borer. The plugs of agar are removed by suction, and the bottom of each well is sealed with a drop of agar in saline (1 g/dL) to prevent diffusion under the agar. When the same antigen... 

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