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  1. Laboratory Methods (Food)

BAM R64: Polymyxin B Disks, 50 Units

Reagents Index for BAM

January 2001

  • Polymyxin B sulfate
  • Distilled water, sterilized
  • Filter paper disk blanks, 5-6 mm or 1/4 inch, sterilized
  • Micropipettor, to deliver 10 µl

Sterilize filter paper disks in glass petri plates. Dissolve polymyxin B in sterile water to yield a final concentration of 5000 units/ml. Place 10 1 of the 5000 units/ml solution on each disk. Dry the disks. Store desiccated and protected from light in refrigerator.

Example: Polymyxin B is sold by activity in USP units per mg. Check reagent bottle for activity of the lot in use. For polymyxin B with antibiotic activity of 8090 USP units per mg, dissolve 0.618 mg in 1 ml sterile water.


  5000 Units/ml   = 0.618 mg/ml
8090 Units/mg

Original Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998.

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