Cylinder-plate assays

Cylinder-plate assays are used to determine the influence of an antibiotic on the growth rate of a target microorganism in a specific medium. Growth of the microorganism is inhibited around the cylinders depending on the potency of the antibiotic.

Potency estimation of a Test sample as recommended by U.S. Pharmacopeia <81>

The following image shows the potency estimation of a Test sample in a cylinder-plate assay as recommended by U.S. Pharmacopeia <81>: Every plate contains six cylinders with three replicates of the Reference step (S3) and alternating one of the four concentration steps from the Standard (S1, S2, S4, S5), or the Test sample (U3). To account for inter-plate variation, a correction method is applied to the response data.

Potency estimation of a Test sample in a cylinder-plate assay as recommended by U.S. Pharmacopeia <81>
Potency estimation of a Test sample as recommended by Japanese Pharmacopoeia Chapter 4.02

The following image shows the potency estimation of a Test sample in a cylinder-plate assay as recommended by Japanese Pharmacopoeia Chapter 4.02: Every plate contains four cylinders with a high and low concentration probe for the Standard and Test sample.

Potency estimation of a Test sample in a cylinder-plate assay as recommended by Japanese Pharmacopoeia Chapter 4.02

Example

  • Sample Report for a cylinder-plate assay as recommended by USP <81> 23 KB
    Example cylinder-plate assay based on USP <81>: Cloxacillin is used as antibiotic substance on the test organism Staphylococcus aureus. The standard consists of five concentration steps (S1 to S5) with S3 being used as reference. The relative potency of the unkown sample U3 is estimated based on the standard. In accordance with USP <81>, the test system includes tests on the relative standard deviation CV (%), the coefficient of determination (r^2), and the relative potency. For a direct comparison, the response values are taken from USP <81>. Moreover, the concentration is log10-transformed as recommended by USP <81>.
  • Sample Report for a cylinder-plate assay as recommended by JP chapter 4.02 32 KB
    Example cylinder-plate assay based on JP 4.02: Erythromycin is used as antibiotic substance on the test organism Staphylococcus aureus. The standard and the test sample consist of a high and a low concentration step. The standard sample is used as reference to determine the relative potency of the test sample TST1. The test system includes tests on the relative response standard deviation (high and low concentration) and the potency factor A.