A comparative study of the microbiological assays currently available for nystatin raw material.

The classical agar diffusion and turbidimetric methods of assay for nystatin are compared with the more recently documented assays for this antibiotic which depend upon physicochemical measurement of the response of micro-organisms. Liquid nitrogen stored inocula were used throughout. It is concluded that the newer methods of assay are as reproducible and reliable as the agar diffusion and turbidimetric methods and that they are generally more sensitive. The choice between the assay methods compared can thus be based on speed, cost and sample through-put.