Evaluation of the growth dynamics of Trichophyton rubrum cultures by morphometry and non-linear curve fitting analysis

To determine the size of dermatophyte thalli, a point‐counting procedure with a square lattice grid is proposed instead of using the one‐dimensional diameter as the size parameter. For an analysis of the growth dynamics of such colonies, the area values might be subjected to a non‐linear curve‐fitting procedure. To demonstrate the method, samples of 15 Trichophyton rubrum strains, isolated from human skin and cultured concomitantly on Sabouraud and Selective agar during a period of 8 weeks, were used. The morphometric assessment of the area of the thalli, subjected to non‐linear curve fitting, disclosed only a slight difference in the growth dynamics.