New staining mount versus KOH mount in direct examination of clinical specimens for dermatophytes by modified phase contrast microscopy

ABSTRACT

This study is based on the use of phase contrast [PC] objective 40X aligned with the light annulus of turret condenser for 100X instead of 40X. This procedure has been resulted in an improved visualization of dermatophytic elements in skin scrapings and hair specimens in the form of 3-dimensional image. Consequently, different fungal elements and confusing artefacts could be easlly verified owing to good delineation of surface variations of such structures. Two preparations for each specimen have been examined; one as KOH mount and second with the new staining mount formulated by the author. Cultures have been done for all specimens. Seventy cases were studied; 16 hair and 54 skin scales specimens. Out of 16 hair specimens, by KOH mount, 8 cases of endothrix type of hair invasion and 4 cases of ectothrix have been observed by the modified phase contrast [MPC] microscopy compared with 9 cases of endothrix and 3 cases of ectothrix observed by the brightfield [BF] and phase contrast [PC] microscopy. After staining, 8 endothrix and 4 ectothrix cases have been noted by BF, PC and MPC. Culture results found correlated more with results of MPC and staining. Out of 54 skin specimens, after KOH mount, 53.7%found positive for dermatophytes by MPC as compared with 50% by BF and PC. After use of the staining mount, positivity was increased up to 64.8% by MPC as compared with 51.9% by BF and 53.7% by PC