Evanthia Tambosis1, Christopher Lim. 1. Department of Microbiology and Infectious Diseases, Concord Hospital, Sydney, New South Wales, Australia. evanthia.tambosis@sswahs.nsw.gov.au
Abstract
BACKGROUND: The cheapest, most rapid method for the diagnosis of mycotic skin and nail infections is direct examination of samples using a KOH preparation. The standard KOH wet mount lacks a color contrast. Various contrast dyes are available. Parker ink is one which has been extensively used, however in recent times the stain no longer provides a suitable color contrast. Two other dyes that are available are Chicago blue and chlorazole black. METHODS: 100 samples of skin or nails were prospectively examined using Chicago blue, chlorazole black, and Parker ink-KOH stains. The samples were also cultured, with culture being the diagnostic gold standard. RESULTS: The sensitivities and specificities of the Chicago blue, chlorazole black and Parker ink stains were 78% & 96%; 63% & 97%; and 48% and 96%, respectively. CONCLUSION: The Chicago blue-KOH stain provides a good color contrast and is a suitable replacement for the Parker ink-KOH stain. It is suitable for use in the dermatologist's office or in the laboratory.
BACKGROUND: The cheapest, most rapid method for the diagnosis of mycotic skin and nail infections is direct examination of samples using a KOH preparation. The standard KOH wet mount lacks a color contrast. Various contrast dyes are available. Parker ink is one which has been extensively used, however in recent times the stain no longer provides a suitable color contrast. Two other dyes that are available are Chicago blue and chlorazole black. METHODS: 100 samples of skin or nails were prospectively examined using Chicago blue, chlorazole black, and Parker ink-KOH stains. The samples were also cultured, with culture being the diagnostic gold standard. RESULTS: The sensitivities and specificities of the Chicago blue, chlorazole black and Parker ink stains were 78% & 96%; 63% & 97%; and 48% and 96%, respectively. CONCLUSION: The Chicago blue-KOH stain provides a good color contrast and is a suitable replacement for the Parker ink-KOH stain. It is suitable for use in the dermatologist's office or in the laboratory.