A simple stain for rapid office diagnosis of fungus infections of the skin

Abstract

The present communication reports a practical, more sensitive modification of the potassium hydroxide prepa¬ ration using chlorazol black E stain. MethodsChlorazol black E stain was prepared by first dissolving the dye in dimethyl sulfoxide (DMSO) (100 mg of chlorazol black E in 10 mL of DMSO). This was then added to 90 mL of water contain¬ ing 5 g of potassium hydroxide. The solution was then used immediately without filtration.The preparation of a microscopic mount with this stain was identical to a routine potassium hydroxide wet mount. Two to three drops of the staining solution were added to the specimen on a clean glass slide and a cover-glass applied. The slide was then gently heated by passing through a flame several times for 15 to 30 s. The cover-glass and slide were pressed between pieces of filter paper to remove excess bubbles and then examined microscopical¬ ly under low ("scanning") power with "high-dry" power used for confirmation of the fungus. (eg, nails).Skin surface biopsies using cyanoacrylate adhesives followed by Gram's and PAS staining78 and using Parker's ink in potassium hydroxide' were frequently painful for the patient. Another drawback to this method is the inability to obtain material from the interdigital areas, nails, palms, or soles. Gram's staining with this technique was usually inadequate in our experience, primarily due to a positive staining of epithelial cell "granules" (thought to be desmosomes7). The method using skin surface biopsies stained with Parker's ink and potassium hydroxide9 was less sensitive in detecting isolated fungal hyphae. The alkaline solution dissolved the cyanoacrylate adhesive (especially if heated) and was usually inadequate in clear¬ ing the relatively thick (three to five cells) sections.Chlorazol black E is an acid tris-azo dye that was originally described by Cannon,10 who later" reviewed its uses. Armitage12 described the compatibility of chlorazol black E with lactophenol, a commonly used mycologie mounting medium. However, the stain is much more soluble in an alkaline solution,'3 and in our trials gave a much better result with potassium hydroxide. This dye has been primarily used as a botanic stain, with only occasion¬ al use in animal tissues.'"'"6 The stain is selective for chitin, which it stains green against a cellular background of colorless to gray-black. As with most mycological stains, young hyphae are stained much more readily than old.Since the stain is selective for chitin, few artifacts are noted.The dye is compatible with the addition of glycerin for those who prefer glycerin in their potassium hydroxide mounts. We have used this staining preparation on skin, hair, and nails with good results. The mycelial elements and spores of Candida and tinea versicolor also stain well.

The Scybala (Fecal Pellets) of Sacroptes scabiei var. hominis Are Obviously Stained with Chlorazol Black E

“…The solution was used without filtration. Skin samples were mounted with this solution for 5 to 10 minutes, and the microscopic mount was observed in a manner identical to the observation of a routine potassium chloride preparation (6).…”

“…Chrolazol black E is an acid tris‐azo (6). This stain provided high sensitivity for detecting fungal hyphae as well as the spores of Candida with few artifacts, as it is selective for chitin (6). The bodies of arthropods consist of chitin, and, therefore, Sacroptes scabies var.…”

I Do Not Like Green Eggs

“…Chlorazol black E was first reported as a stain that, when used in KOH preparations, helped identify the chitinous cell walls of fungi . Pinworm ova have an outer shell composed of two layers of chitin , so chlorazol black E can be used to help identify ova when examining microscopic skin scrapings to assist in making a diagnosis of pinworm infestation.…”

Alkaline Trypan Blue as a stain for superficial fungi

“…S ir , For staining superficial fungi, Parker Blue‐Black Super Quink ® (Sanford L.P., Oakbrook, IL, USA) ink has been used as a standard dye with potassium hydroxide (KOH) for a long time. Recently comments citing precipitation and colour change of Parker ink in KOH solution have appeared in Japanese journals, and the Chlorazol black E (CbE) method 1 is now employed as a major substitute. CbE belongs to the azo dye group and is presumed to be an established fungal stain, although the colour of CbE staining differs from classic Parker ink.…”