fungal infection skin and hair test

[Janice]

I thought this was a good find and it deserves it's own thread.


.diagnosis - hair and scalp fungal infection tests


The Woods lamp for fungal infections

Once upon a time and not so long ago the Wood's lamp was an important part of any dermatology clinic. The Wood's lamp produces invisible long-wave ultraviolet light (340-450 nm wavelength). This UV light can help to detect medications that are taken systemically (tetracycline) or that are applied to the skin as well as help diagnose skin disease inducing infectious agents that have a characteristic fluorescence. The test is simple, the UV light from the Wood's lamp is directed over the area of the suspected infection and the dermatologist looks to see if there is any fluorescence/visible light reflected back.

However, in recent times the Wood's lamp has become less helpful as a diagnostic tool for fungal infections. Up until the 1960s the typical fungal species encountered by a dermatologist readily fluoresced under UV light. But today in the USA, and to a somewhat lesser extent in Europe, the type of fungal species encountered in the dermatology clinic have changed. The species that were common prior to 1970 and were fluorescent under UV light are now in the minority today. The common fungal species that cause skin disease in the Western hemisphere of the twenty first century are predominantly non-fluroescent.

Today the Wood's lamp is used for diagnosing a brown, scaly rash in the scrotum or axilla: erythrasma, caused by the bacterium Corynebacterium minutissimum, fluoresces a brilliant coral red, whereas tinea cruris or cutaneous candidal infections do not fluoresce. UV light can be used for diagnosing tinea (pityriasis) versicolor, which fluoresces pale yellow to white. A minor percentage of tinea capitis cases in North America and Europe caused by two zoophilic Microsporum species that fluoresce blue-green can be identified with a Wood's lamp. The Wood's lamp can also help diagnose Pseudomonas infections, porphyrians, and pigmentary alterations.

The potassium hydroxide test

The potassium hydroxide (KOH) test is used primarily as a method to determine if there is a fungal infection of the skin, nails and/or hair. If a person has flakes of dead skin (dandruff-like scaling) on the hair; broken, crusted, or matted hair; redness, irritation of the scalp or beard; swollen areas and blister-like bumps with pus (kerions); or a patchy hair loss the KOH test may be done. It does not define the specific fungal species involved in any infection, but the process is quick and easy to perform so as a simple diagnostic tool it is very useful.

The KOH test involves taking a sample of skin where the suspected infection is. This can be done with a scalpel if the skin is particularly crusty, but more usually a wet gauze or maybe a tooth brush is used to collect some dead skin scales. With hair fiber infections collecting a sample can be more difficult because hair infections weaken the hair and cause it to break off at the root leaving very little of the infectious agent behind. Normal length hair is probably not infected. However, some damaged hair around the periphery of an infected area is usually present and the dermatologist will take around 10 broken, infected-looking hairs. With nails a sample of the dead skin under the nail plate is used.

The hair or skin sample is placed on a slide with a little of a 10% to 20% concentration potassium hydroxide solution and gently heated. This solution slowly dissolves the hair and skin cells but not the fungus cells. The fungus cells can then be seen with a microscope. Color stains may be used so that the fungus is easier to see. This technique aids the visualization of the fungal hyphae (branching, rod-shaped filaments of uniform width with lines of separation called septa). In tinea capitis, the hair shaft may be uniformly coated with minute dermatophyte spores.

Unfortunately the KOH test is not fool proof. It is possible to get a negative KOH test result when a fungal agent is actually present. In particular, a common fungal agent that causes ringworm called Trichophyton tonsurans does not show up well in a KOH test. Thus, even when a KOH test is negative, a fungal infection may still be suspected. If so, a fungal culture must be done to confimr that a fungal agent is involved.

The fungal culture test

A more advanced and more sensitive test that can be used to determine the particular nature of the fungal species involved in a skin, nail, or hair infection is a fungal culture. Fungal cultures are slow and expensive to perform. They require incubators, culture mediums, and some expertise on the part of the technician looking after the cultures. For this reason fungal culture tests are rarely done in the average dermatology clinic. More usually, a sample is sent away to a laboratory for testing.

The dermatologist will take skin or nail scrapings, or a hair sample. The sample is put into a sterile container and sent to the laboratory. At the laboratory, the container is opened in a sterile chamber and the sample is inoculated on test medium - usually Sabouraud's dextrose agar or something similar. If there are fungal spores present, they will grow on the agar. The culture usually takes 7 to 14 days to be declared positive. It must be held for 21 days without development of fungal growth to be declared negative. If the culture is positive the laboratory can take a sample of the fungal growth and examine it to see which particular species is involved.

A dermatology clinic may conduct a simplified fungal culture test that does not define the fungal species involved, but does provide a more sensitive test than the KOH test. "Dermatophyte test medium" is a commercially available, nutrient-rich culture solution supplied in a form that is ready for direct inoculation in the office. The dermatologist takes a sample of dead skin or a hair sample and puts it in a small tube containing the culture medium. The yellow medium has a phenol red indicator that turns pink in the presence of the alkaline metabolic products produced by fungal agents. It takes up to 7 days of culturing before a conclusion can be made as to whether the test is positive or negative. The medium must be discarded 14 days after opening the culture tube because saprophytes will slowly produce a similar change in the culture medium color. This is a false positive result.

This simplified fungal culture test is more complex to conduct than the KOH test, but easier to conduct than a full scale laboratory fungal culture. These basic fungal culture tests are most likely to be done in mid sized, private dermatology clinics. Large hospital based clinics will most likely have the facilities to do full scale culture testing while small practices will probably run a KOH test first and then if there is still some doubt they may collect a sample and send it to a central test laboratory for culturing.

[sojii]

Janice,
Thank you for that info; do you happen to have a list of drugs used to treat fungal infections and which varieties they treat? If not, I'll google and see what I can find but figured if anyone had that information in one convenient location it would be you! You're a wonder!

[tcmgpt13]

Hi Sojii, I believe Janice posted a longer list in a link on her other fungal thread.

Antifungal Drugs

Clotrimazole
Azole: a broad spectrum antifungal developed in 1967. It was one of the first azoles to be developed. Formulations are now generic in a number of countries. It is effective against Candida albicans and the dermatophytes. Its action is fungistatic or fungicidal, depending upon the concentration used. This azole drug is available in a variety of dosage forms...

Ciclopirox
Antifungal, topical. Ciclopirox olamine is a hydroxypyridone antifungal that is structurally unrelated to other antifungal agents. It was first introduced in 1975 and has been accepted and used in Europe for many years. It was approved by the FDA in 1982 for the treatment of superficial fungal infections...

Ketoconazole
Ketoconazole is an azole medication used to treat a broad spectrum of fungi It was originally developed in the late 1970's in the oral form and granted FDA acceptance in 1981. Shortly after the topical formulations were undergoing trials and proven effective. The 2% cream and 1% shampoo are now available over the counter...

Terbinafine Hydrochloride
Antifungal, allylamine -one of the first antifungals of the allylamine class, discovered in 1974. It was approved for systemic use in the UK in 1991, and for topical use in the USA in 1992. Terbinafine is an antifungal effective against Dermatophytes, Aspergillus sp., and Candida and Pityrosporum yeasts...

Itraconazole
Itraconazole is an antifungal azole. It is a synthetic triazole analogue with a wide spectrum of antifungal activity. It was first synthesized in 1980, and approved in Europe in 1987. It was approved by the FDA in 1992 for systemic mycoses, and then for onychomycoses in 1995, and for use by pulse therapy in 1997. In 2000, itraconazole was also approved to treat blastomycosis, histoplasmosis, and aspergellosis in patients intolerant of amphotericin B...

Fluconazole
Fluconazole is an antifungal azole. It is a broad spectrum antifungal, first approved in Europe in 1988 and then in America in 1990. It was the first single dose treatment approved for vaginal candidiasis. Fluconazole is an effective agent in the treatment and prophylaxis of Candidal infection...

Fungal Guide

[Janice]

Hi, some of the fungi are more resistant to drugs than others, especialy some of the nondermatophytic filamemtous keratinophilic fungi. I think the best route to take is ask your doctor for the test and go from there. Thank you for your kind words soji! Janice

[sojii]

Janice, I just wanted to research the individual drugs on the internet. You know how boring and conservative I am...

[Dzana]

even fungal threads r dividing sort of self replicating from 1 we got 2 lol..............bring on sponge theory Steve haha


there must be a madness of King George III in me.............

[tcmgpt13]

Originally Posted by Dzana

even fungal threads r dividing sort of self replicating from 1 we got 2 lol..............bring on sponge theory Steve haha

there must be a madness of King George III in me.............

So Dzana, do you think it will start bubbling and foaming madly soon then, sort of like the witches cauldron in Macbeth? Ah, yes, lead on Macduff. The sponge will be found anon, as in threads dividing.

[Janice]

Microscopy can identify a dermatophyte by the presence of:

* Fungal hyphae (branched filaments) making up a mycelium
* Arthrospores (broken-off spores)
* Arthroconidia (specialised external spores)
* Spores inside a hair (endothrix) or outside a hair (ectothrix).


Blood tests are not useful for the diagnosis of superficial fungal infections. But in subcutaneous and systemic infection, several tests may be useful.

* Culture
* Antibodies (histoplasmosis, coccidioidomycosis)
* Antigen (cryptococcosis, aspergillus, candidosis, histoplasmosis)





Laboratory tests for fungal infections. DermNet NZ

[janedoe]

i saw my derm yesterday and he gave me permethrin cream, so last night i tried it, it seems to work great so far.
but the bugs have run their little 'cycle' for this time, ill probably be breaking out again in a month or two, the best thing ive found for scars that hels them really fast is clobetasol propionate and its on medical so it costs nothing.that is bar none, the fastest thing ive found that works. but it doesnt stop me from getting them the next time.. THATS what i need to learn, how to NOT get a break out next month..

[Janice]

I think if you have a fugus test... and if your possitive for fungus, treat it. Certain Bugs are attracted to fungus.. it is deeelish to them. No fungus... no bugs. Also take care of the immune system and get it working correctly so you can fight off infections in the future.