Clinico-mycological evaluation of onychomycosis at Bangalore and Jorhat

V Ramesh

 Department of Dermatology & STD, Deen Dayal Upadhyaya Hospital, Hari Nagar, New Delhi -110064, India

Correspondence Address:
V Ramesh
Department of Dermatology & STD, Deen Dayal Upadhyaya Hospital, Hari Nagar, New Delhi -110064
India

Sir,

The significance of this article[1] lies in the fact that the rate of recovery of fungi from the nails in culture is better when compared to other studies, and surprisingly the rate of recovery of non-dermatophytic fungi is also high, almost as much as the dermatophytes. An explanation for the former is given (the drying procedure of Milne), but scant regard has been paid to the latter. Non-dermatophytes are generally considered to be weak pathogens and have thus been usually recovered from the toenails in a predominantly shoe wearing population. In this setting the toenails are enclosed and hence kept moist, a situation that is conducive for the fungi to invade nails. Though occlusive footwear has been mentioned in the article,[1] nothing is known about the site from where the non-dermatophytes were recovered on culture. This is very important when seen in the light that the study was restricted to soldiers. This high rate of recovery of non-dermatophytes cannot simply be attributed to hot and humid weather since these factors favor dermatophytes which are the dominant pathogens. Soldiers comprise a healthy population and it would have been more informative to correlate the isolation of non-dermatophytes with the type, site and number of nails involved. Normally non-dermatophytes infect one or a few nails (often the toenails) and cause superficial infection; multiple nail involvement, particularly when both fingernails and toenails are involved, is not a usual occurrence. Having noted this high rate of non-dermatophyte infection, the author must have at some point in the study adopted the stringent criteria[2] quoted in the article, one of which states that at least 5 out of 20 inocula should grow the non-dermatophyte organism in the absence of a dermatophyte. This criteria too has been revised to ensure that the non-dermatophyte has caused the nail infection and has been discussed in a recent commentary.[3]

No mention has been made at all of the associated cutaneous fungal infection. Dermatophytic onychomycosis is a source of repeated attacks of tinea anywhere on the glabrous skin, a feature not shared by the non-dermatophytes. This history is important for the clinician who cannot always resort to culture to differentiate a dermatophyte from a non-dermatophyte, though rarely the latter too has been implicated in skin involvement. Instead, the author has mentioned that younger patients were cosmetically conscious. This is not completely true. Younger people do not have much time to concentrate on asymptomatic and trivial conditions like onychomycosis, unless many nails are affected. In my experience, such patients, especially with one or two infected fingernails, are often detected when they come to us for fungal skin infections.

The classification of the clinical presentations of onychomycosis is also not clear. These types have been well described.[4],[5] Three points should have been addressed by the author:

1. The mention of proximal superficial onychomycosis in the abstract and text of the article is confusing. There is no such picture described in the previous literature unless the author wants to draw our attention to some new observation.

2. The clinical picture could also have been correlated with the fungus isolated since some fungi are also known to be frequently associated with a particular type of nail infection.

3. Paronychia has been listed as a morphological pattern of onychomycosis. Chronic paronychia is seen in those doing ′wet′ occupations and as such it is not considered as a clinical type of onychomycosis.[4] Candidal onychomycosis includes the one caused by direct invasion of the nail plate in defective immune states like chronic cutaneous candidiasis. In paronychia the nail fold and later the cuticle of the nail plate are eroded, resulting in invasion by yeasts and bacteria. This process ultimately involves the nail matrix and causes the nail dystrophy. In the absence of nail dystrophy one is not justified to classify paronychia under onychomycosis. Though secondary, at least significant nail involvement must be present in chronic paronychia when it is included in a study of onychomycosis.

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