Onychomycosis is a common nail ailment associated with significant physical and
psychological morbidity. Increased prevalence in the recent years is attributed to enhanced
longevity, comorbid conditions such as diabetes, avid sports participation, and emergence
of HIV. Dermatophytes are the most commonly implicated etiologic agents, particularly
Trichophyton rubrum
and
Trichophyton mentagrophytes var.
interdigitale
, followed by
Candida
species and non dermatophytic molds (NDMs). Several clinical variants have been
recognized.
Candida onychomycosis
affects fingernails more often and is accompanied by
paronychia. NDM molds should be suspected in patients with history of trauma and associated
periungual inflammation. Diagnosis is primarily based upon KOH examination, culture and
histopathological examinations of nail clippings and nail biopsy. Adequate and appropriate
sample collection is vital to pinpoint the exact etiological fungus. Various improvisations have
been adopted to improve the fungal isolation. Culture is the gold standard, while histopathology
is often performed to diagnose and differentiate onychomycosis from other nail disorders
such as psoriasis and lichen planus. Though rarely used, DNA-based methods are effective
for identifying mixed infections and quantification of fungal load. Various treatment modalities
including topical, systemic and surgical have been used. Topically, drugs (ciclopirox and
amorolfine nail lacquers) are delivered through specialized transungual drug delivery systems
ensuring high concentration and prolonged contact. Commonly used oral therapeutic agents
include terbinafine, fluconazole, and itraconazole. Terbinafine and itraconazole are given as
continuous as well as intermittent regimes. Continuous terbinafine appears to be the most
effective regime for dermatophyte onychomycosis. Despite good therapeutic response to
newer modalities, long-term outcome is unsatisfactory due to therapeutic failure, relapse,
and reinfection. To combat the poor response, newer strategies such as combination,
sequential, and supplementary therapies have been suggested. In the end, treatment of
special populations such as diabetic, elderly, and children is outlined.
