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[Increasing frequency of onychomycoses--is there a change in the spectrum of infectious agents?]
Abstract:
The recently developed antifungal drugs are not equally effective against the fungi causing onychomycoses: dermatophytes, yeasts and non-dermatophyte filamentous fungi (NDFF). Therapeutic failures may be due to the use of antifungal agents not primarily effective against the particular fungus. Considering the high costs of systemic antifungal therapy, it is necessary to know the frequency distribution of the different fungi causing onychomycosis. In a retrospective study, we have analysed results of fungal cultures performed between 1974 and 1994. In particular, we have compared the time periods 1982-1984 and 1992-1994. Culture results from toe nails showed in 1982-1984 the following fungal pattern (n = 833): dermatophytes 61%, yeasts 15%, NDFF 17%, mixed infections 7%. Results from 1992-1994 (n = 930) revealed an increase of dermatophytes 86% at the expense of yeasts (7%), NDFF (3%) and mixed infections (3%). In finger nails, we found a more pronounced change of infectious agents from 1982-1984 (n = 509; dermatophytes 62%, yeasts 29%, NDFF 1%, mixed infections 7%) to 1992-1994 (n = 348; dermatophytes 45%, yeasts 52%, NDFF 0.3%, mixed infections 3%). The high rate of yeast isolations (52%) from finger nails in 1992-1994 is striking. The role of yeast isolates for pathogenesis of onychomycosis remains to be elucidated. Differentiation between colonisation and infection would be necessary. The effectiveness of oral antifungal drugs against dermatophytic nail infections is well documented. The effectiveness against yeasts and NDFF, however, has not been studied thoroughly, but is not supposed to be equal with the different antifungal agents. Determination of the infectious agents in onychomycoses is recommended in order to avoid therapeutic failures.
Insights
Onychomycosis (nail fungal infection) treatment failures may stem from using antifungals not effective against the specific pathogen. This study tracked fungal prevalence over time, revealing shifts in causative agents. Identifying the specific fungus is crucial for effective nail infection treatment.
Area of Science:
- Medical Mycology
- Dermatology
- Infectious Diseases
Background:
- Antifungal drug efficacy varies across fungi causing onychomycosis (nail fungal infections).
- Therapeutic failures in onychomycosis are often linked to inappropriate antifungal selection.
- Understanding the etiological agent's prevalence is vital for optimizing treatment strategies.
Purpose of the Study:
- To analyze the changing frequency distribution of fungi responsible for onychomycosis.
- To compare etiological patterns between two distinct time periods (1982-1984 and 1992-1994).
- To inform antifungal therapy choices by assessing shifts in fungal prevalence.
Main Methods:
- Retrospective analysis of fungal culture results from nail samples.
- Comparison of fungal prevalence data from 1982-1984 and 1992-1994.
- Categorization of isolates into dermatophytes, yeasts, and non-dermatophyte filamentous fungi (NDFF).
Main Results:
- Toe nail infections showed an increase in dermatophytes (61% to 86%) and a decrease in yeasts and NDFF between the study periods.
- Finger nail infections exhibited a significant shift, with dermatophytes decreasing (62% to 45%) and yeasts increasing dramatically (29% to 52%).
- A notable rise in yeast prevalence in finger onychomycosis was observed in the later period.
Conclusions:
- Fungal prevalence in onychomycosis has changed over time, with distinct patterns in toe versus finger nails.
- The increasing role of yeasts in finger nail infections warrants further investigation into their pathogenic significance.
- Accurate identification of the causative fungal agent is recommended to guide effective antifungal therapy and prevent treatment failures.