Onychomycosis

Zaias, Nardo

doi:10.1001/archderm.1972.01620050069017

Cited by 229 publications

(132 citation statements)

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“…Our model therefore also could partially recreate this type of superficial onychomycosis. Of relevance is that the proximal nail fold was thought to be the point of invasion of dermatophytes into the nail in PSO (27). Another report of a human experiment (2) showed a similar finding, in that the lunula was the most susceptible area.…”

Section: Discussionmentioning

confidence: 89%

Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents

Shimamura

Kubota

Nagasaka

et al. 2011

Antimicrob Agents Chemother

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We developed a novel model of onychomycosis in which we observed fungi in the deep layer of the nail, and we used the model to evaluate the efficacy of two topical antifungal drugs. To establish an experimental, in vivo model of onychomycosis, we applied Trichophyton mentagrophytes TIMM2789 to the nails of the hind limbs of rabbits that underwent steroid treatment. The nails were taken from the rabbits' feet at 0, 2, and 6 weeks after a 2-week infection. The localization of the fungi was evaluated histopathologically. Some fungi were seen to penetrate to the nail bed, and the infection rate in the sample at 0, 2, and 6 weeks after infection was 57, 87, and 93%, respectively. In addition, fungi proliferated and moved proximally into the nail plate in a manner that depended on the duration of infection. Second, using this model we evaluated antifungal efficacy both by the culture recovery method and histopathological examination. Two topical antifungal drugs, 8% ciclopirox nail lacquer and 5% amorolfine nail lacquer, were applied to the nail for 4 weeks in each group. On histopathological examination, two antifungal treatment groups showed no significant difference against the nontreated control group. However, there were a significantly low fungus-positive rate and intensity of the recovery of fungi on culture between antifungal treatment and nontreated control groups. We therefore suggest that we have established an in vivo model of onychomycosis that is useful for the evaluation of the efficacy of antifungal agents.

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Section: Discussionmentioning

confidence: 89%

Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents

Shimamura

Kubota

Nagasaka

et al. 2011

Antimicrob Agents Chemother

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“…A truly invasive organism, therefore, may be poorly represented in the sample. (The physician, however, may have decided in advance that the SWO was an insignificant problem in the case at hand and therefore was not the target of the investigation, despite the known frequent association between Trichophyton mentagrophytes and SWO [44,45].) Likewise, a strategy of mixing samples from several of a patient's nails into the same shipping packet might strongly dilute the occurrence of an etiologic agent, or mix the agents of two different opportunistic onychomycoses together, making the nails simply appear contaminated.…”

Section: Vol 39 2001 Diagnosis Of Nondermatophyte Mold Onychomycosimentioning

confidence: 99%

Utility of Inoculum Counting (Walshe and English Criteria) in Clinical Diagnosis of Onychomycosis Caused by Nondermatophytic Filamentous Fungi

et al. 2001

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Opportunistic onychomycosis caused by nondermatophytic molds may differ in treatment from tinea unguium. Confirmed diagnosis of opportunistic onychomycosis classically requires more than one laboratory analysis to show consistency of fungal outgrowth. Walshe and English in 1966 proposed to extract sufficient diagnostic information from a single patient consultation by counting the number of nail fragments positive for inoculum of the suspected fungus. Twenty fragments were plated per patient, and each case in which five or more fragments grew the same mold was considered an infection by that mold, provided that compatible filaments were also seen invading the nail tissue by direct microscopy. This widely used and often recommended method has never been validated. Therefore, the validity of substituting any technique based on inoculum counting for conventional follow-up study in the diagnosis of opportunistic onychomycosis was investigated. Sampling of 473 patients was performed repeatedly. Nail specimens were examined by direct microscopy, and 15 pieces were plated on standard growth media. After 3 weeks, outgrowing dermatophytes were recorded, and pieces growing any nondermatophyte mold were counted. Patients returned on two to eight additional occasions over a 1-to 3-year period for similar examinations. Onychomycosis was etiologically classified based on long-term study. Opportunistic onychomycosis was definitively established for 86 patients. Counts of nondermatophyte molds in initial examinations were analyzed to determine if they successfully predicted both true cases of opportunistic onychomycosis and cases of insignificant mold contamination. There was a strong positive statistical association between mold colony counts and true opportunistic onychomycosis. Logistic regression analysis, however, determined that even the highest counts predicted true cases of opportunistic onychomycosis only 89.7% of the time. The counting criterion suggested by Walshe and English was correct only 23.2% of the time. Acremonium infections were especially likely to be correctly predicted by inoculum counting. Inoculum counting could be used to indicate a need for repeat studies in cases of false-negative results from laboratory direct microscopy. Inoculum counting cannot serve as a valid substitute for follow-up study in the diagnosis of opportunistic onychomycosis. It may, nonetheless, provide useful information both to the physician and to the laboratory, and it may be especially valuable when the patient does not present for follow-up sampling.

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“…Nail invasion by nondermatophytic molds is generally considered uncommon. Reported prevalence rates range from 0% to 50%, with studies that carefully investigate all such cases usually showing a prevalence of around 3.5% (21,26,54). The fungal species most frequently implicated in onychomycosis caused by molds in temperate parts of the world is Scopulariopsis brevicaulis (15,16,18,50).…”

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confidence: 99%

Forty-Eight-Hour Diagnosis of Onychomycosis with Subtyping ofTrichophyton rubrumStrains

et al. 2006

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A novel strategy for the molecular identification of fungal agents of onychomycosis (including Trichophyton rubrum) has been designed based on the use of species-specific and universal primers in conjunction with a commercial kit that allows the extraction of DNA directly from the nail specimens. The microsatellite marker T1, which is based on a (GT)n repeat, was applied for the species-specific identification of Trichophyton rubrum. To evaluate how often Scopulariopsis spp. are detected in nail specimens, a second primer pair was designed to amplify specifically a 336-bp DNA fragment of the 28S region of the nuclear rRNA gene of S. brevicaulis and closely related species. Other fungal species were identified using amplification of the internal transcribed spacer (ITS) region of the rRNA gene, followed by restriction fragment length polymorphism analysis or sequencing. In addition, polyacrylamide gel separation of the T1-PCR product allowed subtyping of T. rubrum strains. We studied 195 nail specimens (the "nail sample") and 66 previously collected etiologic strains (the "strain sample") from 261 onychomycosis patients from Bulgaria and Greece. Of the etiologic agents obtained from both samples, T. rubrum was the most common organism, confirmed to be present in 76% of all cases and serving as the sole or (rarely) mixed etiologic agent in 199 of 218 cases (91%) where the identity of the causal organism(s) was confirmed. Other agents seen included molds (6% of cases with identified etiologic agents; mainly S. brevicaulis) and other dermatophyte species (4%; most frequently Trichophyton interdigitale). Simultaneous infections with two fungal species were confirmed in a small percentage of cases (below 1%). The proportion of morphologically identified cultures revealed by molecular study to have been misidentified was 6%. Subtyping revealed that all but five T. rubrum isolates were of the common type B that is prevalent in Europe. In comparison to microscopy and culture, the molecular approach was superior. The PCR was more sensitive (84%) than culture (22%) in the nail sample and was more frequently correct in specifically identifying etiologic agents (100%) than microscopy plus routine culture in either the nail or the strain samples (correct culture identifications in 96% and 94% of cases, respectively). Using the molecular approach, the time for diagnosing the identity of fungi causing onychomycosis could be reduced to 48 h, whereas culture techniques generally require 2 to 4 weeks. The early detection and identification of the infecting species in nails will facilitate prompt and appropriate treatment and may be an aid for the development of new antifungal agents.

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Onychomycosis

Cited by 229 publications

References 0 publications

Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents

Establishment of a Novel Model of Onychomycosis in Rabbits for Evaluation of Antifungal Agents

Utility of Inoculum Counting (Walshe and English Criteria) in Clinical Diagnosis of Onychomycosis Caused by Nondermatophytic Filamentous Fungi

Forty-Eight-Hour Diagnosis of Onychomycosis with Subtyping ofTrichophyton rubrumStrains

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