Search Results
Onychomycosis Infections
Do Polymerase Chain Reaction and Culture Reports Agree?
Background:
Mycological culture is the traditional method for identifying infecting agents of onychomycosis despite high false-negative results, slower processing, and complications surrounding nondermatophyte mold (NDM) infections. Molecular polymerase chain reaction (PCR) methods are faster and suited for ascertaining NDM infections.
Methods:
To measure agreement between culture and PCR methods for identification of infecting species of suspected onychomycosis, single toenail samples from 167 patients and repeated serial samples from 43 patients with suspected onychomycosis were processed by culture and PCR for identification of 16 dermatophytes and five NDMs. Agreement between methods was quantified using the kappa statistic (κ).
Results:
The methods exhibited fair agreement for the identification of all infecting organisms (single samples: κ = 0.32; repeated samples: κ = 0.38). For dermatophytes, agreement was moderate (single samples: κ = 0.44; repeated samples: κ = 0.42). For NDMs, agreement was poor with single samples (κ = 0.16) but fair with repeated samples (κ = 0.25). Excluding false-negative reports from analyses improved agreement between methods in all cases except the identification of NDMs from single samples.
Conclusions:
Culture was three or four times more likely to report a false-negative result compared with PCR. The increased agreement between methods observed by excluding false-negative reports statistically clarifies and highlights the major discord caused by false-negative cultures. The increased agreement of NDM identification from poor to fair with repeated sampling along with their poor agreement in the single samples, with and without false-negatives, affirms the complications of NDM identification and supports the recommendation that serial samples help confirm the diagnosis of NDM infections.
Topical Treatments for Onychomycosis
A Historical Perspective
Topical treatment of onychomycosis, in contrast to systemic oral therapy, allows the patient to apply medication directly to the affected area, thereby decreasing the potential for adverse events and drug interactions. Historically, several topical antifungal agents have been used in the treatment of onychomycosis; however, the evidence for their effectiveness is based on very limited data or anecdotal reports. Recently, the development of new, effective topical agents has renewed interest in this form of therapy. As clinical experience with newer topical agents expands, they may be found to be an effective option for the treatment of onychomycosis. (J Am Podiatr Med Assoc 93(2): 136-141, 2003)
Satisfaction with Onychomycosis Treatment
Pulse versus Continuous Dosing
The purpose of this study, which involved two dermatology clinics and two podiatric medical clinics, was to determine whether a difference exists in patient-reported satisfaction and compliance between continuous terbinafine therapy and pulse-dose itraconazole therapy for the treatment of toenail onychomycosis. Patients in this multicenter, open-label, cross-sectional study had previously completed treatment with either oral terbinafine or oral itraconazole for toenail onychomycosis. Patients were interviewed by telephone to assess clinical outcomes, compliance, and satisfaction with treatment; clinical data were collected by medical chart review. Patients reported significantly greater ease and convenience of treatment and higher overall satisfaction with continuous terbinafine therapy compared with pulse-dose itraconazole therapy. (J Am Podiatr Med Assoc 93(5): 373-379, 2003)
Fungal Diversity and Onychomycosis
An Analysis of 8,816 Toenail Samples Using Quantitative PCR and Next-Generation Sequencing
Background:
Onychomycosis is a fungal infection of the nail that is often recalcitrant to treatment and prone to relapse. Traditional potassium hydroxide and culture diagnosis is costly and time-consuming. Therefore, molecular methods were investigated to demonstrate effectiveness in diagnosis and to quantify the microbial flora present that may be contributing to disease.
Methods:
A total of 8,816 clinically suspicious toenail samples were collected by podiatric physicians across the United States from patients aged 0 to 103 years and compared with a control population (N = 20). Next-generation sequencing and quantitative polymerase chain reaction were used to identify and quantify dermatophytes, nondermatophyte molds, and bacteria.
Results:
Approximately 50% of suspicious toenails contained both fungi and bacteria, with the dermatophyte Trichophyton rubrum contributing the highest relative abundance and presence in 40% of these samples. Of the remaining 50% of samples, 34% had bacterial species present and 16% had neither. Fungi only were present in less than 1% of samples. Nondermatophyte molds contributed to 11.0% of occurrences in fungus-positive samples. All of the control samples were negative for fungi, with commensal bacterial species composing most of the flora population.
Conclusions:
Molecular methods were successful in efficiently quantifying microbial and mycologic presence in the nail. Contributions from dermatophytes were lower than expected, whereas the opposite was true for nondermatophyte molds. The clinical significance of these results is currently unknown.
Background
Onychomycosis is the most common infectious nail disorder. Direct mycologic examination is still the cornerstone of diagnosis; however, it may take several weeks to obtain a result. Recently some dermoscopic patterns that can be useful in the diagnosis of onychomycosis were described. However, published data on dermoscopic features of onychomycosis are still limited.
Methods
We performed a prospective dermoscopic study of patients with positive fungal culture between April and December 2016. Patients with a final diagnosis of psoriasis or lichen planus were excluded from the study. Dermoscopy (polarized and nonpolarized) was performed.
Results
Thirty-seven patients were enrolled, 24 women and 13 men (median ± SD age, 48.6 ± 16.1 years). Nail samples were culture positive for Trichophyton rubrum (89.2%), Trichophyton interdigitale (8.1%), and Candida albicans (2.7%). Distal and lateral subungual onychomycosis was the most frequent clinical subtype (59.5%). The most frequent dermoscopic features were subungual keratosis (73.0%), distal subungual longitudinal striae (70.3%), spikes of the proximal margin of an onycholytic area (59.5%), transverse superficial leukonychia (29.7%), and linear hemorrhage (13.5%). Brown chromonychia was most frequently seen with nonpolarized dermoscopy (66.6% versus 24%; P = .027).
Conclusions
Specific dermoscopic signs of onychomycosis are mostly related to the proximal invasion of the nail plate. Detection of these signs is simple and can, in some cases, help avoid mycologic testing.
Evaluating Costs for Onychomycosis Treatments
A Practitioner’s Perspective
Onychomycosis is a common problem. The desired outcome of treatment for patients and clinicians is complete cure (negative culture and negative potassium hydroxide examination results plus a completely normal nail). This cost analysis sought to determine the cost-effectiveness of treatments for onychomycosis using complete cure as a unit of effectiveness. A simplified cost-effectiveness analysis was conducted using complete cure rates from randomized, blinded clinical trials involving at least 50 participants. Trials were identified by searching the literature, manually searching for review articles, and reviewing medication package inserts. For each trial that met the entry criteria, three levels of cost were used to calculate medication cost per complete cure: commercial price, average wholesale price, and Veterans Affairs pharmacy price. In addition, a computerized economic model was used to determine total cost per complete cure, including all medical costs. The most cost-effective treatments were those that involved terbinafine: pulse, continuous, or in combination with other agents. Itraconazole, griseofulvin, and fluconazole were less cost-effective. Ciclopirox nail lacquer was at least three times more expensive than all other agents when evaluating total costs per complete cure. Overall, the lowest cost per complete cure resulted from terbinafine treatment, with most evidence supporting 3 months of continuous therapy. (J Am Podiatr Med Assoc 96(1): 38–52, 2006)
Background:
Onychomycosis is a chronic nail infection caused by dermatophytes, Candida, nondermatophyte molds, and Trichosporon. The purpose of this study was to identify the underlying pathogen in patients with onychomycosis in our region.
Methods:
A retrospective analysis of 225 cases with onychomycosis, diagnosed over a 27-month period at the Department of Dermatoveneorology, Bezmialem Vakif University, Istanbul, Turkey, and confirmed with culture, was performed.
Results:
Patient age ranged from 2 to 87 years (mean ± SD, 41.59 ± 17.61), and female patients were more commonly affected (120 cases, 53.3%) than male patients. Lateral and distal subungual onychomycosis was detected in 180 cases (80%). Etiologic agents were as follows: Trichophyton rubrum, 77 cases (34.2%); Trichophyton mentagrophytes, 30 cases (13.3%), Candida albicans, 28 cases (12.4%); Candida parapsilosis, 25 cases (11.1%); Acremonium species, one case (0.4%); Aspergillus species, two cases (0.9%); Fusarium species, four cases (1.3%); and Trichosporon species, three cases (1.3%).
Conclusions:
The most frequent isolated etiologic agents were T rubrum for toenails and C albicans for fingernails.
Although scanning electron microscope technology has been used for more than 60 years in many fields of medical research, no studies have focused on obtaining high-resolution microscopic images of onychomycosis of the toenail caused by Trichophyton rubrum in a geriatric population. To provide new insight into the intricate structure and behavior of chronic toenail onychomycosis, we produced three-dimensional images of onychomycosis obtained from two geriatric patients with confirmed growth of T rubrum. The photomicrographs illustrate the pervasive integration and penetration of the fungus hyphal elements, underscoring the clinical difficulty of obtaining rapid treatment of fungal infections in the distal and lateral subungual space of the human toenail. Although the scanning electron microscope may not be a practical diagnostic tool for most physicians, it remains invaluable for the researcher to obtain insight into the spatial orientation, behavior, and appearance of onychomycosis. (J Am Podiatr Med Assoc 94(4): 356–362, 2004)
Efficacy of Terbinafine for Toenail Onychomycosis
A Multicenter Trial of Various Treatment Durations
The efficacy of terbinafine (250 mg/day) in the treatment of toenail onychomycosis was evaluated in a large open-label, multicenter trial of 12, 18, and 24 weeks of therapy. All 1,534 patients had onychomycosis, confirmed by either positive potassium hydroxide (KOH) wet mount, positive fungal culture, or both, and all received at least 12 weeks of treatment. Treatment was continued for an additional 6 or 12 weeks, depending on the extent of the disease at follow-up. Mycologic cure rates (negative culture plus negative KOH) at week 72 were 72.1% in the 12-week treatment group, 72.5% in the 18-week group, and 77.0% in the 24-week group. In all groups, clinical cure rates were higher at week 72 than at week 48: 49.5% of the 12-week group, 49.2% of the 18-week group, and 44.6% of the 24-week group experienced clinical cure by the end of the study. Both mycologic and clinical recurrence rates were low in all treatment groups at the 72-week assessment. The results of this study confirm the efficacy of terbinafine in the treatment of toenail onychomycosis as demonstrated in previous registration and large-scale clinical trials. (J Am Podiatr Med Assoc 91(3): 127-131, 2001)
Onychomycosis is a common problem seen in clinical practice. Given the differential diagnosis of dystrophic nails, it is helpful to obtain a definitive diagnosis of dermatophyte infection before initiation of antifungal therapy. Potassium hydroxide preparation and fungal culture, which are typically used in the diagnosis of these infections, often yield false-negative results. Recent studies have suggested that nail plate biopsy with periodic acid–Schiff stain may be a very sensitive technique for the diagnosis of onychomycosis. In this article, we review the literature on the utility of histopathologic analysis in the evaluation of onychomycosis. Many of these studies indicate that biopsy with periodic acid–Schiff is the most sensitive method for diagnosing onychomycosis. We propose that histopathologic examination is indicated if the results of other methods are negative and clinical suspicion is high; therefore, it is a useful complementary technique in the diagnosis of onychomycosis. (J Am Podiatr Med Assoc 95(3): 258–263, 2005)
