Cost-effectiveness of diagnostic tests for toenail onychomycosis: A repeated-measure, single-blinded, cross-sectional evaluation of 7 diagnostic tests

Use of Potassium Hydroxide in Dermatology Daily Practice: A Local Study From Saudi Arabia

Introduction

Potassium hydroxide (KOH) is an inorganic keratolytic test. It is considered one of the most worldwide methods used in the dermatological field with reasonable reliability and sensitivity. One of its major uses is in identifying fungal elements in the skin, hair, nails, and different body secretions. In this study, we aimed to identify the prevalence of KOH usage in different hospitals in the Al-Ahsa region, Saudi Arabia. Additionally, we aimed to identify the dermatological conditions in which KOH is being used and practiced by physicians.

Methods

This was an anonymous questionnaire-based cross-sectional study that was distributed and carried out among dermatologists in Al-Ahsa city in the Eastern province of Saudi Arabia.

Results

A total of 30 dermatologists completed the study questionnaire. Participants’ ages ranged from 29 to 59 years old with a mean age of 39.5 ± 11.4 years old. 14 (46.7%) dermatologists reported that the KOH test is available in their clinic. Using KOH once a day was reported among 14.3% while 21.4% used it once a week. The most reported condition for KOH use was hair dermatophytes (100%).

Conclusion

There is a clear lack of usage and availability of KOH in clinics. The shortage of availability of diagnostic tools, including KOH might affect the diagnosis of several diseases and may cause a waste of resources, wrong prescriptions, and patient’s burden.

Updated Perspectives on the Diagnosis and Management of Onychomycosis

Onychomycosis is the most common nail disease encountered in clinical practice and can cause pain, difficulty with ambulation, and psycho-social problems. A thorough history and physical examination, including dermoscopy, should be performed for each patient presenting with nail findings suggestive of onychomycosis. Several approaches are available for definitive diagnostic testing, including potassium hydroxide and microscopy, fungal culture, histopathology, polymerase chain reaction, or a combination of techniques. Confirmatory testing should be performed for each patient prior to initiating any antifungal therapies. There are several different therapeutic options available, including oral and topical medications as well as device-based treatments. Oral antifungals are generally recommended for moderate to severe onychomycosis and have higher cure rates, while topical antifungals are recommended for mild to moderate disease and have more favorable safety profiles. Oral terbinafine, itraconazole, and griseofulvin and topical ciclopirox 8% nail lacquer, efinaconazole 10% solution, and tavaborole 5% solution are approved by the Food and Drug Administration for treatment of onychomycosis in the United States and amorolfine 5% nail lacquer is approved in Europe. Laser treatment is approved in the United States for temporary increases in clear nail, but clinical results are suboptimal. Oral fluconazole is not approved in the United States for onychomycosis treatment, but is frequently used off-label with good efficacy. Several novel oral, topical, and over-the-counter therapies are currently under investigation. Physicians should consider the disease severity, infecting pathogen, medication safety, efficacy and cost, and patient age, comorbidities, medication history, and likelihood of compliance when determining management plans. Onychomycosis is a chronic disease with high recurrence rates and patients should be counseled on an appropriate plan to minimize recurrence risk following effective antifungal therapy.

A descriptive study of onychoscopic features in various subtypes of onychomycosis

Background

The diagnosis of onychomycosis is usually clinical and is confirmed by 40% KOH examination. A diagnostic dilemma occurs when KOH examination is negative despite strong clinical suspicion. Dermoscopic evaluation of the nail is referred to as onychoscopy. We attempted to assess the dermoscopic findings in Onychomycosis positive with KOH examination.

Methods

A cross sectional study was conducted in a tertiary care center including 122 patients with clinical suspicion of onychomycosis with KOH positivity. After assessment of risk factors and gross nail examination, onychoscopic examination was done to identify the presence of the specific features.

Results

Primary findings of onychoscopic examination were 'spiked pattern' in 80.3% subjects, of which 95 were distal lateral subungual onychomycosis (DLSO), 8 of total dystrophic onychomycosis (TDO). True leukonychia was seen in the single patient of proximal subungual onychomycosis (PSO) and pseudoleukonychia in the single patient of white superficial onychomycosis (WSO). Distal irregular termination was observed in 23% of subjects - 8 from DLSO and in all 20 patients of TDO. 'Ruin appearance' was observed in all 20 patients of TDO, 56 patients with DLSO and not seen in other types of onychomycosis (OM). Presence of spiked pattern, Longitudinal striae, Distal irregular termination and Ruin appearance were found to be statistically significant (p < 0.001).

Conclusion

In suspected onychomycosis, specific onychoscopic findings such as Spiked pattern, Longitudinal striae, Ruin appearance and Distal irregular termination can be used as supporting evidence for diagnosing onychomycosis clinically and initiating antifungal therapy if mycological testing is unavailable or negative.

Deep Learning Assisted Diagnosis of Onychomycosis on Whole-Slide Images

Background: Onychomycosis numbers among the most common fungal infections in humans affecting finger- or toenails. Histology remains a frequently applied screening technique to diagnose onychomycosis. Screening slides for fungal elements can be time-consuming for pathologists, and sensitivity in cases with low amounts of fungi remains a concern. Convolutional neural networks (CNNs) have revolutionized image classification in recent years. The goal of our project was to evaluate if a U-NET-based segmentation approach as a subcategory of CNNs can be applied to detect fungal elements on digitized histologic sections of human nail specimens and to compare it with the performance of 11 board-certified dermatopathologists. Methods: In total, 664 corresponding H&E- and PAS-stained histologic whole-slide images (WSIs) of human nail plates from four different laboratories were digitized. Histologic structures were manually annotated. A U-NET image segmentation model was trained for binary segmentation on the dataset generated by annotated slides. Results: The U-NET algorithm detected 90.5% of WSIs with fungi, demonstrating a comparable sensitivity with that of the 11 board-certified dermatopathologists (sensitivity of 89.2%). Conclusions: Our results demonstrate that machine-learning-based algorithms applied to real-world clinical cases can produce comparable sensitivities to human pathologists. Our established U-NET may be used as a supportive diagnostic tool to preselect possible slides with fungal elements. Slides where fungal elements are indicated by our U-NET should be reevaluated by the pathologist to confirm or refute the diagnosis of onychomycosis.

Diagnosing Onychomycosis: What's New?

An overview of the long-established methods of diagnosing onychomycosis (potassium hydroxide testing, fungal culture, and histopathological examination) is provided followed by an outline of other diagnostic methods currently in use or under development. These methods generally use one of two diagnostic techniques: visual identification of infection (fungal elements or onychomycosis signs) or organism identification (typing of fungal genus/species). Visual diagnosis (dermoscopy, optical coherence tomography, confocal microscopy, UV fluorescence excitation) provides clinical evidence of infection, but may be limited by lack of organism information when treatment decisions are needed. The organism identification methods (lateral flow techniques, polymerase chain reaction, MALDI-TOF mass spectroscopy and Raman spectroscopy) seek to provide faster and more reliable identification than standard fungal culture methods. Additionally, artificial intelligence methods are being applied to assist with visual identification, with good success. Despite being considered the 'gold standard' for diagnosis, clinicians are generally well aware that the established methods have many limitations for diagnosis. The new techniques seek to augment established methods, but also have advantages and disadvantages relative to their diagnostic use. It remains to be seen which of the newer methods will become more widely used for diagnosis of onychomycosis. Clinicians need to be aware of the limitations of diagnostic utility calculations as well, and look beyond the numbers to assess which techniques will provide the best options for patient assessment and management.

Deep learning-based diagnosis models for onychomycosis in dermoscopy

BACKGROUND

Onychomycosis is a common disease. Emerging noninvasive, real-time techniques such as dermoscopy and deep convolutional neural networks have been proposed for the diagnosis of onychomycosis. However, deep learning application in dermoscopic image hasn't been reported.

OBJECTIVES

To explore the establishment of deep learning-based diagnostic models for onychomycosis in dermoscopy to improve the diagnostic efficiency and accuracy.

METHODS

We evaluated the dermoscopic patterns of onychomycosis diagnosed at Sun Yat-sen Memorial Hospital, Guangzhou, China from May 2019 to February 2021 and included nail psoriasis and traumatic onychodystrophy as control groups. Based on the dermoscopic images and the characteristic dermoscopic patterns of onychomycosis, we gain the faster region-based convolutional neural networks to distinguish between nail disorder and normal nail, onychomycosis and non-mycological nail disorder (nail psoriasis and traumatic onychodystrophy). The diagnostic performance is compared between deep learning-based diagnosis models and dermatologists.

RESULTS

All of 1155 dermoscopic images were collected, including onychomycosis (603 images), nail psoriasis (221 images), traumatic onychodystrophy (104 images) and normal cases (227 images). Statistical analyses revealed subungual keratosis, distal irregular termination, longitudinal striae, jagged edge, marble-like turbid area, and cone-shaped keratosis were of high specificity (>82%) for onychomycosis diagnosis. The deep learning-based diagnosis models (ensemble model) showed test accuracy /specificity/ sensitivity /Youden index of (95.7%/98.8%/82.1%/0.809), (87.5%/93.0%/78.5%/0.715) for nail disorder and onychomycosis. The diagnostic performance for onychomycosis using ensemble model was superior to 54 dermatologists.

CONCLUSIONS

Our study demonstrated onychomycosis had distinctive dermoscopic patterns, compared with nail psoriasis and traumatic onychodystrophy. The deep learning-based diagnosis models showed a diagnostic accuracy of onychomycosis, superior to dermatologists.

Diagnosis of Onychomycosis: From Conventional Techniques and Dermoscopy to Artificial Intelligence

Onychomycosis is a common fungal nail infection. Accurate diagnosis is critical as onychomycosis is transmissible between humans and impacts patients' quality of life. Combining clinical examination with mycological testing ensures accurate diagnosis. Conventional diagnostic techniques, including potassium hydroxide testing, fungal culture and histopathology of nail clippings, detect fungal species within nails. New diagnostic tools have been developed recently which either improve detection of onychomycosis clinically, including dermoscopy, reflectance confocal microscopy and artificial intelligence, or mycologically, such as molecular assays. Dermoscopy is cost-effective and non-invasive, allowing clinicians to discern microscopic features of onychomycosis and fungal melanonychia. Reflectance confocal microscopy enables clinicians to observe bright filamentous septate hyphae at near histologic resolution by the bedside. Artificial intelligence may prompt patients to seek further assessment for nails that are suspicious for onychomycosis. This review evaluates the current landscape of diagnostic techniques for onychomycosis.

Ex vivo Confocal Laser Scanning Microscopy: A Potential New Diagnostic Imaging Tool in Onychomycosis Comparable With Gold Standard Techniques

Ex vivo confocal laser scanning microscopy (CLSM) is an innovative imaging tool that enables real-time examination of specimens and may be used in evaluating fungal infections. We aimed to assess the applicability of ex vivo CLSM in the diagnosis of onychomycosis by comparing results to those obtained by histopathology, potassium hydroxide (KOH) examination, and fungal culture. In this prospective study, 57 patients with the clinical diagnosis of distal nail fungal infection were examined and compared using all four of the above-mentioned diagnostic tools in terms of sensitivity, positive and negative predictive value. Ex vivo CLSM showed the highest sensitivity, followed by KOH examination, histopathology and fungal culture. Regarding positive and negative predictive values, ex vivo CLSM was superior and showed even higher sensitivity than the combined gold standard comprised of KOH examination, fungal culture or histopathology.

PAS and GMS utility in dermatopathology: Review of the current medical literature

The American Society of Dermatopathology has established an Appropriate Use Criteria (AUC) Committee with the intention of establishing evidence-based recommendations regarding the appropriateness of various ancillary tests commonly utilized by dermatopathologists. Periodic acid Schiff (PAS) and Grocott (or Gomori) methenamine silver (GMS) stains represent some of the most commonly employed ancillary tests in dermatopathology. The utility of these tests was targeted for evaluation by the AUC. This literature review represents a comprehensive evaluation of available evidence for the utility of PAS and/or GMS staining of skin and nail biopsies. In concert with expert opinion, these data will be incorporated into future recommendations by the AUC for PAS and GMS staining in routine dermatopathology practice.

Epidemiological Characteristics and Risk Factors of Tinea Pedis Disease Among Adults Attending Tikrit Teaching Hospital/ Iraq

BACKGROUND

Tinea pedis is one of the most common skin infections of interdigital toe webspace as well as feet skin and may affect the nail or the hand. It is caused by dermophytes fungi especially Trichophyton species. Direct contact with a contaminated environment or animal is the main mode of transmission. Tinea pedis is more frequent among adults than children and more among those with the previous infection with the disease, diabetes mellites, abnormally increased sweating, and the disease is common among individuals who wear unventilated (occlusive) footwear. Tinea pedis is 2-4 times more common in men than females.

AIM OF THE STUDY

To study the epidemiological characteristics and risk factors of tinea pedis disease.

METHODS

Descriptive study was conducted on patients attending the dermatology outpatient clinic in Tikrit Teaching Hospital, Tikrit, Iraq. The study was done during the period from 1st November 2018-10th June 2019. The sample included 680 persons. The cases were diagnosed clinically and by a direct microscope. The demographic information of patients was obtained according to certain questionnaire design. The study was done to reveal the epidemiology of tenia pedis disease among affected patients.

RESULTS

The frequency of tinea pedis cases among the study sample was 7% (48/ 680). It has been observed that there was no significant association as a result of the difference in gender, body weight, positive family history, history, presence of fungal skin disease, and presence of nail trauma. On the contrary, a significant association was observed as a result of the presence of the young age group, diabetes mellitus, and history of wearing occlusive shoes.

CONCLUSION

The frequency of tinea pedis disease among the study sample was 7%. There was a significant association between age group and the presence of diabetes mellitus disease and wearing occlusive shoes.

[Evaluation of the usefulness of nail biopsy in the diagnosis of onychomycosis]

BACKGROUND

Onychomycosis affects between 2% to 30% of the world population. Nail biopsy may help in making a diagnosis and can distinguish between invasion and colonisation.

AIMS

To evaluate the diagnostic usefulness of nail biopsy with Periodic acid-Schiff (PAS) staining for onychomycosis, compared to direct KOH examination, culture and its combination in a reference laboratory in Colombia.

METHODS

The study included 66 patients in whom a blind and independent reading of the three tests was performed. The usefulness was defined based on the validity (sensitivity, specificity, Youden's index, likelihood ratios), performance (predictive values) efficiency (proportion of correctly diagnosed patients), and reproducibility (kappa coefficient).

RESULTS

The mean age of the patients was 55±16 years, and included 76% women. The direct tests with KOH were positive in 66.7% (n=44), 62.1% (n=41) were positive with culture, and 56.1% (n=37) with the biopsy. The main causal agents were non-dermatophytes moulds in 36.4% (n=24). The most frequent species were Neoscytalidium dimidiatum (n=11), Trichophyton rubrum (n=11), and Candida parapsilosis (n=13). The sensitivity of nail biopsy, when compared to the standard (KOH and/or culture), was 71%, specificity 83%, Youden's index 0.54, positive likelihood ratio 4.25, negative likelihood ratio 0.35, positive predictive value 92%, negative predictive value 52%, efficiency 74% and kappa coefficient 0.45. When biopsy was evaluated only in patients with onycholysis of the nail plate greater than 50%, all the parameters of diagnostic usefulness increased.

CONCLUSIONS

The overall usefulness of the biopsy was moderate for patients with more severe symptomatology, which makes its use advisable in cases of extensive onycholysis, and when discriminating colonisation from invasion is required.

Clinical Diagnostic Accuracy of Onychomycosis: A Multispecialty Comparison Study

Although onychomycosis can be diagnosed clinically, many guidelines still recommend pathologic confirmation of the diagnosis prior to initiation of systemic treatment. We retrospectively reviewed results from 541 toenail clippings (160 by dermatologists, 198 by podiatrists, and 183 by other provider types) sent to the Brigham and Women's Department of Dermatopathology between January 2000 and December 2013 for confirmatory periodic acid-Schiff (PAS) testing of clinically diagnosed onychomycosis. Of these, 93 (58.1%), 125 (63.1%), and 71 (38.8%) were sent for confirmation of onychomycosis (as opposed to diagnosis of onychodystrophy) by dermatologists, podiatrists, and other provider types, respectively. Confirmatory PAS stains were positive in 70 (75.3%), 101 (80.8%), and 47 (66.2%) of samples ordered by dermatologists, podiatrists, and other providers, respectively. Our study demonstrates that clinical diagnosis of onychomycosis in the appropriate clinical setting is accurate across specialties. Further prospective investigation on the accuracy of clinical diagnosis of onychomycosis may be beneficial.

Confirmatory Testing Prior to Initiating Onychomycosis Therapy Is Cost-Effective

Background:

Onychomycosis can be investigated by sampling. Information gleaned includes nail bed involvement, nail plate penetration, fungal viability, and species identification. Testing samples can confirm a diagnosis. While diagnostic testing is considered useful in directing therapy, a substantial number of clinicians do not confirm diagnosis prior to treatment.

Objectives:

The aim of this study is to quantify the benefit of confirmatory testing prior to treating toenail onychomycosis.

Methods:

The cost of mycological cure (negative potassium hydroxide and negative culture) and the cost-effectiveness of confirmatory testing were determined using the average cost of potassium hydroxide (KOH), culture, periodic acid–Schiff (PAS), efinaconazole, ciclopirox, terbinafine, and itraconazole. Costs were obtained through literature searches, public domain websites, and telephone surveys to local pharmacies and laboratories. To represent the potential risks of prescribing onychomycosis treatment, the costs associated with liver monitoring, potential life-threatening adverse events, and drug-drug interactions were obtained through public domain websites, published studies, and product inserts.

Results:

PAS was determined to be the most sensitive confirmatory test and KOH the least expensive. The overall cost of an incorrect diagnosis (no confirmatory test used) ranged between $350 and $1175 CAD per patient for treatment of 3 infected toenails. Comparatively, performing confirmatory testing prior to treatment decreases the overall cost to $320 to $930, depending on the therapy, physician, and test.

Conclusions:

It is preferred to diagnose onychomycosis prior to treatment. Furthermore, there are cost savings when confirmatory testing is performed before initiating treatment with both topical and oral antifungals in Canada.

Point-of-Care Diagnosis of Onychomycosis by Dermoscopy

BACKGROUND

Onychomycosis is one of the most common diseases of the toenails. The costs of diagnosis and treatment are substantial, and as the population ages, the overall cost burden will continue to escalate. The purpose of this study was to correlate dermoscopic features with pathologic diagnosis to support the accuracy of point-of-care diagnosis by dermoscopic examination.

METHODS

Nail unit pathology reports of 52 patients with abnormal great toenails were compared with the dermoscopic features detected by nail unit dermoscopy.

RESULTS

The dermoscopic analysis predicted the laboratory diagnosis in 90.4% of the study patients. The specific dermoscopic findings of short spikes (P < .001), long striae (P < .001), aurora borealis (P < .001), irregular termination (P = .003), dermatophytoma (P = .011), transverse onycholysis (P = .018), and dry scale (P = .04) patterns were all significantly associated with pathology test results consistent with oncyhomycosis. Transverse onycholysis (P = .018) was significantly associated with negative pathology results consistent with the diagnosis of nail dystrophy.

CONCLUSIONS

Point-of-care examination by dermoscopy positively correlates with histopathologic tests and could be used to diagnose onychomycosis while reducing diagnostic costs.

Bedside diagnostics in dermatology: Viral, bacterial, and fungal infections

Viral, bacterial, and fungal infections are frequently encountered in clinical practice, resulting in numerous cutaneous manifestations. Although diagnosis of these infections has changed over time because of technological advancements, such as polymerase chain reaction, bedside diagnostic techniques still play an important role in diagnosis and management, enabling rapid and low-cost diagnosis and implementation of appropriate therapies. This 2-part article will review both common and infrequent uses of bedside diagnostic techniques that dermatologists can incorporate into daily practice. This article examines the utility of bedside tests for the diagnosis of viral, bacterial, and fungal infections. The second article in this series reviews the use of bedside diagnostics for parasitic and noninfectious disorders.

Onychomycosis in the 21st Century: An Update on Diagnosis, Epidemiology, and Treatment

Onychomycosis accounts for 50% of all nail disease cases and is commonly caused by dermatophytes. Diabetes, human immunodeficiency virus, immunosuppression, obesity, smoking, and advancing age are predisposing factors of this fungal infection. Potassium hydroxide and culture are considered the current standard for diagnosing onychomycosis, revealing both fungal viability and species identification. Other diagnostic tests currently available include periodic acid-Schiff staining, polymerase chain reaction techniques, and fluorescent staining. Across 6 recently published epidemiology studies, the global prevalence of onychomycosis was estimated to be 5.5%, falling within the range of previously reported estimates (2%-8%). Newly approved onychomycosis treatments include efinaconazole, tavaborole, and laser therapy with lasers only approved to temporarily increase the amount of clear nail. Additional onychomycosis treatments being investigated include iontophoresis and photodynamic therapy with small open-label studies reported thus far. Preventative strategies, to help decrease recurrence and reinfection rates, include sanitisation of footwear and prophylactic topical antifungal agents.

Long-Pulsed 1064-nm Nd:YAG Laser for the Treatment of Onychomycosis

OBJECTIVE

The aim of this study is to evaluate the efficacy of long-pulsed 1064-nm Nd:YAG laser in penetrating tissue and targeting the fungal overgrowth in the nail plate.

BACKGROUND

Onychomycosis is the most frequent nail disorder. Current treatments include oral and topical antifungal agents, photodynamic therapy, and surgical approaches such as mechanical, chemical, or surgical nail avulsion. Moreover, the use of lasers to treat nail diseases has been approved in the United States by the Food and Drug Administration (FDA). Wide literature has been produced to assess the effectiveness of these devices, but, because the opposing results emerging from current studies, more data are still needed on the long-lasting efficacy and safety of this procedure.

METHODS

Twenty consecutive, unselected patients were enrolled in the study and treated, at intervals of 1 week, for a total of four sessions, using a long-pulsed 1064-nm Nd:YAG laser. In each session, three passages across each nail plate were performed with 1-min pause between each passage. A special lens for dermatoscopy, connected to a digital camera, was used for dermoscopic images.

RESULTS

In fourteen patients (70%; 12F; 3M), excellent results were obtained with an important reduction of chromonychia, onycholysis, opacity, longitudinal striae, and jagged proximal edge. Better results were observed in severe cases in the 2-month follow-up visit.

CONCLUSIONS

Data for treating nail onychomycosis with laser and light therapy seem to be positive. The promising results of our study identify long-pulsed 1064-nm Nd:YAG laser as a possible alternative option for the treatment of onychomycosis. However, increasing subject data, improving study methodology, and output parameters may become an important next step of study in the treatment of nail onychomycosis.

Reappraisal of Conventional Diagnosis for Dermatophytes

Dermatophytoses include a wide variety of diseases involving glabrous skin, nails and hair. These superficial infections are a common cause of consultation in dermatology. In many cases, their diagnosis is not clinically obvious, and mycological analysis therefore is required. Direct microscopic examination of the samples using clearing agents provides a quick response to the clinician and is usually combined with cultures on specific media, which must be used to overcome the growth of contaminating moulds that may hamper the recovery of dermatophytes. Accurate identification of the causative agent (i.e. at the species level), currently based on morphological criteria, is necessary not only to initiate an appropriate treatment but also for setting prophylactic measures. However, conventional methods often lack sensitivity and species identification may require up to 4 weeks if subcultures are needed. Histological analysis, which is considered the "gold standard" for the diagnosis of onychomycoses, is seldom performed, and as direct examination, it does not allow precise identification of the pathogen. Nevertheless, a particular attention to the quality of clinical specimens is warranted. Moreover, the sensitivity of direct examination may be greatly enhanced by the use of fluorochromes such as calcofluor white. Likewise, sensitivity of the cultures could be enhanced by the use of culture media containing antifungal deactivators. With the generalization of molecular identification by gene sequencing or MALDI-TOF mass spectrometry, the contribution of historical biochemical or physiological tests to species identification of atypical isolates is now limited. Nevertheless, despite the recent availability of several PCR-based kits and an extensive literature on molecular methods allowing the detection of fungal DNA or both detection and direct identification of the main dermatophyte species, the biological diagnosis of dermatophytosis in 2016 still relies on both direct examination and cultures of appropriate clinical specimens.

A Retrospective Review of Diagnostic Testing for Onychomycosis of the Foot

BACKGROUND

Onychomycosis is a fungal infection of the nail that can be caused by dermatophytes, yeasts, or nondermatophyte molds. To diagnose onychomycosis, a clinician must use the patient's history, physical findings, and diagnostic testing, which can include calcofluor white/potassium hydroxide (KOH) mount, fungal culture (FC), and periodic acid-Schiff (PAS) stain. Some insurance companies require authorization for antifungal medication and request laboratory results to confirm infection. We sought to compare the reliability of KOH, PAS, and FC diagnostic results for confirmation of fungal disease, to determine the sensitivity and specificity of each test, and to investigate the cost of each test. In addition, we statistically observed the relationship between the test results and demographic variables.

METHODS

Toenail clippings were obtained from 108 patients clinically diagnosed as having onychomycosis. Diagnostic tests were then performed on each sample; the results were obtained from medical records.

RESULTS

For PAS, KOH, and FC, 60.2%, 43.5%, and 39.8% of results, respectively, were positive. Agreement for each pair of tests was slightly higher for FC and KOH. Sensitivities for KOH and PAS were 0.64 and 0.79, respectively. Specificity was 0.79 for KOH and 0.54 for PAS. Both PAS and KOH had a higher percentage of positive test results for men than for women.

CONCLUSIONS

Of the three tests evaluated, PAS gives the most consistent positive results and has the highest sensitivity. Therefore, PAS should be considered as the best test to verify clinically significant onychomycosis.

Mycology - an update part 2: dermatomycoses: clinical picture and diagnostics

Most fungal infections of the skin are caused by dermatophytes, both in Germany and globally. Tinea pedis is the most frequent fungal infection in Western industrial countries. Tinea pedis frequently leads to tinea unguium, while in the elderly, both may then spread causing tinea corporis. A variety of body sites may be affected, including tinea glutealis, tinea faciei and tinea capitis. The latter rarely occurs in adults, but is the most frequent fungal infection in childhood. Following antifungal treatment of tinea unguium and also tinea capitis a dermatophytid or hyperergic reaction to dermatophyte antigens may occur. Yeast infections affect the mucous membranes both of the gastro-intestinal system and the genital tract as candidiasis mostly due to Candida albicans. Cutaneous candidiasis affects predominantely the intertriginous regions such as groins and the inframammary area, but also the intertriginous space of fingers and toes. In contrast, pityriasis versicolor is a superficial epidermal fungal infection primarily on the the trunk. Mold infections are rare in dermatology; they play a role nearly exclusively in nondermatophyte-mold (NDM) onychomycosis. The diagnosis of dermatomycoses comprises the microscopic detection of fungi using the potassium hydroxide preparation or alternatively the fluorescence optical Blankophor preparation together with culture. The histological fungal detection with PAS staining possesses a high sensitivity, and it should play a more important role in particular for diagnosis of onychomycosis. Molecular biological methods, based on the amplification of fungal DNA with use of specific primers for the distinct causative agents are on the rise. With PCR, such as dermatophyte-PCR-ELISA, fungi can be detected directly in clinical material in a highly specific and sensitive manner without prior culture. Today, molecular methods, such as Matrix Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI TOF MS) as culture confirmation assay, complete the conventional mycological diagnostics.

Dermoscopic patterns in patients with a clinical diagnosis of onychomycosis-results of a prospective study including data of potassium hydroxide (KOH) and culture examination

Background:

Onychomycosis is the most common nail disease, representing 50% of cases affecting the nail apparatus. The diagnosis is made by clinical examination along with the KOH exam of the nail and culture of the sample. However, not all dermatologists have access to a mycology lab.

Objective:

To determine the correlation between KOH examination and dermoscopic patterns in patients with clinical diagnosis of onychomycosis.

Patients/Methods:

A descriptive, open, observational, prospective, cross-sectional study of 178 patients with clinical suspicion of onychomycosis was conducted. All patients underwent clinical examination, dermoscopy with a DermLite PHOTO dermatoscope (3Gen, San Juan Capistrano, CA, USA), KOH assessment and culture analysis. The most frequent dermoscopic patterns were identified and their correlation with the clinical subtype of onychomycosis was analyzed.

Results:

The study included 178 patients with clinical suspicion of onychomycosis. Of these, 155 (87.1%) had positive direct KOH examination for onychomycosis. Eighty-seven patients (56.13%) presented with clinical onychomycosis pattern of total dystrophic onychomycosis (TDO), 67 (43.23%) with distal lateral subungual onychomycosis (DLSO), 1 (0.65%) with trachyonychia). Dermoscopic patterns of onychomycosis showed the following frequencies: the spiked pattern was present in 22 patients (14.19%), longitudinal striae pattern in 51 patients (32.9%) and linear edge pattern in 21 patients (13.55%). We identified a pattern described as “distal irregular termination” in 41 patients with TDO and 26 with DLSO.

Conclusions:

This is the fist study conducted in a Mexican population that uses dermoscopy as a diagnostic tool along with the KOH examination for the diagnosis of onychomycosis. Dermoscopy may be used as an important diagnostic tool when evaluating nail disease. However, it should not be used as the only diagnostic criteria for onychomycosis.

Human nail plate modifications induced by onychomycosis: implications for topical therapy

PURPOSE

Through the characterisation of the human onchomycotic nail plate this study aimed to inform the design of new topical ungual formulations.

METHODS

The mechanical properties of the human nail were characterised using a Lloyd tensile strength tester. The nail's density was determined via pycnometry and the nail's ultrastructure by electron microscopy. Raman spectroscopy analysed the keratin disulphide bonds within the nail and its permeability properties were assessed by quantifying water and rhodamine uptake.

RESULTS

Chronic in vivo nail plate infection increased human nailplate thickness (healthy 0.49 ± 0.15 mm; diseased 1.20 ± 0.67 mm), but reduced its tensile strength (healthy 63.7 ± 13.4 MPa; diseased 41.7 ± 5.0 MPa) and density (healthy 1.34 ± 0.01 g/cm(3); diseased 1.29 ± 0.00 g/cm(3)). Onchomycosis caused cell-cell separation, without disrupting the nail disulfide bonds or desmosomes. The diseased and healthy nails showed equivalent water uptake profiles, but the rhodamine penetration was 4-fold higher in the diseased nails using a PBS vehicle and 3 -fold higher in an ethanol/PBS vehicle.

CONCLUSIONS

Onchomycotic nails presented a thicker but more porous barrier, and its eroded intracellular matrix rendered the tissue more permeable to topically applied chemicals when an aqueous vehicle was used.

Comparison of diagnostic methods in the evaluation of onychomycosis

Onychomycosis is a common nail problem, accounting for up to half of all nail diseases. Several nail disorders may mimic the onychomycosis clinically. Therefore, a sensitive, quick, and inexpensive test is essential for screening nail specimens for the administration of the proper drug. The aim of this study was to compare 4 different diagnostic methods in the evaluation of onychomycosis and to determine their sensitivity, specificity, positive predictive value, and negative predictive value. In a cross-sectional study, nail specimens were collected from 101 patients suspected to have onychomycosis during a 14-month period. The nail specimens were examined using potassium hydroxide (KOH) 20 %, KOH-treated nail clipping stained with periodic acid-Schiff (KONCPA), and calcofluor white (CFW) stain, and grew a fungal culture. The culture was chosen as the gold standard for statistical analysis using the McNemar and chi-square tests. Out of 101 patients, 100 (99 %) patients had at least 1 of the 4 diagnostic methods positive for the presence of organisms. The positive rates for the fungal culture, KOH preparation, CFW, and KONCPA were 74.2, 85.1, 91.09, and 99.01 %, respectively. The sensitivity and negative predictive value of KONCPA was 100 %. KONCPA was the most sensitive among the tests and was also superior to other methods in its negative predictive value. KONCPA was easy to perform, rapid, and gave significantly higher rates of detection of onychomycosis compared to the standard methods of KOH preparation and fungal culture. Therefore, KONCPA should be the single method of choice for the evaluation of onychomycosis.

[Fungal nail infections - an update. Part 2 - From the causative agent to diagnosis - conventional and molecular procedures]

Trichophyton (T.) rubrum is the most frequently isolated dermatophyte in onychomycosis, both in Germany and worldwide. T. interdigitale (formerly T. mentagrophytes var. interdigitale) follows in second place. A further however rarely isolated dermatophyte in onychomycosis is Epidermophyton floccosum. Candida parapsilosis, Candida guilliermondii, and Candida albicans, followed by Trichosporon spp. are the most important yeasts which are found in onychomycosis. The molds most often responsible include Scopulariopsis brevicaulis, and several Aspergillus species, e. g. Aspergillus versicolor, and Fusarium spp. These so called non-dermatophyte molds (NDM) are increasingly isolated as emerging pathogens in onychomycosis. The diagnosis of onychomycosis should be verified in the mycology laboratory. Conventional diagnostic methods include the direct examination, ideally using fluorescence staining with Calcofluor® or Blancophor®, and culture. However, new molecular biological methods primarily employing the polymerase chain reaction (PCR) for direct detection of dermatophyte DNA in skin scrapings and nail samples have been introduced into routine mycological diagnostics. The diagnostic sensitivity is higher when both conventional and molecular procedures are combined.

Diagnostic procedures in dermatology

Although most skin diseases can be diagnosed with simple visual inspection, laboratory investigations are necessary in several clinical circumstances. This contribution highlights the usefulness of routine diagnostic procedures that are often overlooked and the innovative methods of molecular biology, which are expensive and require an experienced staff. Among the classic diagnostic investigations are (1) the use of Wood's light in many dermatologic disorders (eg, vitiligo, pityriasis versicolor, erythrasma, porphyrias), (2) cytodiagnosis of Tzanck in dermatologic practice (eg, herpetic infections, molluscum contagiosum, leishmaniasis, pemphigus vulgaris, basal cell carcinoma, erythroplasia of Queyrat, Hailey-Hailey disease), and (3) microscopic examination for fungal and bacterial skin infections as well as for mite infestation using potassium hydroxide, simple saline, and Gram stain. Modern molecular biotechnologies encompassing gene-specific polymerase chain reaction and its variants have a substantial affect in selected cases of viral (especially herpes simplex virus), bacterial, fungal, and protozoan (Leishmania) skin infections.

Is there yet any place for reagent strips in diagnosing spontaneous bacterial peritonitis in cirrhotic patients? An accuracy and cost-effectiveness study in Brazil

BACKGROUND

Diagnosis of spontaneous bacterial peritonitis (SBP) is currently based on ascitic cell counting, but there is a need for a more simple and rapid diagnostic tool. The objectives of this study are to evaluate the accuracy of reagent strips in diagnosing SBP and compare their costs with total and differential cell counts.

PATIENTS AND METHODS

71 cirrhotic in- and outpatients were consecutively included (159 samples). Spontaneous bacterial peritonitis was defined as neutrophil cells >or= 250/microL. The cutoff values for each reagent strip were defined by a receiver operating characteristic (ROC) curve. Sensitivity (S), Specificity (Sp), Positive and Negative Predictive Values (PPV and NPV), Accuracy (Ac) and cost-effectiveness (US$) in comparison to cell count exam were calculated.

RESULTS

Spontaneous bacterial peritonitis was diagnosed in 17 patients (23.9%), 11 of them with positive culture (64.7%). The best cutoff points found in ROC curves were 1+ for Multistix 10 SG and ca. 75 for Choiceline 10 (Multistix 10 SG S = 80%, Sp = 98.5%, PPV = 90.9%, NPV = 96.2%, Ac = 95%; Choiceline 10 S = 76.9%, Sp = 97.7%, PPV = 87%, NPV = 95.6%, Ac = 94%). In terms of cost-effectiveness by cost/accuracy, cell count was 41.5, Multistix 10 SG 0.57, and Choiceline 10, 0.19 (P < 0.001).

CONCLUSION

Reagent strips are a useful tool for diagnosing SBP in cirrhotic patients, but they have some limitations. Strips are especially indicated when total and differential cell counts are not quickly available or sometimes unavailable. They are also indicated as screening test in emergency rooms to anticipate the diagnosis of SBP and allow its early treatment. It's an interesting option in developing countries.

Metabolic syndrome associated with toenail onychomycosis in Taiwanese with diabetes mellitus

BACKGROUND

Onychomycosis is a complication of diabetes mellitus (DM), which has a deleterious impact on the quality of life. Aim To explore the prevalence of onychomycosis amongst Taiwanese diabetics, and to analyze the factors associated with onychomycosis after adjusting for age and sex.

METHODS

A total of 1245 Taiwanese diabetics were enrolled, and a nested case-control study was performed by onychomycosis outcome and the exposures were compared.

RESULTS

The overall prevalence of onychomycosis among DM patients was 30.76% (383/1245), with a significantly higher prevalence in men than in women (P = 0.024). The factors associated with onychomycosis in matched pairs by gender and age were analyzed in 375 pairs. It was found that metabolic syndrome, obesity, triglyceride (TG) levels, and glycosylated hemoglobin (HbA1c) were associated with onychomycosis (P < 0.05).

CONCLUSION

Higher prevalence rates of onychomycosis were found in men and older DM patients. Metabolic syndrome, obesity, high TG levels, and poor glycemic control were associated with onychomycosis.

Conventional methods for the diagnosis of dermatophytosis

Dermatophytes are keratinolytic fungi responsible for a large variety of diseases that can affect glabrous skin, nails and hair. In many cases, the diagnosis is not clinically obvious, and mycological analysis is required. This includes both direct microscopic examination and cultures. First of all, clinical specimens have to be sampled according to localization and characteristics of the lesions. Direct microscopic examination is usually performed using clearing reagents (KOH or Amman's chloral-lactophenol), but its sensitivity may be greatly enhanced by the use of stains or fluorochromes such as Congo red or Calcofluor white. Histological analysis is an efficient method, but it is constraining for the patients and, as direct examination, it does not allow precise identification of the pathogen. Cultures are therefore needed, and specific culture media may be used to overcome the growth of rapidly growing contaminating moulds which may hamper the recovery of dermatophytes. Identification at the species level which may be useful to initiate an appropriate treatment or for setting prophylactic measures, relies on macroscopic and microscopic morphology. Subcultures on culture media which stimulate conidiation and, for some species, the production of pigments, are often necessary. Additionally, in case of atypical isolates, some biochemical or physiological tests may be performed such as the search for urease activity or the in vitro hair perforation test. However, their contribution to species identification is rather limited, and progress is still needed for the development of biochemical or immunological tests allowing an accurate identification at the species level, pending for the availability of molecular biology-based kits.

Use of diagnostic tests by dermatologists, podiatrists and family practitioners in the United States: pilot data from a cross-sectional survey

Before treating onychomycosis, it is important to exclude other conditions such as lichen planus and psoriasis. The purpose of this study was to evaluate physician preferences and uses of diagnostic tests for toenail onychomycosis (TO) by surveying dermatologists (D), podiatrists (P) and family practitioners (FP) in the United States. Surveys were mailed to approximately 1000 randomly sampled physicians from each of the three specialities. The questionnaire consisted of 15 items regarding physician and practice characteristics, number of patients with TO seen and treated, tests used to diagnose TO and reasons for using the tests. Results were analysed using several statistical methods. Response rates were low (D33.7%; P16.6%; FP28.4%). Ds and Ps (75.2%) and FPs (43.4%) reported feeling 'very confident' at diagnosing onychomycosis. KOH was the preferred diagnostic test for all three specialities. More Ds (75.4%) felt 'very confident' interpreting potassium hydroxide (KOH) exams than Ps (24.9%) and FPs (18.5%). Use of KOH exams was statistically associated with confidence interpreting exams (P P = 0.04092; D & FP P < 0.0001). Some FPs (46.6%) and Ps (21.6%) did not obtain a confirmatory diagnostic test prior to the treatment of onychomycosis while 63.6% of Ds 'almost always/always' did. While limited by low-response rate, this study provides pilot information on the diagnostic preferences for TO by American D, P and FP.

Validity of self-reported nail counts in patients with onychomycosis: A retrospective pilot analysis

BACKGROUND

Onychomycosis (fungal infection of the toenails or fingernails) is common, affecting up to 8% of the general population. Telephone and mailed surveys conducted to study this disease are usually completed via patient self-report. The validity of the counts of diseased nails reported by the patients participating in these surveys has not been established.

OBJECTIVE

The aim of this study was to assess the interrater agreement between patient and health care professional (HCP) counts of affected nails in patients with onychomycosis.

METHODS

Patient and HCP counts of infected toenails and fingernails corresponding to a total of 567 patients originating from 3 different clinical trials were retrospectively analyzed. All these patients were initially classified as mycologically positive for toenail onychomycosis, and all 3 trials used identical self-administered questions regarding counts of infected toenails and fingernails. The level of agreement between patient versus HCP counts of infected toenails and fingernails (based on collapsed and uncollapsed counts) was measured using the quadratically weighted kappa statistic.

RESULTS

Thirty-eight percent (213/554, 95% confidence interval [CI] = 35% to 43%) of the 554 patients with self-reported and HCP counts of infected toenails had exact agreement; for these 554 patients, quadratically weighted kappa = 0.47 (95% CI: 0.40 to 0.54). The highest agreement rates-79, 62, and 50%-correspond to the patients with HCP counts of affected toenails equaling 1, 2, and 10, respectively; that is, HCP counts at the extremes. The agreement rates ranged from 3% to 31% for the remaining patients with HCP counts between 3 and 9. Patients tended to undercount affected toenails, irrespective of the number of affected toenails counted by HCPs. No statistically significant association was found between agreement rates and whether or not the patients had been previously treated for toenail onychomycosis (P = .91). A marginally nonsignificant association of increasing agreement rates with increasing disease duration was observed (P = .06). Among the patients who reported one or more affected fingernails (n = 122), percent agreement was similar to that of toenails (41%, 95% CI: 33.0 to 50.0%).

LIMITATIONS

This pilot study is limited by its retrospective design, its homogeneous group of patients (predominantly white, male veterans), and the fact that information on intraobserver and interobserver reliability was not obtained from all of the 3 clinical trials, the sources for this analysis.

CONCLUSIONS

Patients tend to undercount affected nails as compared to HCPs. Reliance on self-reported counts in epidemiological surveys may lead to an inaccurate, underestimate of disease severity.

New fungal nail infections

PURPOSE OF REVIEW

The number of people affected by onychomycosis continues to increase. The prevalence of different pathogens in different areas depends on several factors, such as climate, geography and migration. We reviewed the recent literature to identify new agents responsible for onychomycosis.

RECENT FINDINGS

Recent studies performed in different countries are not only reporting molds and yeasts as contaminants, but are increasingly reporting them as pathogens. Infection by novel agents is also being reported, although the individual cases do not necessarily indicate that these are emerging agents.

SUMMARY

Clinicians should bear in mind the increased number of case series reporting the role of molds and yeasts in onychomycosis, and should not treat the disease without first examining the mycology results. The question remains as to whether these agents are truly new fungi responsible for onychomycosis, or whether improvement of diagnostic techniques and increasing reference to such species in the literature has resulted in better identification of such agents.