Clinical diagnosis of toenail onychomycosis - diagnostic rules

NewsBot · Mar 9, 2011

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Clinical diagnosis of toenail onychomycosis is possible in some patients: cross-sectional diagnostic study and development of a diagnostic rule.
Garcia-Doval I, Cabo F, Monteagudo B, Alvarez J, Ginarte M, Rodríguez-Alvarez MX, Abalde MT, Fernández ML, Allegue F, Pérez-Pérez L, Flórez A, Cabanillas M, Peón G, Zulaica A, Del Pozo J, Gomez-Centeno P.
Br J Dermatol. 2010 Oct;163(4):743-51. doi: 10.1111/j.1365-2133.2010.09930.x.

BACKGROUND: Suspected toenail onychomycosis is a frequent problem. Clinical diagnosis has been considered inadequate.

OBJECTIVES: To assess the diagnostic accuracy of clinical findings for detecting fungi in toenails, and to develop and validate a clinical diagnostic rule aimed at improving dermatologists' diagnosis of onychomycosis.

METHODS: A cross-sectional diagnostic study was performed including a total of 277 patients seen by 12 dermatologists. The gold standard was the presence of dermatophytes on culture or a positive nail plate biopsy. For each sign we described prevalence, sensitivity, specificity, positive and negative predictive values, and likelihood ratios for positive and negative results. We developed a diagnostic clinical rule and validated it in a subsample.

RESULTS: Helpful findings to predict the presence of fungi are: previous diagnosis of fungal disease; abnormal plantar desquamation (affecting > 25% of the sole); onychomycosis considered the most probable diagnosis by a dermatologist; and presence of interdigital tinea. When dermatologists considered onychomycosis the most probable diagnosis and plantar desquamation was present (13% of patients), the positive predictive value for presence of fungi was 81%. When both signs were absent (34% of patients), the positive predictive value for absence of fungi was 71%. In other situations, clinical diagnosis might not give enough information to decide on therapy.

CONCLUSIONs: In 13% of the patients (a large number in absolute terms), when dermatologists consider onychomycosis the most probable diagnosis and plantar desquamation is present, therapy should be started without any further test, as clinical diagnosis is at least as accurate as laboratory tests. In other situations, an optimal management strategy should be defined.
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NewsBot · Dec 18, 2013

Comparison of direct microscopy, culture and calcofluor white for the diagnosis of onychomycosis.
Bonifaz A, Rios-Yuil JM, Arenas R, Araiza J, Fernández R, Mercadillo-Pérez P, Ponce-Olivera RM.
Rev Iberoam Micol. 2013 Apr-Jun;30(2):109-11.

BACKGROUND:
Mycological diagnosis of onychomycosis can be performed by direct microcopy (KOH), cultures and calcofluor white.
AIMS:
To compare the percentage of positivity and the degree of correlation of KOH, cultures and calcofluor white for the diagnosis of onychomycosis.
METHODS:
Descriptive, transversal and comparative study. Samples of toenails with onychomycosis were used for KOH, cultures and calcofluor white under fluorescence. The percentage of positivity of the different techniques was calculated and the degree of correlation between them was determined (Epi Info v 3.4.3(©)).
RESULTS:
KOH was positive in 66.67% of the cases, cultures in 33.33% and calcofluor white in 57.58%. KOH and calcofluor white had a higher percentage of positivity than culture (p<0.01 and p<0.05 respectively). The degree of correlation between KOH and calcofluor white was excellent (κ=0.8085; p<0.0001); however, the degree of correlation between KOH and culture and between calcofluor white and culture was poor.
CONCLUSIONS:
The use of calcofluor white is not recommended in routine laboratories because it does not seem to bring any additional benefits when comparing with KOH. This is especially important when funding is a great problem.
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NewsBot · Jun 6, 2014

Using a Polymerase Chain Reaction as a Complementary Test to Improve the Detection of Dermatophyte Fungus in Nails.
María José Iglesias Sánchez, Ana María Pérez Pico, Félix Marcos Tejedor, María Jesús Iglesias Sánchez, and Raquel Mayordomo Acevedo
Journal of the American Podiatric Medical Association: May 2014, Vol. 104, No. 3, pp. 233-237.

Background: Dermatomycoses are a group of pathologic abnormalities frequently seen in clinical practice, and their prevalence has increased in recent decades. Diagnostic confirmation of mycotic infection in nails is essential because there are several pathologic conditions with similar clinical manifestations. The classical method for confirming the presence of fungus in nail is microbiological culture and the identification of morphological structures by microscopy.

Methods: We devised a nested polymerase chain reaction (PCR) that amplifies specific DNA sequences of dermatophyte fungus that is notably faster than the 3 to 4 weeks that the traditional procedure takes. We compared this new technique and the conventional plate culture method in 225 nail samples. The results were subjected to statistical analysis.

Results: We found concordance in 78.2% of the samples analyzed by the two methods and increased sensitivity when simultaneously using the two methods to analyze clinical samples. Now we can confirm the presence of dermatophyte fungus in most of the positive samples in just 24 hours, and we have to wait for the result of culture only in negative PCR cases.

Conclusions: Although this PCR cannot, at present, substitute for the traditional culture method in the detection of dermatophyte infection of the nails, it can be used as a complementary technique because its main advantage lies in the significant reduction of time used for diagnosis, in addition to higher sensitivity.
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NewsBot · Jun 28, 2014

Molecular Determination of Mixed Infections of Dermatophytes and Nondermatophyte Moulds in individuals with Onychomycosis.
Aditya K. Gupta and Kerry-Ann Nakrieko
Journal of the American Podiatric Medical Association In-Press.

Background: Reports of mixed infections with NDMs and dermatophytes in onychomycosis are rare, possibly due to the inhibition of NDM growth during traditional culture.

Objective: To determine the prevalence of mixed infections in onychomycosis using molecular identification.

Methods: Molecular analyses were utilised to identify infecting organisms directly from at least two serial great toenail samples from each of the 44 subjects.

Results: Mixed infections were present in 41% (18/44) of the subjects. A single co-infecting NDM was the most common mixed infection and was detected in 34% (15/44) of onychomycosis patients, with F. oxysporum present in 14% (6/44), S. brevicaulis in 9% (4/44), Acremonium spp in 2% (1/44), Aspergillus spp. in 4.5% (2/44) and Scytalidium spp. in 4.5% (2/44) of patients. Mixed infections with two NDMs were found in 7% (3/44) of the subjects.

Conclusions: Mixed dermatophyte/NDM onychomycosis infections may be more prevalent than previously reported.
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NewsBot · Sep 10, 2014

Diagnosis and treatment monitoring of toenail onychomycosis by reflectance confocal microscopy: prospective cohort study in 58 patients.
Pharaon M, Gari-Toussaint M, Khemis A, Zorzi K, Petit L, Martel P, Baran R, Ortonne JP, Passeron T, Lacour JP, Bahadoran P.
J Am Acad Dermatol. 2014 Jul;71(1):56-61.

BACKGROUND:
The clinical presentation of onychomycosis is often nonspecific and can lead to inappropriate antifungal therapy. Available mycologic tests share many drawbacks.
OBJECTIVE:
We sought to evaluate the accuracy of reflectance confocal microscopy (RCM) for the diagnosis of onychomycosis compared with standard mycologic tests.
METHODS:
In all, 58 patients with suspected onychomycosis were enrolled prospectively. RCM, potassium hydroxide preparation, and fungal culture were performed at baseline and after treatment in patients with confirmed onychomycosis. RCM diagnosis of onychomycosis was based on the presence of filamentous and/or roundish structures in the nail plate, corresponding respectively to septate hyphae and/or arthroconidia.
RESULTS:
Of patients, 46 of 58 were correctly classified by RCM, with a diagnosis yield of 79.3%, sensitivity of 52.9%, specificity of 90.2%, positive predictive value of 69.2%, and negative predictive value of 82.2%. The use of a handheld RCM imager permitted a faster examination with the same accuracy. RCM performed after treatment in 9 patients showed a normal nail plate, and healing was confirmed by mycologic tests or by follow-up.
LIMITATIONS:
Existing RCM scanner heads are not intended for nail examination.
CONCLUSION:
RCM has excellent specificity and can be used as a rapid, office-based test to strengthen the prescription of antifungal therapy and for follow-up. Technical improvement could aid sensitivity.
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NewsBot · Feb 1, 2016

Onychomycosis – A Small Step for Quality of Care
Shari R. Lipnera & Richard K. Schera
Current Medical Research and Opinion

Onychomycosis is a fungal infection of the nail unit, representing the most common nail disorder and accounting for 50% all nail diseases. Unfortunately, many patients are mismanaged, as physicians routinely treat onychomycosis empirically, falsely believing that they can make the diagnosis based on history and clinical inspection alone. We propose and provide evidence for why the diagnosis of onychomycosis should be confirmed by objective methods in each patient before initiating treatment.
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NewsBot · Mar 30, 2016

Comparison of diagnostic methods for onychomycosis, and proposal of a diagnostic algorithm.
Jung MY et al
Clin Exp Dermatol. 2015 Jul;40(5):479-84

BACKGROUND:
Traditionally, the gold standard for diagnosis of onychomycosis has been the combination of direct microscopy with potassium hydroxide (KOH) staining and fungal culture. However, several studies have suggested that periodic-acid-Schiff (PAS) staining of nail-plate clippings may be a very sensitive method for the diagnosis of onychomycosis.
AIM:
To compare the sensitivities of direct microscopy with KOH, fungal culture and PAS staining of nail-plate clippings, and to define an efficient, high-yield and cost-effective diagnostic strategy for the diagnosis of onychomycosis in the clinical setting.
METHODS:
We evaluated a total of 493 patients with clinically suspected onychomycosis. Group A comprised 400 patient samples, evaluated using fungal culture and PAS stain, while group B comprised 93 patient samples evaluated using KOH, fungal culture and PAS. Diagnosis of onychomycosis was defined as clinical morphology plus at least one positive test result.
RESULTS:
In group A, sensitivities of fungal culture and PAS were 49.5% and 93.1% (P < 0.005), respectively. In group B, the most sensitive single test was PAS (88.2%) followed by KOH (55.9%) and fungal culture (29.4%). The combination of fungal culture and PAS (94.1%) was significantly (P < 0.001) more sensitive than that of KOH and culture (72.1%).
CONCLUSION:
PAS staining of nail clippings is much more sensitive than KOH and fungal culture for the diagnosis of onychomycosis. Based on our results, we propose a diagnostic algorithm for onychomycosis that takes into consideration the sensitivity, cost-effectiveness and necessary time for each test.
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NewsBot · Sep 21, 2016

A Retrospective Study of Onychomycosis, Clinical Diagnosis Versus Laboratory Diagnosis
Arwa M El-Sayed, Marc Karpo, Aisha Jasani, Ebony Love, and Lesly Robinson
Journal of the American Podiatric Medical Association: September 2016, Vol. 106, No. sp1, pp. 5-5.

INTRODUCTION AND OBJECTIVES: Onychomycosis is defined as a fungal infection of the nail usually caused by a dermatophyte. This retrospective study will compare the diagnosis of onychomycosis based on clinical exam findings in comparison to laboratory results.

METHODS: Clinical diagnosis of onychomycosis of the nail is made through visual inspection of the nail. The characteristics that define a clinical diagnosis of onychomycosis include but is not limited to: thickness of nail, discoloration (yellow, black, and/or brown), crumbly texture, subungual debris, subungual fluid, splitting of the nail, and/or nail dystrophy. Patients were treated with either a topical or oral drug and this was based solely on the clinical characteristics of the nail with no further lab testing. The most recent 50 charts from the past three years (1/1/2013 to 1/31/2016) were utilized to conduct this retrospective study. The charts were analyzed based on the following criteria: patients that were clinically diagnosed with onychomycosis and also had a positive laboratory results that included a PAS, PCR, or KOH staining.

RESULTS: We found that there was a higher incidence of clinically positive diagnosis vs. laboratory culture positive results.

CONCLUSIONS: As expected fungal nail cultures are sometimes less sensitive than our clinical evaluation. This may be due to false negatives or failure to obtain an adequate sample for culture analysis. This may effect treatment standard of care and accuracy of treatment.
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NewsBot · Apr 6, 2017

Examining the accuracy of visual diagnosis of tinea pedis and tinea unguium in aged care facilities.
Goto T et al
J Wound Care. 2017 Apr 2;26(4):179-183. doi: 10.12968/jowc.2017.26.4.179.

OBJECTIVE:
The aim of this study was to examine the accuracy of visual diagnosis of tinea pedis (Athlete's foot) and tinea unguium (fungal nail infection), as well as to provide information on skin abnormalities that could help identify these diseases in aged care facilities (long-term care facilities (LTCFs) and nursing homes).
METHOD:
A multicentre, cross-sectional observational study was conducted in a LTCF and two nursing homes. A dermatologist observed the skin abnormalities in the participants' interdigital and plantar areas, to screen for tinea pedis, and in the participants' toenails, to screen for tinea unguium. If abnormalities were noted, samples such as scales or toenails were collected and examined using direct microscopy. The accuracy of the macroscopic observation for each skin abnormality was examined.
RESULTS:
A total of 173 residents were recruited. The accuracy of clinical diagnosis using macroscopic observation was relatively low. The sensitivities and specificities for clinical diagnosis were 0.37 and 0.95 for tinea pedis in the interdigital areas, 0.47 and 0.94 for tinea pedis in the plantar areas, and 0.80 and 0.61 for tinea unguium in toenails, respectively. Scales in the plantar areas and discoloration of the toenails were more frequently observed in residents with tinea pedis and tinea unguium than in those without them.
CONCLUSION:
Several skin abnormalities were observed in the residents recruited in this study, but there was insufficient correlation with tinea pedis and tinea unguium to be used for screening.
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NewsBot · Nov 2, 2017

Comparison of KOH Mount Using Standard Technique and Cellophane Tape
Method for Diagnosis of Superficial Fungal Infections
B. Navya and Saroj Golia
Int.J.Curr.Microbiol.App.Sci (2017) 6(10): 494-499

Superficial fungal infections include Tinea versicolor and Dermatophytosis. Tinea
versicolor infects stratum corneum which is caused by lipophilic yeast-like fungi i.e.
Malassezia species. Dermatophytosis infects keratinised structures (skin, hair and nails)
caused by a group of keratinophilic fungi called dermatophytes. KOH mount is the
preliminary, convenient and inexpensive test for diagnosis of superficial fungal infections.
This study compares the detection rate and visualisation of fungal elements by KOH
mount using standard technique and cellophane tape method. This study was carried out in
the Department of Microbiology, Dr B R Ambedkar Medical College, K G Halli,
Bangalore for a period of 6 months from August 2016 to January 2017. A total of 250 skin
scrapings were collected from clinically diagnosed patients with superficial fungal
infections (Tinea versicolor- 76, Dermatophytosis- 174). Preliminary KOH mount
examination was done by standard technique. The same patients were also studied by a
modified technique by using cellophane tape method for KOH mount. Out of 250 clinical
samples, 71 were positive for Malassezia species, 170 were positive for Dermatophytes
and 9 were negative for fungal elements. Standard technique and cellophane tape method
of KOH mount both were positive for fungal elements in 91.6% of samples. Standard
technique of KOH mount was negative but cellophane tape method was positive in 4.8%
of samples. Both the methods were negative in 3.6% of the samples. The present study
concludes that there is a higher rate of detection and the morphology of fungal elements
were better visualised by cellophane tape method of KOH. Also, the standard technique of
KOH mount is time consuming compared to cellophane tape method. Cellophane tape
method of KOH mount is easier and convenient for collection and transport of specimen as
well. Thus, cellophane tape method of KOH mount serves as a better preliminary
diagnostic tool than the standard conventional technique.
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NewsBot · Jan 1, 2019

Clinical and Laboratory Findings in Trauma-Induced
Nail Dystrophy versus Onychomycosis
Sumanas Bunyaratavej
Siriraj Med J 2018;70: 490-4

Objective: The study aims to investigate prevalence, clinical characteristics, and laboratory findings of traumatic
toenails in comparison with those of onychomycosis.
Methods: This cross-sectional study included hallux valgus (HV) patients attending Foot Clinic. Descriptive statistics,
Chi-square test, Student’s t-test and Mann-Whitney U test were used in statistical analysis.
Results: A total of 81 patients with a mean age of 65 years old, of which 77 were females (95.1%), were enrolled.
The prevalence of onychomycosis was 25.9%, whereas that of trauma-induced nail dystrophy was 55.6%. There
were 18 (22.2%) patients with fungal feet infection. Among 21 patients with nail infections, three had subclinical
presentation. Fifteen patients (71.4%) with onychomycosis were infected with dermatophytes (DMPs). The others
were caused by nondermatophytes (NDMs), of which 14.2% were Neoscytalidium dimidiatum. Comparing with
traumatic nail, statistical analysis revealed HV angle of greater than 30 degrees and the presence of fungal foot
infection to be significantly associated with onychomycosis (p=.011 and p<.001, respectively).
Conclusion: One-fourth of HV patients had onychomycosis. Severe foot deformities and concomitant fungal
foot infection were significantly associated with onychomycosis. Holistic foot and nail examination is essential
for distinguishing onychomycosis and traumatic induced nail dystrophy. Subclinical presentation was common.
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NewsBot · Sep 15, 2023

Developing diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes
Charussri Leeyaphan et al
Heliyon. 2023 Aug 4;9(8):e18963

Background: The predisposing factors and clinical presentations of fungal foot infections caused by non-dermatophytes and dermatophytes are challenging to differentiate. Definite diagnoses of non-dermatophyte infections at first visits facilitate their treatment.

Objectives: This study aimed to develop diagnostic criteria to differentiate fungal foot infections caused by Neoscytalidium dimidiatum and dermatophytes.

Methods: Diagnostic prediction research based on a retrospective, observational, cross-sectional study. The reviewed patients were aged ≥18 and underwent a mycological examination for fungal foot infections. A fungal culture at the initial visit was the gold standard for determining causative organisms.

Results: Analyses were carried out on the data from 371 patients. N. dimidiatum accounted for 184 (49.6%) infections, and dermatophytes caused the remaining 187 (50.4%) cases. Five significant predefined predictors were used to develop the diagnostic criteria and score. They were immunocompetence status, no family history of fungal infections, the absence of pruritus, the absence of other concurrent fungal skin infections, and agricultural work. The lower score cutoff was <8 (sensitivity 97.8% and specificity 25.7%). The higher cutoff was >11 (sensitivity 83.7% and specificity 57.8%). The score showed an area under the receiver operating characteristic curve of 0.755 and was well calibrated.

Conclusions: The criteria and score show promise for clinical use, with acceptable discriminative performance and good calibration. They will help physicians differentiate the causative organisms in patients with fungal foot infections at the first visit, enabling the determination of appropriate antifungal treatment.
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