Modified PAS stain: A new diagnostic method for onychomycosis

BackgroundOnychomycosis is the most common nail disease and represents around 50% of nail disorders. Accurate diagnosis with adequate evidence is ideal before starting any treatment. Current diagnostic methods offer low specificity and sensitivity.AimsTo create a new method for the diagnosis of onychomycosis, and to compare its sensitivity and specificity with the existing methods.MethodsOne hundred and ninety-two samples with clinical suspicion of onychomycosis were included and underwent modified PAS stain (M-PAS), KOH/chlorazol black (KOH/CB) and culture testing. Sensitivity, specificity, positive and negative predictive values were calculated.ResultsIn 152 out of 192 samples (79.2%) fungi structures were found in at least one of the three tests performed, and the patients were diagnosed with onychomycosis; 40 samples out of 192 (20.8%) were negative. Using M-PAS, filaments and/or spores were seen in 143 samples from the 152 positive (94%); 39 of them were negative to KOH/CB and positive to M-PAS (25.6%). With KOH/CB, filaments and/or spores were seen in 113 cases from the 152 positive samples (73.8% of the onychomycosis cases). Thirty-five cultures were positive, of which 77% were identified as Trichophyton rubrum; 117 onychomycosis cases were diagnosed despite the negative culture (76.9%). M-PAS showed 92.5% sensitivity and 55.55% specificity, a 67.5% positive predictive value and a 81.6% negative productive value.ConclusionsThis procedure, a combination of the existing methods to diagnose onychomycosis, KOH/CB together with a nail clipping biopsy, proved to have high sensitivity, as well as being rapid, easy, inexpensive and readily available in most hospital settings. M-PAS allowed us to diagnose 39 cases (25.6% of the cases of onychomycosis) that were false negative using only KOH/CB and culture.     

Onychomycosis due to saprophytic fungi

Twenty five cases of onychomycosis due to filamentous saprophytic agents were diagnosed within the period 1981–1982 in two mycology laboratories in Medellín, Colombia. These cases represented 4.5% and 9.5% respectively of the total fungal nail lesions (FNL) seen at those institutions. No explanation was found for the high frequencies, which sharply contrast with the previous local experience with the disease (0.4% of FNL). The responsible agents belonged to the following genera in decreasing order of frequency: Fusarium, Aspergillus, Scopulariopsis, Penicillium and Lasiodiplodia; two patients were infected with unidentified dematiaceous fungi and two more had the association of a saprophyte and a dermatophyte. In every case direct KOH preparations revealed septate hyphae, associated in 14 patients (56%) with chlamydoconidia. The only predisposing factors that were common to all these patients were age above 20 years and the use of footwear.     

Non-dermatophytic Molds as Agents of Onychomycosis in Izmir,Turkey – A Prospective Study

The purpose of this study was to determine the prevalence of causative non-dermatophytic filamentous fungi in onychomycosis. Totally 1,222 (1,222 × 3 = 3,666) samples of nail scrapings from 1,146 patients (from 76 patients two specimens: both from finger- and toe-nails) with prediagnosis of onychomycosis sent to the Mycology Laboratory from the Clinic of Dermatology, Ege University Hospital, Izmir, Turkey, July 2001–December 2003, were prospectively studied with conventional mycological procedures. The set criteria for the diagnosis of onychomycosis due to non-dermatophytic molds were: (1) Observation of fungal elements in 15% KOH-preparations made from nail scrapings, (2) growth of the same mold in all three consecutive cultures of the specimens taken three times from the same patient with one-week intervals, (3) no growth of a dermatophyte or yeast in three consecutive cultures. As agents of onychomycosis molds were detected in 33 (9%), dermatophytes in 175 (48%), yeasts in 150 (41%), and mixed (two different fungi) in 8 (2%) patients. In cases of mold onychomycosis, 11 (33%) had finger-nail and 22 (67%) toe-nail infection; 25 (76%) were female and 8 (24%) male; and 27 (82%) were above 40 years of age. The agents of mold onychomycosis, in order of frequency, were Aspergillus niger (7), Acremonium spp. (6), Fusarium spp. (6), Ulocladium spp. (4), sterile mycelia (2), Alternaria sp. (1), Aspergillus flavus (1), Aspergillus fumigatus (1), Aspergillus terreus (1), Cladosporium sp. (1), Paecilomyces spp. (1), Scopulariopsis sp. (1) and Trichoderma sp. (1). In conclusion, this study showed that non-dermatophytic molds were responsible for nearly 10% of onychomycoses cases attending the dermatology outpatient clinic of a university hospital in Izmir, Turkey. Since molds are common contaminants in the laboratory, cultures from consecutively taken nail scrapings should be made and carefully evaluated in order to diagnose a “mold onychomycosis”.     

Study of onychomycosis in Córdoba,Spain: Prevailing fungi and pattern of infection

From a total of 20 004 patients seen during two years, we carried out a mycologic nail investigation (direct microscopy and repeated cultures). Ninety-three (43.2%) of the nails were judged to be infected by their clinical appearance. They fulfilled the laboratory criteria required to start antifungal treatment (isolation of the same fungus in culture on two consecutive occasions), but only in 64 cases (29.7%) was there a clinical and mycological recovery once antifungal treatment and follow up were completed.Yeasts were isolated in two thirds of the cases of onychomycosis, mainly from fingernails. Candida albicans, C. parapsilosis or both were the most prevalent species. Dermatophytes were found in 18.8% of the samples, especially from toenails. Trichophyton rubrum was the predominant species. Non-dermatophytic filamentous fungi were cultured in 17.2%, Scopulariopsis brevicaulis being the most prevalent species.The highest prevalence of onychomycosis was found in patients between 50 and 70 years of age. Females were affected more frequently than males. Fingernails were affected more frequently than toenails. Proximal subungual onychomycosis, secondary to paronychia (PSOp), was the most prevalent clinical type, although primary distal and lateral subungual onychomycosis (DLSO) and total dystrophic onychomycosis (TDO) were also frequent. PSOp was only observed in fingernails, while DLSO was almost only seen in toenails and TDO in both fingernails and toenails. All the clinical types were more frequent in women except TDO, which showed a similar prevalence in both sexes.This revised version was published online in October 2005 with corrections to the Cover Date.     

Mycological study of 100 cases of ungual lesions of Rosario city (Republica Argentina)

The aim of present work was to analyze several diagnostic methods of nail infections relating to various etiological agents with the different types of lesions and their probable predisposing causes. One hundred nail samples were studied including the following laboratory test: Direct microscopic exams with 40% KOH, direct exams in fluorescence microscope with calcoflúor white and mycological cultures. One or more of these methods gave positive results in 65% of the samples tested. The fungi isolated by culture were the following: Candida (predominantly non-albicans, which appeared in 70.8% of the cases), dermatophytes (25% of the cases) and opportunistic fungi (4.2%). Females showed a higher incidence of fungal infection. Candida were more frequent in finger nails, while dermatophytes occurred mainly in toe nails. The clinical characteristic of the lesions produced by Candida were: tricophytoid type (67%) and periungeal type (33%). On the other hand, dermatophytes and opportunistic fungi produced distal subungual type lesions. Since correlation between direct examination and cultures is not always found in mycological studies, based in our present results we suggest that, although they must always be carried out, both should be repeated with the addition of direct examination with calcoflúor in the cases in which the diagnosis is difficult.     

The frequency of Candida species in onychomycosis

Mycological investigation of 108 nail specimens taken from a total of 41 patients examined over three years included direct microscopy and repeated cultures. A higher incidence of onychomycosis of the fingernails (75%) was observed in women while afflictions of the toenails (71%) prevailed in men. The highest prevalence of onychomycosis was found in patients between 50 and 70 years of age.Candida albicans was the dominant organism causing onychomycosis (prevalence rate 60.9%), followed byC. parapsilosis (19.6%),C. tropicalis (9.8),C. krusei (4.9),C. guilliermondii andC. zeylanoides (2.4% each).     

Toenail Onychomycosis in a Portuguese Geriatric Population

Onychomycosis is a common fungal infection of the nail but few data of mycological features in geriatric Portuguese population are yet available. The aim of this study was to perform a mycological examination and characterization of fungal nail pattern of a geriatric population from the north of Portugal clinically suspected of onychomycosis. A total of 108 patients attending the Podology Service in the Centro Hospitalar do Alto Ave (Portugal) from October 2007 to January 2009 were enrolled. All were suspected of having onychomycosis by the abnormal appearance of their nails. From these, 59.3% were diabetic. Distal and lateral subungual onychomycosis was the more common clinical pattern followed by total dystrophic onychomycosis. In 21.3% cases, every nail in both feet had an abnormal appearance. In 86%, the hallux was involved in at least one foot. Fifty samples were culture positive, and fifty-four isolates were reported regardless of the questionable pathogenicity of the infectious agent. In three cases, clinical feature of the nail, direct microscopy, and culture were consistent with Scopulariopsis infection. Fusarium spp. were identified in three cases; however, only one isolate was preceded by the observation of branching septate filaments by direct microscopy. No mixed infections with dermatophytes were reported. Trichophyton rubrum was the dermatophyte most frequently isolated (83.3%) followed by Trichophyton interdigitale. In Portugal, onychomycosis is still viewed by general population as a cosmetic condition. Health risk is enhanced in geriatrics that only perceived the severity of their condition when experiencing further foot complications that include bacterial infection and pain.     

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.     

Candidal onychomycosis: A Mini-Review

Onychomycosis is a common fungal infection affecting nails. The primary cause for onychomycosis is dermatophytes, while Candida species have emerged as second-line pathogens. Onychomycosis due to Candida (candidal onychomycosis) is increasingly found in individuals having defective immunity consequential to aging, diabetes mellitus, vascular diseases, HIV infection and drug therapies such as immunosuppressives and broad-spectrum antibiotics. Breached local immunity at the nail complex due to trauma, chronic exposure to moisture and chemicals including smoke, detergents, soap, etc., also contribute to candidal onychomycosis. Adhesion, filamentation, secretion of extracellular enzymes and the development of antifungal resistance are some of the virulence mechanisms of Candida species associated with onychomycosis. Diagnosis of onychomycosis depends on history and clinical examination, direct microscopic investigation, mycological culture and histopathology. Restoration of immune defenses, elimination of fungi using appropriate drug therapy and improvement of nail hygiene with the removal of predisposing factors are key aspects in the management of candidal onychomycosis.     

Onychomycosis in Rome,Italy

This report presents the results of a study conducted between 1985 and 1994 on onychomycosis observed in the city of Rome. Six thousand six hundred and eighty eight patients were examined during this period. Among them 1,762 (26.3%) were affected by fungal nail infections. Because the etiologic agents could not be isolated in 105 cases (6%), the results refer to 1,657 subjects (24.8% of the total), presenting with positive microscopic and cultural examinations. Thirty eight patients (2.3%) had onychomycosis of both their hands and feet.From an etiological point of view, 59.1% of the nail infections were caused by yeasts, 23.2% were infected with dermatophytes and 17.6% by non-dermatophytic fungi. The etiology of onychomycosis of the hands differed from that of the feet. Yeasts were primarily responsible for onychomycosis of the hands (86.2%), while dermatophytes caused tinea unguium peduum (48%). Fungal fingernail infections by Candida spp. were the most common (50.3%), followed by those of the feet by dermatophytes (20%). Candida albicans was responsible for 70.6% of the hand infections but for only 15.9% of those of the feet. Trichophyton rubrum and T mentagrophytes were the most common dermatophytes, mainly causing toenail infections (23.4% and 21%, respectively), while Aspergillus spp., Scopulariopsis brevicaulis, Acremonium spp. and Aspergillus niger were the most common non-dermatophytes observed.With regard to sex, the fungal nail infections were more widespread in women (72.1%) and in subjects of both sexes over the age of 50.     

Medically important fungi found in hallux nails of university students from Cali, Colombia

The presence of medically important fungi was studied in hallux nails scrapings obtained from 504 students (204 males, 300 females) of three universities in Cali. Specimens were examined by direct microscopic examination and fungal culture. Medically important fungi were found in 49 (9.7%) students, 24 (4.8%) had onychomycosis while the rest did not have nail lesions. Trichophyton rubrum was the most commonly isolated fungi in students with lesions, where as T. mentagrophytes predominated in healthy nails. Most of the students with fungi were males. The prevalence of fungi was higher in individuals between 26 and 35 years. No association was observed between fungi and practicing sports or undergoing pedicures. These results suggest that dermatophytes can be found in healthy hallux nails, which can be reservoirs of pathogenic fungi.     

Onychomycosis: Multicentre epidemiological, clinical and mycological study

BackgroundOnychomycosis accounts for up to 50% of all nail disorders. They can be caused by: yeasts, dermatophytes and non-dermatophyte moulds.Objectives and methodsA multicentre study designed to determine the prevalence, mycological test results, aetiological agents, and clinical presentation of onychomycosis was carried out. All fingernail and toenail samples taken during a one year period at 9 diagnostic centres were included.ResultsA total of 5,961 samples were analysed, of which 82.3% were from toenails and 17.7% from fingernails. The mean age of the patients was 49.7 years, and 66% were females. Direct microscopic examination was positive in 61% of the samples. In adults, 61.2% of toenails were positive using potassium hydroxide (KOH), and 43.7% were positive in cultures. The prevailing aetiological agents belong to the dermatophyte group (82.8%), and distal subungual was the most common clinical form. In fingernails, direct examination showed 59.8% positive samples, and cultures were positive in 52.9%. The prevailing agents were yeasts belonging to Candida species, and onycholysis was the most common lesion.ConclusionsDirect mycological examinations were positive in 61%, a higher value than that found in other series. Dermatophytes were prevalent in toenails of both sexes, and in finger nails yeast were prevalent in females, and dermatophytes in males. Non-dermatophyte moulds corresponded to 4.8% of toenail and 2.05% of fingernails isolates.     

甲癣的病原学研究进展

甲真菌病是由皮肤癣菌、酵母菌及霉菌引起的甲板和甲下组织感染,皮肤癣菌是主要致病菌,其所致的甲真菌病称为甲癣.皮肤癣菌分为3个属:毛癣菌属、小孢子菌属和表皮癣菌属.随着医学真菌学基础知识的普及和真菌学诊疗水平的提高,越来越多的皮肤癣菌在甲中分离,临床上对甲癣致病真菌的正确鉴定对于制定治疗方案、评价预后以及流行病学监测等都有重要的指导意义.该文对国内外现有文献报道的甲癣的致病菌进行综述.     

Onychomycosis in Malaysia

The common etiological agents of onychomycosis are dermatophytes, molds and yeasts. A mycological nail investigation of onychomycosis using direct microscopy and culture was conducted by the Mycology Unit, Department of Medical Microbiology, University of Malaya from March 1996 to November 1998. The study involved 878 nail clippings or subungal scrapings from subjects with onychomycosis. On direct microcopy examination, 50% of the specimens were negative for fungal elements. On culture, 373 specimens had no growth; bacteria were isolated from 15 nail specimens. Among the 490 specimens with positive fungal cultures, 177 (36.1%) were dermatophytes, 173 (35.5%) were molds and 130 (26.5%) were Candida. There were 2% (10/490) mixed infections of molds, yeasts and dermatophytes. Trichophyton rubrum (115/177) and Trichophyton mentagrophytes (59/177) were the main dermatophytes isolated. The molds isolated were predominantly Aspergillus niger (61/173), Aspergillus nidulans (30/173), Hendersonula toruloidea (26/173) and Fusarium species (16/173). 96.9% of the Candida species identified were Candida albicans.This revised version was published online in October 2005 with corrections to the Cover Date.     

甲真菌病患者甲微生物群分析

目的研究甲真菌病患者甲微生物群的构成,为进一步阐明甲真菌病的发病机制提供线索。方法本研究共纳入47例甲真菌病患者及7例健康志愿者。取患者病甲的甲屑进行真菌镜检及培养鉴定;提取患者病甲、患者对侧健甲及健康人甲的DNA,对真菌rDNA ITS区及细菌16S rDNA V3-V4区PCR扩增,分析微生物群构成,并进行α多样性、β多样性、Simper分析及Spearman相关性分析。结果甲真菌病患者病甲的微生物群构成与对侧健甲及健康人甲存在差异。患者病甲的真菌菌群的丰富度高于对侧健甲。患者对侧健甲细菌菌群的多样性高于病甲及健康人甲,且患者对侧健甲细菌菌群的构成与患甲和健康人甲均有部分重叠。结论患者对侧健甲的细菌菌群构成具有由健康人甲向患者病甲转变的趋势。且在患者病甲的微生物群中,某些真菌和细菌菌属可能具有相关性。     

Onychomycosis in Cali,Colombia

This study presents the epidemiological and mycological aspects of 299 patients with nail lesions who were referred to three diagnostic laboratories in the city of Cali. The diagnosis of mycoses was established through visualization of mycotic structures in a direct microscopic examination of skin scrapings and by isolation. Onychomycosis was found in 183 cases (61.2%), of which 141 were in toenails (44 in males and 97 in females), 38 in fingernails (9 males and 29 females), and 4 cases in toenails and fingernails simultaneously (all females). No statistically significant relation was found between sex and onychomycosis. Yeasts accounted for 40.7% of the mycoses, dermatophytes for 38%, nondermatophyte molds for 14% and the etiology was mixed in the remaining cases (7.3%). Candida albicans was the most commonly isolated yeast species; the most common dermatophyte was Trichophyton rubrum and Fusarium spp. and Scytalidium dimidiatum were the most common nondermatophytic molds. Them common fungi found in fingernails were yeasts; in toenails dermatophytes were more prevalent (chi2 with Yates' correction = 19.75, P= 0.000088). Yeasts were observed more frequently in females while dermatophytes were more common in males. The difference between these two etiologic groups was statistically significant (chi2 with Yates' correction = 7.43, P = 0.0064); no relation was observed according to age.     

Epidemiology of superficial mycosis (tinea pedis, onychomycosis) in elementary school children in Istanbul, Turkey

The purpose of this study is to determine the prevalence of tinea pedis and onychomycosis in children of elementary school age and to examine the socio-demographic attributes that may be effective in correlation of both mycoses. 3,390 female and 3,768 male children between ages 6-14 have been examined in seven schools. Skin scrapings and nail samples were taken from 13 students who were suspected to have tinea pedis and from 49 students who were suspected to have onychomycosis. According to direct microscopy (10-15% KOH+calcofluor white) and culturel examination (Sabouraud dextrose agar and dermatophyte test medium) 11 students were diagnosed as tinea pedis and 24 were diagnosed as onychomycosis. Trichophyton rubrum was isolated in 3 students with tinea pedis whose culture was positive and five Candida albicans, five Candida glabrata and one Candida tropicalis cases were isolated from 11 samples with onychomycosis. Tinea pedis prevalence has been found to be 3.3%0. Differences between onychomycosis prevalence based on age have been found to be significant (p < 0.001). In conclusion, it has been determined that the prevalence of tinea pedis and onychomycosis among children is low. Candida spp. was isolated from all of the 14 samples diagnosed as onychomycosis. Our study shows similar results with previous studies done in Turkey and that Trichophyton rubrum continues to be the most isolated agent.     

威海地区547例甲真菌病真菌培养结果分析

目的了解山东省威海地区甲真菌病的临床分类、菌种构成等流行情况。方法对547例镜检阳性的甲真菌病患者进行真菌培养、鉴定和临床分析。结果547例患者中真菌培养阳性423例,阳性率77.3%,远端侧位甲下型甲真菌病(DLSO)295例(53.9%),白色浅表型甲真菌病(SWO)36例(6.5%),近端侧位甲下型甲真菌病(PSO)78例(14.2%),全甲营养不良型甲真菌病(TDO)138例(25.2%)。共分离出429株真菌,其中皮肤癣菌354株(82.5%),酵母菌61株(14.2%),非皮肤癣菌霉菌14株(3.3%)。结论山东省威海地区甲真菌病病原体的分布以皮肤癣菌为主,其次为酵母菌和非皮肤癣菌霉菌,红色毛癣菌是最常见的皮肤癣菌,临床类型以DLSO型居多,其他依次是TDO、PSO、SWO。就诊人群中以20～50岁年龄段为最多见。     

Analysis of Dermatomycoses in Lanzhou District of Northwestern China

The skin mycoses, perticularly dermatophytoses, in Lanzhou district, Northwestern China, was investigated during July 2002–June 2003. The specimens from patients suspected of having dermatomycoses were examined microscopically in KOH preparations and cultured on Sabouraud dextrose agar (SDA). Among 1443 suspected cases, 594 were KOH positive and 221 cultures of fungi were isolated. The most frequently isolated fungi were Trichophyton rubrum (43.9%) Trichophyton mentagrophytes (29.4%) and Candida species (14.0%). The frequency of tinea pedis, onychomycosis and tinea manuum were 38.7, 27.8 and 13.5%, respectively. In Lanzhou district, tinea pedis is the most commonly seen dermatophytoses, and T. rubrum is the most frequent etiologic agent.     

A prospective epidemiologic survey on the prevalence of onychomycosis and dermatophytosis in male boarding school residents

Dermatophyte infections and onychomycosis are not usually serious in term of mortality; however, they may have significant clinical consequences such as secondary bacterial infections, chronicity, therapeutic difficulties and esthetic disfigurement in addition to serving as a reservoir of infection. Our aim was to determine the prevalence of onychomycosis and dermatophytosis in a selected high risk group, consisting of male boarding school residents. A total of 410 males inhabiting two houses were evaluated by two dermatologists. In cases of clinical suspicion, appropriate samples were taken for direct microscopy and culture. The results showed that the prevalences of tinea pedis (athletes foot) and pure pedal onychomycosis were 51.5% (n:211) and 4.4% (n:18), respectively. Thirty cases of those with tinea pedis were complicated by toenail onychomycosis. Tinea cruris was present only in five cases with tinea pedis. Interestingly 71.1% of those with tinea pedis and 45.8% of those with onychomycosis, associated with or without tinea pedis were unaware of their diseases. The most common fungal isolate was Trichophyton rubrum (76.6%) followed by Epidermophyton floccosum (11.6%), T. interdigitale (10.55%). Approximately one third of the cultures from nail specimens yielded pure growths of nondermatophyte moulds or Candida albicans. In conclusion, we found unexpectedly high prevalences of occult athletes foot and toenail onychomycosis among the male residents of student houses. Our results indicate that health-care workers of such common boarding-houses should be more aware of clinical and subclinical dermatophyte infections and onychomycosis, and have more active approaches to educational measures and management strategies to prevent further infections. To our knowledge, this is the first epidemiologic study on the prevalences of dermatophytosis and onychomycosis in boarding-houses from Turkey.