Application of PCR to the identification of dermatophyte fungi

Isolation, screening and characterization of efficient cellulose-degrading fungal and bacterial strains and preparation of their consortium under in vitro studies

In this investigation, cellulose-degrading fungi and bacteria were isolated from different partially decomposed cellulose-rich substrates, such as groundnut residues, rice straw, and rotten wood, following dilution plating techniques on carboxymethyl cellulose agar media and screening for potential cellulose degradation ability. The development of a clear halo zone surrounding the microbial colonies during the initial screening process using the Congo red test (20 isolates) suggested cellulose hydrolysis, and the highest cellulase production activity was implied by the isolates with the largest clear zone ratio (9 isolates). Using both macroscopic and microscopic examinations, as well as standard biochemical tests outlined in Bergey's Manual of Determinative Bacteriology, the genus-level identification of fungi and bacteria was accomplished. In order to molecularly identify the 4 isolated fungal and bacterial strains at the species level after being ultimately selected for cellulase production potential under in vitro studies, fungal and bacterial DNA was extracted and amplified by PCR using the universal primers ITS1 and ITS4 for fungi (ITS rRNA, 5.8S rRNA) and 8F and 1492R for bacterial isolates (16S rRNA). After sequencing, the PCR results were compared to other comparable sequences in GenBank (NCBI). Based on the available NCBI data, phylogenetic analysis of their ribosomal gene partial sequences revealed that DAJ2 (PP086700) shares 100% homology with Aspergillus foetidus, DTJ4 (PP086699) shares 99.74% similarity with Trichoderma atrobrunnium, DBJ6 (PP082584) shares 100% identity with Priestia megaterium, and DMB9 (PP082585) shares 99.88% homology with Micrococcus yunnanensis. The cellulolytic potential of Phanerochaete chrysosporium is well established. Therefore, it was considered a standard culture for comparison and was collected from the MTCC, Chandigarh, India. Overall, all 4 selected isolates and the check organism were mutually compatible or synergistic with each other, and their consortium is useful for the accelerated decomposition of organic constituents during rapid composting.

Multiplex real-time PCR for skin fungal infections: The diagnostic reliability in a one-year non-interventional study

The skin fungal infection diagnostic workflow currently includes microscopic and culture-based methods as the gold standard. Recent published data described the possible limitations of these conventional techniques documenting the possibility of reducing response time intervals. The present study reports an evaluation of the DermaGenius® (DG) multiplex kit (PathoNostics) for rapid C. albicans and dermatophytes identification directly from skin samples. The investigations involved 90 specimens that underwent DNA extraction and amplification simultaneously to microscopic and culture methods. According to current guidelines, we defined a dermatophytic skin infection as the simultaneous presence of clinical evidence of skin lesions and positive results for dermatophyte elements from microscopy and/or cultures. The collected data remarked on the advantages of the molecular assay, especially in terms of sensitivity and rapidity. A statistical evaluation analysed a comparison between conventional and innovative diagnostic methods. The sensitivity, specificity, positive predictive value, and negative predictive value of DG-PCR in the cutaneous dermatophytosis were, respectively, 94.7%, 78.8%, 88.5%, and 89.6%. Based on our experience, the molecular technique could represent a diagnostic confirmation in the case of previous antifungal treatment, little biological material available, or urgent clinical conditions.

Clinical evaluation of a dermatophyte RT-PCR assay and its impact on the turn-around-time: A prospective study

Onychomycosis is an important public health problem whose prevalence continues to grow and impact public health at several levels. Nevertheless, today the main diagnostic methods used in routine practice have many drawbacks. The aim of this study was to evaluate, for the first time, the clinical performance of a new multiplex polymerase chain reaction (PCR) (Novaplex®) in the identification of the causative agent on nail samples, and its impact on the turnaround time, compared to our traditional laboratory methods. From June 2022 to December 2022, all nail samples sent to our laboratory for suspected onychomycosis were included in this prospective study. We collected for each sample the results obtained with the Novaplex® PCR method and with the traditional direct microscopy examination and culture. Each discordant result was checked using a third method, which is another PCR method (DermaGenius® kit) as a resolver. For culture-positive samples, a turnaround time was calculated and compared to the one obtained with the Novaplex® method. A total of 131 samples were included. Among them, 5 were positive (3.8%) on direct microscopy, 33 were positive (25.2%) after culture, and 98 were negative (74.8%). All positive (n = 33) and negative (n = 69) cultures were also positive/negative with the Novaplex® PCR. Twenty-nine samples were positive with the Novaplex® method but negative with culture (discordant results). The percentage agreement between the culture and the Novaplex® methods was 77.9% (102 out of 131). While tested with the resolver (DermaGenius® PCR), 28 out of 29 discordant results were similarly found positive. The percentage agreement between the two PCR methods (Novaplex® and DermaGenius®) was 96.6%. The Novaplex® PCR method evaluated proved to be very reliable and allowed the direct identification of 62 out of 131 positive samples (47.3%) with the following distribution: 79.0% of Trichophyton rubrum complex, 11.3% of Trichophyton mentagrophytes complex, 6.5% of both Trichophyton rubrum complex and Trichophyton mentagrophytes complex, and 3.2% of Candida albicans. The median time [± 95% CI] for positive culture (between incubation and validation of the final identification) was 15 [12-23] days, while the turnaround time for the Novaplex® method adapted to our clinical laboratory routine is ≤7 days. Laboratory confirmation of onychomycosis is crucial and should always be obtained before starting treatment. The evaluated PCR method offered a rapid, reliable, robust, and inexpensive method of identification of the causative agent compared to traditional methods.

Detection of Microsporum canis and Trichophyton mentagrophytes by loop-mediated isothermal amplification (LAMP) and real-time quantitative PCR (qPCR) methods

BACKGROUND

Dermatophytes are infectious zoonotic fungal agents that are common in animals worldwide. A new loop-mediated isothermal amplification (LAMP) method and quantitative (q)PCR can be used for identifying these agents. Both methods have high specificity and sensitivity, and are simple and quick to use.

HYPOTHESIS/OBJECTIVES

To develop a LAMP and a rapid multiplex qPCR method for detecting Microsporum canis and Trichophyton mentagrophytes, which are the most common fungal species isolated from cats and dogs.

MATERIAL AND METHODS

Both methods targeted the CHS-1 gene. Their specificity and sensitivity were tested using 64 M. canis and 44 T. mentagrophytes field strains. The validation of the methods was performed using 250 clinical fungal-positive hair samples.

RESULTS

The specificity value was 100% for both methods. For LAMP, the sensitivity value was 96.9% for M. canis and 93.2% for T. mentagrophytes. For qPCR, the sensitivity values were 98.4% for M. canis and 97.7% for T. mentagrophytes. Similar specificity and sensitivity results were obtained from the validation study using 250 clinical hair samples. LAMP and multiplex qPCR took 30 and 45 min (respectively) for both targets. The limit of detection (LOD) assays for both targets were 10 and 1 spore/mL for LAMP and multiplex qPCR, respectively.

CONCLUSION

These findings demonstrate that the LAMP and multiplex qPCR methods targeting CHS-1 gene developed in this study can be used both for point-of-care testing and in the laboratory for detecting M. canis and T. mentagrophytes with high specificity and sensitivity with an internal control.

Evaluation of the Multiplex Real-Time PCR DermaGenius® Assay for the Detection of Dermatophytes in Hair Samples from Senegal

For the successful treatment of dermatophytoses, especially tinea capitis, there is a need for accurate and rapid diagnostic methods. A lot of recent literature has focused on the detection of dermatophytes directly on sample material such as nails, hair and skin scrapings. Molecular tools offer the ability to rapidly diagnose dermatophytosis within 48 h. This study aimed to compare the results of a commercial real-time PCR (real-time PCR) assay DermaGenius^®(DG) 2.0 complete multiplex kit with those of conventional diagnostic methods (direct microscopy and culture). A total of 129 hair samples were collected in Dakar (Senegal) from patients suspected of dermatophytosis. DG was applied for the molecular detection of Candida albicans, Trichophyton rubrum/soudanense, T. interdigitale, T. tonsurans, T. mentagrophytes, T. violaceum, Microsporum canis, M. audouinii, Epidermophyton floccosum, T. benhamiae and T. verrucosum. Dermatophytes species and C. albicans were differentiated by melting curve analysis. The sensitivity and specificity of the PCR assay were 89.3% and 75.3%, respectively. DG PCR was significantly more sensitive than culture (p < 0.001). DG PCR is fast and robust to contamination. In this paper, the main questions discussed were the replacement of culture by a broad-spectrum fungal real-time PCR and the implementation of DG PCR into a routine laboratory in Senegal.

Molecular diagnosis of dermatophyte isolates from canine and feline dermatophytosis in Northeast Iran

Background

Dermatophytes are the most common causes of cutaneous fungal diseases. Dermatophytosis is a common skin disorder in dogs and cats. Species identification of these fungi is important from a therapeutic and epidemiological aspect. Conventional methods used to identify dermatophyte species are often lengthy and may be inefficient in many circumstances. Recently broad varieties of several molecular DNA‐based techniques were successfully utilised for species detection of dermatophytes.

Objectives

The aim of this study was to determine the molecular detection of dermatophyte isolates from canine and feline dermatophytosis in Mashhad, Iran.

Methods

Thirty dermatophytes isolated from dogs and cats with skin lesions and one standard strain of Microsporum canis were cultured onto Mycosel agar, and then internal transcribed spacer (ITS) region of the ribosomal DNA was amplified using the universal fungal primers ITS1 and ITS4. PCR products were subjected to sequencing and sequence analysis.

Results

Based on the sequencing of the ITS1‐5.8S‐ITS2 region on all samples, all the studied strains were M. canis and their sexual stage (teleomorph) was Arthroderma otae.

Conclusions

Microsporum canis was the only species found among dogs and cats, and its high prevalence can increase the rate of transmission to humans. In practice, ITS‐PCR, with sequence analysis, is a useful and reliable method to identify and differentiate various pathogenic species, and it can be used in clinical and epidemiological fields, even for the rapid diagnosis of dermatophyte species that are closely interrelated.

Detection of Dermatophytes from Dermatophytosis-Suspected Cases in Iran, Evaluation of Polymerase Chain Reaction-Sequencing Method

Background

Dermatophytosis is mostly caused by dermatophytes species, and the diagnosis of disease is very important for early treatment. The aim of this study was to identify the commonly dermatophytes species isolated directly from the clinical samples, using the polymerase chain reaction (PCR) and evaluate both conventional and molecular methods.

Materials and Methods

This study was performed on 115 clinical samples. Dermatophyte isolates were initially identified by conventional method and confirmed by the sequencing molecular method. In this study, the molecular technique is implemented directly on clinical samples. Statistical analysis of the information was performed by the SPSS software, and the results were statistically analyzed.

Results

Our findings demonstrated that the most abundant dermatophyte species by PCR-sequencing were Trichophyton mentagrophytes (20%), followed by Trichophyton tonsurans (10%), Trichophyton rubrum (6.7%), T. interdigital (6.7%), Arthroderma otae, and Arthroderma vanbreuseghemii, (3.3%) for each one.

Conclusion

For medical laboratories, routine procedures are still preferred because of their lower cost, and the results are almost the same as the molecular methods. The sensitivity and specificity values for PCR under our laboratory condition were 60% and 87%, respectively. This study shows that molecular results performed better in nails than other samples, by culture results.

Recent trends in rapid diagnostic techniques for dermatophytosis

Dermatophytosis is a common contagious disease of both humans and animals. It is caused by a group of filamentous fungi known as dermatophytes, including several genera and various species. An accurate diagnosis of dermatophytes as a causative agent of a skin lesion requires up to one month of conventional laboratory diagnostics. The conventional gold standard diagnostic method is a direct microscopic examination followed by 3 to 4 weeks of Sabouraud's dextrose agar (SDA) culturing, and it may require further post-culturing identification through biochemical tests or microculture technique application. The laborious, exhaustive, and time-consuming gold standard method was a real challenge facing all dermatologists to achieve a rapid, accurate dermatophytosis diagnosis. Various studies developed more rapid, accurate, reliable, sensitive, and specific diagnostic tools. All developed techniques showed more rapidity than the classical method but variable specificities and sensitivities. An extensive bibliography is included and discussed through this review, showing recent variable dermatophytes diagnostic categories with an illustration of weaknesses, strengths, and prospects.

Entomopathogenic Fungi as Endophytes for Biological Control of Subterranean Termite Pests Attacking Cocoa Seedlings

This study was conducted in the scope of developing a sustainable effective approach against subterranean termite pests using entomopathogenic and endophytic fungus-based biopesticides. Termites, Odontotermes spp. workers, were tested for their susceptibility to 15 entomopathogenic fungal isolates through the direct spraying of conidia suspensions at 1 × 10⁸ conidia/mL. In general, all the isolates screened were pathogenic, with 100% mortality 4-7 days post-inoculation. However, the most virulent isolates were Metarhizium brunneum Cb15-III; the M. anisopliae isolates ICIPE 30 and ICIPE 60; Hypocrea lixii F3ST1; and the Beauveria bassiana isolates ICIPE 279, ICIPE 706 and ICIPE 662. These isolates were further tested for their endophytic colonization of cocoa seedlings using seed soaking, soil drench and foliar spray at 1 × 10⁸ conidia/mL. The colonization of the plant tissues by the fungi was determined using a culture-based technique. Only the B. bassiana isolates ICIPE 706 and ICIPE 279, and H. lixii F3ST1 colonized the cocoa seedlings, with varied colonization rates among isolates and inoculation methods. Three naturally occurring endophytes-Trichoderma asperellum, Fusarium solani and F. redolens-were also isolated from the cocoa seedling tissues. These findings suggest that cocoa seedlings are conducive to endophytic fungal growth either occurring naturally or from artificial inoculation Our findings could possibly lead to an innovative approach to the management of herbivory and subterranean termite pests in cocoa agroforests.

Recent advances in the diagnosis of dermatophytosis

Dermatophytosis is a disease of global significance caused by pathogenic keratinolytic fungi called dermatophytes in both animals and humans. The recent taxonomy of dermatophytes classifies them into six pathogenic genera, namely Microsporum, Trichophyton, Epidermophyton, Nannizzia, Lophophyton and Arthroderma. It is because of the delayed diagnostic nature and low accuracy of dermatophyte detection by conventional methods that paved the path for the evolution of molecular diagnostic techniques, which provide the accurate and rapid diagnosis of dermatophytosis for an appropriate, timely antifungal therapy that prevents the nonspecific over-the-counter self-medication. This review focuses on the importance of rapid and accurate diagnosis of dermatophytosis, limitations of conventional methods, selection of targets in diagnosis, and factors affecting sensitivity and specificity of various molecular diagnostic technologies in the diagnosis of dermatophytosis. Generally, all the molecular techniques have a significant edge over the conventional methods of culture and microscopy in the dermatophytosis diagnosis. However, in mycology laboratory, the suitability of any molecular diagnostic technique in the diagnosis of dermatophytosis is driven by the requirement of time, economy, complexity, the range of species spectrum detected and the scale of diagnostic output required. Thus, various choices involved in the pursuit of a diagnosis of dermatophytosis are determined by the available conditions and the facilities in the laboratory.

Assessment of a pan-dermatophyte nested-PCR compared with conventional methods for direct detection and identification of dermatophytosis agents in animals

Conventional direct microscopy with potassium hydroxide (KOH) and culture were found to lack the ability to establish a fast and specific diagnosis of dermatophytosis. A pan-dermatophyte nested-PCR assay was developed using a novel primer pair targeting the translation elongation factor 1-α (Tef-1α) sequences for direct detection and identification of most veterinary relevant dermatophytes in animal samples suspected to dermatophytosis. A total of 140 animal skin and hair samples were subjected to direct microscopy, culture, and ITS-RFLP/ITS-sequencing of culture isolates for the detection and identification of dermatophytosis agents. Nested-PCR sequencing was performed on all the extracted DNAs using a commercial kit after dissolving the specimens by mechanical beating. Nested-PCR was positive in 90% of samples, followed by direct microscopy (85.7%) and culture (75%). The degree of agreement between nested-PCR and direct microscopy (94.4%) was higher than with culture (83.3%). In 105 culture-positive cases, the measures of agreement for the identification of dermatophytosis agents were as follows: 100% between nested-PCR sequencing and ITS-RFLP/ITS-sequencing and 63.8% between nested-PCR sequencing and culture. The developed nested-PCR was faster as well as more sensitive and specific than conventional methods for detection and identification of dermatophytes in clinical samples, which was particularly suitable for epidemiological studies.

Characterizing the clinical isolates of dermatophytes in Hamadan city, Central west of Iran, using PCR-RLFP method

OBJECTIVE

Dermatophytosis is one of the most common mycotic infections, which considered as a public health problem in the major of countries. This study evaluated the molecular epidemiology of dermatophytosis in patients referred to Farshchian hospital in Hamadan city with PCR-RFLP method.

MATERIALS AND METHODS

Four hundred and five specimens from clinically suspected patients of dermatophytosis were collected and analyzed by direct microscopic and culture. The isolates were identified by PCR-RFLP method using the MvaI restriction enzyme.

RESULTS

Of the 405 specimens, 88 specimens were positive in direct examination and culture. Among the patients, 64.8% were males and35.2% females. Tinea pedis (31.8%) was the most common type of dermatophytosis followed by tinea corporis (22.7%), tinea cruris (20.5%), tinea capitis (10.2%), tinea manuum (5.7%), tinea faciei (4.6%) and tinea unguium (4.6%). Trichophyton interdigitale (36.4%) was the most common isolate followed by Trichophyton rubrum (27.3%), Epidermophyton floccosum (17%), Trichophyton tonsurans (11.4%), Microsporum canis (4.5%), Microsporum gypseum (2.3%) and Trichophyton benhamiae (1.1%).

CONCLUSION

Our finding showed that the anthropophilic dermatophyte species causing dermatophytosis are increasing, and molecular methods are reliable assays for accurse identification of dermatophyte species in epidemiological studies.

A Comparative Study of Polymerase Chain Reaction-Restriction Fragment Length Polymorphism and Fungal Culture for the Evaluation of Fungal Species in Patients with Tinea Cruris

BACKGROUND:

Tinea cruris is the second most common dermatophytosis in the world and the most common in Indonesia. The conventional laboratory tests for dermatophyte infection are slow and less specific. Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) is a PCR method with the addition of enzyme after amplification, therefore enabling for more specific results.

AIM:

This study aimed to find whether the PCR-RFLP test could yield the same fungal species result as a fungal culture.

METHODS:

The specimens were skin scrapings from thirty-one patients suspected tinea cruris. The tools and materials that were used were Sabaroud’s dextrose agar media, primer ITS 1 and ITS 4 and MvaI.

RESULTS:

The equation percentage of the test result species between PCR-RFLP and fungal culture was 50% of 12 subjects whose the test results were both positive from the fungal culture and PCR-RFLP. The percentage of the test result with fungal culture the fungal species were found, but in the PCR-RFLP test which the fungal species was not found, the percentage was 50% of 12 subjects which the test results were both positive as fungi from the culture and PCR-RFLP test.

CONCLUSIONS:

The species from PCR-RFLP examination was the same with the fungal culture.

Clinical application of a molecular assay for the detection of dermatophytosis and a novel non-invasive sampling technique

The dermatophytoses are the most common superficial fungal infections worldwide. Clinical diagnosis is not reliable as there are many differentials, and laboratory diagnosis is required to gain access to treatment in more severe disease. Traditional diagnostic methods are limited by suboptimal sensitivity, specificity and prolonged turnaround times. Molecular methods are being used increasingly in the diagnostic algorithm in the clinical microbiology laboratory. The aim of this study was to evaluate a real-time polymerase chain reaction (RT-PCR) targeting the chitin synthase 1 gene (CHS1) of dermatophytes for analytical specificity, and to assess its clinical application by comparing it to the current methods of microscopy and culture. We also assessed a novel non-invasive sample collection technique involving adhesive tape impressions of suspected lesions. The PCR was highly specific, being able to discern between cultures of dermatophytes and other microorganisms. It also proved to be more sensitive than traditional methods at detecting dermatophytes in clinical samples. Similar sensitivities were seen on the samples assessed by the adhesive tape technique. An internal control system allowed for the detection of inhibition in certain culture and clinical specimens. This rapid and cost-effective technique could be incorporated into the initial diagnostic algorithm for dermatophytosis in Australian laboratories.

Relapse after Oral Terbinafine Therapy in Dermatophytosis: A Clinical and Mycological Study

Background:

The incidence of recurrent tinea infections after oral terbinafine therapy is on the rise.

Aim:

This study aims to identify the appearance of incomplete cure and relapse after 2-week oral terbinafine therapy in tinea corporis and/or tinea cruris.

Materials and Methods:

A total of 100 consecutive patients clinically and mycologically diagnosed to have tinea corporis and/or tinea cruris were included in the study. The enrolled patients were administered oral terbinafine 250 mg once daily for 2 weeks. All clinically cured patients were then followed up for 12 weeks to look for any relapse/cure.

Results:

The common dermatophytes grown on culture were Trichophyton rubrum and Trichophyton tonsurans in 55% and 20% patients, respectively. At the end of 2-week oral terbinafine therapy, 30% patients showed a persistent disease on clinical examination while 35% patients showed a persistent positive fungal culture (persisters) at this time. These culture positive patients included all the clinically positive cases. Rest of the patients (65/100) demonstrated both clinical and mycological cure at this time (cured). Over the 12-week follow-up, clinical relapse was seen in 22 more patients (relapse) among those who had shown clinical and mycological cure at the end of terbinafine therapy. Thus, only 43% patients could achieve a long-term clinical and mycological cure after 2 weeks of oral terbinafine treatment. Majority of the relapses (16/22) were seen after 8 weeks of completion of treatment. There was no statistically significant difference in the body surface area involvement or the causative organism involved between the cured, persister, or relapse groups.

Conclusions:

Incomplete mycological cure as well as relapse is very common after standard (2-week) terbinafine therapy in our patients of tinea cruris/corporis.

Molecular Markers Useful for Intraspecies Subtyping and Strain Differentiation of Dermatophytes

Dermatophytosis is a very common skin disorder and the most frequent infection encountered by practicing dermatologists. The identification, pathogenicity, biology, and epidemiology of dermatophytes, the causative agents of dermatophytosis, are of interest for both dermatologists and medical mycologists. Recent advances in molecular methods have provided new techniques for identifying dermatophytes, including intraspecies variations. Intraspecies subtyping and strain differentiation have made possible the tracking of infections, the identification of common sources of infections, recurrence or reinfection after treatment, and analysis of strain virulence and drug resistance. This review describes molecular methods of intraspecies subtyping and strain differentiation, including analyses of mitochondrial DNA and non-transcribed spacer regions of ribosomal RNA genes, random amplification of polymorphic DNA, and microsatellite markers, along with their advantages and limitations.

Use of Restriction Fragment Length Polymorphism to Rapidly Identify Dermatophyte Species Related to Dermatophytosis

BACKGROUND

Dermatophytes are a group of keratinophilic fungi worldwide, which can infect the skin, hair and nails of humans and animals. This genus includes several species that present different features of dermatophytosis. Although, laboratory diagnosis of dermatophytes is based on direct microscopy, biochemical tests and culture, these manners are expensive, time consuming and need skilled staff. Therefore, molecular methods like PCR-RFLP are the beneficial tools for identification, which are rapid and sensitive. Thus, dermatophyte species are able to generate characteristic band patterns on agarose gel electrophoresis using PCR-RFLP technique, which leads to successful identification at the species level within a 5-hour period.

OBJECTIVES

The purpose of this study was to study inter- and intraspecific genomic variations for identification of clinically important dermatophyte species obtained from clinical specimens in Isfahan, Iran using PCR-RFLP.

MATERIALS AND METHODS

From March 2011 to August 2012, 135 clinical isolates were collected from infected patients at Isfahan, Iran. ITS1-5.8S-ITS2 region of rDNA was amplified using universal fungal primers. Subsequently, amplified products were digested by the MvaI restriction enzyme. Using discriminating band profiles on agarose gel, dermatophyte species were identified. However, DNA sequencing was used for unidentifiable strains.

RESULTS

The specimens were obtained from skin scrapings (70.3%), nail (24.4%) and hair (5.1%) clippings. Most patients were between 21 - 30 years and the ratio of male to female was 93/42. Trichophyton interdigitale was the commonest isolate (52.5%) in our findings, followed by Epidermophyton floccosum (24.4%), T. rubrum (16.2%), Microsporum canis (2.2%), T. erinacei (1.4%), T. violaceum (1.4%), T. tonsurans (0.7%) and M. gypseum (0.7%) based on PCR-RFLP.

CONCLUSIONS

Combination of traditional methods and molecular techniques considerably improves identification of dermatophytes in the species level in clinical laboratories, which can lead to properly antifungal therapy and successful management of infections. However, restriction and specificity and sensitivity should be lowered and increased, respectively, to be useful for a wide variety of clinical applications.

Prevalence of Tinea capitis in school going children from Mathare, informal settlement in Nairobi, Kenya

Background

Tinea capitis is a common infection especially in poor resource settings. This study was aimed at determining the prevalence Tinea capitis in children from selected schools from an urban slum in Nairobi city of Kenya.

Methods

A cross-sectional study was carried out in 150 school going children during the period between May and September 2013. A questionnaire was administered and cultures of scalps, skin scrapping/hair stubs samples were performed and the etiological agents identified and confirmed.

Results

In a total of one hundred and fifty (150) children recruited 89 (59.3%) were males and 61 (40.7%) females aged between 3 and 14 years. The overall prevalence rates in dermatophytes infection was 81.3% (122/150) with etiological agents consisting Trichophyton spp. (61.3%), Microsporum spp. (13.3%) and Epidermophyton spp. (7.3%) infections with infections occurring either singly (56%), duo (38%) or tipple co-infections (6%).

Conclusion

This study demonstrates a high prevalence of Tinea infections with Trichophyton tonsurans as the predominant etiological agent in school going children of the urban slums of Nairobi.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1240-7) contains supplementary material, which is available to authorized users.

Dermatophyte and non dermatophyte fungi in Riyadh City, Saudi Arabia

Background

Dermatophytes are a scientific label for a group of three genera (Microsporum, Epidermophyton and Trichophyton) of fungus that causes skin disease in animals and humans. Conventional methods for identification of these fungi are rapid and simple but are not accurate comparing to molecular methods.

Objective

This study aimed to isolate human pathogenic dermatophytes which cause dermatophytosis in Riyadh City, Saudi Arabia and to identify these fungi by using conventional and molecular methods.

Methods

The study was conducted in Medical Complex, Riyadh and King Saud University. Samples of infected skin, hairs and nails were collected from 112 patients. Diagnosis of skin infections, direct microscopic test, isolation and identification of dermatophytes by conventional and molecular methods were carried out.

Results

The results indicated that the tinea capitis infection had the highest prevalence among the patients (22.3%) while Tinea barbae had the lowest. In this study the identified dermatophyte isolates belong to nine species as Trichophyton violaceum, Trichophyton verrucosum, Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton schoenleinii, Trichophyton concentricum, Microsporum canis, Microsporum audouinii and Epidermophyton floccosum which cause skin infections were isolated during this study. Non dermatophyte isolates included 5 isolates from Aspergillus spp. 4 isolates from Acremonium potronii and 15 isolates from Candida spp. M. canis were the most common species (25% of isolated dermatophytes). Out of the 52 dermatophyte isolates identified by conventional methods, there were 45 isolates identified by the molecular method.

Conclusions

The results concluded that approximately M. canis caused a quarter of dermatophyte cases, tinea capitis infection was prevalent and the molecular method was more accurate than conventional methods.

A comparative study on morphological versus molecular identification of dermatophyte isolates

OBJECTIVE

Dermatophytes are taxonomically classified in the genera Trichophyton, Microsporum, and Epidermophyton. Pleomorphism, cultural variability, slow growth and sporulation, and the need for additional physiological tests make dermatophytes notoriously difficult to identify. The present study aimed to compare the results of morphological and molecular identification of certain groups of clinical isolates of dermatophytes with a view to evaluating the accuracy of molecular methods.

PATIENTS AND METHODS

For each sample, the ITS1-5.8S-ITS2 rDNA region was amplified using the primers ITS1 and ITS4. PCR products were subjected to restriction fragment length polymorphism (RFLP) analysis using the enzyme MvaI and isolate identification was performed by comparing the electrophoretic RFLP patterns with reference profiles obtained previously. Finally, paired comparative analyses of molecular and conventional methods were performed.

RESULTS

While morphology results from routine daily reports of the laboratories indicated that 18 (6.8%) and 136 (52.10%) of the isolates were T. rubrum and T. interdigitale, respectively, PCR-RFLP results suggested that T. rubrum was the most common etiological agent of ringworm accounting for 94 (36.01%), followed by T. interdigitale accounting for 71 (27.20%). Interestingly, 80.8% out of the 94 isolates identified as T. rubrum by molecular testing had been identified by morphological examination as belonging to different species, such as T. interdigitale (75.5%), E. floccosum (2.1%) and M. canis, T. verrucosum, and T. tonsurans (each 1.06%). Ten strains out of 261 (T. interdigitale, n=8; E. floccosum, n=2) had been defined as unknown species by morphological tests.

CONCLUSION

An unexpected high percent of isolates identified as T. interdigitale by conventional methods were in effect T. rubrum shown by PCR-RFLP, and regarding the necessity of correct identification of dermatophytes recovered from different clinical forms of the infection, we highly recommend ITS-sequencing or ITS-RFLP of the isolates, particularly for epidemiological research studies.

Identification of dermatophytes by polymerase chain reaction-restriction fragment length polymorphism analysis of metalloproteinase-1

Background

Transgenic research on metalloproteinase-1 is an emerging field in the area of plant molecular biology. The new method reported here can similarly be applied in fungal molecular biology to identify different dermatophytes. Our method is more accurate than traditional methods such as molecular analyses.

Objective

To identify Trichophyton rubrum, T. mentagrophytes var. mentagrophytes, T. tonsurans, T. mentagrophytes var. interdigitale, Microsporum canis and M. gypseum, by using the restriction fragment length polymorphism (RFLP) analysis and polymerase chain reaction (PCR) to detect polymorphisms in the metalloproteinase-1 gene (MEP1).

Methods

From each fungal strain, we isolated genomic DNA and performed PCR to amplify the region coding for metalloproteinase-1. Primers for the metalloproteinase-1 gene were designed based on the sequence in NCBI GenBank. Subsequently, we purified the amplified PCR product and performed RFLP analysis. After restriction enzyme digestion, BsrDI (NEB, England), the samples were subjected to electrophoresis. Four different patterns of DNA fragments were observed among 6 fungal species.

Results

The DNA fragments for T. mentagrophytes var. mentagrophytes, T. mentagrophytes var. interdigitale and T. tonsurans showed similar patterns on electrophoresis and were not distinguishable, whereas T. rubrum, M. canis, and M. gypseum showed different patterns.

Conclusion

To our knowledge, it is the first study to introduce the analysis of the nucleotide sequence of metalloproteinase-1 enzyme to study differentiation in dermatophytes. Based on our results, more accurate differentiation and subtyping of T. rubrum and T. mentagrophytes var. interdigitale might be possible. This might contribute to better understanding of the epidemiology and pathogenesis of dermatophyte.

Using a polymerase chain reaction as a complementary test to improve the detection of dermatophyte fungus in nails

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.

Morphological and molecular identification of two strains of dermatophytes

In this study, we used traditional morphological and molecular identification methods to preliminarily identify two strains of dermatophytes. The two strains were observed under the microscope. And then the dermatophytes were cultured on Sabouraud's dextrose agar (SDA). The 18S rRNA regions of the two dermatophyte strains were amplified by polymerase chain reaction (PCR), and the PCR products were sequenced and compared with GenBank data. BLAST tools and DNAMAN software were used to analyze the sequences. To further determine highly homologous sequences, a phylogenetic tree was constructed using the Neighbor-Joining method. The two strains of dermatophytes were identified by traditional morphological identification as Epidermophyton floccosum and Microsporum ferrugineum. The 18S rRNA sequence analyses showed high similarities to Cladosporium cladosporioides isolate C115LM-UFPR and Ascomycete sp. LB68A1A2. Epidermophyton and Cladosporium belong to dermatophyte, while Microsporum ferrugineum and Ascomycete belong to microsporum. The two novel strains of dermatophytes were therefore identified as Cladosporium cladosporioides isolate C115LM-UFPR (JN650537, Cladosporium) and Ascomycete sp. LB68A1A2 (AY770409, Ascomycete sp).

Molecular epidemiology, phylogeny and evolution of dermatophytes

Dermatophytes are fungi that invade and propagate in the keratinized skin of mammals, including humans, often causing contagious infections. The species of medical concern belong to the genera Microsporum, Trichophyton, Epidermophyton (in their anamorphic state) and Arthroderma (in their telomorphic state), which were traditionally identified based on their morphology and biochemical characters. Nonetheless, limitations linked to the differentiation of closely related agents at species and strains level have been recently overcome by molecular studies. Indeed, an accurate identification of dermatophytes is pivotal for the establishment of effective control and prevention programs as well as for determining the most appropriate and effective antifungal therapies to be applied. This article reviews the DNA techniques and the molecular markers used to identify and to characterize dermatophyte species, as well as aspects of their phylogeny and evolution. The applications of typing molecular strain to both basic and applied research (e.g., taxonomy, ecology, typing of infection, antifungal susceptibility) have also been discussed.

Rapid methods for the extraction and archiving of molecular grade fungal genomic DNA

The rapid and inexpensive extraction of fungal genomic DNA that is of sufficient quality for molecular approaches is central to the molecular identification, epidemiological analysis, taxonomy, and strain typing of pathogenic fungi. Although many commercially available and in-house extraction procedures do eliminate the majority of contaminants that commonly inhibit molecular approaches, the inherent difficulties in breaking fungal cell walls lead to protocols that are labor intensive and that routinely take several hours to complete. Here we describe several methods that we have developed in our laboratory that allow the extremely rapid and inexpensive preparation of fungal genomic DNA.

Management of tinea capitis in childhood

Tinea capitis (TC) is a common dermatophyte infection affecting primarily prepubertal children. The causative pathogens belong to only two genera: Trichophyton and Microsporum. Although there is a great local variation in the epidemiology of TC worldwide, T. tonsurans is currently the most common cause of TC with M. canis second. Even though there is an emerging number of anthropophilic scalp infections, M. canis remains the predominant causative organism in many countries of the Mediterranean basin, the most important dermatophyte carriers being stray cats and dogs as well as pet puppies, kittens and rabbits. TC always requires systemic treatment because topical antifungal agents do not penetrate down to the deepest part of the hair follicle. Since the late 1950s, griseofulvin has been the gold standard for systemic therapy of TC. It is active against dermatophytes and has a long-term safety profile. The main disadvantage of griseofulvin is the long duration of treatment required which may lead to reduced compliance. The newer oral antifungal agents including terbinafine, itraconazole, ketokonazole, and fluconazole appear to have efficacy rates and potential adverse effects similar to those of griseofulvin in children with TC caused by Trichophyton species, while requiring a much shorter duration of treatment. They may, however, be more expensive.

Application of polymerase chain reaction (PCR) and PCR based restriction fragment length polymorphism for detection and identification of dermatophytes from dermatological specimens

OBJECTIVE

To develop and optimize polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) targeting 18S rDNA and internal transcribed spacer (ITS) region of fungi for rapid detection and identification of dermatophytes.

MATERIALS AND METHODS

Two PCR-RFLP methods targeting 18S rDNA and ITS regions of fungi were optimized using standard and laboratory isolates of dermatophytes and other fungi. Sixty-eight dermatological clinical specimens (nail clippings (56), material obtained from blisters (8), hair root (2), scraping from scaly plaque of foot (1) and skin scraping (1) collected by the dermatologist were subjected to both the optimized PCR-RFLP and conventional mycological (smear and culture) methods.

RESULTS

PCRs targeting 18S rDNA and the ITS region were sensitive to detect 10 picograms and 1 femtogram of T. rubrum DNA, respectively. PCR targeting 18S rDNA was specific for dermatophytes and subsequent RFLP identified them to species level. PCR-RFLP targeting the ITS region differentiated dermatophytes from other fungi with identification to species level. Among the 68 clinical specimens tested, both PCR-RFLP methods revealed the presence of dermatophytes in 27 cases (39.7%), whereas culture revealed the same only in 2 cases (7.40%), increasing the clinical sensitivity by 32.3%. Among 20 smear positive specimens, both PCR-RFLP methods detected dermatophytes in 12 (17.6%). Both the methods detected the presence of dermatophytes in 13 (19.11%) smear and culture negative specimens, increasing the clinical sensitivity by 36.1%.

CONCLUSION

PCR-RFLP methods targeting 18S rDNA and the ITS regions of fungi were specific and highly sensitive for detection and speciation of dermatophytes.

Phylogenetic analysis of Trichophyton mentagrophytes human and animal isolates based on MnSOD and ITS sequence comparison

Dermatophytes are keratinophilic fungi able to infect keratinized tissues of human or animal origin. Among them, Trichophyton mentagrophytes is known to be a species complex composed of several species or variants, which occur in both human and animals. Since the T. mentagrophytes complex includes both anthropophilic and zoophilic pathogens, accurate molecular identification is a critical issue for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Here, 41 T. mentagrophytes isolates from either human patients (14 isolates) or animals (27 isolates) with dermatophytosis were prospectively isolated by culture and identified on morphological bases at the University Hospital Centres of Lille and Poitiers, and the Veterinary School of Alfort, respectively. The isolates were differentiated by DNA sequencing of the variable internal transcribed spacer (ITS) regions flanking the 5.8S rDNA, and of the housekeeping gene encoding the manganese-containing superoxide dismutase (MnSOD), an enzyme which is involved in defence against oxidative stress and has previously provided interesting insight into both fungal taxonomy and phylogeny. ITS1-ITS2 regions and MnSOD sequences successfully differentiate between members of the T. mentagrophytes complex and the related species Trichophyton rubrum. Whatever the phylogenetic marker used, members of this complex were classified into two major clades exhibiting a similar topology, with a higher variability when the ITS marker was used. Relationships between ITS/MnSOD sequences and host origin, clinical pattern and phenotypic characteristics (macroscopic and microscopic morphologies) were analysed.

Trichophyton mentagrophytes sive interdigitale? A dermatophyte in the course of time

Originally, the Trichophyton (T.) mentagrophytes complex distinguished between the anthropophilic subspecies T. mentagrophytes var. interdigitale, T. mentagrophytes var. nodulare (synonym T. krajdenii), and T. mentagrophytes var. goetzii and the zoophilic subspecies T. mentagrophytes var. granulosum (rodents), T. mentagrophytes var. erinacei (hedgehog), and T. mentagrophytes var. quinckeanum (mice). In addition, two sexual species (teleomorph) of this complex are known. These are Arthroderma (A.) benhamiae Ajello and Cheng 1967 and Arthroderma vanbreuseghemii Takashio 1973. According to recent molecular studies,the species T.mentagrophytes is synonymous with only the zoophilic subspecies T.mentagrophytes var. quinckeanum which is rare in Western Europe. The anthropophilic subspecies of T. mentagrophytes, as well as many of the zoophilic strains, formerly differentiated as var. mentagrophytes or var. granulosum, are indistinguishable and are now designated T.interdigitale. The morphological differentiation between anthropophilic and zoophilic T. interdigitale strains by classical microscopical and biochemical methods is often problematic. In particular, it is impossible to differentiate between the zoophilic strains of T. interdigitale, T. mentagrophytes, and the Trichophyton anamorph of A. benhamiae. In these cases, molecular identification methods may be applied to answer epidemiological, taxonomical and therapeutic questions.

Five-hour diagnosis of dermatophyte nail infections with specific detection of Trichophyton rubrum

A rapid two-step DNA extraction method and a multiplex PCR for the detection of dermatophytes in general and Trichophyton rubrum specifically were developed and evaluated with DNA extracted from pure cultures and from clinically diseased nails. DNA from the following dermatophytes was used: Epidermophyton floccosum, Microsporum audouinii, Microsporum canis, Microsporum gypseum, Microsporum nanum, Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton soudanense, Trichophyton terrestre, Trichophyton tonsurans, Trichophyton verrucosum, and Trichophyton violaceum. Human DNA and DNA from the following nondermatophyte fungi were included as controls: Alternaria, Aspergillus niger, Candida albicans, Candida glabrata, Candida krusei, Malassezia furfur, Saccharomyces cerevisiae, and Scopulariopsis brevicaulis. A total of 118 nail samples received for routine microscopy and culture for dermatophytes were subsequently tested by the two PCRs separately and in a multiplex format. Using DNA extracted from pure cultures and the pan-dermatophyte PCR, the T. rubrum-specific PCR sequentially and in a multiplex format correctly detected all dermatophytes and additionally correctly identified T. rubrum. Comparison of the traditional diagnostic evaluation (microscopy and culture) of nail samples with PCR on DNA directly extracted from the nails showed excellent agreement between PCR and microscopy, but the number of samples with dermatophyte species identification was increased considerably from 22.9% to 41.5%, mainly due to the identification of T. rubrum by PCR in microscopy-positive but culture-negative samples. In conclusion, this 5-hour diagnostic test was shown to increase not only the speed but also the sensitivity of investigation for nail dermatophytosis.

DNA and the classical way: Identification of medically important molds in the 21st century

The advent of the 21st century has seen significant advances in the methods and practices used for identification of medically important molds in the clinical microbiology laboratory. Historically, molds have been identified by using observations of colonial and microscopic morphology, along with tables, keys and textbook descriptions. This approach still has value for the identification of many fungal organisms, but requires expertise and can be problematic in determining a species identification that is timely and useful in the management of high-risk patients. For the increasing number of isolates that are uncommon, atypical, or unusual, DNA-based identification methods are being increasingly employed in many clinical laboratories. These methods include the commercially available GenProbe assay, methods based on the polymerase chain reaction such as single-step PCR, RAPD-PCR, rep-PCR, nested PCR, PCR-RFLP, PCR-EIA, and more recent microarray-based, Luminex technology-based, and real-time PCR-based methods. Great variation in assay complexity, targets, and detection methods can be found, and many of these methods have not been widely used or rigorously validated. The increasing availability of DNA sequencing chemistry has made comparative DNA sequence analysis an attractive alternative tool for fungal identification. DNA sequencing methodology can be purchased commercially or developed in-house; such methods display varying degrees of usefulness depending on the breadth and reliability of the databases used for comparison. The future success of sequencing-based approaches will depend on the choice of DNA target, the reliability of the result, and the availability of a validated sequence database for query and comparison. Future studies will be required to determine sequence homology breakpoints and to assess the accuracy of molecular-based species identification in various groups of medically important filamentous fungi. At this time, a polyphasic approach to identification that combines morphologic and molecular methods will ensure the greatest success in the management of patients with fungal infections.

Ultra-rapid preparation of total genomic DNA from isolates of yeast and mould using Whatman FTA filter paper technology – a reusable DNA archiving system

Conventional methods for purifying PCR-grade fungal genomic DNA typically require cell disruption (either physical or enzymatic) coupled with laborious organic extraction and precipitation stages, or expensive column-based technologies. Here we present an easy and extremely rapid method of preparing yeast and mould genomic DNAs from living cultures using Whatman FTA filter matrix technology. Aqueous suspensions of yeast cells or hyphal fragments and conidia (in the case of moulds) are applied directly (or after freeze-thawing) to dry FTA filters. Inoculated filters are then subjected to brief microwave treatment, to dry the filters and inactivate the organisms. Filter punches are removed, washed rapidly, dried and placed directly into PCR reactions. We show that this procedure inactivated all of the 38 yeast and 75 mould species tested, and generated PCR-grade DNA preparations in around 15 minutes. A total of 218 out of 226 fungal isolates tested liberated amplifiable DNA after application to FTA filters. Detection limits with yeast cultures were approximately 10 colony-forming units per punch. Moreover, we demonstrate that filter punches can be recovered after PCR, washed and used in fresh PCR reactions without detectable cross-contamination. Whatman FTA technology thus represents a cheap, ultra-rapid method of fungal genomic DNA preparation, and also potentially represents a powerful fungal DNA archiving and storage system.

Phenotypical and molecular characterization of Microsporum canis strains in north-east Brazil

AIMS

This study investigated the possible correlation between the phenotypical and genotypical characteristics of Microsporum canis isolated from cats and dogs in north-east Brazil.

METHODS AND RESULTS

The mycological study was conducted by direct microscopic examination and by fungal culture. Polymerase chain reaction-restriction enzyme analysis and random amplification of polymorphic DNA techniques were used for the genotypical analysis. The morphological analysis showed a considerable diversity of colonies as well as different morphologies of conidia, despite the M. canis strains having been isolated under the same conditions. However, the molecular analysis showed that all analysed strains are genetically similar.

CONCLUSIONS

This study, based on phenotypical and molecular analysis, evidences the wide spectrum of phenotypical variations in M. canis in contrast to the stable genotypes of such dermatophytes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings of this study indicate that M. canis isolated from cats and dogs with dermatophytosis in north-east Brazil may be clones, well adapted to the conditions of this region, despite M. canis showing different morphological features.

Strain differentiation of Trichophyton rubrum by random amplification of polymorphic DNA (RAPD)

Trichophyton rubrum is an important cause of dermatomycoses. Molecular strain typing methods have recently been developed to address questions about epidemiology and source of relapse following treatment. This report describes the application of RAPD for molecular strain differentiation of this fungus utilizing the primers 1- (5'-d[GGTGCGGGAA]-3') and 6- (5'-d[CCCGTCAGCA]-3'). A total of five RAPD patterns were observed among 10 strains of T. rubrum, with each of the primers used. We conclude that RAPD analysis using primers 1 and 6 can be used in epidemiological studies.