Development of enzyme immunoassays (ELISA and Western blot) for the serological diagnosis of dermatophytosis in symptomatic and asymptomatic cats

Diagnostic ability of Peptidase S8 gene in the Arthrodermataceae causing dermatophytoses: A metadata analysis

An unambiguous identification of dermatophytes causing dermatophytoses is necessary for accurate clinical diagnosis and epidemiological implications. In the current taxonomy of the Arthrodermataceae, the etiological agents of dermatophytoses consist of seven genera and members of the genera Trichophyton are the most prevalent etiological agents at present. The genera Trichophyton consists of 16 species that are grouped as clades, but the species borderlines are not clearly delimited. The aim of the present study was to determine the discriminative power of subtilisin gene variants (SUB1-SUB12) in family Arthrodermataceae, particularly in Trichophyton. Partial and complete reads from 288 subtilisin gene sequences of 12 species were retrieved and a stringent filtering following two different approaches for analysis (probability of correct identification (PCI) and gene gap analysis) conducted to determine the uniqueness of the subtilisin gene subtypes. SUB1 with mean PCI value of 60% was the most suitable subtilisin subtype for specific detection of T.rubrum complex, however this subtype is not reported in members of T. mentagrophytes complex which is one of the most prevalent etiological agent at present. Hence, SUB7 with 40% PCI value was selected for testing its discriminative power in Trichophyton species. SUB7 specific PCR based detection of dermatophytes was tested for sensitivity and specificity. Sequences of SUB7 from 42 isolates and comparison with the ITS region showed that differences within the subtilisin gene can further be used to differentiate members of the T. mentagrophytes complex. Further, subtilisin cannot be used for the differentiation of T. benhamiae complex since all SUB subtypes show low PCI scores. Studies on the efficiency and limitations of the subtilisin gene as a diagnostic tool are currently limited. Our study provides information that will guide researchers in considering this gene for identifying dermatophytes causing dermatophytoses in human and animals.

Development and diagnostic evaluation of indirect enzyme linked immunosorbent assay for Epidermophyton floccosum infection in humans

BACKGROUND

Epidermophyton floccosum is an anthrophophilic dermatophyte widely distributed in the tropics and subtropics. It can invade keratinized tissues of humans and cause superficial mycoses called dermatophytosis (ringworm).

OBJECTIVE

The main objective of this study was to develop an in-house indirect enzyme-linked immunosorbent assay (ELISA) and to evaluate its performance for the immunological diagnosis of E. floccosum infection in humans.

METHODS

An in-house indirect ELISA was developed using partially purified E. floccosum antigens, pre immunized rabbit serum as negative control, immunized rabbit polyclonal antibodies as positive control, enzyme labeled goat anti rabbit antibodies and goat anti human antibodies. A total of 50 serum samples from E. floccosum infected patients as confirmed by direct microscopy and culture and 30 samples from humans without history of dermatophyte infection that served as controls were used to evaluate the performance of an in-house indirect ELISA developed in this study. Analytical and diagnostic performance characteristics were determined to evaluate its diagnostic value.

RESULTS

The diagnostic sensitivity, specificity, positive and negative predictive values of E. floccosum indirect ELISA were 90.00 %, 83.33 %, 90.83 %, 83.83 % respectively. The performance of indirect ELISA assay was compared with gold standard diagnostic tests such as KOH hydrolysis test and fungal culture. The correlation coefficients of E. floccosum indirect ELISA with KOH hydrolysis and fungal culture method were 0.612** and 0.826** (P < 0.01) respectively indicating significant correlation between these tests.

CONCLUSION

This revealed the great potentiality of E. floccosum indirect ELISA in early, specific and precise detection of E. floccosum infection in humans.

Reliability of using Wood's lamp by shelter personnel to diagnose Microsporum canis in cats

Optimising diagnostic methods in shelters so that they are as economical as possible for the shelter is especially important because shelters often have a significant lack of funds and so usually do not carry out preventive screening of cats. Dermatophyte fungi spread quickly and can infect shelter staff. The aim of our work was to identify the occurrence of Microsporum canis in shelter cats. It aimed to determine the prevalence of M. canis in cats at the selected shelter and compare the efficiency of detection using a Wood's lamp and culturing on Sabouraud's agar. All cats present in the shelter at the time of the study (n = 70) were examined with Wood's lamp and hair sampling followed by subsequent culturing on Sabouraud's agar. Identification of fungi was based on microscopic proof of macroconidia and microconidia. The prevalence of M. canis by diagnosis on Sabouraud's agar was 64.29% of cats, with the help of Wood's lamp 48.57% of cats showed positive fluorescence. The sensitivity of the Wood lamp examination was 71% and the specificity was 92%. Our study suggests that Wood's lamp could be used by trained shelter personnel for the first examination of cats at reception and could significantly reduce the risk of spreading M. canis in shelters.

Current Topics in Dermatophyte Classification and Clinical Diagnosis

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. Classification of many of these species has recently changed due to genetic analysis, potentially affecting clinical diagnosis and disease management. In this review, we discuss dermatophyte classification including name changes for medically important species, current and potential diagnostic techniques for detecting dermatophytes, and an in-depth review of Microsporum canis, a prevalent zoonotic dermatophyte. Fungal culture is still considered the “gold standard” for diagnosing dermatophytosis; however, modern molecular assays have overcome the main disadvantages of culture, allowing for tandem use with cultures. Further investigation into novel molecular assays for dermatophytosis is critical, especially for high-density populations where rapid diagnosis is essential for outbreak prevention. A frequently encountered dermatophyte in clinical settings is M. canis, which causes dermatophytosis in humans and cats. M. canis is adapting to its primary host (cats) as one of its mating types (MAT1-2) appears to be going extinct, leading to a loss of sexual reproduction. Investigating M. canis strains around the world can help elucidate the evolutionary trajectory of this fungi.

Development of Indirect ELISA and its evaluation in Comparison with KOH hydrolysis and Fungal culture for the immuno diagnosis of Trichophyton rubrum and Trichophyton mentagrophytes infection in Humans

Trichophyton is a keratinophilic fungus that can invade keratinized tissues of humans and cause superficial mycoses called dermatophytosis. The objective of this study was to develop and evaluate indirect ELISA in comparison with gold standard methods such as direct microscopic examination of KOH mounts and fungal culture for the diagnosis of Trichophyton infection in humans. The present investigation reports the production and partial purification of T. rubrum mycelial antigens and production of specific polyclonal antibodies. It also reports the development and optimization of indirect ELISA and evaluation of its potential in comparison with gold standard methods for the diagnosis of Trichophyton infection in humans. The diagnostic sensitivity and specificity of Trichophyton indirect ELISA was 93.75% and 93.33 % respectively. The positive and negative predictive values were high as well, found to be 93.75% and 90.00% respectively indicating usefulness of the assay. In all comparisons, the correlation coefficient (r) value was >0.5 indicating strong correlation between KOH hydrolysis test, fungal culture method and indirect ELISA. A significant correlation coefficient of 0.856 (P < 0.0001) was obtained between indirect ELISA and fungal culture method. This shows a good agreement between fungal culture method and indirect ELISA. The present study clearly shows diagnostic performance of Trichophyton indirect ELISA developed in this study is efficient as fungal culture method for the diagnosis of Trichophyton infection in humans.

Trends and Applications of Omics Technologies to Functional Characterisation of Enzymes and Protein Metabolites Produced by Fungi

Identifying and adopting industrial applications for proteins and enzymes derived from fungi strains have been at the focal point of several studies in recent times. To facilitate such studies, it is necessary that advancements and innovation in mycological and molecular characterisation are concomitant. This review aims to provide a detailed overview of the necessary steps employed in both qualitative and quantitative research using the omics technologies that are pertinent to fungi characterisation. This stems from the understanding that data provided from the functional characterisation of fungi and their metabolites is important towards the techno-economic feasibility of large-scale production of biological products. The review further describes how the functional gaps left by genomics, internal transcribe spacer (ITS) regions are addressed by transcriptomics and the various techniques and platforms utilised, including quantitive reverse transcription polymerase chain reaction (RT-qPCR), hybridisation techniques, and RNA-seq, and the insights such data provide on the effect of environmental changes on fungal enzyme production from an expressional standpoint. The review also offers information on the many available bioinformatics tools of analysis necessary for the analysis of the overwhelming data synonymous with the omics approach to fungal characterisation.

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.

Comparison of carpet and toothbrush techniques for the detection of Microsporum canis in cats

OBJECTIVES

The aim of this study was to evaluate the diagnostic concordance between the toothbrush and carpet techniques for the detection of Microsporum canis in cats in a field study.

METHODS

Thirty-nine Persian cats from a cattery were used. Fungal culture samples from the haircoat of each cat were collected by stroking the coat with a sterile toothbrush and a 5 × 5 cm-sized sterile carpet square (n = 78 total samples). Specimens were inoculated onto Mycosel Agar and incubated at 25°C for 21 days. Both techniques were compared using the following parameters: number of plates without fungal growth, number of plates with contaminant growth and number of plates positive for dermatophytes.

RESULTS

The feline population in the study cattery was 39. Thirty (77%) were symptomatic and nine (23%) asymptomatic. The diagnosis was made via carpet and toothbrush methods and 78 cultures were performed. On day 21, M canis was detected in all culture plates. No contaminant molds were observed.

CONCLUSIONS AND RELEVANCE

The concordance rate between the carpet and toothbrush techniques among the 78 evaluable culture plates was 100%. Both methods are equally effective for collecting material for Mcanis culture. Additionally, both techniques are inexpensive and easy to perform in feline clinical practice.

Microbiological Sensing Technologies: A Review

Microorganisms have a significant influence on human activities and health, and consequently, there is high demand to develop automated, sensitive, and rapid methods for their detection. These methods might be applicable for clinical, industrial, and environmental applications. Although different techniques have been suggested and employed for the detection of microorganisms, and the majority of these methods are not cost effective and suffer from low sensitivity and low specificity, especially in mixed samples. This paper presents a comprehensive review of microbiological techniques and associated challenges for bioengineering researchers with an engineering background. Also, this paper reports on recent technological advances and their future prospects for a variety of microbiological applications.

Development and evaluation of indirect enzyme linked immunosorbent assay for the serological diagnosis of Microsporum canis infection in humans

PURPOSE

The aim of this study was to develop and evaluate the diagnostic potential of indirect enzyme-linked immunosorbent assay (I-ELISA) for the rapid and precise diagnosis of Microsporum canis infection in humans.

BASIC PROCEDURES

The present study reports the production, partial purification and SDS-PAGE analysis of M. canis mycelial antigens and production of specific polyclonal antibodies. It also reports the development and optimization of indirect ELISA and evaluation of its potential for the diagnosis of M. canis infection in humans.

MAIN FINDINGS

An I-ELISA showed the sensitivity of 94.55% and specificity of 93.33%. Positive and negative predictive values were 96.30% and 90.32% respectively. Receiver operating characteristic (ROC) curve analysis of the data showed higher diagnostic accuracy. The area under the curve (AUC) was 0.925. A significant correlation coefficient of 0.8771 (P<0.0001) was obtained between I-ELISA and fungal culture method.

PRINCIPAL CONCLUSIONS

In conclusion, the present study clearly shows the detection of specific antibodies by indirect ELISA using M. canis antigens. The assay is sensitive, specific and easy to perform, could enable rapid and more convenient diagnosis of dermatophytosis in humans.

Manipulation of Light Signal Transduction Factors as a Means of Modifying Steroidal Glycoalkaloids Accumulation in Tomato Leaves

Steroidal glycoalkaloids (SGAs) are cholesterol-derived specialized metabolites produced by Solanaceous plant species. They contribute to pathogen defense but are considered as anti-nutritional compounds and toxic to humans. Although the genes involved in the SGA biosynthetic pathway have been successfully cloned and identified, transcription factors regulating this pathway are still poorly understood. We report that silencing tomato light signal transduction transcription factors ELONGATED HYPOCOTYL 5 (SlHY5) and PHYTOCHROME INTERACTING FACTOR3 (SlPIF3), by virus-induced gene silencing (VIGS), altered glycoalkaloids levels in tomato leaves compared to control plant. Electrophoretic mobility shift assay (EMSA) and Chromatin immunoprecipitation (ChIP) analysis confirmed that SlHY5 and SlPIF3 bind to the promoter of target genes of GLYCOALKALOID METABOLISM (GAME1, GAME4, GAME17), affecting the steady-state concentrations of transcripts coding for SGA pathway enzymes. The results indicate that light-signaling transcription factors HY5 and PIF3 regulate the abundance of SGAs by modulating the transcript levels of these GAME genes. This insight into the regulation of SGA biosynthesis can be used for manipulating the level of these metabolites in crops.