Identification of dermatophytes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

An easy adjustment of instrument settings ('Peak MALDI') improves identification of organisms by MALDI-ToF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) is a mature technolaogy with 'auto-execute' instrument settings and peak processing parameters tailored for rapid bacterial identification. Adoption for other organisms has been problematic, with optimisation efforts focusing on sample preparation. Using the Bruker MALDI Biotyper, we demonstrate 'Peak MALDI': easily-applied settings that immediately enhance sensitivity, improve spectrum quality, and increase identification confidence for any target, establishing its potential value for all MALDI-ToF MS systems.

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.

Mass spectrometry in research laboratories and clinical diagnostic: a new era in medical mycology

Diagnosis by clinical mycology laboratory plays a critical role in patient care by providing definitive knowledge of the cause of infection and antimicrobial susceptibility data to physicians. Rapid diagnostic methods are likely to improve patient. Aggressive resuscitation bundles, adequate source control, and appropriate antibiotic therapy are cornerstones for success in the treatment of patients. Routine methods for identifying clinical specimen fungal pathogen are based on the cultivation on different media with the subsequent examination of its phenotypic characteristics comprising a combination of microscopic and colony morphologies. As some fungi cannot be readily identified using these methods, molecular diagnostic methods may be required. These methods are fast, but it can cost a lot. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is suitable for high-throughput and rapid diagnostics at low costs. It can be considered an alternative for conventional biochemical and molecular identification systems in a microbiological laboratory. The reliability and accuracy of this method have been scrutinized in many surveys and have been compared with several methods including sequencing and molecular methods. According to these findings, the reliability and accuracy of this method are very high and can be trusted. With all the benefits of this technique, the libraries of MALDI-TOF MS need to be strengthened to enhance its performance. This review provides an overview of the most recent research literature that has investigated the applications and usage of MT-MS to the identification of microorganisms, mycotoxins, antifungal susceptibility examination, and mycobiome research.

Phylogenetic and ecological reevaluation of the order Onygenales

The order Onygenales is classified in the class Eurotiomycetes of the subphylum Pezizomycotina. Families in this order have classically been isolated from soil and dung, and two lineages contain causative agents of superficial, cutaneous and systemic infections in mammals. The ecology and habitat choices of the species are driven mainly by the keratin and cellulose degradation abilities. The present study aimed to investigate whether the ecological trends of the members of Onygenales can be interpreted in an evolutionary sense, linking phylogenetic parameters with habitat preferences, to achieve polyphasic definitions of the main taxonomic groups. Evolutionary processes were estimated by multiple gene genealogies and divergence time analysis. Previously described families, namely, Arthrodermataceae, Ajellomycetaceae, Ascosphaeraceae, Eremascaceae, Gymnoascaceae, Onygenaceae and Spiromastigoidaceae, were accepted in Onygenales, and two new families, Malbrancheaceae and Neogymnomycetaceae, were introduced. A number of species could not be assigned to any of the defined families. Our study provides a revised overview of the main lines of taxonomy of Onygenales, supported by multilocus analyses of ITS, LSU, TUB, TEF1, TEF3, RPB1, RPB2, and ribosomal protein 60S L10 (L1) (RP60S) sequences, combined with available data on ecology, physiology, morphology, and genomics.

The qualitative accuracy of clinical dermatophytes via matrix-assisted laser desorption ionization-time of flight mass spectrometry: a meta-analysis

Dermatophytes are an important part of superficial fungal infections, and accurate diagnosis is paramount for successful treatment. Recently, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a powerful tool to identify clinical pathogens; its advantages are cost-effectiveness, rapid detection, and high accuracy. However, as the accurate identification of clinical dermatophytes via MALDI-TOF MS has still not been fully evaluated, we performed a meta-analysis for systematic evaluation it. Fifteen eligible studies were involved and showed high accuracy with an identification ratio of 0.96 (95%CI = 0.92─1.01) and 0.91 (95%CI = 0.86─0.96) at the genus and species levels, respectively. The results showed higher accuracy ratio of Vitek MS (91%) than MALDI Biotyper (85%). Dermatophytes such as Trichophyton interdigitale (0.99, 95%CI = 0.97─1.02), T. mentagrophytes var interdigitale (1.00, 95%CI = 0.98─1.02), and Microsporum canis (0.97, 95%CI = 0.89─1.04) showed high accuracy in detected clinical dermatophytes. Moreover, a library with self-built database set up by laboratories showed higher accuracy than commercial database, and 15-day cultivation for dermatophytes showed highest accuracy considering culture time. High heterogeneity was observed and decreased only with the subgroup analysis of species. The subgroup analysis of mass spectrometry, library database, and culture time also exhibited high heterogeneity. In summary, our results showed that MALDI-TOF MS could be used for highly accurate detection of clinically pathogenic dermatophytes, which could be an alternative diagnostic method in addition to morphological and molecular methods.

LAY ABSTRACT

This meta-analysis comprehensively investigated the qualitative accuracy of clinical dermatophytes through MALDI-TOF MS. Owing to the high accuracy observed at both genus and species levels, this approach could be an alternative diagnostic method in addition to morphological and molecular methods.

An exploratory MALDI-TOF MS library based on SARAMIS superspectra for rapid identification of Aspergillus section Nigri

Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is a broadly used technique for identification and typing of microorganisms. However, its application to filamentous fungi has been delayed. The objective of this study was to establish a data library for rapid identification of the genus Aspergillus sect. Nigri using MALDI-TOF MS. With respect to sample preparation, we compared the utility of using mature mycelia, including conidial structures, to accumulate a wider range of proteins versus the conventional method relying on young hyphae. Mass spectral datasets obtained for 61 strains of 17 species were subjected to cluster analysis and compared with a phylogenetic tree based on calmodulin gene sequences. Specific and frequent mass spectral peaks corresponding to each phylogenetic group were selected (superspectra for the SARAMIS system). Fifteen superspectra representing nine species were ultimately created. The percentage of correct identification for 217 spectra was improved from 36.41% to 86.64% using the revised library. Additionally, 2.76% of the spectra were assigned to candidates that comprised several related species, including the correct species.

Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry

Dermatophytoses represent a major health burden in animals and man. Zoophilic dermatophytes usually show a high specificity to their original animal host but a zoonotic transmission is increasingly recorded. In humans, these infections elicit highly inflammatory skin lesions requiring prolonged therapy even in the immunocompetent patient. The correct identification of the causative agent is often crucial to initiate a targeted and effective therapy. To that end, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The objective of this study was to evaluate the reliability of species identification of zoophilic dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based identification of the most common zoophilic dermatophyte Microsporum canis. Trichophyton (T.) spp. usually achieved scores only around the cutoff value for secure species identification because of a small number of reference spectra. Moreover, these results need to be interpreted with caution due to the close taxonomic relationship of dermatophytes being reflected in very similar spectra. In our study, the analysis of 50 clinical samples of hedgehogs revealed no correct identification using the provided databases, nor for zoophilic neither for geophilic causative agents. After DNA sequencing, adaptation of sample processing and an individual extension of the in-house database, acceptable identification scores were achieved (T. erinacei and Arthroderma spp., respectively). A score-oriented distance dendrogram revealed clustering of geophilic isolates of four different species of the genus Arthroderma and underlined the close relationship of the important zoophilic agents T. erinacei, T. verrucosum and T. benhamiae by forming a subclade within a larger cluster including different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the identification of zoophilic dermatophytes provided fresh cultures are used and the reference library was previously extended with spectra of laboratory-relevant species. Performing independent molecular methods, such as sequencing, is strongly recommended to substantiate the findings from morphologic and MALDI-TOF MS analyses, especially for uncommon causative agents.

Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry: Protocol standardisation, comparison and database expansion for faster and reliable identification of dermatophytes

BACKGROUND

Accurate and early identification of dermatophytes enables prompt antifungal therapy. However, phenotypic and molecular identification methods are time-consuming. MALDI-TOF MS-based identification is rapid, but an optimum protocol is not available.

OBJECTIVES

To develop and validate an optimum protein extraction protocol for the efficient and accurate identification of dermatophytes by MALDI-TOF MS.

MATERIALS/METHODS

Trichophyton mentagrophytes complex (n = 4), T. rubrum (n = 4) and Microsporum gypseum (n = 4) were used for the optimisation of protein extraction protocols. Thirteen different methods were evaluated. A total of 125 DNA sequence confirmed clinical isolates of dermatophytes were used to create and expand the existing database. The accuracy of the created database was checked by visual inspection of MALDI spectra, MSP dendrogram and composite correlation index matrix analysis. The protocol was validated further using 234 isolates.

RESULT

Among 13 protein extraction methods, six correctly identified dermatophytes but with a low log score (≤1.0). The modified extraction protocol developed provided an elevated log score of 1.6. Significant log score difference was observed between the modified protocol and other existing protocols (T. mentagrophytes complex: 1.6 vs. 0.2-1.0, p < .001; T. rubrum: 1.6 vs. 0.4-1.0, p < .001; M. gypseum:1.6 vs. 0.2-1.0, p < .001). Expansion of the database enabled the identification of all 234 isolates (73.5% with log score ≥2.0 and 26.4% with log scores range: 1.75-1.99). The results were comparable to DNA sequence-based identification.

CONCLUSION

MALDI-TOF MS with an updated database and efficient protein extraction protocol developed in this study can identify dermatophytes accurately and also reduce the time for identifying them.

A Household Microsporum canis Dermatophytosis Suggested by Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry Analysis

Case series

Patients: Female, 4-year-old • her family (father, mother, sister)

Final Diagnosis: Microsporum canis dermatophytosis

Symptoms: Itiching

Medication: —

Clinical Procedure: Time-of-flight mass spectrometry (TOF-MS)

Specialty: Infectious Diseases

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.

Epidemiology and Diagnostic Perspectives of Dermatophytoses

Dermatophytoses affect about 25% of the world population, and the filamentous fungus Trichophyton rubrum is the main causative agent of this group of diseases. Dermatomycoses are caused by pathogenic fungi that generally trigger superficial infections and that feed on keratinized substrates such as skin, hair, and nails. However, there are an increasing number of reports describing dermatophytes that invade deep layers such as the dermis and hypodermis and that can cause deep infections in diabetic and immunocompromised patients, as well as in individuals with immunodeficiency. Despite the high incidence and importance of dermatophytes in clinical mycology, the diagnosis of this type of infection is not always accurate. The conventional methods most commonly used for mycological diagnosis are based on the identification of microbiological and biochemical features. However, in view of the limitations of these conventional methods, molecular diagnostic techniques are increasingly being used because of their higher sensitivity, specificity and rapidity and have become more accessible. The most widely used molecular techniques are conventional PCR, quantitative PCR, multiplex PCR, nested, PCR, PCR-RFLP, and PCR-ELISA. Another promising technique for the identification of microorganisms is the analysis of protein profiles by MALDI-TOF MS. Molecular techniques are promising but it is necessary to improve the quality and availability of the information in genomic and proteomic databases in order to streamline the use of bioinformatics in the identification of dermatophytes of clinical interest.

The change of causative pathogens in toenail onychomycosis

BACKGROUND

Toenail dystrophies are among the most common diseases in adulthood. Onychomycosis is one of the most frequently observed infectious diseases of the nail.

AIM

The aim of this study was to determine the prevalence of fungal agents in the etiology of nail dystrophies such as discoloration, thickening, subungual hyperkeratosis, and onycholysis in toenails and to emphasize the importance of diagnosis by other laboratory confirmation tests since various nail diseases may mimic onychomycosis.

SUBJECTS AND METHODS

Nail samples taken from 53 patients who were admitted to the dermatology clinic with the complaint of toenail disorders were examined by using potassium hydroxide mount, fungal culture, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry methods. Each nail was photographed, and descriptive analysis of the data was performed.

RESULTS

Of 53 patients included in the study, 39 were female (73.6%) and 14 were male (26.4%). The ages of the patients ranged from 14 to 70 years, and the mean age was 37.8 years. No fungi could be isolated in 17 (32%) patients with nail dystrophy, while fungal pathogens were observed in 36 (68%) patients on potassium hydroxide mount, culture, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry examinations. Among nondermatophyte molds, Aspergillus species (52.7%) were identified as the most common fungal pathogen causing onychomycosis.

CONCLUSION

Although fungal pathogenic agents are mostly detected among the diseases causing color changes and deformities in the nails, it should be kept in mind that nail findings of systemic or other skin diseases may mimic onychomycosis and the diagnosis should be confirmed by laboratory tests in addition to clinical manifestations for accurate treatment.

STUDY LIMITATIONS

Other systemic diseases causing nail dystrophy were not questioned in the study.

Antifungal susceptibility testing of dermatophytes: Development and evaluation of an optimised broth microdilution method

BACKGROUND

Dermatophytosis is one of the most common infections affecting 3%-17% of the population. Resistance to antifungals so far was not of concern in the therapeutic management. However, recent reports of terbinafine-resistant strains in several countries are worrisome making antifungal susceptibility testing inevitable.

OBJECTIVES

We aimed to develop and evaluate an optimised broth microdilution assay for antifungal drug susceptibility testing of dermatophytes.

METHODS

We first studied the effect of different inocula, incubation temperatures and incubation times to establish an optimised assay. Subsequently, we tested 79 clinical strains of 11 dermatophyte species with 13 antifungals.

RESULTS

We found inoculating with 0.5-5 × 10⁴ colony forming units (CFU) and incubating at 29°C ± 1°C for 4 days to be appropriate. Terbinafine was the most active antifungal agent with minimum inhibitory concentration (MIC) values ≤ 0.06 µg/mL, expect for one resistant T mentagrophytes strain, which was isolated from an Indian patient. Also, a majority of MICs of other antifungals that are commonly used to treat dermatophytosis were low, except those of fluconazole. Fluconazole MICs do not correlate with the good efficacy in the clinical management.

CONCLUSIONS

Our assay enables fast and reliable susceptibility testing of dermatophytes with a large panel of different antifungals. This helps to improve the therapeutic management of dermatophytosis by detecting resistant strains.

Evaluation of the new Id-Fungi plates from Conidia for MALDI-TOF MS identification of filamentous fungi and comparison with conventional methods as identification tool for dermatophytes from nails, hair and skin samples

OBJECTIVES

We first compare the efficiency of mould/dermatophyte identification by MALDI-TOF MS using a new medium called Id-Fungi plates (IDFP) from Conidia^® and two different databases. For the second purpose, we evaluated a new version of the medium supplemented with cycloheximide, Id-Fungi plates Plus (IDFPC) for the direct inoculation of nails, hair and skin samples and compared the efficiency of MALDI-TOF MS identification of dermatophytes to classical methods based on culture and microscopy.

METHODS

A total of 71 strains have been cultured IDFP and Sabouraud gentamicin plates (SGC2) and were identified by MALDI-TOF MS. For the evaluation of the combination IDFPC/ MALDI-TOF MS as a method of identification for dermatophytes, 428 samples of hair nails and skin were cultivated in parallel on IDFPC and Sabouraud + cycloheximide medium (SAB-ACTI).

RESULTS

For Aspergillus sp and non-Aspergillus moulds, the best performances were obtained on IDFP after maximum 48-h growth, following protein extraction. For dermatophytes, the best condition was using the IDFP at 72 hours, after extended direct deposit. Regarding the direct inoculation of nails, hair skin on IDFPC, 129/428 (30.1%) showed a positive culture against 150/428 (35%) on SAB-ACTI medium. Among the 129 positive strains, the identification by MALDI-TOF MS was correct for 92/129 (71.4%).

CONCLUSION

The IDFP allows the generation of better spectra by MALDI-TOF MS compared to SGC2. It facilitates sampling and deposit. Regarding the use of IDFPC, this medium seems less sensitive than SAB-ACTI but among positive strains, the rate of correct identification by MALDI-TOF MS is satisfactory.

MALDI-TOF MS for the rapid identification and drug susceptibility testing of filamentous fungi

The present study aimed to evaluate the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identifying filamentous fungi and assessing the in vitro activities of common antifungal drugs against different kinds of filamentous fungi that are commonly encountered in a clinical setting. A total of 123 strains of filamentous fungi (24 species) were submitted for identification by MALDI-TOF MS, and the findings were compared with those obtained by conventional methods. The discrepancies were further investigated by internal transcribed spacer (ITS) sequence analysis. Then, 79 strains were randomly selected for further testing by the minimum inhibitory concentration Etest method. MALDI-TOF MS correctly identified 114 (92.70%) of the 123 filamentous fungi and failed to identify six isolates (4.9%). By contrast, the conventional identification methods made 113 (91.9%) correct identifications. In addition, 15 isolates of filamentous fungi were further identified by ribosomal DNA-ITS sequencing. In the in vitro antifungal susceptibility test, voriconazole showed the strongest antifungal activity among the tested drugs against a broad range of filamentous fungi. Caspofungin showed a better in vitro antifungal activity than fluconazole, itraconazole, and amphotericin B. MALDI-TOF MS offers a cost/time-saving, high-throughput and accurate working protocol for identifying filamentous fungi. Voriconazole could still serve as the first-line drug for treating serious infections caused by filamentous fungi, while caspofungin may be another treatment option for fungal infections.

Mating analyses of Trichophyton benhamiae offspring reveals linkage of genetic markers used in taxonomy

Mating experiments were conducted with four clinical Trichophyton benhamiae isolates, genetically similar to the Trichophyton benhamiae CBS 112371, featuring the plus mating type and with two minus type strains. One minus type strain belonged to the white subgroup, and the other minus type strain, DSM 6916, showed genetic kinship to the yellow subgroup. Only two plus type strains were able to form mature, pigmented gymnothecia with DSM 6916. These two plus type strains demonstrated dark pigmentation and powdery mycelium on Takashio agar, whereas the other three strains exhibited a low degree of pigmentation on the same medium. All five plus strains were able to mate with the minus type strain of their own white subgroup. Cultures from single ascospore isolates showed highly variable morphology and pigmentation. Three genetic markers (ITS, mating type, EF1 alpha) were analyzed in polymerase chain reaction (PCR) experiments with optimized primers and PCR conditions to discriminate between subgroups. Furthermore, RAPD-PCR was used to generate a DSM 6916-specific DNA-fragment which served as an additional genetic marker. Assessing the isolates with recombinant genotypes, it was found that three genetic markers behave like linked genes. The recombination of plus mating type went together with ITS, EF1 alpha and RAPD marker of the DSM 6916 parental strain and was most frequently isolated, whereas plus types recombinants in this case were completely missing. This shows a high imbalance in mating type distribution of recombinants.

Multicenter Study Demonstrates Standardization Requirements for Mold Identification by MALDI-TOF MS

Objectives

Rapid and accurate mold identification is critical for guiding therapy for mold infections. MALDI-TOF MS has been widely adopted for bacterial and yeast identification; however, few clinical laboratories have applied this technology for routine mold identification due to limited database availability and lack of standardized processes. Here, we evaluated the versatility of the NIH Mold Database in a multicenter evaluation.

Methods

The NIH Mold Database was evaluated by eight US academic centers using a solid media extraction method and a challenge set of 80 clinical mold isolates. Multiple instrument parameters important for spectra optimization were evaluated, leading to the development of two specialized acquisition programs (NIH method and the Alternate-B method).

Results

A wide range in performance (33–77%) was initially observed across the eight centers when routine spectral acquisition parameters were applied. Use of the NIH or the Alternate-B specialized acquisition programs, which are different than those used routinely for bacterial and yeast spectral acquisition (MBT_AutoX), in combination with optimized instrument maintenance, improved performance, illustrating that acquisition parameters may be one of the key limiting variable in achieving successful performance.

Conclusion

Successful mold identification using the NIH Database for MALDI-TOF MS on Biotyper systems was demonstrated across multiple institutions for the first time following identification of critical program parameters combined with instrument optimization. This significantly advances our potential to implement MALDI-TOF MS for mold identification across many institutions. Because instrument variability is inevitable, development of an instrument performance standard specific for mold spectral acquisition is suggested to improve reproducibility across instruments.

[Hedgehog fungi in a dermatological office in Munich : Case reports and review]

Patient 1: After contact to a central European hedgehog (Erinaceus europaeus), a 50-year-old female with atopy developed erythrosquamous tinea manus on the thumb and thenar eminence of the right hand. The patient had previously been scalded by hot steam at the affected site. The zoophilic dermatophyte Trichophyton erinacei could be cultured from the hedgehog as well as from scrapings from the woman's skin. Antifungal treatment of the hedgehog was initiated using 2 weekly cycles of itraconazole solution (0.1 ml/kg body weight, BW). In addition, every other day enilconazole solution was used for topical treatment. The patient was treated with ciclopirox olamine cream and oral terbinafine 250 mg daily for 2 weeks, which led to healing of the Tinea manus .Patient 2: An 18-year-old woman presented for emergency consultation with rimmed, papulous, vesicular and erosive crusted skin lesions of the index finger, and an erythematous dry scaling round lesion on the thigh. The patient worked at an animal care facility, specifically caring for hedgehogs. One of the hedgehogs suffered from a substantial loss of spines. Fungal cultures from skin scrapings of both lesions yielded T. erinacei. Treatment with ciclopirox olamine cream and oral terbinafine 250 mg for 14 days was initiated which led to healing of the lesions. Identification of all three T. erinacei isolates from both patients and from the hedgehog was confirmed by sequencing of the internal transcribed spacer (ITS) region of the ribosomal DNA, and of the translation elongation factor (TEF)-1-alpha gene. Using ITS sequencing discrimination between T. erinacei strains from European and from African hedgehogs is possible. T. erinacei should be considered a so-called emerging pathogen. In Germany the zoophilic dermatophyte T. erinacei should be taken into account as causative agent of dermatomycoses in humans after contact to hedgehogs.

Rapid characterization of aquatic hyphomycetes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Protein fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI--TOF MS) is a rapid, reliable, and economical method to characterize isolates of terrestrial fungi and other microorganisms. The objective of our study was to evaluate the suitability of MALDI-TOF MS for the identification of aquatic hyphomycetes, a polyphyletic group of fungi that play crucial roles in stream ecosystems. To this end, we used 34 isolates of 21 aquatic hyphomycete species whose identity was confirmed by spore morphology and internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) nuc rDNA sequencing. We tested the efficiency of three protein extraction methods, including chemical and mechanical treatments using 13 different protocols, with the objective of producing high-quality MALDI-TOF mass spectra. In addition to extraction protocols, mycelium age was identified as a key parameter affecting protein extraction efficiency. The dendrogram based on mass-spectrum similarity indicated good and relevant taxonomic discrimination; the tree structure was comparable to that of the phylogram based on ITS sequences. Consequently, MALDI-TOF MS could reliably identify the isolates studied and provided greater taxonomic accuracy than classical morphological methods. MALDI-TOF MS seems suited for rapid characterization and identification of aquatic hyphomycete species.

A Moldy Application of MALDI: MALDI-ToF Mass Spectrometry for Fungal Identification

As a result of its being inexpensive, easy to perform, fast and accurate, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF MS) is quickly becoming the standard means of bacterial identification from cultures in clinical microbiology laboratories. Its adoption for routine identification of yeasts and even dimorphic and filamentous fungi in cultures, while slower, is now being realized, with many of the same benefits as have been recognized on the bacterial side. In this review, the use of MALDI-ToF MS for identification of yeasts, and dimorphic and filamentous fungi grown in culture will be reviewed, with strengths and limitations addressed.

[Trichophyton mentagrophytes-from snow leopard to man : A molecular approach for uncovering the chain of infection]

Sources of infection for Trichophyton (T.) mentagrophytes-a zoophilic dermatophyte-comprise pet rodents (guinea pigs, mice, rabbits) and sometimes cats. Human infections due to dermatophytes after contact with zoo animals, however, are extreme rare. Four zoo keepers from Basel Zoo were diagnosed to suffer from tinea manus and tinea corporis due to T. mentagrophytes. The 22-year-old daughter of one zoo keeper was also infected with tinea corporis after having worked in the snow leopard section for one day. The strain of the index patient was confirmed by a direct uniplex-PCR-EIA and sequence analysis of the ribosomal internal transcribed spacer (ITS) region (18S rRNA, ITS1, 5.8S rRNA, ITS2, 28S rRNA) as T. mentagrophytes. Three young snow leopards from Basel Zoo were identified as the origin of the fungal skin infection. The transmission occurred due to direct contact of the zoo keepers with the young snow leopards when removing hedgehog ticks (Ixodes hexagonus). Two adult snow leopards had developed focal alopecia of the facial region which was diagnosed as dermatomycoses due to T. mentagrophytes by the zoo veterinarians. By sequence analysis, both the strains from the animals and a single strain of the index patient showed 100% accordance proving transmission of T. mentagrophytes from animals to the zoo keepers. Molecular biological identification revealed a strong relationship to a strain of T. mentagrophytes from European mink (Mustela lutreola) from Finland. Treatment of patients was started using topical ointment with azole antifungals, and oral terbinafine 250 mg once daily for 4 weeks. Both adult snow leopards and the asymptomatic young animals were treated with oral itraconazole.

Competition of As and other Group 15 elements for surface binding sites of an extremophilic Acidomyces acidophilus isolated from a historical tin mining site

An arsenic-resistant fungal strain, designated WKC-1, was isolated from a waste roaster pile in a historical tin mine in Cornwall, UK and successfully identified to be Acidomyces acidophilus using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) proteomic-based biotyping approach. WKC-1 showed considerable resistance to As⁵⁺ and Sb⁵⁺ where the minimal inhibitory concentration (MIC) were 22500 and 100 mg L^-1, respectively, on Czapex-Dox Agar (CDA) medium; it was substantially more resistant to As⁵⁺ than the reference strains CBS 335.97 and CCF 4251. In a modified CDA medium containing 0.02 mg L^-1 phosphate, WKC-1 was able to remove 70.30% of As⁵⁺ (100 mg L^-1). Sorption experiment showed that the maximum capacity of As⁵⁺ uptake was 170.82 mg g^-1 dry biomass as predicted by the Langmuir model. The presence of Sb⁵⁺ reduced the As⁵⁺ uptake by nearly 40%. Based on the Fourier-transform infrared spectroscopy (FT-IR) analysis, we propose that Sb is competing with As for these sorption sites: OH, NH, CH, SO₃ and PO₄ on the fungal cell surface. To our knowledge, this is the first report on the impact of other Group 15 elements on the biosorption of As⁵⁺ in Acidomyces acidophilus.

Ultra-High-Resolution Mass Spectrometry for Identification of Closely Related Dermatophytes with Different Clinical Predilections

In the present study, an innovative top-down liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the identification of clinically relevant fungi is tested using a model set of dermatophyte strains. The methodology characterizes intact proteins derived from Trichophyton species, which are used as parameters of differentiation. To test its resolving power compared to that of traditional Sanger sequencing and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF), 24 strains of closely related dermatophytes, Trichophyton rubrum, T. violaceum, T. tonsurans, T. equinum, and T. interdigitale, were subjected to this new approach. Using MS/MS and different deconvolution algorithms, we identified hundreds of individual proteins, with a subpopulation of these used as strain- or species-specific markers. Three species, i.e., T. rubrum, T. violaceum, and T. interdigitale, were identified correctly down to the species level. Moreover, all isolates associated with these three species were identified correctly down to the strain level. In the T. tonsurans-equinum complex, eight out of 12 strains showed nearly identical proteomes, indicating an unresolved taxonomic conflict already apparent from previous phylogenetic data. In this case, it was determined with high probability that only a single species can be present. Our study successfully demonstrates applicability of the mass spectrometric approach to identify clinically relevant filamentous fungi. Here, we present the first proof-of-principle study employing the mentioned technology to differentiate microbial pathogens. The ability to differentiate fungi at the strain level sets the stage to improve patient outcomes, such as early detection of strains that carry resistance to antifungals.

Fast identification of dermatophytes by MALDI-TOF/MS using direct transfer of fungal cells on ground steel target plates

Dermatophytes cause human infections limited to keratinised tissues. We showed that the direct transfer method allows reliable identification of non-dermatophytes mould and yeast by MALDI-TOF/MS. We aimed at assessing whether the direct transfer method can be used for dermatophytes and whether an own mass spectra library would be superior to the Bruker library. We used the Bruker Biotyper to build a dermatophyte mass spectra library and assessed its performance by 1/testing a panel of mass spectrum produced with strains genotypically identified and, 2/comparing MALDI-TOF/MS identification to morphology-based methods. Identification of dermatophytes using the Bruker library is poor. Our library provided 97% concordance between ITS sequencing and MALDI-TOF/MS analysis with a panel of 1104 spectra corresponding to 276 strains. Direct transfer method using unpolished target plates allowed proper identification of 85% of dermatophytes clinical isolates most of which were common dermatophytes. A homemade dermatophyte MSP library is a prerequisite for accurate identification of species absent in the Bruker library but it also improves identification of species already listed in the database. The direct deposit method can be used to identify the most commonly found dermatophytes such as T. rubrum and T. interdigitale/mentagrophytes by MALDI-TOF/MS.

[Tinea faciei caused by Nannizzia persicolor : An underdiagnosed dermatophyte?]

We report on a tinea faciei caused by Nannizzia (N.) persicolor. The 4‑year-old boy had probably been infected by a guinea pig. Unambiguous infections caused by N. persicolor are rarely seen in Germany; however, this zoophilic and geophilic dermatophyte may only be rarely identified due to its resemblance to Trichophyton (T.) mentagrophytes. Therefore, the diagnostic attributes of N. persicolor and its differentiation from T. mentagrophytes are described. Particularly in case of contact with rodents, N. persicolor should be kept in mind.

Rapid one-step extraction method for the identification of molds using MALDI-TOF MS

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized fungal identification. Previously, we developed a MALDI-TOF MS mold extraction procedure and comprehensive database. While MALDI-TOF MS has become routine in a few laboratories, it has not yet become widespread. A major obstacle is the lack of a simple, reproducible and uniform protein extraction procedure. In this study, we developed and validated a rapid one-step protein extraction protocol for filamentous fungi. Excised molds were placed into tubes containing zirconia-silica beads and extraction solution without washing or ethanol inactivation steps. Extraction solutions containing different ratios of acetonitrile and formic acid were evaluated. Samples were then processed using a PowerLyzer high power bead based homogenizer and supernatants spotted for MALDI-TOF MS. The rapid method was evaluated prospectively and in parallel to our current mold extraction protocol for 3 months. Analysis of 106 clinical mold isolates resulted in an improved performance and a decrease in extraction time by 30 minutes to a total of 5 minutes of hands-on time. Acceptable identification scores (≥ 2.00) were achieved for up to 63.0% of mold isolates by the rapid method compared with 52.8% of isolates by the current routine protocol. Score comparisons between duplicate spots showed higher reproducibility of the rapid method as compared to the routine method. The rapid extraction method allows efficient analysis of clinical mold isolates both in scheduled batch runs and on an in-demand basis while providing a simple starting platform for laboratories adopting MALDI-TOF MS for mold identification.

Multicenter Evaluation of the Vitek MS v3.0 System for the Identification of Filamentous Fungi

Invasive fungal infections are an important cause of morbidity and mortality affecting primarily immunocompromised patients. While fungal identification to the species level is critical to providing appropriate therapy, it can be slow and laborious and often relies on subjective morphological criteria. The use of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry has the potential to speed up and improve the accuracy of identification. In this multicenter study, we evaluated the accuracy of the Vitek MS v3.0 system in identifying 1,601 clinical mold isolates compared to identification by DNA sequence analysis and supported by morphological and phenotypic testing. Among the 1,519 isolates representing organisms in the v3.0 database, 91% (n = 1,387) were correctly identified to the species level. An additional 27 isolates (2%) were correctly identified to the genus level. Fifteen isolates were incorrectly identified, due to either a single incorrect identification (n = 13) or multiple identifications from different genera (n = 2). In those cases, when a single identification was provided that was not correct, the misidentification was within the same genus. The Vitek MS v3.0 was unable to identify 91 (6%) isolates, despite repeat testing. These isolates were distributed among all the genera. When considering all isolates tested, even those that were not represented in the database, the Vitek MS v3.0 provided a single correct identification 98% of the time. These findings demonstrate that the Vitek MS v3.0 system is highly accurate for the identification of common molds encountered in the clinical mycology laboratory.

A case of tinea incognita and differential diagnosis of figurate erythema

A patient with tinea incognita is presented together with a review of the literature of figurate erythema. Figurate lesions are emblematic for dermatology and perhaps the most picturesque efflorescences. The differential diagnosis can be broad and sometimes challenging. Many clinical entities with resembling primary and secondary efflorescences have to be considered as differentials and can be due to anti-infectious, paraneoplastic, allergic, autoimmune or other immune reactions.

Decision criteria for MALDI-TOF MS-based identification of filamentous fungi using commercial and in-house reference databases

BACKGROUND

Several Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry protocols, which differ in identification criteria, have been developed for mold and dermatophyte identification. Currently, the most widely used approach is Bruker technology, although no consensus concerning the log(score) threshold has been established. Furthermore, it remains unknown how far increasing the number of spots to compare results might improve identification performance. In this study, we used in-house and Bruker reference databases as well as a panel of 422 isolates belonging to 126 species to test various thresholds. Ten distinct identification algorithms requiring one to four spots were tested.

RESULTS

Our findings indicate that optimal results were obtained by applying a decisional algorithm in which only the highest score of four spots was taken into account with a 1.7 log(score) threshold. Testing the entire panel enabled identification of 87.41% (in-house database) and 35.15% (Bruker database) of isolates, with a positive predictive value (PPV) of 1 at the genus level for both databases as well as 0.89 PPV (in-house database) and 0.72 PPV (Bruker database) at the species level. Applying the same rules to the isolates for which the species were represented by at least three strains in the database enabled identification of 92.1% (in-house database) and 46.6% (Bruker database) of isolates, with 1 PPV at the genus level for both databases as well as 0.95 PPV (in-house database) and 0.93 PPV (Bruker database) at the species level.

CONCLUSIONS

Depositing four spots per extract and lowering the threshold to 1.7, a threshold which is notably lower than that recommended for bacterial identification, decreased the number of unidentified specimens without altering the reliability of the accepted results. Nevertheless, regardless of the criteria used for mold and dermatophyte identification, commercial databases require optimization.

Identification of Molds by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

Although to a lesser extent than diagnostic bacteriology, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently revolutionized the diagnostic mycology workflow. With regard to filamentous fungi (or molds), the precise recognition of pathogenic species is important for rapid diagnosis and appropriate treatment, especially for invasive diseases. This review summarizes the current experience with MALDI-TOF MS-based identification of common and uncommon mold species of Aspergillus, Fusarium, Mucorales, dimorphic fungi, and dermatophytes. This experience clearly shows that MALDI-TOF MS holds promise as a fast and accurate identification tool, particularly with common species or typical strains of filamentous fungi.

MALDI-TOF-Based Dermatophyte Identification

MALDI-TOF MS has become increasingly popular for microorganism identification in the routine laboratory. Compared with conventional morphology-based techniques, MALDI-TOF is relatively inexpensive (per-unit identification), involves a rapid result turnaround time and yields more accurate results without the need for highly qualified staff. However, this technology has been technically difficult to implement for filamentous fungi identification. Identification of dermatophytes, a type of filamentous fungi, remains particularly challenging, partly due to the lack of clear species definition for some taxa or within some species complexes. Review of the ten studies published between 2008 and 2015 shows that the accuracy of MALDI-TOF MS-based identification varied between 13.5 and 100 % for dermatophytes. This variability was partly due to inconsistencies concerning critical steps of the routine clinical laboratory process. Use of both a complete formic acid-acetonitrile protein extraction step and a manufacturer library supplemented with homemade reference spectra is essential for an accurate species identification. This technique is conversely unaffected by variations in other routine clinical laboratory conditions such as culture medium type, incubation time and type of mass spectrometry instrument. Provided that a reference spectra library is adequate for dermatophyte identification, MALDI-TOF MS identification is more economical and offers an accuracy comparable to that of DNA sequencing. The technique also represents an advantageous alternative to the protracted and labor-intensive dermatophyte identification via macroscopic and microscopic morphology in the routine clinical laboratory.

Trichophyton erinacei in pet hedgehogs in Spain: Occurrence and revision of its taxonomic status

Hedgehogs have increased in popularity as pets in Spain but there are no data of infection rates of this exotic animal with dermatophytes in our country. During the period of 2008-2011 a total of 20 pet hedgehogs (19 African pygmy hedgehogs and 1 Egyptian long-eared hedgehog) suspected of having dermatophytoses were studied. This is the first survey of the occurrence of T. erinacei in household hedgehogs in Spain. The T. erinacei infection rate was 50% (9 out of 19 African pygmy hedgehogs, and the one Egyptian long-eared hedgehog surveyed). Morphological identification of the isolates was confirmed by molecular analysis. All the strains had the same ITS sequence and showed 100% sequence similarity to T. erinacei type strain CBS 511.73 (AB 105793). The Spanish isolates were confirmed as T. erinacei urease positive. On the basis of ITS sequences, T. erinacei is a species close to but separate from the taxa included in the A. benhamiae complex. Review of the current literature on DNA-based methods for identification of species included in this complex has highlighted the urgent need to reach a consensus in species circumscription and classification system accepted by all mycologists.

Diagnosis of Dermatophytosis Using Molecular Biology

Identification of fungi in dermatological samples using PCR is reliable and provides significantly improved results in comparison with cultures. It is possible to identify the infectious agent when negative results are obtained from cultures. In addition, identification of the infectious agent can be obtained in 1 day. Conventional and real-time PCR methods used for direct fungus identification in collected samples vary by DNA extraction methods, targeted DNA and primers, and the way of analysing the PCR products. The choice of a unique method in a laboratory is complicated because the results expected from skin and hair sample analysis are different from those expected in cases of onychomycosis. In skin and hair samples, one dermatophyte among about a dozen possible species has to be identified. In onychomycosis, the infectious agents are mainly Trichophyton rubrum and, to a lesser extent, Trichophyton interdigitale, but also moulds insensitive to oral treatments used for dermatophytes, which renders fungal identification mandatory. The benefits obtained with the use of PCR methods for routine analysis of dermatological samples have to be put in balance with the relative importance of getting a result in a short time, the price of molecular biology reagents and equipment, and especially the time spent conducting laboratory manipulations.

Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry System for Identification of Clinically Relevant Filamentous Fungi

Invasive fungal infections have a high rate of morbidity and mortality, and accurate identification is necessary to guide appropriate antifungal therapy. With the increasing incidence of invasive disease attributed to filamentous fungi, rapid and accurate species-level identification of these pathogens is necessary. Traditional methods for identification of filamentous fungi can be slow and may lack resolution. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid and accurate method for identification of bacteria and yeasts, but a paucity of data exists on the performance characteristics of this method for identification of filamentous fungi. The objective of our study was to evaluate the accuracy of the Vitek MS for mold identification. A total of 319 mold isolates representing 43 genera recovered from clinical specimens were evaluated. Of these isolates, 213 (66.8%) were correctly identified using the Vitek MS Knowledge Base, version 3.0 database. When a modified SARAMIS (Spectral Archive and Microbial Identification System) database was used to augment the version 3.0 Knowledge Base, 245 (76.8%) isolates were correctly identified. Unidentified isolates were subcultured for repeat testing; 71/319 (22.3%) remained unidentified. Of the unidentified isolates, 69 were not in the database. Only 3 (0.9%) isolates were misidentified by MALDI-TOF MS (including Aspergillus amoenus [n = 2] and Aspergillus calidoustus [n = 1]) although 10 (3.1%) of the original phenotypic identifications were not correct. In addition, this methodology was able to accurately identify 133/144 (93.6%) Aspergillus sp. isolates to the species level. MALDI-TOF MS has the potential to expedite mold identification, and misidentifications are rare.

Development of a high-resolution melting analysis assay for rapid and high-throughput identification of clinically important dermatophyte species

Accurate identification of dermatophyte species is important both for epidemiological studies and for implementing antifungal treatment strategies. Although nucleic acid amplification-based assays have several advantages over conventional mycological methods, a major disadvantage is their high cost. The aim of this study was to develop a rapid and accurate real-time PCR-based high-resolution melting (HRM) assay for differentiation of the most common dermatophyte species. The oligonucleotide primers were designed to amplify highly conserved regions of the dermatophyte ribosomal DNA. Analysis of a panel containing potentially interfering fungi demonstrated no cross reactivity with the assay. To evaluate the performance characteristics of the method, a total of 250 clinical isolates were tested in comparison with the long-established PCR-RFLP method and the results were reassessed using DNA sequencing, as the reference standard method. The assay is able to type dermatophytes using normalised melting peak, difference plot analysis or electrophoresis on agarose gel methods. The results showed that, in comparison to PCR-RFLP, the developed HRM assay was able to differentiate at least 10 common dermatophytes species with a higher speed, throughput and accuracy. These results indicate that the HRM assay will be a useful sensitive, high throughput and cost-effective method for differentiating the most common dermatophyte species.

Pushing the Limits of MALDI-TOF Mass Spectrometry: Beyond Fungal Species Identification

Matrix assisted laser desorption ionization time of flight (MALDI-TOF) is a powerful analytical tool that has revolutionized microbial identification. Routinely used for bacterial identification, MALDI-TOF has recently been applied to both yeast and filamentous fungi, confirming its pivotal role in the rapid and reliable diagnosis of infections. Subspecies-level identification holds an important role in epidemiological investigations aimed at tracing virulent or drug resistant clones. This review focuses on present and future applications of this versatile tool in the clinical mycology laboratory.

Trichophyton species of Arthroderma benhamiae - a new infectious agent in dermatology

In Germany, infections due to the zoophilic dermatophyte Trichophyton (T.) species of Arthroderma benhamiae are being more frequently diagnosed. The source of infection of this emerging pathogen overlaps with that of the zoophilic species T. interdigitale. The most common source are guinea pigs. T. species of Arthroderma benhamiae causes inflammatory dermatophytosis in children and adolescents. In addition to tinea capitis, it may cause both tinea corporis, tinea manus and frequently tinea faciei. In Germany, T. species of Arthroderma benhamiae is a frequent zoophilic dermatophyte, which in regions is probably more frequent than Microsporum canis. The mycological identification of the isolates with their yellow stained colonies is based on their macroscopic and microscopic features. However, some exhibit colony features consistent with those of T. interdigitale. These strains only can be identified unambiguously by means of molecular techniques. Using detection methods such as PCR-ELISA or real-time PCR, the dermatophyte can be identified directly from clinical material. Sequencing of the internal transcribed spacer region (ITS) of the ribosomal DNA has been approved as culture confirmation test for T. species of Arthroderma benhamiae. In addition, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) is useful. Widespread dermatophytosis due to T. species of Arthroderma benhamiae, in particular of tinea capitis, requires oral antifungal agents. Terbinafine is most effective, alternatives are fluconazole and itraconazole.

Development and optimization of a new MALDI-TOF protocol for identification of the Sporothrix species complex

Accurate species identification of the Sporothrix schenckii complex is essential, since identification based only on phenotypic characteristics is often inconclusive due to phenotypic variability within the species. We used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification of 70 environmental and clinical isolates of the Sporothrix complex. A reference database was established for MALDI-TOF MS-based species identification according to minor adjustments in the manufacturer's guidelines. The MALDI-TOF MS clearly distinguished strains of Sporothrix brasiliensis, Sporothrix globosa, Sporothrix mexicana, S. schenckii, Sporothrix luriei and Sporothrix pallida, enabling identification of all isolates at the species level, as confirmed by partial calmodulin gene sequence analyses. The present methodology is simple, reliable, rapid and highly suitable for routine identification in clinical mycology laboratories and culture collections, particularly for updating and reclassifying of deposited Sporothrix isolates.

MALDI-TOF MS for the Diagnosis of Infectious Diseases

BACKGROUND

First introduced into clinical microbiology laboratories in Europe, MALDI-TOF MS is being rapidly embraced by laboratories around the globe. Although it has multiple applications, its widespread adoption in clinical microbiology relates to its use as an inexpensive, easy, fast, and accurate method for identification of grown bacteria and fungi based on automated analysis of the mass distribution of bacterial proteins.

CONTENT

This review provides a historical perspective on this new technology. Modern applications in the clinical microbiology laboratory are reviewed with a focus on the most recent publications in the field. Identification of aerobic and anaerobic bacteria, mycobacteria, and fungi are discussed, as are applications for testing urine and positive blood culture bottles. The strengths and limitations of MALDI-TOF MS applications in clinical microbiology are also addressed.

SUMMARY

MALDI-TOF MS is a tool for rapid, accurate, and cost-effective identification of cultured bacteria and fungi in clinical microbiology. The technology is automated, high throughput, and applicable to a broad range of common as well as esoteric bacteria and fungi. MALDI-TOF MS is an incontrovertibly beneficial technology for the clinical microbiology laboratory.

Tinea capitis and tinea faciei in the Zurich area - an 8-year survey of trends in the epidemiology and treatment patterns

BACKGROUND

Tinea capitis and tinea faciei are dermatophyte infections of the scalp and glabrous skin of the face affecting mainly prepubertal children. During the past 30 years, a significant increase and a change in the pattern of infectious agents has been noted for tinea capitis.

OBJECTIVES

The aim of this study was to determine trends in the current epidemiological situation of tinea capitis and tinea faciei in the Zurich area, Switzerland and adjacent Central and Eastern Switzerland.

METHODS

Consecutive cases diagnosed between 2006 and 2013 were studied retrospectively.

RESULTS

A total of 90 tinea capitis and 40 tinea faciei cases were observed. Anthropophilic isolates (primarily Trichophyton violaceum and Microsporum audouinii) accounted for 76% of tinea capitis cases. In contrast, zoophilic isolates (primarily T. interdigitale) were responsible for 73% of tinea faciei cases. The peak incidence in both conditions was in 4-8 year-old children. While the annual number of tinea faciei cases remained stable over the past 8 years, a trend for an increase in T. violaceum-positive tinea capitis has been observed. This was mainly due to patients of African ethnicity.

CONCLUSIONS

Anthropophilic isolates accounted for three quarters of tinea capitis and one quarter of tinea faciei cases. T. violaceum-positive tinea capitis was primarily linked to patients of African ethnicity. Tinea capitis caused by Microsporum spp. was more refractory to therapy and needed longer treatment than Trichophyton spp.-induced infection.