Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry

[Conventional and molecular diagnostics in onychomycosis-part 2 : Molecular identification of causative dermatophytes by polymerase chain reaction and sequence analysis of the internal transcribed spacer region of ribosomal DNA]

Dermatophyte identification using traditional methods such as optics-based direct fluorescence microscopy and culture is nowadays supplemented by molecular biological methods. The validity of dermatophyte DNA detection with direct uniplex-polymerase chain reaction-enzyme immunoassay (PCR-EIA) in nail samples was proven by sequence analysis of the ribosomal internal transcribed spacer (ITS) region. A total of 108 dermatophytes, isolated from patients with onychomycosis, were positive for Trichophyton rubrum (TR) and Trichophyton interdigitale (TI) in culture and/or uniplex-PCR-EIA. Conventional methods for dermatophyte identification were complemented by direct uniplex-PCR-EIA and sequence analysis of the ribosomal ITS region (18S rRNA, ITS1, 5.8S rRNA, ITS2, 28S rRNA). Of 108 patients (average age 62, median age 73), 56 showed cultural growth with 31 of them being identified as TR and 23 as TI. There was high agreement with the sequence analysis. Surprisingly, the pathogen of a single nail sample was identified as T. quinckeanum (formerly T. mentagrophytes sensu stricto), a rare zoophilic dermatophyte in Germany. A single TI strain turned out to be a misidentified T. tonsurans based on the sequence analysis. In all, 34 of the 52 specimens lacking cultural growth were detected by PCR as TR, and 18 specimens could be identified as TI. The results of dermatophyte identification of culture-negative nail samples were also in agreement with the results of sequence analysis. Molecular biological methods are well applicable, and they show high reliability for direct dermatophyte identification in nail samples without prior cultivation. Especially for nail samples without cultural growth, PCR-based dermatophyte identification was highly specific and sensitive.

Unravelling Childhood Tinea Capitis: A Multi-Dimensional Investigation Using Dermoscopy, Scanning Electron Microscopy and Mass Spectrometry

Tinea capitis, a common cutaneous fungal infection, shows an increasing prevalence with the increasing number of pets. We present tinea capitis in a 4-year-old girl presenting without typical symptoms such as alopecia or hair breakage. After a comprehensive evaluation including dermoscopy, Wood's light, direct KOH fluorescent staining, scanning electron microscopy, fungal culture and mass spectrometry analysis, a diagnosis of tinea capitis infected Microsporum canis carried by domestic cats was made. We preliminarily explored the two modes of hair erosion by tinea capitis fungi and analyzed the possibility of the feature in this case. This case highlights the importance of accurate diagnosis and appropriate therapeutic intervention in cases of paediatric tinea capitis, particularly in households with resident pets.

Comparative assessment of regulated methods and PCR in the diagnosis of trichophytosis in veterinary mycology

Background

There is an increase in the incidence of human and animal infectious skin diseases of fungal etiology in the world. The main source of infecting the population has become agricultural and stray animals.

Aim

The objective of this study was to examine the morphophysiological and microbiological characteristics of pathogenic fungi belonging to the species Trichophyton verrucosum. This species is known to cause diseases in both humans and livestock in Kazakhstan. In addition, the study aimed to assess the feasibility of using the polymerase chain reaction (PCR) method for detecting T. verrucosum. This assessment was conducted in comparison to the outcomes of conventional laboratory diagnostic tests commonly employed for trichophytosis.

Methods

The research focused on analyzing 141 samples of pathological material obtained from calves in Almaty, Turkestan, and Kyzylorda regions. These calves exhibited clinical symptoms of skin disease. The study aimed to identify the causative agent using various techniques, including microscopic examination, microbiological methods involving the isolation of pure cultures, and PCR.

Results

The detection of the causative agent of dermatophytosis using conventional methods was relatively low, 86% for the microscopic method, and 79% for the microbiological method with the isolation of the culture of the pathogen. Extraction and detection of the genetic material of the causative agent of the disease for PCR was carried out according to the method developed by the authors. The effectiveness of the PCR method was 97.9%, which is significantly higher (p < 0.05) compared with the diagnostic effectiveness of conventional methods. The PCR method using specific primers identified the causative agent in 98% of cases, which significantly (p < 0.05) exceeded the results obtained using conventional diagnostic methods. Accordingly, the PCR method had better sensitivity and specificity indicators.

Conclusion

The conducted study recommends the method of PCR diagnosis of dermatophytosis for fast and reliable confirmation of the diagnosis of dermatophytosis in humans and animals in Kazakhstan.

Mini-Review: The Diagnostic Methods of Tinea Capitis

Tinea capitis is a widespread superficial fungal infection that affects children predominately. Microscopic examination and fungal culture are the conventional gold standards for diagnosis, but they are insensitive and time-consuming. In recent years, new diagnostic methods have been developed to facilitate the diagnosis and identification of causative pathogens. Trichoscopy examination showed high sensitivity and specificity for diagnosing tinea capitis with the characteristic signs of comma hairs, corkscrew hairs, bar code-like hairs and zigzag hairs. Reflectance confocal microscopy has also been used in the rapid diagnosis of tinea capitis in several studies. Molecular assays such as polymerase chain reaction and matrix-assisted desorption/ionization time to flight mass spectrometry are extensively utilized for rapid and accurate identification of the pathogens. Early diagnosis and treatment can aid in disease control and scarring reduction.

Comparison of Autof Ms1000 and EXS3000 MALDI-TOF MS Platforms for Routine Identification of Microorganisms

Purpose

Matrix-assisted laser desorption-ionization-time of flight mass spectrometry (MALDI-TOF) has recently been widely used in clinical microbiology laboratories, with the advantages of being reliable, rapid, and cost-effective. Here, we reported the performance of two MALDI-TOF MS instruments, EXS3000 (Zybio, China) and Autof ms1000 (Autobio, China), which are commonly used in clinical microbiology field.

Methods

A total of 209 common clinical common isolates, including 70 gram-negative bacteria strains, 58 gram-positive bacteria strains, 33 yeast strains, 15 anaerobic bacteria strains, and 33 mold strains, and 19 mycobacterial strains were tested. All strains were identified by EXS3000 (Zybio, China) and Autof ms1000 (Autobio, China). Sequence analysis of 16S rRNA or ITS regions was used to verify all strains.

Results

Current study found that species-level discrimination was found to be 191 (91.39%) and 190 (90.91%) by EXS3000 and Autof ms1000, respectively. Genus-level discrimination was 205 (98.09%) by the EXS3000 and 205 (98.09%) by the Autof ms1000, respectively. The correct results at species level of the EXS3000 were 91.43% (64/70) for gram-negative bacteria, 93.1% (54/58) for gram-positive cocci, 93.94% (31/33) for yeast, 100% (15/15) for anaerobes and 81.82% (27/33) for filamentous fungi. The correct results at species level of the Autof ms1000 were 92.86% (65/70) for gram-negative bacteria, 91.38% (53/58) for gram-positive cocci, 93.94% (31/33) for yeast, 100% (15/15) for anaerobes and 78.79% (26/33) for filamentous fungi.

Conclusion

Although the results show that the EXS3000 and Autof ms1000 systems are equally good choices in terms of analytical efficiency for routine procedures, the test result of EXS3000 is slightly better than Autof ms1000. It's worth mentioning that the target plate of the EXS 3000 instrument is reusable, but the target plate of the Autof ms1000 is disposable, making the EXS3000 more effective in reducing costs.

Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in veterinary medicine: Recent advances (2019-present)

Matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) has become a valuable laboratory tool for rapid diagnostics, research, and exploration in veterinary medicine. While instrument acquisition costs are high for the technology, cost per sample is very low, the method requires minimal sample preparation, and analysis is easily conducted by end-users requiring minimal training. Matrix-assisted laser desorption ionization-time-of-flight MS has found widespread application for the rapid identification of microorganisms, diagnosis of dermatophytes and parasites, protein/lipid profiling, molecular diagnostics, and the technique demonstrates significant promise for 2D chemical mapping of tissue sections collected postmortem. In this review, an overview of the MALDI-TOF technique will be reported and manuscripts outlining current uses of the technology for veterinary science since 2019 will be summarized. The article concludes by discussing gaps in knowledge and areas of future growth.

Laboratory Diagnosis and In Vitro Antifungal Susceptibility of Trichophyton quinckeanum from Human Zoonoses and Cats

The “One Health” concept increasingly demonstrates the global spread of pathogenic (also eukaryotic) microorganisms and their zoonotic potential. Dermatophytes can cause superficial mycoses in humans and animals. Furthermore, the number of transmissions from asymptomatic carriers to humans has been on the rise over the last few years. This study was focused on the detailed characterisation of clinical isolates of Trichophyton quinckeanum with epidemiological analyses and characterisation of their in vitro antifungal susceptibility patterns. The isolated dermatophytes were identified with a combination of conventional and molecular methods. In turn, their susceptibility in vitro was tested according to the Clinical and Laboratory Standards Institute (CLSI) M38 ed.3 protocol. A total of 36 strains were isolated, with 21 cases of T. quinckeanum zoonoses resulting from direct contact with symptomatic cats (58.3%). The other 15 strains (41.7%) were isolated simultaneously from healthy cats and their owners. All strains showed high susceptibility to allylamine, pyridinone, and phenyl morpholine derivatives but were resistant to fluconazole and ketoconazole. In conclusion, our study shows the frequency of zoonoses contracted from asymptomatic cats. Moreover, the antifungal susceptibility profiles indicate the serious risk posed to animal owners by resistant strains of T. quinckeanum, which are often responsible for recalcitrant-to-treatment cases.