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An Omics Approach to Diagnosing or Investigating Fungal Keratitis. Int J Mol Sci 2019; 20:ijms20153631. [PMID: 31349542 PMCID: PMC6695605 DOI: 10.3390/ijms20153631] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/21/2019] [Accepted: 07/23/2019] [Indexed: 02/05/2023] Open
Abstract
Fungal keratitis (FK) is one of the most severe corneal infectious diseases. FK often leads to poor visual prognosis and thus requires accurate diagnosis. Conventional approaches, including clinical diagnoses, smears, and cultures, often fail to provide reliable diagnostic value. Omics approaches, such as those using genomic, metagenomic, and tear proteomic data sources, provide promising features for improving the diagnosis and monitoring the progression of FK. Genomic approaches are based mainly on detecting amplicons of ribosomal RNA genes, and internal transcribed spacers are gradually gaining popularity in clinical practices. A metagenomic approach based on 16S rRNA genes may help monitor the dynamic change of conjunctival microbiota associated with an FK event, whereas that based on shot-gun and 18S rRNA target enrichment sequencing could have the potential to diagnose FK using clinical samples. A tear proteomic approach may provide comprehensive information about ocular surface defense and injury during FK. Representative up- and down-regulated proteins during FK could also be used as biomarkers to determine the clinical course and develop a treatment strategy in different stages of FK. Consequently, a personalized tear proteomic approach will soon play a key role in FK management.
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Abstract
PURPOSE OF REVIEW The evolution of molecular-based methods over the last two decades has provided new approaches to identify and characterize fungal communities or "mycobiomes" at resolutions previously not possible using traditional hazard identification methods. The recent focus on fungal community assemblages within indoor environments has provided renewed insight into overlooked sources of fungal exposure. In occupational studies, internal transcribed spacer (ITS) region sequencing has recently been utilized in a variety of environments ranging from indoor office buildings to agricultural commodity and harvesting operations. RECENT FINDINGS Fungal communities identified in occupational environments have been primarily placed in the phylum Ascomycota and included classes typically identified using traditional fungal exposure methods such as the Eurotiomycetes, Dothideomycetes, Sordariomycetes, and Saccharomycetes. The phylum Basidiomycota has also been reported to be more prevalent than previously estimated and ITS region sequences have been primarily derived from the classes Agaricomycetes and Ustilaginomycetes. These studies have also resolved sequences placed in the Basidiomycota classes Tremellomycetes and Exobasidiomycetes that include environmental and endogenous yeast species. These collective datasets have shown that occupational fungal exposures include a much broader diversity of fungi than once thought. Although the clinical implications for occupational allergy are an emerging field of research, establishing the mycobiome in occupational environments will be critical for future studies to determine the complete spectrum of worker exposures to fungal bioaerosols and their impact on worker health.
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Colabella C, Corte L, Roscini L, Bassetti M, Tascini C, Mellor JC, Meyer W, Robert V, Vu D, Cardinali G. NGS barcode sequencing in taxonomy and diagnostics, an application in " Candida" pathogenic yeasts with a metagenomic perspective. IMA Fungus 2018; 9:91-105. [PMID: 30018874 PMCID: PMC6048569 DOI: 10.5598/imafungus.2018.09.01.07] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 05/10/2018] [Indexed: 11/29/2022] Open
Abstract
Species identification of yeasts and other Fungi is currently carried out with Sanger sequences of selected molecular markers, mainly from the ribosomal DNA operon, characterized by hundreds of tandem repeats of the 18S, ITS1, 5.8S, ITS2 and LSU loci. The ITS region has been recently proposed as a primary barcode marker making this region the most used one in taxonomy, phylogeny and diagnostics. The introduction of NGS is providing tools of high efficacy and relatively low cost to amplify two or more markers simultaneously with great sequencing depth. However, the presence of intra-genomic variability between the repeats requires specific analytical procedures and pipelines. In this study, 286 strains belonging to 11 pathogenic yeasts species were analysed with NGS of the region spanning from ITS1 to the D1/D2 domain of the LSU encoding ribosomal DNA. Results showed that relatively high heterogeneity can hamper the use of these sequences for the identification of single strains and even more of complex microbial mixtures. These observations point out that the metagenomics studies could be affected by species inflection at levels higher than currently expected.
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Affiliation(s)
- Claudia Colabella
- Microbiology Section, Department of Pharmaceutical Sciences, University of Perugia, 06121, Italy
| | - Laura Corte
- Microbiology Section, Department of Pharmaceutical Sciences, University of Perugia, 06121, Italy
| | - Luca Roscini
- Microbiology Section, Department of Pharmaceutical Sciences, University of Perugia, 06121, Italy
| | - Matteo Bassetti
- Infectious Diseases Division, Santa Maria Misericordia University Hospital, Udine, 33100, Italy
| | - Carlo Tascini
- Infectious Diseases Division, Cotugno Hospital Napoli, 80131, Italy
| | | | - Wieland Meyer
- Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School, Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Westmead Institute for Medical Research, Sydney, NSW 2006, Australia
| | - Vincent Robert
- Bioinformatics Unit, Westerdijk Fungal Biodiversity Institute, 3508 CT, Utrecht, Netherlands
| | - Duong Vu
- Bioinformatics Unit, Westerdijk Fungal Biodiversity Institute, 3508 CT, Utrecht, Netherlands
| | - Gianluigi Cardinali
- Microbiology Section, Department of Pharmaceutical Sciences, University of Perugia, 06121, Italy.,CEMIN Research Centre of Excellence, University of Perugia, Borgo 20 Giugno 74, 06121, Italy
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