Purpose: As a result of a growing number of people settling into urban lifestyles, we’re spending a greater amount of time with the microbes found in our homes. Some of these microbes could have a negative effect on our health. Dust is a valuable matrix to analyse since it may reflect the history of patients’ homes. Several molecular-based studies have linked indoor microbial community exposures to human health outcomes, such as respiratory allergen challenge, and childhood asthma development and severity. Recently, rapid advances in DNA sequencing technology have spurred increased study of the relationships between fungal biodiversity of the human and house dust environment. This study focuses on the diversity of environmental and pathogenic moulds in settled dust compared with the diversity of environmental and allergenic moulds in pre-existing sputum samples from patients with chronic pulmonary aspergillosis (CPA).
Methods: Twenty dust samples were collected from vacuum cleaners in randomly-selected homes of CPA patients in Greater Manchester, UK. Seventy-six sputum samples were collected from the same CPA patients. DNA was extracted from dust and sputum samples and amplified using ITS-1 and ITS-2 primers to the internal transcribed spacer (ITS) region between 5.8S and 18S ribosomal DNA (rDNA). Amplicons were used as templates in next generation sequencing; sequencing data was analysed using the bioinformatics software QIIME, an open-source bioinformatics pipeline for analyzing microbial communities sampled through marker gene amplicon sequencing.
Results: Fungal diversity was significantly detected using next generation sequencing technique on the Illumina MiSeq platform. DNA sequencing experiments found that Ascomycota and Basidiomycota were the most represented Divisions in both dust and sputum samples. Aspergillus and Emericella (the sexual state of Aspergillus) specieswere the most common fungi isolated and present in the majority of samples. There was no difference among the fungi isolated from sputum and dust samples. This suggests that there is a connection between the mycobiome of the patients’ indoor home environment and their respiratory tract. The study presented here comprises the diversity of fungal types present in both dust and sputum samples. After analysis high-quality fungal sequences were detected yielding a total of more than 62 different types of fungi from sputum samples and only 35 types from house dust. These included well-known fungi such as Aspergillus, Penicillium, Cladosporium and Saccharomyces. This high degree of richness in sputum samples revealed that Inhalation is the main exposure route and dust is basically used a surrogate for airborne exposure. Thus, dust and sputum shared higher percentages of sequences data.
Conclusion: Assessing the home microbiome precisely and accurately is essential in order to understand the potential interactions between the house dust microbiome and human health. Molecular techniques such as next generation sequencing are useful in identifying the species in the mycobiome of dust and sputum samples, particularly for non-cultivatable species. Next generation sequencing is also key for investigating indoor microbial ecology. All the obtained fungal taxa are generally associated with humans, supporting the claim that humans are important sources of indoor airborne. Future work will expand the scope of these findings.
Full conference title:
- AAA 8th (2018)