Screening for indoor allergens in different settings at University of Évora

Abstract

Background: The health problems associated with indoor air qualityhave acquired high importance in recent years. Biological particles in the indoor environment include viruses, bacteria, fungal spores, and house dust mites (HDM). These may cause a set of different res-piratory dysfunctions including infection and allergic and/or other inflammatory manifestations. There is no established methodologyto identify all bioaerosols and the existing ones are time-consuming and need experienced taxonomists. The aim of this work was to detect the presence of HDM, bacteria, and fungal genes in indoor environments, using molecular methods. Method: Electrostatic dust- fall collectors (EDC) were used for in -door sample collection and placed in 15 selected rooms at the University of Évora, regularly frequented by students and staff, on the 23rd-30th of November 2023, following a protocol developed in the COST Action ADOPT CA-18226. The bioaerosols counting was executed using standard Hirst-type traps and identified by optical microscopy, according to the standard methodology (REA.com). For Real-Time PCR, two species of HDM were considered, Dermatophagoides pteronyssinus (DP) and Dermatophagoides farinae (DF); for fungal and bacterial detection the ITS1-ITS2 and thev3-v4 regions, respectively, were selected. Results: The results of the bioaerosol counts showed that the largest outdoor contribution is represented by fungi. The PCR and electrophoresis results showed that DP was detected in 5 samples (33%)(1 canteen, 1 classroom, 1 laboratory and 2 outdoor samples). DF was detected in 13% (1 canteen and 1 classroom). The 16S rRNA gene was detected in 20% of the samples (1 classroom, 1 laboratory and 1 outdoor sample). Sixty percent of the samples tested positive for the fungal genes, namely 2 libraries, 2 classrooms, 1 canteen,1 laboratory, 1 toilet, 1 animal reception room and 1 outdoor sample. Total DNA concentration extracted from the EDCs were around4 ng/μL. Nevertheless, the low amount was still able to detect several bioaerosols in the indoor environment that are more difficult to detect by the standard methods. Conclusion: In conclusion, molecular methods are potent tools to identify different components of the bioaerosol using affordable collection devices, in the indoor environment. This approach establishes the bases for the development monitoring strategies, thus useful in disease prevention.