Dust Microorganisms Research Articles

Elemental composition of household dusts extracted in simulated body fluids and their impact on culturable pathogenic bacteria responses

In the last decade, a great deal of research has focused on the determination of potential toxic elements by total concentration and identification the microorganisms in dust. However, determining bio-relevant (e.g., inhalable) forms of elements instead of total contents in acids is necessary for human health. Moreover, examination of the behavior of microorganism under these bio-relevant conditions and revealing the interaction between elements and pathogens is vital and necessary for deeper understanding. However, previous studies have ignored these topics. Therefore, the present study aimed to (i) investigate elements in household dusts extracted in simulated lung fluids, (ii) examine the total concentration of culturable bacteria and their biochemical responses with exposure to bio-fractions of household dusts, and (iii) assess their relations and risks using the model approaches by inhalation. Here, settled dusts were collected in 25 houses, and extracted in four simulated body fluids to determine bio-fractions of elements. Moreover, total count of potentially pathogenic and heterotrophic bacteria, and four clinically important culturable pathogens were incubated in the presence of household-dusts extracted in simulated body fluids. The activity, biofilm, biochemical and oxidative responses of pathogens were measured following household-dust exposures. Afterward, the relationship between elements and pathogen responses were evaluated, and model and derived approaches were used for risk assessments of elements and pathogens. The higher daily intake of elements obtained in artificial lysosomal fluid fraction of household dust mimicking the inflammatory condition compared to other body fluids. Moreover, bacterial responses were mainly influenced from bio-fractions of household dusts and their elemental contents.

Infectious Diseases Associated with Desert Dust Outbreaks: A Systematic Review.

Background: Desert dust outbreaks and dust storms are the major source of particulate matter globally and pose a major threat to human health. We investigated the microorganisms transported with desert dust particles and evaluated their potential impact on human health. Methods: A systematic review of all reports on the association between non-anthropogenic desert dust pollution, dust microorganisms and human health is conducted. Results: In total, 51 articles were included in this review. The affected regions studied were Asia (32/51, 62.7%) followed by Europe (9/51, 17.6%), America (6/51, 11.8%), Africa (4/51, 7.8%) and Australia (1/51, 2.0%). The Sahara Desert was the most frequent source of dust, followed by Asian and American deserts. In 39/51 studies the dust-related microbiome was analyzed, while, in 12/51 reports, the association of desert dust with infectious disease outbreaks was examined. Pathogenic and opportunistic agents were isolated from dust in 24/39 (61.5%) and 29/39 (74.4%) of the studies, respectively. A significant association of dust events with infectious disease outbreaks was found in 10/12 (83.3%) reports. The infectious diseases that were mostly investigated with dust outbreaks were pneumonia, respiratory tract infections, COVID-19, pulmonary tuberculosis and coccidioidomycosis. Conclusions: Desert dust outbreaks are vehicles of a significant number of pathogenic or opportunistic microorganisms and limited data indicate an association between dust events and infectious disease outbreaks. Further research is required to strengthen the correlation between dust events and infectious diseases and subsequently guide preventive public health measures.

Viable bacterial communities on hospital window components in patient rooms.

Previous studies demonstrate an exchange of bacteria between hospital room surfaces and patients, and a reduction in survival of microorganisms in dust inside buildings from sunlight exposure. While the transmission of microorganisms between humans and their local environment is a continuous exchange which generally does not raise cause for alarm, in a hospital setting with immunocompromised patients, these building-source microbial reservoirs may pose a risk. Window glass is often neglected during hospital disinfection protocols, and the microbial communities found there have not previously been examined. This pilot study examined whether living bacterial communities, and specifically the pathogens Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile (C. difficile), were present on window components of exterior-facing windows inside patient rooms, and whether relative light exposure (direct or indirect) was associated with changes in bacterial communities on those hospital surfaces. Environmental samples were collected from 30 patient rooms in a single ward at Oregon Health & Science University (OHSU) in Portland, Oregon, USA. Sampling locations within each room included the window glass surface, both sides of the window curtain, two surfaces of the window frame, and the air return grille. Viable bacterial abundances were quantified using qPCR, and community composition was assessed using Illumina MiSeq sequencing of the 16S rRNA gene V3/V4 region. Viable bacteria occupied all sampled locations, but was not associated with a specific hospital surface or relative sunlight exposure. Bacterial communities were similar between window glass and the rest of the room, but had significantly lower Shannon Diversity, theorized to be related to low nutrient density and resistance to bacterial attachment of glass compared to other surface materials. Rooms with windows that were facing west demonstrated a higher abundance of viable bacteria than those facing other directions, potentially because at the time of sampling (morning) west-facing rooms had not yet been exposed to sunlight that day. Viable C. difficile was not detected and viable MRSA was detected at very low abundance. Bacterial abundance was negatively correlated with distance from the central staff area containing the break room and nursing station. In the present study, it can be assumed that there is more human traffic in the center of the ward, and is likely responsible for the observed gradient of total abundance in rooms along the ward, as healthcare staff both deposit more bacteria during activities and affect microbial transit indoors. Overall, hospital window components possess similar microbial communities to other previously identified room locations known to act as reservoirs for microbial agents of hospital-associated infections.

QPCR standard operating procedure for measuring microorganisms in dust from dwellings in large cohort studies

The aim of the present study was to assess performance, feasibility and relevance of a Standard Operational Procedure (SOP) for large-scale use in the microbial analysis of children's indoor environments.We analyzed dust settled on Electrostatic Dust Fall Collectors (EDCs) by using qPCR which targeted 6 molds, 3 bacteria and 1 mite, chosen for their involvement in allergic or inflammatory processes. Six types of commercialized electrostatic wipes were tested for their releasing capacity of fungal DNA from fungal spores captured by the wipes. Specificity, repeatability and detection limits of the qPCR procedure were tested using calibrated microbial suspensions. The feasibility and relevance of this sampling and analysis method were assessed in a 75-home pilot study.Our result showed that one specific make of wipe was more effective than the others in releasing fungal DNA. qPCR procedure showed good repeatability. The quantification limit was about 5fgDNA/μL for all species except Penicillium chrysogenum (0.5fgDNA/μL) and Dermatophagoïdes pteronyssinus (10fgDNA/μL). No cross-reactivity was observed.DNA concentrations in the 53/75 homes participating in the pilot study were between 0 and 24 625, 0 and 69 738 equivalent cells per cm2 for the fungi and bacteria, and between 0 and 1 equivalent mites per cm2 for D. pteronyssinus. Using the SOP described, we were able to classify the 53 dwellings from the least to the most contaminated according to the quantity of DNA measured for each species.Our SOP measured fungi, bacteria and mites using a cost-efficient, discreet and well-accepted sampling method with just one qPCR tool. The whole procedure can be used for microbial analysis in large cohort studies such as the ELFE study (“Etude Longitudinale Française depuis l'Enfance”) and could help improve our understanding of the interactions between the environment, allergic diseases and child development.

Application of PCR-SSCP for molecular epidemiological studies on the exposure of farm children to bacteria in environmental dust

The environmental exposure of farm children to microorganisms in dust has become a focus of interest, since microbial exposure on farms has been related to a reduced prevalence of asthma and atopic diseases in children. Previous studies almost exclusively focused on the determination of microbial counts using conventional culturing or the determination of microbial compounds i.e. endotoxins. In this study PCR-SSCP (single-strand conformation polymorphism) was modified for characterising bacterial communities in environmental dusts and their sensitivity and reproducibility was validated. A fivefold repeated PCR-SSCP analyses of a well homogenised mattress dust, cow-shed dust, swine-shed dust, chicken-shed dust and a horse-shed dust sample, respectively, showed similarities, based on Pearson correlations, ranging from 89.7% to 95.2%. The reproducibility of day to day variations (five days) and gel to gel variations (five gels) was also around 90%. The detection limit of Escherichia coli was 7 × 10 1 cfu g − 1 whereas Listeria monocytogenes and Bacillus licheniformis containing 30% spores showed visible bands at 7 × 10 2 cfu g − 1 . Application of this method to dust samples of 37 sheds and 63 children's mattresses showed that distinct farm environment dusts reflected different SSCP profiles. However, digital analysis of the gels showed that some bands in the profiles of shed- and mattress dusts were found at the same position in the gels. By excision, cloning, sequencing and phylogenetic analyses, these bands were identified as Corynebacterium tuberculostearicum, Corynebacterium mucifaciens, Staphylococcus epidermidis, Acinetobacter lwoffii, Brevibacterium iodinum, Brevibacterium linens and Arthrobacter spp, respectively. These results may reflect transfer of microorganisms from animal sheds to mattresses. In conclusion this study demonstrates that PCR-SSCP is a promising method with sensitive detection limits and moderate sample variances to be applied for epidemiological studies characterizing the exposure of farmers using environmental dust.

Fungal spores enhance basophil histamine release

The effects of whole spores from moulds were examined concerning histamine release using leukocyte suspensions from normal (non-atopic) individuals and grass pollen-allergic patients. Spores fromChaetomium globosum, Mucor racemosus andAspergillus terreus caused no histamine release in concentrations up to 0.1 or 1 mg/ml, but they enhanced mediator release triggered by both IgE-dependent stimuli (grass-pollen allergen and anti-IgE antibody) and non-immunological stimuli (Staphylococcus aureus and calcium ionophore). Organic dust contains microfungi as well as bacteria and endotoxins. Earlier we have shown that bacteria release mediators from human lung cells and that bacteria and their endotoxins potentiate mediator release. It is now demonstrated that fungal spores also have potentiating ability. The content of all these microorganisms in dust may therefore be responsible for the symptoms observed after occupational exposure to organic dusts.