Assessment of pets (cats and dogs) in homes using electrostatic dust collectors and QPCR: new tools to evaluate exposure and risk of allergies

Contradictory results are found in the literature concerning fungi, bacteria, and pet exposure and the risk of developing asthma. All these allergens have been thoroughly studied separately in cohort studies, and a variety of sampling and analytical methods are used. It is already possible to characterize fungi, mites, and bacteria by QPCR. The aim of our study is to evaluate QPCR systems to quantify the presence of cats and dogs in homes. Twenty-four houses were sampled with an Electrostatic Dust Collector which was analyzed by QPCR. Questionnaires on the presence of pets in homes were completed. The results from QPCR were correlated for real presence of cats and dogs, and highlighted indirect exposure. This study provides a useful screening tool that will be used in future large cohort studies, such as the ELFE cohort study.

Microbiological consequences of indoor composting

Recycling of organic waste appeals to more and more people. The aim of this study was to evaluate the microbiological contamination around organic waste bins at three distances over a 12-month period. Contamination near the customary trash of control households was evaluated at the beginning to ensure that there is no recruitment bias. Air samples using the MAS 100 impactor were carried out in 38 dwellings that do household waste composting and in 10 dwellings of controls. Collection of particles by CIP 10 rotating cup sampler and dust samples collected by electrostatic dust collector cloths were acquired in dwellings that do household waste composting. Samples were analyzed by culture and by real-time quantitative PCR. Information about dwelling characteristics and inhabitant practices was obtained by a standardized questionnaire. The genera most often isolated were Penicillium, Aspergillus, Cladosporium and Streptomyces. Near the organic waste bins, bioaerosol samples showed an increase of Acarus siro (P = 0.001). Sedimented dust analyses highlighted an increase of A. siro, Wallemia sebi, Aspergillus versicolor, and Cladosporium sphaerospermum concentrations after a 12-month survey compared to the beginning. Composting favors microorganism development over time, but does not seem to have an effect on the bioaerosol levels and the surface microbiota beyond 0.5 m from the waste bin.

Fungal food choices of Dermatophagoides farinae affect indoor fungi selection and dispersal

House dust mite (HDM) feces and molds are the main allergens involved in allergic asthma. Differences exist between the housing fungal biome of allergic patients and standard or unhealthy housing. House dust mite (HDM) feed off spores and transport them on their bodies, but do they have fungal food preferences? We observed Dermatophagoïdes farinae in vitro with 16 mold menus and repeated the experiment 10 times. This observation led us to define Alternaria alternata, Cladosporium sphaerospermum, and Wallemia sebi as "tasty" molds and Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum as "repulsive" molds. The food preferences of D. farinae may play a role in the following two phenomena: a decrease in spore numbers due to HDM consumption and a scattering of spores that stick to the bodies of HDMs. The extent of these two phenomena should be estimated in future studies for other common domestic HDM species.