Filamentous fungi and yeasts on mattresses covered with different encasings

Besides mites, filamentous fungi and yeasts play an important role as domes tic allergens. Among different allergen avoidance strategies the efficacy o f synthetic mattress encasings has been demonstrated for the reduction of h ouse dust mites. Whether these synthetic encasings arc also able to reduce the growth of fungi on the mattress under domestic conditions has not been assessed so far. To determine if the fungal growth on mattresses can be reduced by the use o f synthetic encasings we assessed the fungal colonisation of mattresses cov ered either by conventional cotton encasings or by polyurethane encasings i mpermeable to particles > 3 mum. Within a 12-month period dust samples were obtained from the mattresses. Fungal quantities were measured by counting colonies on agar plates incubated at 20 degreesC and 37 degreesC. The counts of fungi were significantly higher on mattresses with cotton enc asings. Penicillium spp. and Aspergillus spp. were isolated most frequently . Therefore the application of synthetic encasings with similar properties to the encasings used in this investigation is recommended as part of an alle rgen avoidance strategy for patients sensitised to fungal allergens.