Characteristics of the home bacterial contamination and endotoxin related release

In several occupational settings, endotoxin, a characteristic external fraction from the outer membrane of Gram negative bacteria (GNB), is an important component of the environmental endotoxin exposure may have a dual influence on atopy and asthma. The aim of this study was to characterise the bacterial and endotoxin composition of settled and airborne dusts from domestic environments. In the nine studied homes, 52 species of GNB were identified on settled dusts and only 13 in the airborne dust. Bacterial levels ranged from 2.76 10(5) to 1.14 10(8) CFU/g in mattresses and from 7.82 10(5) to 6.38 10(7) CFU/g in carpets. In the air 0.39 10(3) to 4.66 10(3) cfu/m3were recorded. Endotoxin varied from 1.85 to 549.0 EU/mg dust and was higher in the carpets compared with the mattresses. The medians of airborne endotoxin levels were 0.239 EU/m3 and 0.062 EU/m3 in inhalable and respirable particles, respectively. Our investigation demonstrates clearly the presence of numerous GNB in domestic environments and shows that domestic environnements contain in some cases relative high amounts of endotoxin.