The abundance of urban endotoxins as measured with an impinger-based sampling strategy

摘要

Endotoxins are components of Gram-negative bacteria with inherently high pro-inflammatory potential. In an urban environment, airborne endotoxins may associate with pollutants such as particulate matter, increasing the severity of the immune response by acting as a natural adjuvant to augment inflammatory respiratory disease development. Here, we present a closer look at outdoor urban endotoxins by applying a microbial-targeted collection strategy. Results from 87 samples distributed throughout the city of Antwerp ranged from 0.45 to 93.71EU/m(3), with a geometric mean of 4.49EU/m(3) and 95% confidence interval of 3.53-5.71EU/m(3). Sample collection was also coupled with the use of a Coulter counter, for which the particle count (2.5-10m/m(3)) showed a significant correlation with endotoxin concentration (R-2=0.24; p0.0001; n=64). In addition, the analysis of the cultivable bacterial colony-forming units on Reasoner's 2A agar (expressed CFU/m(3)) showed to be a good indicator for airborne endotoxins (R-2=0.57; p0.0001; n=58). Moreover, identification of dominant bacterial colonies on these culture plates gave some indications on potential sources of these urban outdoor bacteria and endotoxins.