Heterogeneity in microbial exposure in schools in Sweden, Poland and Jordan revealed by analysis of chemical markers

Abstract

We used gas chromatography-tandem mass spectrometry to analyze microbial components in 85 samples of airborne dust from schools in Jordan, Sweden, and Poland. To collect the samples, we allowed dust to settle on plexiglass plates hanging in the breathing zone in school buildings during both summer and winter. In each of the three countries, we conducted such sampling in two schools: one in an urban environment and the other in rural surroundings. The microbial marker profiles differed significantly between the schools and seasons. For example, samples from Jordan contained remarkably low levels of ergosterol (marker of fungal biomass) and high levels of 3-hydroxy acids (markers of lipopolysaccharide) of 10, 12, and 14 carbon chain lengths relative to such acids of 16 and 18 carbons in comparison with samples from Sweden and Poland. This dissimilarity in 3-hydroxy fatty acid distribution indicates significant differences in the populations of Gram-negative bacteria. We also noted that muramic acid (marker of bacterial biomass) exhibited the smallest variation between schools and seasons. In summary, our results demonstrate that exposure to microorganisms in indoor air in school buildings may differ markedly between countries, between seasons, and between urban and rural environments.

Determinants, reproducibility, and seasonal variation of bacterial cell wall components and viable counts in house dust

“…The concentrations of muramic acid and LPS reported by Wady et al. () for schools in Sweden, Poland and Jordan were comparable to Finnish homes, but the bacterial agents in classrooms were determined from airborne settled dust, while in our study determinations were done from vacuumed floor dust. We found concentrations of microbial cell wall agents to be higher in dust bag dust samples compared to floor dust samples, and this effect was more pronounced for muramic acid.…”

“…One objective of this study was to determine and compare the factors affecting concentrations of the bacterial cell wall components muramic acid and 3‐OH FAs in vacuumed floor dust of farming and non‐farming homes (study 1). Information on determinants of these agents is limited (Sordillo et al., ; Wady et al., ), even more so when viewed side‐by‐side with traditional cultivation based enumeration of bacteria (Hyvärinen et al., ). In addition, we studied aspects of seasonal variation, the reproducibility of 3‐OH FAs and muramic acid determination in house dust samples, and the effect of expressing the microbial results either as concentration (analyte per mass) or as load (analyte per sampling area) in a set of urban homes (study 2).…”

Suppression of ionization and optimization of assay for 3‐hydroxy fatty acids in house dust using ion‐trap mass spectrometry

“…However, the method was not as sensitive as the TMS-based methods. 3-OHFAs as a marker of LPS in indoor environments have been studied extensively using TMS derivatization methods for which those presented here represent a refinement [Saraf et al, 1997;Fox et al, 2003Fox et al, , 2005Sebastian and Larsson, 2003;Park et al, 2004;Wady et al, 2004;Sebastian et al, 2005]. The strong correlation with Limulus bioassay in previous studies suggests that, although there may be some contribution from other sources, 3-hydroxy C10:0, C12:0, and C14:0 in house dust are primarily derived from gram-negative bacteria [Saraf et al, 1997].…”

Characterization of the microbial community in indoor environments by chemical marker analysis: an update and critical evaluation

“…Chemical marker analysis can be used to characterize microbial communities in indoor environments. We have noted differences in marker compositions in dusts from damp vs. non‐damp buildings (Nilsson et al., 2004), bed vs. shelf vs. basement in the same house (Sebastian and Larsson, 2003), unoccupied vs. occupied class‐rooms (Fox et al., 2003), aircraft cabins vs. offices/homes (Hines et al., 2003), and between schools in different geographic regions (Wady et al., 2004). This approach was also applied to study the possible presence of microbiological material in lunar dust collected at the Apollo 11 mission in 1969 (Kozar et al., 2001).…”

“…However, it is clear that parts of floor dust may never have been airborne or subjected to inhalation. Wady et al (2004) used dust sedimented during 4 weeks on the same type of plexiglass plates as in the present study to reveal a microbiological heterogeneity, in terms of marker composition, of air in schools in Jordan, Poland and Sweden. This type of controlled dust sedimentation represents a convenient way of sampling that does not depend upon the spatial distribution of the plates in a given room.…”