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Spore trap analysis and MSQPCR in evaluating mold burden: a flooded gymnasium case study
Citation:
Lin, K., M. Schrantz, O. Sandagdorj, Y. Keng, G. Boothe, AND S. J. VESPER. Spore trap analysis and MSQPCR in evaluating mold burden: a flooded gymnasium case study. FRONTIERS IN BIOSCIENCE. Frontiers in Bioscience, ALBERTSON, NY, 3(1):108-114, (2011).
Impact/Purpose:
The analysis of mold populations in homes has historically been completed by some type of capturing or collection of a sample, most often from the air but sometimes from dust or building material (e.g. dry wall), and the microscopic enumeration, either directly by observing the spores/cells/fragments or by culturing from the sample collected. The Department of Housing and Urban Development (HUD) in its Report to Congress described the resulting situation succinctly (HUD 2005). “Standard approaches to mold testing include: (1) viable count methods that involve collecting spores in air and dust samples or through direct contact with the mold, then culturing the spores on nutrient media and counting the number of colonies that grow and classifying them by species: and (2) spore counts that involve counting the number of mold spores in air or dust samples and, if possible, identifying individual species or groups. These techniques are time consuming and require considerable technical expertise. Another problem is the difficulty in interpreting test results, since mold spores are ubiquitous and there is no consensus among experts regarding what constitutes acceptable indoor spore concentrations in indoor air or house dust, or which species are most problematic.” As a result of the situation described by HUD above, EPA guidance to consumers has been not to test for mold but rather remove all molds and eliminate the underlying water source (US EPA 2002). However, as HUD also noted (HUD 2005): “Yet even now there are situations where reliable test methods are needed, including the identification of hidden mold problems and …to better define mold-related hazards based on significant association with adverse health effects in residents.” In addition, one of the major recommendations espoused by the Institutes of Medicine report (IOM 2004) regarding mold, moisture and health was the need for the development of a molecular based method of mold analysis.
Description:
A school gymnasium was accidentally flooded by the fire-suppression sprinkler system. The surface water was removed but after 25 days, the school decided to evaluate whether there was any mold growth in the gymnasium. Thirty, five-minute air samples (75 m3 air) were collected with Air-O-Cell (AOC) cassettes and the mold structures (MS) quantified by microscopy. These samples were compared to two identical outdoor air samples. In addition, two longer duration indoor air samples (1000 m3 air) and two surface dust samples were collected and quantified by mold specific quantitative PCR (MSQPCR). The average MS concentration for the 30 indoor AOC samples was 271 MS/m3 air with a range of 52 to 707 MS/m3 air. The MS concentrations in the two outdoor AOC samples were 187 and 253 MS/m3 air. The other samples, analyzed by MSQPCR, demonstrated significant correlations; Spearman’s rho analysis correlation (R=0.83) between the two long-term air samples and between the two dust samples (R=0.93). Samples analyzed by MSQPCR demonstrated that there was widespread mold growth in the gymnasium, including Aspergillus fumigatus, A. flavus, A. niger and Stachybotrys chartarum. Air sample comparisons of indoors to outdoors resulted in an ambiguous evaluation of mold growth in the gymnasium.