Bacteria in a water-damaged building: associations of actinomycetes and non-tuberculous mycobacteria with respiratory health in occupants

Abstract

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty-nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu-like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m2) in dust were associated with FEV1/FVC [coefficient =−2.8 per interquartile range change, P = 0.02], percent predicted FEF25–75% (coefficient =−12.9, P = 0.01), and any granulomatous disease-like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45–6.73]. Mycobacteria (median = 658 CFU/m2) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97–2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71–1.00) and positively associated with FEV1/FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease-like symptoms (OR = 0.8, 95% CI = 0.67–0.98) and asthma (0.8, 0.67–0.96). Fungi or (1→3)-β-D-glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non-tuberculous mycobacteria may have played a role in the occupants’ respiratory outcomes in this water-damaged building.

Characterization of fungi in office dust: Comparing results of microbial secondary metabolites, fungal internal transcribed spacer region sequencing, viable culture and other microbial indices

“…We collected floor dust samples from 120 rooms or cubicles in the study building that had a history of water incursions. The sampling and dust processing method have been previously described . Briefly, we vacuumed floor dust in a polyethylene filter sock (Midwest Filtration Company, Fairfield, OH, USA) using a standardized sampling protocol.…”

“…for 2 hours before partitioning into aliquots for various analyses. All dust samples were analysed for culturable fungi and bacteria, (1→3)‐β‐D‐glucan and endotoxin as previously described . For the current comparison study, we analysed 28 of those 120 samples for microbial secondary metabolites and 22 of those 28 (6 samples did not have enough dust to run the analyses) for fungal DNA …”

“…The sampling and dust processing method have been previously described. 12 Briefly, we vacuumed floor dust in a polyethylene filter sock (Midwest Filtration Company, Fairfield, OH, USA) using a standardized sampling protocol. In the laboratory, hair, lint and other larger objects were removed from each sample and the dust was transferred into a conical tube.…”

“…Serially diluted sample aliquots were spread onto malt extract, dichloran glycerol 18 and cellulose agars for fungi; trypticase soy agar (TSA) with 5% sheep blood for total bacteria; colistin nalidixic acid (CNA) agar for the selection of Gram-positive bacteria; and MacConkey agar for the selection of Gram-negative bacteria and incubated for 7-10 days. 12 Fungal species were identified by examiners with expertise in identifying fungi based on morphological and physiological characteristics as previously described. 12 We used Limulus amoebocyte lysate assay to analyse for (1→3)β-D-glucan and endotoxin as described previously.…”

“…12 Dampness and mold-related environmental conditions of the building and occupants' health have been described in detail elsewhere. 12,13 We examined whether these 3 analytical methods provide consistent results about abundance or diversity of fungi, and what kinds of fungal secondary metabolites are present in floor dust.…”