title: Dustborne and airborne Gram-positive and Gram-negative bacteria in high versus low ERMI homes.
abstract: The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified into low (<5) and high (>5) ERMI groups based on the average ERMI values as well as 2011 ERMI values. Dust and air samples were collected from the homes in 2011 and all samples were analyzed for Gram-positive and Gram-negative bacteria using QPCR assays, endotoxin by the LAL assay, and N-acetyl-muramic acid using HPLC. In addition, air samples were analyzed for culturable bacteria. When average ERMI values were considered, the concentration and load of Gram-positive bacteria determined with QPCR in house dust, but not air, were significantly greater in high ERMI homes than in low ERMI homes. Furthermore, the concentration of endotoxin, but not muramic acid, in the dust was significantly greater in high ERMI than in low ERMI homes. In contrast, when ERMI values of 2011 were considered, Gram-negative bacteria determined with QPCR in air, endotoxin in air, and muramic acid in dust were significantly greater in high ERMI homes. The results suggest that both short-term and long-term mold contamination in homes could be linked with the bacterial concentrations in house dust, however, only the current mold status was associated with bacterial concentrations in air. Although correlations were found between endotoxin and Gram-negative bacteria as well as between muramic acid and Gram-positive bacteria in the entire data set, diverging associations were observed between the different measures of bacteria and the home moldiness. It is likely that concentrations of cells obtained by QPCR and concentrations of cell wall components are not equivalent and represent too broad categories to understand the bacterial composition and sources of the home microbiota.
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States. Electronic address: atin.adhikari@uc.edu.
authors.forename: Atin
authors.initials: A
authors.lastname: Adhikari
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Kettleson
authors.affiliation: National Exposure Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Vesper
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Sudhir
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, United States.
authors.forename: David L
authors.initials: DL
authors.lastname: Popham
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schaffer
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Reshmi
authors.initials: R
authors.lastname: Indugula
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Kanistha
authors.initials: K
authors.lastname: Chatterjee
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Karteek K
authors.initials: KK
authors.lastname: Allam
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Grinshpun
authors.affiliation: Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45267-0056, United States.
authors.forename: Tiina
authors.initials: T
authors.lastname: Reponen
mesh_terms: D000391:Air Microbiology; D016902:Air Pollution, Indoor / Q000032:analysis* / Q000706:statistics & numerical data; D004391:Dust / Q000032:analysis*; D004731:Endotoxins / Q000032:analysis*; D004784:Environmental Monitoring; D005658:Fungi / Q000254:growth & development / Q000302:isolation & purification; D006090:Gram-Negative Bacteria / Q000254:growth & development* / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000254:growth & development* / Q000302:isolation & purification; D006798:Housing / Q000706:statistics & numerical data
chemical_list: D004391:Dust; D004731:Endotoxins
keywords: Bacteria; ERMI; Endotoxin; Indoor air quality; Mold; Muramic acid