Assessment of Indoor Microbial Exposures

Abstract

Indoor microbial exposures, including to colonizing opportunistic skin pathogens such as Staphylococcus aureus, can be common in household and school environments and may be linked to both infectious and chronic disease outcomes. We have adapted methods for culture-based and/or culture-independent assessment of S. aureus, Escherichia coli, and other microbes from indoor surface and dust samples and have applied these methods in a variety of settings, including household and school environments. Children may spend a disproportionately high percentage of their time in household and school environments and are a particularly important population to target since these exposures occur during critical developmental windows. Methods range from electrostatic-cloth-based assessment of microbial contamination of surfaces to quantitative polymerase chain reaction (qPCR) assessment of microbial genes in vacuum dust. The goal of this presentation is to describe these methods, discuss their strengths and limitations, and provide examples of how the methods can be applied to outcomes of methicillin-resistant S. aureus (MRSA) skin or soft-tissue infection, environmental enteropathy, and asthma. We will show that exposures to S. aureus and MRSA are common in household and school environments. We will link exposure to MRSA on household surfaces with MRSA re-colonization among urban and rural U.S. adults and children who previously cleared MRSA colonization. We will examine E. coli exposures in household environments as these relate to outcomes of environmental enteropathy among rural Peruvian children. We will demonstrate a high burden of exposure to S. aureus and genes related to staphylococcal enterotoxins in the homes of inner-city children with asthma, and link environmental exposure to asthma outcomes. We will discuss the implications for this work and how the methods may be adapted to assessment of other microbial exposures, including bacterial and fungal communities.