Microbial Biogeography of Public Restroom Surfaces

Abstract

We spend the majority of our lives indoors where we are constantly exposed to bacteria residing on surfaces. However, the diversity of these surface-associated communities is largely unknown. We explored the biogeographical patterns exhibited by bacteria across ten surfaces within each of twelve public restrooms. Using high-throughput barcoded pyrosequencing of the 16 S rRNA gene, we identified 19 bacterial phyla across all surfaces. Most sequences belonged to four phyla: Actinobacteria, Bacteriodetes, Firmicutes and Proteobacteria. The communities clustered into three general categories: those found on surfaces associated with toilets, those on the restroom floor, and those found on surfaces routinely touched with hands. On toilet surfaces, gut-associated taxa were more prevalent, suggesting fecal contamination of these surfaces. Floor surfaces were the most diverse of all communities and contained several taxa commonly found in soils. Skin-associated bacteria, especially the Propionibacteriaceae, dominated surfaces routinely touched with our hands. Certain taxa were more common in female than in male restrooms as vagina-associated Lactobacillaceae were widely distributed in female restrooms, likely from urine contamination. Use of the SourceTracker algorithm confirmed many of our taxonomic observations as human skin was the primary source of bacteria on restroom surfaces. Overall, these results demonstrate that restroom surfaces host relatively diverse microbial communities dominated by human-associated bacteria with clear linkages between communities on or in different body sites and those communities found on restroom surfaces. More generally, this work is relevant to the public health field as we show that human-associated microbes are commonly found on restroom surfaces suggesting that bacterial pathogens could readily be transmitted between individuals by the touching of surfaces. Furthermore, we demonstrate that we can use high-throughput analyses of bacterial communities to determine sources of bacteria on indoor surfaces, an approach which could be used to track pathogen transmission and test the efficacy of hygiene practices.

Aerosolization of Ebola Virus Surrogates in Wastewater Systems

“…Studies on aerosol generation by modern flush toilets found that up to 145,000 droplets less than 2 µ m in size can be produced per flush 26 Many studies have detected microorganisms in ambient air in bathrooms and on the toilet surface, indicating the production of bioaerosols and the potential for disease transmission. [27][28][29][30][31] Microorganisms have been detected in air 90 minutes after flushing and 25 cm above the toilet seat. These aerosolized microorganisms can maintain their viability and spread in ambient air.…”

“…These aerosolized microorganisms can maintain their viability and spread in ambient air. 28,29,31,32 The potential for EBOV to spread via this route is not known. Previous studies have focused mainly on bacteria rather than viruses, and they have not measured the full range of aerosol sizes produced by flush toilets.…”

“…22 Bacterial and fungi, including pathogenic ones, have been detected in the surrounding air, [23][24][25][26][27][28][29][30][31][32] demonstrating that wastewater treatment processes have the potential to generate bioaerosols. However, few studies have focused on aerosolization of viruses in wastewater systems.…”

The bacterial composition of ventilation filter dust in Norwegian pre-school nurseries

“…16 Primers were designed for use with the GS Junior system (454 Life Sciences, Branford, CT, USA). Adaptors and multiplex identifiers (MIDs) were included in primer sequences which were purchased from Eurofins Genomics laboratories (Ebersberg, Germany).…”

“…12,13 It has been shown that human occupants leave a distinct human microbial fingerprint indoors, and different room types and surfaces will have different fingerprints depending on their specific use. [14][15][16] Heating, ventilation and air conditioning (HVAC) systems are necessary for meeting energy and air quality demands in modern buildings. These systems transport large quantities of air into and out of buildings and have extensive inner surface areas in the form of ventilation ducts and filters.…”