Microbial biogeography of public restroom surfaces

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 16S 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.

人类一生中的绝大多数时间都在室内度过，持续接触附着于各类物体表面的细菌。然而，这类附着于表面的微生物群落的多样性在很大程度上仍未被探明。本研究针对12间公共卫生间内的10类物体表面开展细菌群落调研，旨在揭示其呈现的生物地理分布格局。通过对16S核糖体RNA（16S rRNA）基因进行高通量条形码焦磷酸测序，我们在所有采样表面中共鉴定出19个细菌门。绝大多数序列隶属于4个优势细菌门：放线菌门（Actinobacteria）、拟杆菌门（Bacteroidetes）、厚壁菌门（Firmicutes）与变形菌门（Proteobacteria）。微生物群落可划分为三大类群：与马桶相关的表面菌群、卫生间地面菌群，以及日常手部接触的表面菌群。马桶相关表面的菌群中，肠道关联类群占比更高，提示这些表面存在粪便污染。卫生间地面菌群的多样性为所有类群之首，且包含多种常见于土壤中的微生物类群。日常手部接触的表面菌群则以皮肤关联细菌为主，其中尤以丙酸杆菌科（Propionibacteriaceae）最为优势。部分微生物类群在女卫生间中的检出率显著高于男卫生间：与阴道相关的乳杆菌科（Lactobacillaceae）在女卫生间中广泛分布，这大概率源于尿液污染。通过源追踪算法（SourceTracker）分析，我们验证了多项分类学观测结果：人体皮肤是卫生间表面细菌的主要来源。综上，本研究结果表明，卫生间表面栖息着多样性相对较高的微生物群落，其优势类群为人体关联菌群，且不同人体部位菌群与卫生间表面菌群之间存在明确的关联。从更广泛的意义上来说，本研究对公共卫生领域具有参考价值：我们证实人体关联菌群广泛存在于卫生间表面，这意味着细菌病原体可通过接触物体表面在个体间快速传播。此外，本研究证实可通过细菌群落的高通量分析来确定室内表面细菌的来源，该方法可用于追踪病原体传播路径，并评估卫生清洁措施的实际效果。