Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is the causative agent of serious hospital- and community-associated infections. Due to the global rise in community-associated MRSA, the respective lineages are increasingly introduced into hospitals. This raises the question whether and, if so, how they adapt to this new environment. The present study was aimed at investigating how MRSA isolates of the USA300 lineage, infamous for causing infections in the general population, have adapted to the hospital environment. To this end, a collection of community- and hospital-associated USA300 isolates was compared by RNA-sequencing. Here we report that merely 460 genes were differentially expressed between these two epidemiologically distinct groups, including genes for virulence factors, oxidative stress responses and the purine, pyrimidine and fatty acid biosynthetic pathways. Differentially regulated virulence factors included leukotoxins and phenol-soluble modulins, implicated in staphylococcal escape from immune cells. We therefore investigated the ability of the studied isolates to survive internalization by human neutrophils. This showed that the community-associated isolates have the highest neutrophil-killing activity, while the hospital-associated isolates are better adapted to intra-neutrophil survival. Importantly, the latter trait protects internalized staphylococci against a challenge with antibiotics. We therefore conclude that prolonged intra-neutrophil survival serves as a relatively simple early adaptation of S. aureus USA300 to the hospital environment where antibiotic pressure is high.
Project description:The built indoor microbiome has importance for human health. Residents leave their microbial fingerprint but nothing is known about the transfer from plants. Our hypothesis that indoor plants contribute substantially to the microbial abundance and diversity in the built environment was experimentally confirmed as proof of principle by analyzing the microbiome of the spider plant Chlorophytum comosum in relation to their surroundings. The abundance of Archaea, Bacteria, and Eukaryota (fungi) increased on surrounding floor and wall surfaces within 6 months of plant isolation in a cleaned indoor environment, whereas the microbial abundance on plant leaves and indoor air remained stable. We observed a microbiome shift: the bacterial diversity on surfaces increased significantly but fungal diversity decreased. The majority of cells were intact at the time of samplings and thus most probably alive including diverse Archaea as yet unknown phyllosphere inhabitants. LEfSe and network analysis showed that most microbes were dispersed from plant leaves to the surrounding surfaces. This led to an increase of specific taxa including spore-forming fungi with potential allergic potential but also beneficial plant-associated bacteria, e.g., Paenibacillus. This study demonstrates for the first time that plants can alter the microbiome of a built environment, which supports the significance of plants and provides insights into the complex interplay of plants, microbiomes and human beings.
Project description:Buildings are complex ecosystems that house trillions of microorganisms interacting with each other, with humans and with their environment. Understanding the ecological and evolutionary processes that determine the diversity and composition of the built environment microbiome--the community of microorganisms that live indoors--is important for understanding the relationship between building design, biodiversity and human health. In this study, we used high-throughput sequencing of the bacterial 16S rRNA gene to quantify relationships between building attributes and airborne bacterial communities at a health-care facility. We quantified airborne bacterial community structure and environmental conditions in patient rooms exposed to mechanical or window ventilation and in outdoor air. The phylogenetic diversity of airborne bacterial communities was lower indoors than outdoors, and mechanically ventilated rooms contained less diverse microbial communities than did window-ventilated rooms. Bacterial communities in indoor environments contained many taxa that are absent or rare outdoors, including taxa closely related to potential human pathogens. Building attributes, specifically the source of ventilation air, airflow rates, relative humidity and temperature, were correlated with the diversity and composition of indoor bacterial communities. The relative abundance of bacteria closely related to human pathogens was higher indoors than outdoors, and higher in rooms with lower airflow rates and lower relative humidity. The observed relationship between building design and airborne bacterial diversity suggests that we can manage indoor environments, altering through building design and operation the community of microbial species that potentially colonize the human microbiome during our time indoors.