Biology subjects

Bateman, A. C.

Publications and source records attributed to Bateman, A. C..

3 recordsLinked to original sources

bioRxiv2019

Moving microbes: the dynamics of transient microbial residence on human skin

The human skin microbiome interacts intimately with human health, yet the drivers of skin microbiome composition and diversity are not well-understood. The composition of the skin microbiome has been characterized as both highly variable and relatively stable, depending on the time scale under consideration, and it is not clear what role contact with environmental sources of microbes plays in this variability. We experimentally mimicked human skin contact with two common environmental sources of microorganisms -- soils and plant leaves -- and characterized the dynamics of microbial acquisition and persistence on skin on very short time scales. Repeatable changes in skin community composition following encounters with environmental sources were observed, and these trajectories largely depend on donor community biomass distributions. Changes in composition persisted for at least 24 hours and through a soap and water wash following exposures to relatively high biomass soil communities. In contrast, exposures to lower biomass leaf communities were undetectable after a 24 hour period. Absolute abundances of bacterial taxa in source communities predicted transmission probabilities and residence times, independent of phylogenetic considerations. Our results suggest that variability in the composition of the skin microbiome can be driven by transient encounters with common environmental sources, and that these relatively transient effects can persist when the source is of sufficient biomass.\n\nImportanceHumans come into contact with environmental sources of microbes, such as soil or plants, constantly. Those microbial exposures have been linked to health through training and modulation of the immune system. While much is known about the human skin microbiome, the short term dynamics after a contact event, such as touching soil, have not been well characterized. In this study, we examine what happens after such a contact event, describing trends in microbial transmission to and persistence on the skin. Additionally, we use computational sampling model simulations to interrogate null expectations for these kinds of experiments. This work has broad implications for infection control strategies and therapeutic techniques that rely on modification of the microbiome, such as probiotics and faecal transplantation.

microbiology↗

bioRxiv2016

Cleanliness in context: reconciling hygiene with a modern microbial perspective

The concept of hygiene is rooted in the relationship between cleanliness and the maintenance of good health. Since the widespread acceptance of the germ theory of disease, hygiene has become increasingly conflated with that of sterilization. Recent research on microbial ecology is demonstrating that humans have intimate and evolutionarily significant relationships with a diverse assemblage of microorganisms (our microbiota). Human skin is home to a diverse, skin habitat specific community of microorganisms; this includes members that exist across the ecological spectrum from pathogen through commensal to mutualist. Most evidence suggests that the skin microbiota is likely of direct benefit to the host, and only rarely exhibits pathogenicity. This complex ecological context suggests that the conception of hygiene as a unilateral reduction or removal of microbes has outlived its usefulness. As such, we suggest the explicit definition of hygiene as those actions and practices that reduce the spread or transmission of pathogenic microorganisms, and thus reduce the incidence of disease. To examine the implications of this definition, we review the literature related to hand drying as an aspect of hand hygienic practice. Research on hand drying generally focuses on hygienic efficacy, a concept not typically defined explicitly, but nearly always including alterations to bulk microbial load. The corresponding literature is differentiable into two divisions: research supporting the use of forced air dryers, which typically includes effectiveness of drying as an aspect of hygienic efficacy; and research supporting the use of paper towels, which typically includes risk of aerosolized spread of microbes from hands as an aspect of hygienic efficacy. Utilizing a definition of hygiene that explicitly relies on reduction in disease spread rather than alterations to bulk microbial load would address concerns raised on both sides of the debate. Future research should take advantage of cultivation-independent techniques, working to bridge the gap between the two existing divisions of research by using health outcomes (such as the spread of disease) as dependent variables, taking into account the microbial community context of the skin microbiota, and focusing on understanding the relative contribution of bioaerosols and residual moisture to the risk of disease transmission.

microbiology↗

bioRxiv2016

Standard Issue: Copy number heterogeneity of JC virus standards discovered through next-generation sequencing

Quantitative PCR is a diagnostic mainstay of clinical virology, and accurate quantitation of viral load among labs requires the use of international standards. However, the use of multiple passages of viral isolates to obtain sufficient material for international standards may result in genomic changes that complicate their use as quantitative standards. We performed next-generation sequencing to gain single-nucleotide resolution and relative copy number of JC virus (JCV) clinical standards. Strikingly, the WHO international standard and ExactTM v1/v2 prototype standards for JCV showed 8-fold and 4-fold variation in genomic coverage between different loci in the viral genome, respectively, due to large deletions in the large T-antigen region. No such variation was seen for a clinical sample with high copy-number of JCV nor a plasmid control. Intriguingly, several of the JCV standards sequenced in this study with large T-antigen deletions were cultured in cell lines immortalized using SV40 T-antigen, suggesting the possibility of trans-complementation in cell culture. Using a cut-off of 2% variant allele fraction for junctional reads to define the presence of a strain, 11 different strains were present in the WHO standard. In summary, targeting of different regions of the same international standard could result in up to an 8-fold difference in quantitation. We recommend the use of next-generation sequencing to validate standards in clinical virology.

microbiology↗