Laboratory for Bacterial Evolution and Pathogenesis (LBEP)

Discovering the evolutionary origins of global livestock-associated Staphylococcus aureus

New article exploring the evolutionary history and global dissemination of bovine Staphylococcus aureus, a leading cause of mastitis in dairy cows

Our recent publication in PNAS ‘Multiclonal human origin and global expansion of an endemic bacterial pathogen of livestock’ traces the evolutionary origins of major global lineages of bovine Staphylococcus aureus to host switching events from humans The work was championed by LBEP alumnus Dr Gonzalo Yebra , with PhD student Josh-Harling Lee conducting a pangenome analysis that identified unique, potentially host-adapted genes associated with bovine lineages.


Most new pathogens of humans and animals arise via switching events from distinct host species. However, our understanding of the evolutionary and ecological drivers of successful host adaptation, expansion, and dissemination are limited. Staphylococcus aureus is a major bacterial pathogen of humans and a leading cause of mastitis in dairy cows worldwide. Here we trace the evolutionary history of bovine S. aureus using a global dataset of 10,254 S. aureus genomes including 1,896 bovine isolates from 32 countries in 6 continents. We identified 7 major contemporary endemic clones of S. aureus causing bovine mastitis around the world and traced them back to 4 independent host-jump events from humans that occurred up to 2,500 y ago. Individual clones emerged and underwent clonal expansion from the mid-19th to late 20th century coinciding with the commercialization and industrialization of dairy farming, and older lineages have become globally distributed via established cattle trade links. Importantly, we identified lineage-dependent differences in the frequency of host transmission events between humans and cows in both directions revealing high risk clones threatening veterinary and human health. Finally, pangenome network analysis revealed that some bovine S. aureus lineages contained distinct sets of bovine-associated genes, consistent with multiple trajectories to host adaptation via gene acquisition. Taken together, we have dissected the evolutionary history of a major endemic pathogen of livestock providing a comprehensive temporal, geographic, and gene-level perspective of its remarkable success.


Full Citation:

Yebra, Gonzalo, et al. "Multiclonal human origin and global expansion of an endemic bacterial pathogen of livestock." Proceedings of the National Academy of Sciences 119.50 (2022): e2211217119.