Staphylococcal persistence studied in a chronically infected dairy cow
In a study at the University of Veterinary Medicine, Vienna, an international team of researchers led by Tom Grunert investigated the adaptation of Staphylococcus aureus within the host animal over the course of three months in a naturally infected dairy cow with chronic, subclinical mastitis.
The analysis of the bacterial genomes revealed a complete replacement of the original bacterial strain by another genetic variant – caused by an adaptation through mutation and selection. The findings are published in Scientific Reports.
This study was the first to observe a genetic and phenotypical adaptation of S. aureus within its bovine host.
Helene Marbach from the Unit of Functional Microbiology at Vetmeduni Vienna said, “The mutation in the bacterial genome involves in particular only a single base exchange in a gene. The newly evolved clone exhibits strong changes in infection-relevant phenotypes, such as higher proteolytic activity and biofilm formation.”
The researchers say they have demonstrated a new, alternative mechanism for persistence of S. aureus, leading away from intracellular towards extracellular persistence.
Article: Marbach, H., Mayer, K., Vogl, C., Lee, J.Y.H., Monk, I.R., Sordelli, D.O., Buzzola, F.R., Ehling-Schulz, M., Grunert, T. (2019). Within-host evolution of bovine Staphylococcus aureus selects for a SigB-deficient pathotype characterized by reduced virulence but enhanced proteolytic activity and biofilm formation. Scientific Reports 9:13479, doi: 10.1038/s41598-019-49981-6
[SOURCE: Vetmeduni Vienna]