Molecular diversity of plasmids in Staphylococcus aureus isolates from private hospitals in Gauteng, South Africa

This research focused on understanding the molecular diversity of plasmids in Staphylococcus aureus isolates from private hospitals in Gauteng, South Africa, and how these plasmids contributed to antibiotic resistance and virulence. Staphylococcus aureus remained a major clinical concern due to its ability to rapidly develop resistance to antibiotics, often through the acquisition of plasmids carrying antibiotic resistance genes (ARGs) and virulence factors. These plasmids were transferred between bacteria through horizontal gene transfer (HGT), making it essential to study their genetic diversity and role in the spread of resistance. One of the key aspects of plasmid characterisation involved analysing their replication initiation (rep) genes, which helped categorise plasmids into specific families. Previous studies had linked certain plasmid families to antibiotic resistance, but there was limited information on the diversity of S. aureus plasmids in South Africa. By investigating the molecular diversity of these plasmids and their association with resistance and virulence genes, this study provided valuable insights into the genetic mechanisms driving antibiotic resistance in clinical settings.To achieve this, S. aureus isolates were analysed using a combination of molecular techniques, including multiplex polymerase chain reaction (M-PCR), PCR-based replicon typing, and whole-genome sequencing (WGS). These methods allowed for confirmation of species identity, detection of virulence genes, and classification of plasmids based on their rep genes. Understanding the relationship between specific plasmid types and antibiotic resistance patterns helped trace the spread of resistant S. aureus strains and provided important data for infection control strategies. The research was crucial for addressing the growing challenge of antibiotic resistance in South Africa. By identifying key plasmid types associated with resistance, this study emphasized the need for stronger surveillance systems to monitor and curb the spread of resistant S. aureus strains in healthcare settings. Implementing such measures could help protect public health and improve patient outcomes by limiting the transmission of antibiotic-resistant and virulent bacteria.