Beyond Commensalism: Investigating the Virulence Mechanisms of Streptococcus mitis in Bacteraemia

About the Project

Streptococcus pneumoniae is a common nasopharyngeal commensal but is also the most common cause of pneumonia globally. Invasive pneumococcal disease causes over a million deaths per year worldwide, especially in children under the age of 5, despite the availability of vaccines. S. pneumoniae strains considerably vary in virulence but why this is remains unclear. Streptococcus mitis, the closest genetic relative of S. pneumoniae, is a common respiratory tract commensal found in the oropharynx. Despite the close genetic relationship, S. mitis is weakly virulent when compared to S. pneumoniae. S. mitis is not however avirulent and is an increasingly important opportunistic pathogen, associated with dental disease, endocarditis and immunocompromised patients. There is increasing evidence that many patients become infected with their own commensal strains. Though the rates of bacteraemia due to S. mitis remains relatively constant, strains isolated from bacteraemic patients frequently demonstrate resistance to frontline antibiotics.

The laboratory of Dr Helina Marshall at the University of Strathclyde is seeking a highly motivated and scientifically curious student to work on a project aimed at exploring the virulence mechanisms of Streptococcus mitis, a commensal bacterium that, despite its benign nature, is increasingly associated with serious infections such as bacteraemia and infective endocarditis, particularly in immunocompromised patients.

This PhD project will utilise a combination of genomic, phenotypic, and taxonomic approaches to investigate the virulence mechanisms of Streptococcus mitis isolates associated with bacteraemia. The successful candidate will receive comprehensive training in microbiology, whole genome sequencing (WGS), comparative genomics, infection-focussed and molecular techniques for assessing bacterial virulence. Additionally, the project will involve working with international collaborators.

Ideal candidates will have a strong background in microbiology, genetics, or related fields, and an interest in the molecular mechanisms of bacterial pathogenesis.