Tatiana Dimitriu

Tatiana Dimitriu is a Royal Society University Research Fellow studying the interactions between bacteria and their mobile genetic elements (MGEs). Promoting successful transmission of MGEs within bacterial communities can benefit us in several contexts, from phage therapy to biotechnological applications. On the other hand, MGEs frequently confer antimicrobial resistance (AMR) and virulence traits to pathogens, making the control of their transmission of great interest for public health.

The spread of AMR is for a large part due to the carriage of AMR genes on conjugative plasmids, genetic elements that can spread horizontally by conjugation. To limit AMR spread, it is key to understand what factors control conjugative transmission of AMR plasmids. To defend themselves against their parasites, bacteria carry a wide range of defence systems including restriction-modification systems and CRISPR-Cas systems. Defence systems are mostly studied as a defence against phages, viruses which cause bacterial death, however, they can also act on conjugative plasmids. However, there is little data on how defence systems act against plasmid conjugation. In addition to immune systems, plasmids themselves can be a direct barrier to AMR plasmid transmission, as plasmids compete with each other within and between cells and resident plasmids that do not carry AMR genes can act as a barrier to AMR plasmid carriage. However, what drives the distribution of these competing plasmids in nature is unknown. Thus, we aim to understand the impact of AMR plasmids, bacterial defence systems and antibiotic treatment on the overall spread of AMR, with the ultimate goal of suggesting treatments that limit AMR prevalence.

We use molecular biology, bacterial genetics and experimental evolution approaches to understand the mechanistic and evolutionary drivers of MGE transmission and AMR spread in bacteria.

We aim to determine plasmid and host defence dynamics at multiple spatial (within-cell to populations) and temporal (physiological to coevolutionary) scales, to answer the following questions:  

1. how antibiotics and defences quantitatively affect the short-term spread of AMR plasmids
2. by which mechanisms antibiotics, defences and their interaction modulate plasmid transmission
3. how plasmids and defences co-evolve and the effect on long-term AMR spread.  

PhD in Evolutionary Biology (2014) - Université Paris-Descartes (France)

"The co-evolution of gene mobility and sociality in bacteria"

MSc in Genetics and Evolution (2010) - Université Paris-Sud and ENS Cachan (France)

Mobile genetic elements; Antibiotic resistance; Horizontal gene transfer; Bacterial defence systems