24 November 2014
By Claire Chewapreecha
Under Professors Julian Parkhill and Stephen Bentley’s kind supervisions, my phd research at the Wellcome Trust Sanger Institute centred on the use of genome sequences to understand the evolution of the bacterial pathogen, Streptococcus pneumoniae (the pneumococcus), which causes 1.6 million deaths worldwide each year. Despite high casualties, treatments have become more difficult as the pathogen rapidly develops antibiotic resistance.
To conduct this research, we used a collection of over 3,000 pneumococcal isolates from a refugee camp on the border of Thailand and Myanmar through our active collaboration with Drs Paul and Claudia Turner. It was a great privilege to work on this project, having seen first-hand how pneumococcal infections had affected people at the camp.
The analyses highlighted recombination, a process by which the bacteria exchange their genetic contents. This mechanism allows the species to adapt rapidly, developing resistance to the antibiotics we use to treat infections. This finding was published earlier this year, and voiced the concern over rapid spread of antibiotic resistance in this region.
To aid clinical surveillance of resistant bacteria, I further identified genetic determinants of antibiotic resistance. Genome-wide association study (GWAS) was employed to locate the single-nucleotide changes in the DNA code of the bacterium that enable it to evade antibiotic treatment. The technique has been used to identify genetic causes of disease in humans but was thought to be impossible to use on bacterial DNA until recently.
Based on collaborative links between Department of Medicine, University of Cambridge; the Wellcome Trust Sanger Institute in UK; and Mahidol University in Thailand, my postdoctoral project will focus on the evolution of another pathogenic bacterium, Burkholderia pseudomallei. The pathogen causes melioidosis, a disease endemic in many agricultural areas with particular importance in Southeast Asia.
I hope that a better understanding of this bacterium will help prevent infection and improve patient outcomes.
This month I have been honoured to receive an Anglo-Thai Society Education Award for Medical Science in recognition of my work on Streptococcus pneumoniae. This work would not be possible without strong support from my supervisors and colleagues who offer insightful and invaluable advice, and keep me going when times are tough.
In 2017, I will return to work in Bangkok, the city where I grew up, to continue my research and to pass on the expertise I have gained from my research at Cambridge University and the Sanger Institute.
Claire Chewapreecha recently completed her PhD at the Wellcome Trust Sanger Institute in the Pathogen Genomics Team. She received an Anglo-Thai Society Education Award for Medical Science in recognition of her work on Streptococcus pneumoniae earlier this month.
- Chewapreecha, C et al (2014). Comprehensive Identification of Single Nucleotide Polymophisms Associated with Beta-lactam Resistance within Pneumococcal Mosaic Genes. PLOS Genetics. DOI: 10.1371/journal.pgen.1004547
- Chewapreecha, C et al (2013). Dense genomic sampling identifies highways of pneumococcal recombination. Nature Genetics. DOI:10.1038/ng.2895
- Chewapreecha, C (2012). SDF-Genome Watch: Natural transformers. Nature Reviews Microbiology . DOI:10.1038/nrmicro2865