Authors: Martha Powell, Future Science Group
Researchers have carried out a global genomic survey of Streptococcus pneumoniae, discovering 621 strains across over 50 countries and revealing how the bacteria evolve in response to vaccination.
S. pneumoniae is the most common cause of bacterial pneumonia and although many countries have introduced the pneumococcal conjugate vaccine, which targets the bacterial coat, the vaccine is only effective against approximately 13 coat types, while over a hundred remain unknown. Moreover, despite the vaccine, pneumonia rates remain high.
This study, published recently in The Lancet Infectious Diseases, reveals the strains of S. pneumoniae that are circulating and provides an explanation for why pneumonia rates are still a concern.
The project, termed the Global Pneumococcal Sequencing project, carried out genomic surveillance of S. pneumoniae worldwide, with the team sequencing over 20,000 samples from infected individuals across 50 countries
Samples were collected both before and after the vaccine introduction and the DNA sequences and health data were compared. The researchers identified 621 strains globally, each associated with one or more coat type. They also observed that the levels of non-vaccine type bacteria rose after the introduction of the vaccine, suggesting bacteria evolve in response to the vaccine.
Author Stephen Bentley (Wellcome Sanger Institute, Cambridge, UK) commented: “Pneumonia is a huge threat to health worldwide. We now have an unprecedented view of the global population of S. pneumoniae bacteria, the usual cause of bacterial pneumonia, and can see evolutionary changes that lead to vaccine evasion. This will give crucial information for future vaccine strategy worldwide and help save lives.”
This work will help predict which strains will be important for new pneumococcal vaccines and it also shows that ongoing global genomic surveillance is vital. Principal Investigator, Robert Breiman ( Emory Global Health Institute, GA, USA) concluded: “The Global Pneumococcal Sequencing project turns a spotlight onto a new era in which the intersection of genomics and public health enables unparalleled capacity for optimizing prevention strategies, while providing an immensely valuable tool for forecasting and addressing new challenges ahead.”
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Source: Lo s, Gladstone R et al. Pneumococcal lineages associated with serotype replacement and antibiotic resistance in childhood invasive pneumococcal disease in the Post-PCV13 era: An international whole genome sequencing study. The Lancet Infect. Dis. doi:10.1016/ S1473-3099(19)30297-X.