Emergence of a Dominant Multi-Drug Resistant Typhoid Plasmid
Author Information
Author(s): Kathryn E. Holt, Minh Duy Phan, Stephen Baker, Thanh Duy Pham, Vu Thieu Nga Tran, Satheesh Nair, A. Keith Turner, Ciara Walsh, Séamus Fanning, Sinéad Farrell-Ward, Shanta Dutta, Sam Kariuki, François-Xavier Weill, Julian Parkhill, Gordon Dougan, John Wain
Primary Institution: Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
Hypothesis
Is the recent global spread of multi-drug resistant (MDR) Salmonella Typhi due to the emergence of a dominant plasmid type?
Conclusion
The study found that the global spread of MDR typhoid is largely due to a single plasmid-host combination, specifically the H58 S. Typhi carrying the PST6 plasmid.
Supporting Evidence
- Over 300 single nucleotide polymorphisms (SNPs) were identified within conserved regions of the IncHI1 plasmid.
- 98% of MDR S. Typhi from 1995 onwards were of the same plasmid sequence type (PST6) and haplotype (H58).
- The PST6 plasmid conferred the ability to grow in high salt medium, indicating a selective advantage.
Takeaway
Scientists studied a type of bacteria that causes typhoid fever and found that a specific version of it has become very common and resistant to many medicines. This happened because of a special piece of DNA that helps the bacteria survive.
Methodology
The study involved SNP typing of over 450 S. Typhi isolates and analysis of plasmid sequences to trace the emergence and spread of MDR strains.
Limitations
The study may not account for all possible plasmid types and their interactions with different S. Typhi haplotypes.
Participant Demographics
The study included S. Typhi isolates from various regions, primarily Asia and Africa, collected from 1958 to 2007.
Digital Object Identifier (DOI)
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