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DNA sequence-based subtyping and evolutionary analysis of selected Salmonella enterica serotypes
Sharinne Sukhnanand1, Sam Alcaine, Lorin D Warnick
1Department of Food Science, 412 Stocking Hall, Cornell University, Ithaca, NY 14853, USA.
Journal of Clinical Microbiology
|August 6, 2005
Summary
A new three-gene sequence typing scheme accurately predicts Salmonella serotypes and differentiates subtypes, aiding in understanding bacterial evolution and transmission.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genetics
Background:
- Traditional Salmonella characterization methods like serotyping and phage typing lack sensitivity for evolutionary analysis.
- Sensitive subtyping is crucial for studying Salmonella transmission, ecology, and evolution.
Purpose of the Study:
- To develop and evaluate a multilocus sequence typing (MLST) scheme for Salmonella.
- To assess the utility of a simplified three-gene scheme for Salmonella subtyping and serotype prediction.
Main Methods:
- Developed an MLST scheme targeting seven genes in 25 Salmonella enterica isolates.
- Selected three highly discriminatory genes (manB, fimA, mdh) for a simplified scheme.
- Sequenced an additional 41 isolates, totaling 66, to validate the three-gene scheme.
Main Results:
- The initial seven-gene MLST scheme identified eight MLST types among 25 isolates.
- The three-gene scheme identified 25 sequence types (STs) among 66 isolates.
- STs correlated well with serotypes, enabling within-serotype differentiation for most serotypes.
- Phylogenetic analyses revealed distinct evolutionary lineages within serotypes Kentucky and Newport.
Conclusions:
- A three-gene sequence typing scheme provides accurate Salmonella serotype prediction.
- This scheme allows for limited but valuable subtype discrimination within clinically relevant serotypes.
- The findings support the complex evolutionary nature of Salmonella serotypes, with both monophyletic and polyphyletic lineages.