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Differences in gene content among Salmonella enterica serovar typhi isolates
E F Boyd1, S Porwollik, F Blackmer
1Sidney Kimmel Cancer Center, San Diego, California 92121, USA.
Journal of Clinical Microbiology
|August 9, 2003
Summary
Salmonella Typhi genomes show significant genomic variation, with absent or divergent gene regions including prophages and islets. This instability highlights the dynamic nature of bacterial populations, even within clonal lineages.
Area of Science:
- Microbiology
- Genomics
- Bacterial Pathogenesis
Background:
- Salmonella enterica serovar Typhi is a significant human pathogen.
- Understanding genomic diversity is crucial for tracking and controlling Typhi outbreaks.
Purpose of the Study:
- To assess the genomic content variation among diverse Salmonella Typhi isolates.
- To identify regions of absent or divergent genes in Typhi strains compared to a reference genome.
Main Methods:
- Comparative genomic hybridization using a nonredundant microarray.
- Analysis of Salmonella enterica serovar Typhimurium LT2 and Typhi CT18 genomes.
Main Results:
- Thirteen regions of absent or divergent gene content were identified in eight Typhi strains.
- Specific prophage regions, gene islets, IS1 elements, and a P4-like phage were variably absent or divergent.
- One strain lacked a large region encoding Vi antigen biosynthesis, while another showed gene amplification and aberrant replication patterns.
Conclusions:
- Significant genomic instability exists within Salmonella Typhi populations, even in highly clonal lineages.
- Variations in gene content, including phage and virulence factor genes, contribute to bacterial adaptability.