Abstract
For microbial pathogens, phylogeographic differentiation seems to be relatively common. However, the neutral population structure of Salmonella enterica serovar Typhi reflects the continued existence of ubiquitous haplotypes over millennia. In contrast, clinical use of fluoroquinolones has yielded at least 15 independent gyrA mutations within a decade and stimulated clonal expansion of haplotype H58 in Asia and Africa. Yet, antibiotic-sensitive strains and haplotypes other than H58 still persist despite selection for antibiotic resistance. Neutral evolution in Typhi appears to reflect the asymptomatic carrier state, and adaptive evolution depends on the rapid transmission of phenotypic changes through acute infections.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptation, Physiological
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Africa
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Alleles
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Anti-Bacterial Agents / pharmacology
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Anti-Bacterial Agents / therapeutic use
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Asia
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Biological Evolution*
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Carrier State / microbiology*
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DNA Gyrase / genetics
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Drug Resistance, Bacterial
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Drug Resistance, Multiple, Bacterial
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Fluoroquinolones / pharmacology
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Fluoroquinolones / therapeutic use
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Genes, Bacterial*
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Genetic Variation
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Haplotypes
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Humans
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Molecular Sequence Data
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Mutation
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Polymorphism, Genetic
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Polymorphism, Single Nucleotide
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Salmonella typhi / drug effects
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Salmonella typhi / genetics*
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Selection, Genetic
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Typhoid Fever / drug therapy
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Typhoid Fever / microbiology*
Substances
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Anti-Bacterial Agents
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Fluoroquinolones
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DNA Gyrase