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Genetic analysis of Escherichia coli K1 gastrointestinal colonization
J Martindale1, D Stroud, E R Moxon
1University Department of Paediatrics, John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK.
Insights
Researchers identified essential genes for Escherichia coli K1 colonization in infant guts using signature-tagged mutagenesis. This study reveals key factors for E. coli K1
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Escherichia coli K1 strains are a primary cause of Gram-negative septicaemia and meningitis in neonates.
- These bacteria colonize the infant large intestine, posing significant health risks.
Purpose of the Study:
- To identify genes crucial for E. coli K1 colonization of the gastrointestinal tract.
- To understand the genetic basis of E. coli K1 pathogenesis in neonates.
Main Methods:
- Signature-tagged mutagenesis (STM) was employed to screen 2140 mTn5 mutants.
- Infant rats were used as a model to assess bacterial colonization capacity.
- Immunohistochemistry was utilized to analyze colonization defects.
Main Results:
- Sixteen E. coli K1 mutants with defective GI colonization were identified.
- Mutations affected genes involved in cell surface structures, transport, regulation, metabolism, and unknown functions (dgc).
- Three novel dgc genes were identified, with related sequences in other pathogenic E. coli and Shigella flexneri.
Conclusions:
- STM is an effective method for identifying colonization factors in E. coli K1.
- The identified genes are critical for E. coli K1 gastrointestinal tract colonization.
- Findings contribute to understanding enteric infection pathogenesis.
Abstract:
Strains of Escherichia coli expressing the K1 polysaccharide capsule colonize the large intestine of newborn infants, and are the leading cause of Gram-negative septicaemia and meningitis in the neonatal period. We used signature-tagged mutagenesis (STM) to identify genes that E. coli K1 requires to colonize the gastrointestinal (GI) tract. A total of 2140 mTn5 mutants was screened for their capacity to colonize the GI tract of infant rats, and 16 colonization defective mutants were identified. The mutants have transposon insertions in genes affecting the synthesis of cell surface structures, membrane transporters, transcriptional regulators, enzymes in metabolic pathways, and in genes of unknown function, designated dgc (defective in GI colonization). Three dgcs are absent from the whole genome sequence of E. coli K-12, although related sequences are found in other pathogenic strains of E. coli and in Shigella flexneri. Additionally, immunohistochemistry was used to define the nature of the colonization defect in five mutants including all dgc mutants. STM was successfully applied to examine the factors involved in E. coli K1 colonization, and the findings are relevant to the pathogenesis of other enteric infections.