Analysis of Escherichia coli K1 Virulence Genes by Transposon-Directed Sequencing.

Transposon-directed insertion site sequencing (TraDIS) combines random transposon mutagenesis and massively parallel sequencing to shed light on bacterial gene function on a genome-wide scale and in a high-throughput manner. The technique has proven to be successful in the determination of the fitness contribution of every gene under specific conditions both in vitro and in vivo. In this contribution, we describe the procedure used for the identification of Escherichia coli K1 genes essential for in vitro growth, survival in pooled human serum and gastrointestinal colonisation in a rodent model of neonatal invasive infection. TraDIS has broad application for systems-level analysis of a wide range of pathogenic, commensular and saprophytic bacteria.