Genome sequence determination and comparative genomics of Uropathogenic E. coli ST127

Uropathogenic E. coli (UPEC) is the most frequent cause of UTI, being responsible for up to 85% of community acquired UTI and 25% of nosocomial UTI. An in vivo study using Galleria mellonella showed that larvae inoculated with ST127 isolates (104 colony-forming units) had significantly higher mortality compared to other UPEC including those from ST73 (P≤ 0.0024) and ST131 (P≤ 0.0004). However, an interesting result to emerge from the data was the observation that one strain of ST127 (EC18) did not show any lethal effects, even for high inoculum doses (up to 2.33×107 cfu/10µl).Using comparative genomic analyses to identify the genetic basis for UPEC ST127 EC18 non-lethality in the Wax moth model G.mellonella. The genomic analyses revealed a major deletion in the O-antigen cluster, which is likely to explain the lack of virulence in the larvae. Evidence of bacterial insertion sequence IS1 was seen at the position where the O-antigen deletion occurs in EC18. This study illustrates that G.mellonella can be used to investigate the virulence of UPEC strains. The outcome of this analysis will give considerable insight into the association of different E. coli virulence genes with lethality in the experimental model of G. mellonella larvae infection.