B-194. Genomic Islands of Uropathogenic Escherichia coli Contribute to Virulence
The genome of the uropathogenic Escherichia coli (UPEC) strain CFT073 is 590 kb larger than that of commensal E. coli strain K-12 MG1655, with the majority of the difference attributed to large insertions in CFT073. Thirteen genomic islands >30 kb comprise 12.8% (672 kb) of the E. coli CFT073 genome. We hypothesized that virulence properties reside on these genomic islands, and tested the contribution of these islands to virulence. Isogenic mutants in genomic islands in CFT073 have been constructed using the lambda red recombinase system in which 11 of 13 islands were deleted. Six mutants have been tested in the mouse model of ascending urinary tract infection. In co-challenge infections with wild-type CFT073, genomic island mutants ΔPAI-CFT073-aspV (100 kb) and ΔPAI-CFT073-metV (32 kb) were significantly out-competed in both the bladder and kidneys (P<0.05) of mice at 48 hours post inoculation (hpi). ΔPAI-CFT073-asnT (32 kb) was significantly out-competed in the kidneys (P=0.0078) but not in the bladder at 48 hpi. Deletions of GI-CFT073-asnW, GI-CFT073-selC and f-CFT073-potB did not attenuate strain CFT073. Several mutants have been studied in greater detail, including the creation of smaller deletions in PAI-CFT073-aspV (originally 100 kb) and comparing mutants in known or suspected virulence genes to whole islands containing these genes (ΔPAI-CFT073-aspV versus Δc0345; ΔPAI-CFT073-metV versus Δc3391-c3392). Metabolic differences between wild-type CFT073 and several isogenic mutants have been assessed using BioLog phenotype microarrays including their ability to utilize various carbon, nitrogen, phosphorous and sulfur sources. The number of negative metabolic phenotypes correlated directly with the size of the genomic island deletion. This study confirms the importance of genomic islands for virulence in E. coli CFT073.