[Construction and functional studies of uropathogenic E. coli strains with ompT gene knockout]

To explore the role of ompT gene in uropathogenic E. coli (UPEC) CFT073 strain in urinary tract infection (UTI).

An ompT deletion mutant (COTD) was generated by λ Red recombineering in the UPEC CFT073 strain, which was characterized by PCR and sequencing. C57B/L6 mouse models of acute UTI with the mutant and wild-type strains were established to compare the colonization abilities of the two strains in the bladder. The adhesion of CFT073 mutant to human unthelial 5637 cells was also investigated in vitro.

PCR and DNA sequencing confirmed the loss of ompT gene in the mutant COTD. The in vitro adhesion rate of the mutant strain COTD to 5637 cells was (6.7±2.2)%, significantly lower than that of (8.3±1.9)% of the wild-type strain (P<0.05). In the murine models of acute UTI, the mutant strain showed a mean colonization number of about (17±8)×10⁴ cfu, which was significantly lower than that of (7∓2)×10⁵ cfu of the wide-type CFT073 strain (P<0.05).

OmpT gene can be involved in the colonization of UPEC in the bladder tissue and plays an important role in the pathogenesis of UPEC-induced UTI.