Escherichia coli O25b-ST131 clone is a worldwide pandemic clone, causing predominantly community-onset antimicrobial-resistant infection. A high prevalence of the clone (30%–60%) has been identified amongst fluoroquinolone-resistant E. coli. In addition, it potentially harbours a variety of β-lactamase genes. A broad distribution has been demonstrated amongst antimicrobial-resistant E. coli from human infection in Europe, North America, Canada, Japan and Korea. The clinical spectrum of disease described is similar to that for other E. coli, with urinary tract infection predominant. Description ranges from uncomplicated cystitis to severe infection complicated by bacteraemia, renal abscess and emphysematous pyelonephritis. Other sites of infection have included the respiratory tract, ascitic fluid, intra-abdominal abscess, bones/joints and bacteraemia without a clinically apparent focus. The O25b-ST131 clone has also been reported as a prominent cause of E. coli neonatal sepsis. The clone thus constitutes a major public health concern and there is an unmet need for the development of new method for detecting it. Phenotypic detection of the ST131 clone is not possible and DNA-based techniques, including MLST and PCR, remains time consuming.
The present invention relates to methods and kits for the rapid detection of the E. coli O25b-ST131 clone. The inventors have isolated a podoviridae bacteriophage (LM33_P1) infecting the E. coli strain LM33 isolated from ventilator associated pneumonia and which belongs to clone STI31-025b. By testing different strains of E coli belonging to 129 others various distinct serotypes (including twelve O25a) they show that LM33_P1 is able to infect exclusively O25b strains (none of non-O25b strains could be infected by LM33_P1). The specificity displayed by LM33_P1 to infect only O25b serotype strains is based on a very specific polypeptide (Gp17) used by LM33_P1 to attach the bacterial cell via LPS molecule.
Scientific publication(s):
J Antimicrob Chemother., 2016 Nov, Dufour N. et al., Bacteriophage LM33_P1, a fast-acting weapon against the pandemic ST131-O25b:H4 Escherichia coli clonal complex, doi: 10.1093/jac/dkw253