(316b) Engineered Probiotics for the Treatment of Multidrug Resistant E.coli

A single extraintestinal E.coli strain, ST131, has recently emerged as the most dominant strain in clinical laboratories across the globe. ST131 causes a variety of extraintestinal infections but is notorious for those in the urinary tract (UTIs), causing up to 95% of UTIs worldwide. Since its identification in 2008, ST131 has rapidly risen to ‘superbug’ status, now being identified as the single most common multidrug resistant E.coli strain. The resistance phenotype of ST131 is primarily attributed to the H30-Rx subclone which is fluoroquinolone and extended-spectrum cephalosphorin resistant, making it increasingly difficult to treat in the clinic. There is pressing need to develop novel antimicrobial strategies to mitigate the dissemination and spread of ST131 and to more effectively treat infected patients.

Probiotics are safe-to-consume organisms that have been proposed as a potential treatment option for ST131.In collaboration with the Veteran’s Affairs Medical Center, we have engineered the probiotic E.coli strain, Nissle 1917 (EcN), to elicit strong antagonistic activity against the H30-Rx subclone, JJ1886. We have designed an EcN strain that is capable of producing high-titers of three diverse antimicrobial peptides (AMPs), Microcin C7, Microcin V, and Microcin N, using a combination of different peptide secretion mechanisms. AMPs have been researched for years for their antibiotic properties but have failed in translational success due to their high synthesis costs and rapid degradation rates in the body. Using a probiotic host, we can overcome these hurdles enabling localized production at the site of infection. In this work, we have screened dozens of AMPs for activity against JJ1886. We have chosen three peptides that act by orthogonal mechanisms on JJ1886 which we demonstrate decreases resistance development. We also take an in-depth look at the remaining resistant subpopulation, examining growth characteristics and screening for antibiotics and human-produced peptides that have increased susceptibility on this persistent subset.