Development of Engineered Probiotics to Deliver Narrow-Spectrum Siderophore Antimicrobial Peptides Against Drug-Resistant Enteric Bacteria

• Applicant: Dr. Benedikt Mortzfeld
• Subject Area: Medical Microbiology and Mycology, Hygiene, Molecular Infection Biology ; Microbial Ecology and Applied Microbiology
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 457837076

Infections due to multidrug-resistant (MDR) organisms have become a major issue in modern healthcare around the world. Especially carbapenem-resistant Enterobacteriaceae are considered one of most dangerous bacterial families that colonize the human intestine and cause severe healthcare-associated infections worldwide. Working towards the development of antibiotic alternatives, I leverage the ability to heterologously produce and purify siderophore antimicrobial peptides (sAMPs) in order to inhibit growth of drug-resistant enteric bacteria. sAMPs are vastly underexplored bacteriocins known to be produced by certain strains of the genera Escherichia and Klebsiella that observe a narrow activity spectrum against closely related bacterial strains or species. With the hypothesis that sAMPs are a common trait among Enterobacteriaceae, I will develop a bioinformatic approach to mine publicly available genome databases for new, putative sAMPs in order to create a potent library to target clinically relevant MDR Enterobacteriaceae. The newly identified sAMPs will be systematically synthesized, overexpressed in the known probiotic E. coli Nissle 1917, and tested for activity against a large collection of MDR bacteria. Moreover, I will investigate the molecular targets as well as emergence of resistance to further characterize the newly identified antimicrobial compounds.The intestinal tract serves as a natural reservoir for MDR bacteria, including Klebsiella pneumoniae. In preliminary results for this project I can show that the previously uncharacterized sAMP MccI47 effectively inhibits growth of Klebsiella pneumoniae in vitro. Therefore, in my second aim I will investigate the capabilities of MccI47 to eradicate carbapenem-resistant Klebsiella pneumoniae colonization from the gastrointestinal environment and whether it reduces transmission between individuals in vivo. Mice infected with Klebsiella pneumoniae will be treated with either the purified sAMP, a live producing strain of genetically modified E. coli Nissle or the respective mock controls and the gastrointestinal colonization pattern will be followed over time. Further, treated mice will be co-housed with susceptible individuals to investigate the decolonization effect on ‘patient-to-patient’ transmission.Engineering well-known probiotic strains like E. coli Nissle 1917 with the ability to overproduce potent antimicrobial compounds could serve as an alternative to overused antibiotics and provides a novel strategy for the treatment of antibiotic resistant pathogenic gastrointestinal infections.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor Vanni Bucci, Ph.D.