APTC-EC-2A: A Lytic Phage Targeting Multidrug Resistant E. coli Planktonic Cells and Biofilms

Abstract

<i>Escherichia coli</i> (<i>E. coli</i>) are common bacteria that colonize the human and animal gastrointestinal tract, where they help maintain a balanced microbiome. However, some <i>E. coli</i> strains are pathogenic and can cause serious infectious diseases and life-threatening complications. Due to the overuse of antibiotics and limited development of novel antibiotics, the emergence of antibiotic-resistant strains has threatened modern medicine, whereby common infections can become lethal. Phage therapy has once again attracted interest in recent years as an alternative treatment option to antibiotics for severe infections with antibiotic-resistant strains. The aim of this study was to isolate and characterize phage against multi-drug resistant <i>E. coli</i> isolated from clinical samples and hospital wastewater. For phage isolation, wastewater samples were collected from The Queen Elizabeth Hospital (Adelaide, SA, Australia) followed by phage enrichment as required. Microbiological assays, electron microscopy and genomic sequencing were carried out to characterize the phage. From the 10 isolated <i>E. coli</i> phages, <i>E. coli</i> phage APTC-EC-2A was the most promising and could lyse 6/7 <i>E. coli</i> clinical isolates. APTC-EC-2A was stable at a broad pH range (3-11) and could lyse the host <i>E. coli</i> at temperatures ranging between 30-50 °C. Furthermore, APTC-EC-2A could kill <i>E. coli</i> in planktonic and biofilm form. Electron microscopy and genomic sequencing indicated the phage to be from the <i>Myoviridae</i> family and of lytic nature. In conclusion, the newly isolated phage APTC-EC-2A has the desired properties that support its potential for development as a therapeutic agent against therapy refractory <i>E. coli</i> infections.