The emergence of multidrug-resistant (MDR) Escherichia coli infections in swine farms, reported globally, including in Thailand, causes symptoms ranging from mild to severe and leads to economic losses. Numerous studies have demonstrated a correlation between antibiotic use and the development of antibiotic resistance, highlighting the risk associated with antibiotic misuse and overuse. However, no practical alternative for E. coli infection in swine and their environments has been established. In this study, an Escherichia phage specific to MDR E. coli, named phage vBEcoMPPW9 (phage vECPPW9), was isolated and characterized. The antibacterial and antibiofilm activities of the phage were evaluated. This phage formed small plaques with halos, and transmission electron microscopy revealed that it possessed an icosahedral head and a contractile tail. Phage vECPPW9 lysed 40% of the tested E. coli isolates and exhibited high adsorption efficacy, a short latent period, large burst size, and moderate stability across various temperatures and pH levels. Even at low multiplicity of infection, the phage demonstrated strong lytic activity, confirmed by observations of bacterial morphology under a scanning electron microscope. Genomic analysis revealed that phage vECPPW9 had a linear double-stranded DNA genome of 152, 457 base pairs, comprising 284 predicted coding sequences and 13 tRNA genes, and lacked genes associated with virulence or antibiotic resistance. Phylogenetic analysis classified phage vECPPW9 as a novel member of the Phapecoctavirus genus within the Stephanstirmvirinae subfamily. Additionally, phage vECPPW9 exhibited strong antibiofilm activity by inhibiting biofilm formation and reducing established biofilms, as demonstrated by biofilm biomass measurements and bacterial cell viability counting. This antibiofilm effect was also observed on both rubber tube and stainless steel surfaces. Given the urgent need for antibiotic stewardship and alternative antimicrobial strategies, phage vECPPW9 represents a promising candidate for controlling MDR E. coli infections in swine farming.
Wintachai et al. (Tue,) studied this question.