Isolation of lytic bacteriophages of Escherichia coli from swine

Abstract

Bacteriophages (phages) are small viruses that infect bacteria and represent nature’s most abundant biological entities. After infection, new phages are produced during their lytic reproductive cycle, causing disruption of the bacterial cell and releasing bacteriophages into the environment. Thus, phages have been used as a possible strategy for controlling bacterial infections in several areas, including pig farming, where multi-resistant pathogenic strains of Escherichia coli represent one of the leading agents associated with diseases in swine. In this sense, phagotherapy as an alternative treatment requires the selection of specific bacteriophages for the strains of interest. Therefore, this work aimed to isolate E. coli lytic bacteriophages from fecal swine samples, using standard E. coli strains as hosts for the infection. Four infective bacteriophages for E. coli ATCC 8739 and two for each of the E. coli K12 strains MG1655 and DH5α were isolated. The phage suspensions obtained had their virulence (titer) determined. Infection and cell lysis assays revealed that they were capable of breaking bacterial cells when added to liquid cultures, reducing cell growth by approximately 75% after 2 h, evidencing the possibility of being used as an alternative tool to antibiotics in the treatment of bacterial infections, in addition to the traditional antibiotics. Further studies using in vivo models should be considered.