Isolation and Characterization of a Novel Phage Collection against Avian-Pathogenic Escherichia coli.

The increase in antibiotic-resistant avian-pathogenic Escherichia coli (APEC), the causative agent of colibacillosis in poultry, warrants urgent research and the development of alternative therapies. This study describes the isolation and characterization of 19 genetically diverse, lytic coliphages, 8 of which were tested in combination for their efficacy in controlling in ovo APEC infections. Genome homology analysis revealed that the phages belong to nine different genera, one of them being a novel genus (Nouzillyvirus). One phage, REC, was derived from a recombination event between two Phapecoctavirus phages (ESCO5 and ESCO37) isolated in this study. Twenty-six of the 30 APEC strains tested were lysed by at least one phage. Phages exhibited varying infectious capacities, with narrow to broad host ranges. The broad host range of some phages could be partially explained by the presence of receptor-binding protein carrying a polysaccharidase domain. To demonstrate their therapeutic potential, a phage cocktail consisting of eight phages belonging to eight different genera was tested against BEN4358, an APEC O2 strain. In vitro, this phage cocktail fully inhibited the growth of BEN4358. In a chicken lethality embryo assay, the phage cocktail enabled 90% of phage-treated embryos to survive infection with BEN4358, compared with 0% of nontreated embryos, indicating that these novel phages are good candidates to successfully treat colibacillosis in poultry. IMPORTANCE Colibacillosis, the most common bacterial disease affecting poultry, is mainly treated by antibiotics. Due to the increased prevalence of multidrug-resistant avian-pathogenic Escherichia coli, there is an urgent need to assess the efficacy of alternatives to antibiotherapy, such as phage therapy. Here, we have isolated and characterized 19 coliphages that belong to nine phage genera. We showed that a combination of 8 of these phages was efficacious in vitro to control the growth of a clinical isolate of E. coli. Used in ovo, this phage combination allowed embryos to survive APEC infection. Thus, this phage combination represents a promising treatment for avian colibacillosis.

Reviving Phage Therapy for the Treatment of Cholera.

Cholera remains a major risk in developing countries, particularly after natural or man-made disasters. Vibrio cholerae El Tor is the most important cause of these outbreaks, and is becoming increasingly resistant to antibiotics, so alternative therapies are urgently needed. In this study, a single bacteriophage, Phi_1, was used to control cholera prophylactically and therapeutically in an infant rabbit model. In both cases, phage-treated animals showed no clinical signs of disease, compared with 69% of untreated control animals. Bacterial counts in the intestines of phage-treated animals were reduced by up to 4 log10 colony-forming units/g. There was evidence of phage multiplication only in animals that received a V. cholerae challenge. No phage-resistant bacterial mutants were isolated from the animals, despite extensive searching. This is the first evidence that a single phage could be effective in the treatment of cholera, without detectable levels of resistance. Clinical trials in human patients should be considered.

Fleas and smaller fleas: virotherapy for parasite infections.

Bacteriophages are viruses of bacteria that are used for controlling bacterial food-borne pathogens and have been proposed for more extensive usage in infection control. Protists are now recognised to harbour viruses and virus-like particles. We propose that investigation of their prevalence in parasites be intensified. We also propose that such viruses might be considered for virotherapy to control certain parasite infections of man and animals.