Investigation of Salmonella Phage–Bacteria Infection Profiles: Network Structure Reveals a Gradient of Target-Range from Generalist to Specialist Phage Clones in Nested Subsets

From MDPI via Jisc Publications RouterHistory: accepted 2021-06-23, pub-electronic 2021-06-28Publication status: PublishedFunder: Horizon 2020 Framework Programme; Grant(s): 767015Funder: The International Science and Technology Center; Grant(s): ISTC grant A-2140Bacteriophages that lyse Salmonella enterica are potential tools to target and control Salmonella infections. Investigating the host range of Salmonella phages is a key to understand their impact on bacterial ecology, coevolution and inform their use in intervention strategies. Virus–host infection networks have been used to characterize the “predator–prey” interactions between phages and bacteria and provide insights into host range and specificity. Here, we characterize the target-range and infection profiles of 13 Salmonella phage clones against a diverse set of 141 Salmonella strains. The environmental source and taxonomy contributed to the observed infection profiles, and genetically proximal phages shared similar infection profiles. Using in vitro infection data, we analyzed the structure of the Salmonella phage–bacteria infection network. The network has a non-random nested organization and weak modularity suggesting a gradient of target-range from generalist to specialist species with nested subsets, which are also observed within and across the different phage infection profile groups. Our results have implications for our understanding of the coevolutionary mechanisms shaping the ecological interactions between Salmonella phages and their bacterial hosts and can inform strategies for targeting Salmonella enterica with specific phage preparations

Genomic insights into the safety and bacteriocinogenic potential of isolates from artisanal fermented milk Matsoni

Matsoni is a fermented milk common in the Caucasian region. In this study, whole-genome sequencing was performed with the aim of determining the taxonomic position of 25 previously selected candidate Matsoni starter cultures, identifying bacteriocin genes and prophages in their genomes, and evaluating their safety. In silico prediction of antibiotic resistance genes, virulence factors, bacteriocin genes and prophages was performed using dedicated databases and bioinformatics tools. With the exception of Enterococcus faecalis, which contained the mobile genetic element Tn916 with tetM and virulence factors, and Streptococcus thermophilus with mefE, the isolates were found to be safe for use as starter cultures. Thermophilin A, thermophilin 13, streptide and Blp genes were predicted in isolates of Streptococcus thermophilus, and genes for enterocins A, B, and X were found in Enterococcus faecium, but inhibition between strains was not observed. Several complete prophages were also detected in the genomes of Lactobacillus delbrueckii ssp. lactis. Lacticaseibacillus rhamnosus, Limosilactobacillus fermentum, Streptococcus thermophilus, Enterococcus faecalis, and Enterococcus faecium. Some of these isolates are good candidates for customised autochthonous Matsoni starter cultures which are an alternative to the commercial starter cultures currently used in the industry

In Vitro Evaluation of the Therapeutic Potential of Phage VA7 against Enterotoxigenic Bacteroides fragilis Infection

Since the beginning of the 20th century, bacteriophages (phages), i.e., viruses that infect bacteria, have been used as antimicrobial agents for treating various infections. Phage preparations targeting a number of bacterial pathogens are still in use in the post-Soviet states and are experiencing a revival in the Western world. However, phages have never been used to treat diseases caused by Bacteroides fragilis, the leading agent cultured in anaerobic abscesses and postoperative peritonitis. Enterotoxin-producing strains of B. fragilis have been associated with the development of inflammatory diarrhea and colorectal carcinoma. In this study, we evaluated the molecular biosafety and antimicrobial properties of novel phage species vB_BfrS_VA7 (VA7) lysate, as well as its impact on cytokine IL-8 production in an enterotoxigenic B. fragilis (ETBF)-infected colonic epithelial cell (CEC) culture model. Compared to untreated infected cells, the addition of phage VA7 to ETBF-infected CECs led to significantly reduced bacterial counts and IL-8 levels. This in vitro study confirms the potential of phage VA7 as an antibacterial agent for use in prophylaxis or in the treatment of B. fragilis infections and associated colorectal carcinoma

Investigation of Salmonella phage–bacteria infection profiles: network structure reveals a gradient of target-range from generalist to specialist phage clones in nested subsets

Bacteriophages that lyse Salmonella enterica are potential tools to target and control Salmonella infections. Investigating the host range of Salmonella phages is a key to understand their impact on bacterial ecology, coevolution and inform their use in intervention strategies. Virus–host infection networks have been used to characterize the “predator–prey” interactions between phages and bacteria and provide insights into host range and specificity. Here, we characterize the target-range and infection profiles of 13 Salmonella phage clones against a diverse set of 141 Salmonella strains. The environmental source and taxonomy contributed to the observed infection profiles, and genetically proximal phages shared similar infection profiles. Using in vitro infection data, we analyzed the structure of the Salmonella phage–bacteria infection network. The network has a non-random nested organization and weak modularity suggesting a gradient of target-range from generalist to specialist species with nested subsets, which are also observed within and across the different phage infection profile groups. Our results have implications for our understanding of the coevolutionary mechanisms shaping the ecological interactions between Salmonella phages and their bacterial hosts and can inform strategies for targeting Salmonella enterica with specific phage preparations

Selection of Potential Therapeutic Bacteriophages that Lyse a CTX-M-15 Extended Spectrum β-Lactamase Producing Salmonella enterica Serovar Typhi Strain from the Democratic Republic of the Congo

Recently, a Salmonella Typhi isolate producing CTX-M-15 extended spectrum β-lactamase (ESBL) and with decreased ciprofloxacin susceptibility was isolated in the Democratic Republic of the Congo. We have selected bacteriophages that show strong lytic activity against this isolate and have potential for phage-based treatment of S. Typhi, and Salmonella in general

Selection of Potential Therapeutic Bacteriophages that Lyse a CTX-M-15 Extended Spectrum β-Lactamase Producing Salmonella enterica Serovar Typhi Strain from the Democratic Republic of the Congo

Recently, aTyphi isolate producing CTX-M-15 extended spectrum β-lactamase (ESBL) and with decreased ciprofloxacin susceptibility was isolated in the Democratic Republic of the Congo. We have selected bacteriophages that show strong lytic activity against this isolate and have potential for phage-based treatment of. Typhi, andin general.status: publishe