Search Results (124)

The emergence of multidrug-resistant Shiga toxin-producing Escherichia coli (STEC) poses a major challenge to public health and necessitates the development of alternative antimicrobial strategies. This study aimed to isolate and characterize five lytic bacteriophages belonging to the genus Mosigvirus and evaluate their potential as biocontrol against MDR STEC strains and their biofilms. The five bacteriophages, designated vB_EcoM-pJBB (ΦB), vB_EcoM-pJBC (ΦC), vB_EcoM-pJBJ (ΦJ), vB_EcoM-pJBK (ΦK), and vB_EcoM-pJBL (ΦL), were isolated from sewage treatment plant samples using STEC ATCC 43895 as host. Biological characterization included host range determination against 19 MDR STEC strains, one-step growth analysis, environmental stability assays, bacteriolytic activity assessment, and antibiofilm efficacy testing. Whole-genome sequencing and phylogenetic analyses were performed to determine genomic features and taxonomic classification. The phages demonstrated varying infectious capacities, lysing between six and 12 strains, with ΦL exhibiting the broadest spectrum of activity. All phages showed MOI-independent antibiofilm activity, preventing biofilm formation by approximately 70% and disrupting pre-formed biofilms by up to 80.3%. Genomic analysis revealed the absence of lysogeny markers, virulence factors, and antimicrobial resistance genes, while identifying putative depolymerase genes associated with tail fiber proteins. Phylogenetic analysis confirmed the taxonomic position of these phages within the Mosigvirus genus in the Straboviridae family. Our findings indicate that the newly identified Mosigvirus phages are promising candidates for phage-based biocontrol applications. Full article

Antimicrobial resistance (AMR) is a major public health threat that urgently requires alternative strategies to address this challenge. Klebsiella spp. are among the most important clinical pathogens and a leading cause of opportunistic nosocomial infections, with high morbidity and mortality associated with strains resistant to last-line antimicrobials such as carbapenems. Bacteriophages are considered a promising therapeutic option for treating infections caused by Klebsiella strains. Hence, the aim of this work was to isolate and characterize a phage capable of infecting carbapenem-resistant Klebsiella strains. The phage KpCCP1 was isolated using the double layer agar method (DLA), from the influent of a wastewater treatment plant, which was characterized through phenotypic and genomic analyses. Morphological characteristics were determined using TEM, and its host range was evaluated against a collection of 133 Klebsiella strains. Its whole genome was sequenced using the Illumina NovaSeq X Plus platform and then assembled and annotated. VICTOR was used for phylogenetic analysis of the isolated phage, and VIRIDIC to compare its genome with those of its closest relatives. KpCCP1 is a tailed dsDNA lytic phage with a genome size of 177,276 bp and a GC content of 41.82%. It encodes 292 ORFs, including two tRNA genes. Phage KpCCP1 is a member of the Slopekvirus genus in the Straboviridae family. It is capable of infecting 22 carbapenem-resistant Klebsiella strains, including K. pneumoniae and K. michiganensis. Notably, it does not contain virulence or antibiotic resistance genes and harbors putative anti-CRISPR genes, therefore representing a promising candidate for phage therapy against clinically critical Klebsiella strains. Full article

The emergence of multidrug-resistant (MDR) Proteus mirabilis poses a significant threat in porcine farming and public health, highlighting the need for alternative biocontrol agents. This study aimed to isolate and characterize a lytic bacteriophage with therapeutic potential against MDR P. mirabilis. Using the clinical MDR P. mirabilis strain Pm 07 as host, a bacteriophage, vB_Pmc_P-07 (P-07), was successfully isolated from fecal and sewage samples via an enrichment protocol. Phage P-07 forms plaques surrounded by a distinct translucent “halo,” suggesting the production of depolymerase. It achieved high titers of up to 1.40 × 10⁸ PFU/mL and exhibited a narrow host range, high stability across a broad range of temperatures (40–60 °C) and pH (4–12), as well as considerable anti-biofilm activity. An optimal multiplicity of infection (MOI) of 0.001 was determined. Whole-genome sequencing revealed a linear double-stranded DNA genome of 58,582 bp with a GC content of 46.91%, encoding 63 open reading frames. Crucially, no virulence or antibiotic resistance genes were detected, supporting its safety profile. Phylogenetic analysis classified P-07 within the Casjensviridae family, closely related to phages PM87 and pPM01. These findings indicate that phage P-07 is a novel, safe, and effective lytic phage with strong potential as a biocontrol agent against biofilm-forming MDR P. mirabilis in swine. Full article

The study investigated the antimicrobial and antiviral effects of polypropylene foil coated with hydroxypropyl methylcellulose (HPMC) layer containing tea tree oil (TTO) as the active agent. Moreover, the influence of accelerated aging using Q-SUN treatment on the efficacy of the non-coated and coated foils was also investigated. The results of the study indicated a slight antimicrobial effect of the irradiated coating against S. aureus, noticeable antibacterial activity of both irradiated and non-irradiated coating against E. coli and a complete inhibition of B. cereus growth by the irradiated coating. However, both of these coatings exhibited strong antiviral properties, confirmed by a method consisting of two separate tests conducted on the Φ6 phage as the infectious agent: real-time measurement of the host’s OD during co-culture with the phage and observation of the host’s growth on copper mesh grids using scanning electron microscopy (SEM). The characteristics of non-irradiated and irradiated foils were also determined using SEM and FT-IR. Full article

Pseudomonas aeruginosa is a gram-negative opportunistic pathogen that poses a significant threat due to its increasing multidrug resistance, particularly in clinical settings. This study aimed to isolate and characterize a novel bacteriophage, phiLCL12, from hospital wastewater and evaluate its potential in combination with antibiotics to combat P. aeruginosa infections and biofilm formation. Transmission electron microscopy revealed that phiLCL12 possesses a long contractile tail. The isolated phage exhibited a broad host range of 82.22% and could adsorb up to 98% of its target within 4 min. It was effective against multidrug-resistant strains at both high and low multiplicities of infection (MOIs) levels in lysis tests. Taxonomic classification was determined using PhaGCN2 and Whole genomic analysis, and the results identified phiLCL12 as a member of the Pbunavirus. In vitro experiments demonstrated that phiLCL12 significantly enhanced biofilm clearance and inhibited biofilm formation when combined with sub-inhibitory concentrations of imipenem. Furthermore, in vivo experiments using a zebrafish model showed that phage–antibiotic synergy (PAS) improved survival rate compared to antibiotic treatment alone. This study demonstrates that phiLCL12 is effective in both eradicating and preventing P. aeruginosa biofilm formation. The combination of phiLCL12 and imipenem provides a synergistic effect, significantly enhancing survival outcomes in a zebrafish model. These findings highlight the potential of phage–antibiotic synergy as a promising therapeutic strategy against biofilm-associated infections. Full article

Bacteriophages grown on Caulobacter vibrioides strain CB15 have reduced plating efficiency on other Caulobacter strains. To determine the cause of this reduced plating efficiency, we performed a series of experiments that demonstrated that the reduced plating efficiency is due to a novel set of restriction and modification (RM) enzymes that are present in most of the Caulobacter strains that we tested. We then demonstrated that one of these RM systems recognizes the nucleotide sequence 5′-ATNNAT-3′. A careful inspection of the genome nucleotide sequences of each of the strains revealed that the genes coding for these RM enzymes have not been annotated or identified, suggesting that the proteins may differ from the common types of bacterial restriction and modification enzymes. In addition, the host strain NA1000 contains a 26 kb mobile element that provides resistance to incoming phages. Full article

Bacteriophages (phages) have coevolved with their bacterial hosts for billions of years. With the rise of antibiotic resistance, the significance of using phages in therapy is increasing. Investigating the dynamics of phage evolution can provide valuable insights for pre-adapting phages to more challenging clones of their hosts that may arise during treatment. Two primary models describe interactions in phage–bacteria systems: arms race dynamics and fluctuating selection dynamics. Numerous factors influence which dynamics dominate the interactions between a phage and its host. These dynamics, in turn, affect the coexistence of phages and bacteria, ultimately determining which organism will adapt more effectively to the other, and whether a stable state will be reached. In this review, we summarize key findings from research on phage–bacteria coevolution, focusing on the different concepts that can describe these interactions, the factors that may contribute to the prevalence of one model over others, and the effects of various dynamics on both phages and bacteria. Full article

Six novel Microbacterium phages belonging to the Tectiviridae family were isolated using Microbacterium testaceum as a host. Phages MuffinTheCat, Badulia, DesireeRose, Bee17, SCoupsA, and LuzDeMundo were purified from environmental samples by students participating in the Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) program at Alliance University, New York. The phages have linear dsDNA genomes 15,438–15,636 bp with 112–120 bp inverted terminal repeats. Transmission electron microscopy (TEM) imaging analysis revealed that the six novel phages have six-sided icosahedral double-layered capsids with an internal lipid membrane that occasionally forms protruding nanotubules. Annotation analysis determined that the novel Microbacterium phages all have 32–34 protein-coding genes and no tRNAs. Like other Tectiviridae, the phage genomes are arranged into two segments and include three highly conserved family genes that encode a DNA polymerase, double jelly-roll major capsid protein, and packaging ATPase. Although the novel bacteriophages have 91.6 to 97.5% nucleotide sequence similarity to each other, they are at most 58% similar to previously characterized Tectiviridae genera. Consequently, these novel Microbacterium phages expand the diversity of the Tectiviridae family, and we propose they form the sixth genus, Zetatectivirus. Full article

Leukocidins of Staphylococcus (S.) aureus are bicomponent toxins that form polymeric pores in host leukocyte membranes, leading to cell death and/or triggering apoptosis. Some of these toxin genes are located on prophages and are associated with specific hosts. The genes lukP/Q have been described from equine S. aureus isolates. We examined the genomes, including the lukP/Q prophages, of S. aureus strains belonging to clonal complexes CC1, CC350, CC816, and CC8115. In addition to sequencing, phages were characterised by mitomycin C induction and transmission electron microscopy (TEM). All lukP/Q prophages integrated into the lip2=geh gene, and all included also the gene scn-eq encoding an equine staphylococcal complement inhibitor. The lukP/Q prophages clustered, based on gene content and allelic variants, into three groups. One was found in CC1 and CC97 sequences; one was present mainly in CC350 but also in other lineages (CC1, CC97, CC133, CC398); and a third one was exclusively observed in CC816 and CC8115. Prophages of the latter group additionally included a rare enterotoxin A allele (sea_320E). Moreover, a prophage from a CC522 goat isolate was found to harbour lukP. Its lukF component could be regarded as chimaera comprising parts of lukQ and of lukF-P83. A putative kinase gene of 1095 basepairs was found to be associated with equine strains of S. aureus. It was also localised on prophages. However, these prophages were different from the ones that carried lukP/Q, and three different integration sites of kinase-carrying phages were identified. These observations confirmed the presence of prophage-located important virulence-associated genes in equine S. aureus and that certain prophages might determine the host specificity of the staphylococcal strains they reside in. Full article

Using Escherichia coli BW25113 as a host, we isolated a novel lytic phage from the commercial poly-specific therapeutic phage cocktail Sextaphage^® (Microgen, Russia). We provide genetic and phenotypic characterization of the phage and describe its host range on the ECOR collection of reference E. coli strains. The phage, hereafter named Sxt1, is a close relative of classical coliphage T3 and belongs to the Teetrevirus genus, yet its internal virion proteins, forming an ejectosome, differ from those of T3. In addition, the Sxt1 lateral tail fiber (LTF) protein clusters with those of the phages from the Berlinvirus genus. A comparison of T7, T3, and Sxt1 LTFs reveals the presence of insertions leading to the elongation of Sxt1 tail fibers, which, together with the difference in the HRDRs (host range-determining regions), might explain the expanded host specificity for the Sxt1. Full article

Background/Objectives: Antimicrobial resistance (AMR) is a major public health threat, which is exacerbated by the lack of new antibiotics and the emergence of multidrug-resistant (MDR) superbugs. Comprehensive efforts and alternative strategies to combat AMR are urgently needed to prevent social, medical, and economic consequences. Pseudomonas aeruginosa is a pathogen responsible for a wide range of infections, from soft tissue infections to life-threatening conditions such as bacteremia and pneumonia. Bacteriophages have been considered as a potential therapeutic option to treat bacterial infections. Our aim was to isolate phages able to infect MDR P. aeruginosa strains. Methods: We isolated two lytic phages, using the conventional double layer agar technique (DLA), from samples obtained from the influent of a wastewater treatment plant in Concepción, Chile. The phages, designated as PaCCP1 and PaCCP2, were observed by electron microscopy and their host range was determined against multiple P. aeruginosa strains using DLA. Moreover, their genomes were sequenced and analyzed. Results: Phage PaCCP1 is a member of the Septimatrevirus genus and phage PaCCP2 is a member of the Pbunavirus genus. Both phages are tailed and contain dsDNA. The genome of PaCCP1 is 43,176 bp in length with a GC content of 54.4%, encoding 59 ORFs, one of them being a tRNA gene. The genome of PaCCP2 is 66,333 bp in length with a GC content of 55.6%, encoding 102 non-tRNA ORFs. PaCCP1 is capable of infecting five strains of P. aeruginosa, whereas phage PaCCP2 is capable of infecting three strains of P. aeruginosa. Both phages do not contain bacterial virulence or AMR genes and contain three and six putative Anti-CRISPR proteins. Conclusions: Phages PaCCP1 and PaCCP2 show promise as effective treatments for MDR P. aeruginosa strains, offering a potential strategy for controlling this clinically important pathogen through phage therapy. Full article

Antibiotics resistance is expanding amongst pathogenic bacteria. Phage therapy is a revived concept for targeting bacteria with multiple antibiotics resistances. In the present study, we isolated and characterized a novel phage from hospital treatment plant input, using Escherichia coli (E. coli) as host bacterium. Phage lytic activity was detected by using soft agar assay. Whole-genome sequencing of the phage was performed by using Next-Generation Sequencing (NGS). Host range was determined using other species of bacteria and representative genogroups of E. coli. Whole-genome sequencing of the phage revealed that Escherichia phage Ioannina is a novel phage within the Dhillonvirus genus, but significantly diverged from other Dhillonviruses. Its genome is a 45,270 bp linear double-stranded DNA molecule that encodes 61 coding sequences (CDSs). The coding sequence of CDS28, a putative tail fiber protein, presented higher similarity to representatives of other phage families, signifying a possible recombination event. Escherichia phage Ioannina lytic activity was broad amongst the E. coli genogroups of clinical and environmental origin with multiple resistances. This phage may present in the future an important therapeutic tool against bacterial strains with multiple antibiotic resistances. Full article

Bacterial spot is a serious disease caused by several species of Xanthomonas affecting pepper and tomato production worldwide. Since the strategies employed for disease management have been inefficient and pose a threat for environmental and human health, the development of alternative methods is gaining relevance. The aim of this study is to isolate and characterize lytic phages against Xanthomonas pathogens. Here, we isolate two jumbo phages, named XaC1 and XbC2, from water obtained from agricultural irrigation channels by the enrichment technique using X. vesicatoria as a host. We determined that both phages were specific for inducing the lysis of X. vesicatoria strains, but not of other xanthomonads. The XaC1 and XbC2 phages showed a myovirus morphology and were classified as jumbo phages due to their genomes being larger than 200 kb. Phylogenetic and comparative analysis suggests that XaC1 and XbC2 represent both different and novel genera of phages, where XaC1 possesses a low similarity to other phage genomes reported before. Finally, XaC1 and XbC2 exhibited thermal stability up to 45 °C and pH stability from 5 to 9. All these results indicate that the isolated phages are promising candidates for the development of formulations against bacterial spot, although further characterization is required. Full article

Spiroplasma virus 4 (SpV4) is a bacteriophage of the Microviridae, which packages circular ssDNA within non-enveloped T = 1 icosahedral capsids. It infects spiroplasmas, which are known pathogens of honeybees. Here, the structure of the SpV4 virion is determined using cryo-electron microscopy to a resolution of 2.5 Å. A striking feature of the SpV4 capsid is the mushroom-like protrusions at the 3-fold axes, which is common among all members of the subfamily Gokushovirinae. While the function of the protrusion is currently unknown, this feature varies widely in this subfamily and is therefore possibly an adaptation for host recognition. Furthermore, on the interior of the SpV4 capsid, the location of DNA-binding protein VP8 was identified and shown to have low structural conservation to the capsids of other viruses in the family. The structural characterization of SpV4 will aid future studies analyzing the virus–host interaction, to understand disease mechanisms at a molecular level. Furthermore, the structural comparisons in this study, including a low-resolution structure of the chlamydia phage 2, provide an overview of the structural repertoire of the viruses in this family that infect various bacterial hosts, which in turn infect a wide range of animals and plants. Full article

The emergence of multidrug-resistant bacteria is undoubtedly one of the most serious global health threats. One response to this threat that has been gaining momentum over the past decade is ‘phage therapy’. According to this, lytic bacteriophages are used for the treatment of bacterial infections, either alone or in combination with antimicrobial agents. However, to ensure the efficacy and broad applicability of phage therapy, several challenges must be overcome. These challenges encompass the development of methods and strategies for the host range manipulation and bypass of the resistance mechanisms developed by pathogenic bacteria, as has been the case since the advent of antibiotics. As our knowledge and understanding of the interactions between phages and their hosts evolves, the key issue is to define the host range for each application. In this article, we discuss the factors that affect host range and how this determines the classification of phages into different categories of action. For each host range group, recent representative examples are provided, together with suggestions on how the different groups can be used to combat certain types of bacterial infections. The available methodologies for host range expansion, either through sequential adaptation to a new pathogen or through genetic engineering techniques, are also reviewed. Full article