Use Of Phage Therapy Research Articles

Rapid Bacteriophage Quantification by Digital Biosensing on a SlipChip Microfluidic Device.

The rise of antimicrobial resistance (AMR) is a major global public health concern, and it is urgent to develop new antimicrobial drugs and alternative therapies. There has been growing interest in the use of phage therapy as an alternative to treat AMR, and it has shown promising results in early studies and clinical trials. Phage quantification is a crucial step in the development and application of phage therapy. The traditional double-layer plaque assay requires cumbersome manual operations and typically takes up to 18 h to yield a rough phage estimation. Spectrophotometry, flow cytometry, and PCR-based methods cannot distinguish between infectious and noninfectious phages. Here, we developed a digital biosensing method for rapid bacteriophage quantification on a digital phage SlipChip (dp-SlipChip) microfluidic device containing 2304 microdroplets in 3 nL. By compartmentalizing the phages and bacteria in nanoliter droplets and analyzing the growth profile of bacteria at 3 h, the number of infectious phages can be precisely quantified. The results from the dp-SlipChip were consistent with the traditional double-layer plaque assay method and exhibited higher consistency and repeatability. The dp-SlipChip does not require a complex fluidic handling instrument to generate and manipulate droplets. This SlipChip-based digital biosensing method not only provides a promising tool for rapid phage quantification, which is important for the use of phages in clinical practice to treat antimicrobial-resistant bacteria, but can also be used as an ultrasensitive, high-specificity method to detect bacteria. Furthermore, this approach can be applied to other digital biology studies that require analysis at the single-object level.

Advancement of Phage Therapy Approaches in The Battle of Multi-Drug Resistance: A Review

One of the most significant issues faced by humanity today is antibiotic resistance. Drugs are used in such vast amounts for human health, aquatic life, and agricultural animals that harmful bacteria have developed antibiotic resistance to various antibiotics. Further, the usage of antibiotics is increasing because of situations such as increased infections and chronic diseases that need antimicrobial treatment. Since antimicrobial resistance is rising, it is necessary to take action to help reduce and eliminate infectious diseases and ensure animal and human health. Because of this, many attempts are being made to tackle multi-drugresistant bacteria. Among the many advanced techniques that are occurring, the use of phage therapy is one such emerging procedure. The main aim of this prospective review is to identify the various new phage formulations available as a potential therapeutic intervention to combat multidrug resistance among bacteria and the objective is to identify the various reasons associated with the induction of the phenomenon of "multidrug resistance" among different bacteria, focusing on the use of phage therapy, its advantages as well as disadvantages over antibiotics as a possible therapeutic intervention. Various phage formulations, such as phage cocktails with antibiotics, nanoparticles, phage-delivering hydrogels, and many more, are emerging formulations that have successful results in fighting against multi-drug-resistant bacteria. Commercial phage solutions have helped combat antimicrobial resistance in poultry and livestock farms, improving everyone's health worldwide. As a result, this study shall serve as a source of information and understanding of the concerns mentioned above for the entirety of society and every human community.

Phage Therapy in Germany-Update 2023.

Bacteriophage therapy holds promise in addressing the antibiotic-resistance crisis, globally and in Germany. Here, we provide an overview of the current situation (2023) of applied phage therapy and supporting research in Germany. The authors, an interdisciplinary group working on patient-focused bacteriophage research, addressed phage production, phage banks, susceptibility testing, clinical application, ongoing translational research, the regulatory situation, and the network structure in Germany. They identified critical shortcomings including the lack of clinical trials, a paucity of appropriate regulation and a shortage of phages for clinical use. Phage therapy is currently being applied to a limited number of patients as individual treatment trials. There is presently only one site in Germany for large-scale good-manufacturing-practice (GMP) phage production, and one clinic carrying out permission-free production of medicinal products. Several phage banks exist, but due to varying institutional policies, exchange among them is limited. The number of phage research projects has remarkably increased in recent years, some of which are part of structured networks. There is a demand for the expansion of production capacities with defined quality standards, a structured registry of all treated patients and clear therapeutic guidelines. Furthermore, the medical field is still poorly informed about phage therapy. The current status of non-approval, however, may also be regarded as advantageous, as insufficiently restricted use of phage therapy without adequate scientific evidence for effectiveness and safety must be prevented. In close coordination with the regulatory authorities, it seems sensible to first allow some centers to treat patients following the Belgian model. There is an urgent need for targeted networking and funding, particularly of translational research, to help advance the clinical application of phages.

Aspects of Phage-Based Vaccines for Protein and Epitope Immunization.

Because vaccine development is a difficult process, this study reviews aspects of phages as vaccine delivery vehicles through a literature search. The results demonstrated that because phages have adjuvant properties and are safe for humans and animals, they are an excellent vaccine tool for protein and epitope immunization. The phage genome can easily be manipulated to display antigens or create DNA vaccines. Additionally, they are easy to produce on a large scale, which lowers their manufacturing costs. They are stable under various conditions, which can facilitate their transport and storage. However, no medicine regulatory agency has yet authorized phage-based vaccines despite the considerable preclinical data confirming their benefits. The skeptical perspective of phages should be overcome because humans encounter bacteriophages in their environment all the time without suffering adverse effects. The lack of clinical trials, endotoxin contamination, phage composition, and long-term negative effects are some obstacles preventing the development of phage vaccines. However, their prospects should be promising because phages are safe in clinical trials; they have been authorized as a food additive to avoid food contamination and approved for emergency use in phage therapy against difficult-to-treat antibiotic-resistant bacteria. Therefore, this encourages the use of phages in vaccines.

Assessment of clinical data and the species composition of pathogens in the upper respiratory tract of patients with COVID-19 AND Determination of sensitivity to essential etiotropic drugs

Objective. To comparatively analyze the clinical and microbiological data of outpatients with COVID-19 who took a bacteriophage-based drug and who did not. Subjects and methods. The investigation involved 42 outpatients with COVID-19 who were divided into two groups: a study group of 30 patients who received standard therapy for COVID-19, as well as an oral bacteriophage-based drug (15 ml thrice a day for 10 days); a control group of 12 patients who had only the standard COVID-19 therapy. After 10 days of therapy, the clinical manifestations of the disease were comparatively evaluated in the examined groups. A repeated study of the material for bacterial microflora to assess the eradication of the pathogenic microflora in the respiratory tract was conducted on day 21 after the start of therapy. Results. Klebsiella pneumoniae (77%), Staphylococcus aureus (17%), and streptococci (Streptococcus agalactiae and Streptococcus pyogenes) (6%) were identified in the structure of bacterial pathogens in patients with COVID-19. Microbiological monitoring revealed multidrug-resistant K. pneumoniae in 50% of the patients; that sensitive to antibiotics in 26.7% of cases and that sensitive to a bacteriophage in 100%. The investigation results showed that the use of a polyvalent K. pneumoniae bacteriophage in patients with COVID-19 to prevent bacterial complications contributed to a significant (p < 0.001) elimination of K. pneumoniae. The pathogen isolation rate in the study group decreased significantly (p < 0.001). Thus, the use of phage therapy in combination with etiotropic therapy can be recommended to prevent bacterial complications in patients with COVID-19.

Isolation and identification of specific lytic bacteriophages as a biocontrol agent against Serratia odorifera PBA-IAUF-1 and Kluyvera intermedia PBA-IAUF-6 causing bacterial canker in the grape and Siberian pear.

Bacterial canker, a prevalent disease among fruit trees, is a significant concern. The use of phage therapy is presently seen as a dependable biological strategy to control bacterial diseases in fruits. The objective of this research was to use various biochemical and molecular techniques to determine the types of bacteria responsible for causing cankers in various fruits. Additionally, their ability to cause disease in the fruit tissues was assessed, the specific bacteriophages targeting these bacteria were isolated and identified. The bacteria were separated from different parts of the infected fruits like grapes and Siberian pears. The selection of fruit tissues showing signs of canker disease was performed, and the validation of the isolates' pathogenicity was confirmed following Koch's principles. Subsequently, in order to establish a conclusive identification of the bacterial species, molecular identification was conducted through the sequencing of a specific fragment within the 16S rRNA following amplification by PCR by using universal primers, RW01 and DG74. Isolation and titration of phages specific to fruit spoilage bacteria was done by spot and double-layer agar method, and the growth curve of the isolated bacteriophage was drawn. The phages were detected by transmission electron microscopy (TEM). The results of the study proved the presence of canker causing agents, Kluyvera intermedia PBA-IAUF-6 with the code Sh6 in the Siberian pears, and Serratia odorifera PBA-IAUF-1 with the code Rz3 in the grape fruits, which were deposited in GenBank with the accession numbers of KU878579 and KU168605, respectively. Isolation of the specific bacteriophages to the S. odorifera PBA-IAUF-1 and K. intermedia PBA-IAUF-6 bacterial strains were done from the effluent of South Isfahan wastewater treatment plant and Caspian Sea water, respectively. The titer of the specific phage to S. odorifera PBA-IAUF-1 and K. intermedia PBA-IAUF-6 was detected in the samples as 2.2×10-5 and 5×10-11 PFU/ml, respectively. An electron micrograph of a bacteriophage that targets two different bacterial strains revealed phages with a geometrically shaped head and a flexible tail, which resembled viruses from the Siphoviridae family.

Biological Properties of 12 Newly Isolated Acinetobacter baumannii-Specific Bacteriophages.

Infections with the opportunistic Gram-negative bacterium Acinetobacter baumannii pose a serious threat today, which is aggravated by the growing problem of multi-drug resistance among bacteria, caused by the overuse of antibiotics. Treatment of infections caused by antibiotic-resistant A. baumannii strains with the use of phage therapy is not only a promising alternative, but sometimes the only option. Therefore, phages specific for clinical multi-drug resistant A. baumannii were searched for in environmental, municipal, and hospital wastewater samples collected from different locations in Poland. The conducted research allowed us to determine the biological properties and morphology of the tested phages. As a result of our research, 12 phages specific for A. baumannii, 11 of which turned out to be temperate and only one lytic, were isolated. Their lytic spectra ranged from 11 to 75%. The plaques formed by most phages were small and transparent, while one of them formed relatively large plaques with a clearly marked 'halo' effect. Based on Transmission Electron Microscopy (TEM), most of our phages have been classified as siphoviruses (only one phage was classified as a podovirus). All phages have icosahedral capsid symmetry, and 11 of them have a long tail. Optimal multiplicity of infections (MOIs) and the adsorption rate were also determined. MOI values varied depending on the phage-from 0.001 to 10. Based on similarities to known bacteriophages, our A. baumannii-specific phages have been proposed to belong to the Beijerinckvirinae and Junivirinae subfamilies. This study provides an additional tool in the fight against this important pathogen and may boost the interest in phage therapy as an alternative and supplement to the current antibiotics.

Role of adherent invasive Escherichia coli in pathogenesis of inflammatory bowel disease.

Gut microbiota imbalances play an important role in inflammatory bowel disease (IBD), but no single pathogenic microorganism critical to IBD that is specific to the IBD terminal ileum mucosa or can invade intestinal epithelial cells has been found. Invasive Escherichia coli (E. coli) adhesion to macrophages is considered to be closely related to the pathogenesis of inflammatory bowel disease. Further study of the specific biological characteristics of adherent invasive E. coli (AIEC) may contribute to a further understanding of IBD pathogenesis. This review explores the relationship between AIEC and the intestinal immune system, discusses the prevalence and relevance of AIEC in Crohn's disease and ulcerative colitis patients, and describes the relationship between AIEC and the disease site, activity, and postoperative recurrence. Finally, we highlight potential therapeutic strategies to attenuate AIEC colonization in the intestinal mucosa, including the use of phage therapy, antibiotics, and anti-adhesion molecules. These strategies may open up new avenues for the prevention and treatment of IBD in the future.

Bacteriophage-antibiotic combination therapy against extensively drug-resistant Pseudomonas aeruginosa infection to allow liver transplantation in a toddler

Post-operative bacterial infections are a leading cause of mortality and morbidity after ongoing liver transplantation. Bacteria causing these infections in the hospital setting can exhibit high degrees of resistance to multiple types of antibiotics, which leads to major therapeutic hurdles. Alternate ways of treating these antibiotic-resistant infections are thus urgently needed. Phage therapy is one of them and consists in using selected bacteriophage viruses – viruses who specifically prey on bacteria, naturally found in various environmental samples – as bactericidal agents in replacement or in combination with antibiotics. The use of phage therapy raises various research questions to further characterize what determines therapeutic success or failure. In this work, we report the story of a toddler who suffered from extensively drug-resistant Pseudomonas aeruginosa sepsis after liver transplantation. He was treated by a bacteriophage-antibiotic intravenous combination therapy for 86 days. This salvage therapy was well tolerated, without antibody-mediated phage neutralization. It was associated with objective clinical and microbiological improvement, eventually allowing for liver retransplantation and complete resolution of all infections. Clear in vitro phage-antibiotic synergies were observed. The occurrence of bacterial phage resistance did not result in therapeutic failure, possibly due to phage-induced virulence tradeoffs, which we investigated in different experimental models.

RB49-like Bacteriophages Recognize O Antigens as One of the Alternative Primary Receptors.

The power of most of the enterobacterial O antigen types to provide robust protection against direct recognition of the cell surface by bacteriophage receptor-recognition proteins (RBP) has been recently recognized. The bacteriophages infecting O antigen producing strains of E. coli employ various strategies to tackle this nonspecific protection. T-even related phages, including RB49-like viruses, often have wide host ranges, being considered good candidates for use in phage therapy. However, the mechanisms by which these phages overcome the O antigen barrier remain unknown. We demonstrate here that RB49 and related phages Cognac49 and Whisky49 directly use certain types of O antigen as their primary receptors recognized by the virus long tail fibers (LTF) RBP gp38, so the O antigen becomes an attractant instead of an obstacle. Simultaneously to recognize multiple O antigen types, LTFs of each of these phages can bind to additional receptors, such as OmpA protein, enabling them to infect some rough strains of E. coli. We speculate that the mechanical force of the deployment of the short tail fibers (STF) triggered by the LTF binding to the O antigen or underneath of it, allows the receptor binding domains of STF to break through the O polysaccharide layer.

Current knowledge in the use of bacteriophages to combat infections caused by Pseudomonas aeruginosa in cystic fibrosis.

Pseudomonas aeruginosa (PA) is considered the first causal agent of morbidity and mortality in people with cystic fibrosis (CF) disease. Multi-resistant strains have emerged due to prolonged treatment with specific antibiotics, so new alternatives have been sought for their control. In this context, there is a renewed interest in therapies based on bacteriophages (phages) supported by several studies suggesting that therapy based on lytic phages and biofilm degraders may be promising for the treatment of lung infections in CF patients. However, there is little clinical data about phage studies in CF and the effectiveness and safety in patients with this disease has not been clear. Therefore, studies regarding on phage characterization, selection, and evaluation in vitro and in vivo models will provide reliable information for designing effective cocktails, either using mixed phages or in combination with antibiotics, making a great progress in clinical research. Hence, this review focuses on the most relevant and recent findings on the activity of lytic phages against PA strains isolated from CF patients and hospital environments, and discusses perspectives on the use of phage therapy on the treatment of PA in CF patients.

Biological aspects of phage therapy versus antibiotics against Salmonella enterica serovar Typhimurium infection of chickens.

Phage therapy is a promising alternative treatment of bacterial infections in human and animals. Nevertheless, despite the appearance of many bacterial strains resistant to antibiotics, these drugs still remain important therapeutics used in human and veterinary medicine. Although experimental phage therapy of infections caused by Salmonella enterica was described previously by many groups, those studies focused solely on effects caused by bacteriophages. Here, we compared the use of phage therapy (employing a cocktail composed of two previously isolated and characterized bacteriophages, vB_SenM-2 and vB_Sen-TO17) and antibiotics (enrofloxacin and colistin) in chickens infected experimentally with S. enterica serovar Typhimurium. We found that the efficacies of both types of therapies (i.e. the use of antibiotics and phage cocktail) were high and very similar to one another when the treatment was applied shortly (one day) after the infection. Under these conditions, S. Typhimurium was quickly eliminated from the gastrointestinal tract (GIT), to the amount not detectable by the used methods. However, later treatment (2 or 4 days after detection of S. Typhimurium in chicken feces) with the phage cocktail was significantly less effective. Bacteriophages remained in the GIT for up to 2-3 weeks, and then were absent in feces and cloaca swabs. Interestingly, both phages could be found in various organs of chickens though with a relatively low abundance. No development of resistance of S. Typhimurium to phages or antibiotics was detected during the experiment. Importantly, although antibiotics significantly changed the GIT microbiome of chickens in a long-term manner, analogous changes caused by phages were transient, and the microbiome normalized a few weeks after the treatment. In conclusion, phage therapy against S. Typhimurium infection in chickens appeared as effective as antibiotic therapy (with either enrofloxacin or colistin), and less invasive than the use the antibiotics as fewer changes in the microbiome were observed.

The Isolation and Characterization of a Broad Host Range Bcep22-like Podovirus JC1.

Bacteriophage JC1 is a Podoviridae phage with a C1 morphotype, isolated on host strain Burkholderia cenocepacia Van1. Phage JC1 is capable of infecting an expansive range of Burkholderia cepacia complex (Bcc) species. The JC1 genome exhibits significant similarity and synteny to Bcep22-like phages and to many Ralstonia phages. The genome of JC1 was determined to be 61,182 bp in length with a 65.4% G + C content and is predicted to encode 76 proteins and 1 tRNA gene. Unlike the other Lessieviruses, JC1 encodes a putative helicase gene in its replication module, and it is in a unique organization not found in previously analyzed phages. The JC1 genome also harbours 3 interesting moron genes, that encode a carbon storage regulator (CsrA), an N-acetyltransferase, and a phosphoadenosine phosphosulfate (PAPS) reductase. JC1 can stably lysogenize its host Van1 and integrates into the 5′ end of the gene rimO. This is the first account of stable integration identified for Bcep22-like phages. JC1 has a higher global virulence index at 37 °C than at 30 °C (0.8 and 0.21, respectively); however, infection efficiency and lysogen stability are not affected by a change in temperature, and no observable temperature-sensitive switch between lytic and lysogenic lifestyle appears to exist. Although JC1 can stably lysogenize its host, it possesses some desirable characteristics for use in phage therapy. Phage JC1 has a broad host range and requires the inner core of the bacterial LPS for infection. Bacteria that mutate to evade infection by JC1 may develop a fitness disadvantage as seen in previously characterized LPS mutants lacking inner core.

Prevalence of genetically similar Flavobacterium columnare phages across aquaculture environments reveals a strong potential for pathogen control.

SummaryIntensive aquaculture conditions expose fish to bacterial infections, leading to significant financial losses, extensive antibiotic use and risk of antibiotic resistance in target bacteria. Flavobacterium columnare causes columnaris disease in aquaculture worldwide. To develop a bacteriophage‐based control of columnaris disease, we isolated and characterized 126 F. columnare strains and 63 phages against F. columnare from Finland and Sweden in 2017. Bacterial isolates were virulent on rainbow trout (Oncorhynchus mykiss) and fell into four previously described genetic groups A, C, E and G, with genetic groups C and E being the most virulent. Phage host range studied against a collection of 227 bacterial isolates (from 2013 to 2017) demonstrated modular infection patterns based on host genetic group. Phages infected contemporary and previously isolated bacterial hosts, but bacteria isolated most recently were generally resistant to previously isolated phages. Despite large differences in geographical origin, isolation year or host range of the phages, whole‐genome sequencing of 56 phages showed high level of genetic similarity to previously isolated F. columnare phages (Ficleduovirus, Myoviridae). Altogether, this phage collection demonstrates a potential for use in phage therapy.

Phage Revolution Against Multidrug-Resistant Clinical Pathogens in Southeast Asia.

Southeast Asia (SEA) can be considered a hotspot of antimicrobial resistance (AMR) worldwide. As recent surveillance efforts in the region reported the emergence of multidrug-resistant (MDR) pathogens, the pursuit of therapeutic alternatives against AMR becomes a matter of utmost importance. Phage therapy, or the use of bacterial viruses called bacteriophages to kill bacterial pathogens, is among the standout therapeutic prospects. This narrative review highlights the current understanding of phages and strategies for a phage revolution in SEA. We define phage revolution as the radical use of phage therapy in infectious disease treatment against MDR infections, considering the scientific and regulatory standpoints of the region. We present a three-phase strategy to encourage a phage revolution in the SEA clinical setting, which involves: (1) enhancing phage discovery and characterization efforts, (2) creating and implementing laboratory protocols and clinical guidelines for the evaluation of phage activity, and (3) adapting regulatory standards for therapeutic phage formulations. We hope that this review will open avenues for scientific and policy-based discussions on phage therapy in SEA and eventually lead the way to its fullest potential in countering the threat of MDR pathogens in the region and worldwide.

Considerations for the Use of Phage Therapy in Clinical Practice

ABSTRACTIncreasing antimicrobial resistance and medical device-related infections have led to a renewed interest in phage therapy as an alternative or adjunct to conventional antimicrobials. Expanded access and compassionate use cases have risen exponentially but have varied widely in approach, methodology, and clinical situations in which phage therapy might be considered. Large gaps in knowledge contribute to heterogeneity in approach and lack of consensus in many important clinical areas. The Antibacterial Resistance Leadership Group (ARLG) has convened a panel of experts in phage therapy, clinical microbiology, infectious diseases, and pharmacology, who worked with regulatory experts and a funding agency to identify questions based on a clinical framework and divided them into three themes: potential clinical situations in which phage therapy might be considered, laboratory testing, and pharmacokinetic considerations. Suggestions are provided as answers to a series of questions intended to inform clinicians considering experimental phage therapy for patients in their clinical practices.

Safety and Efficacy Assessment of Bacteriophages Isolated from Kibera, Kenya Wastewater Plant, against Multidrug-Resistant<i> Pseudomonas aeruginosa</i> Infection in BALB/c Mice

Pseudomonas aeruginosa is a pathogen of great clinical importance to both humans and animals. It causes pneumonia in cystic fibrosis patients, and it is responsible for the infections of blood and lungs during surgery. Increased antibiotic use has led to the emergence of multidrug-resistant strains of P. aeruginosa. Recently, phage therapy has attracted much attention as a promising alternative against the increasing antimicrobial resistance. This study determined the safety and efficacy of phage therapy against virulent P. aeruginosa in a murine model. Phage PaCIKb2 was isolated from sewage water. Morphological characterization by transmission electron microscope was done. We assessed the phages' antimicrobial effect in vitro and in biofilms, its growth kinetics, host ranges, temperature and pH stability. Therapeutic safety and efficacy were observed 24 hours post-infection with virulent P. aeruginosa in a murine model. Transmission Electron Microscopy revealed phage PaCIKb2 to belong to the family myoviridae. The phage was found to be high temperature tolerant (up to 50°C). It was active between pH ranges (5 and 11), had a latent period of 15 minutes with a burst size of 316 viral particles, and exhibited a narrow host range. After intravenous phage administration dose (2×109 PFU/ml) post-infection with virulent P. aeruginosa, the presence of phages in vivo and reduction of bacterial loads in mice was observed. A reduction in mice tissue inflammation suggested the effectiveness of phage PaCIKb2 phage therapy. This research gives data that supports the use of phage therapy against multidrug-resistant P. aeruginosa.

Phage therapeutics: from promises to practices and prospectives.

The rise in multi-drug resistant bacteria and the inability to develop novel antibacterial agents limits our arsenal against infectious diseases. Antibiotic resistance is a global issue requiring an immediate solution, including the development of new antibiotic molecules and other alternative modes of therapy. This article highlights the mechanism of bacteriophage treatment that makes it a real solution for multidrug-resistant infectious diseases. Several case reports identified phage therapy as a potential solution to the emerging challenge of multi-drug resistance. Bacteriophages, unlike antibiotics, have special features, such as host specificity and do not impact other commensals. A new outlook has also arisen with recent advancements in the understanding of phage immunobiology, where phages are repurposed against both bacterial and viral infections. Thus, the potential possibility of phages in COVID-19 patients with secondary bacterial infections has been briefly elucidated. However, significant obstacles that need to be addressed are to design better clinical studies that may contribute to the widespread use of bacteriophage therapy against multi-drug resistant pathogens. In conclusion, antibacterial agents can be used with bacteriophages, i.e. bacteriophage-antibiotic combination therapy, or they can be administered alone in cases when antibiotics are ineffective. Key points • AMR, a consequence of antibiotic generated menace globally, has led to the resurgence of phage therapy as an effective and sustainable solution without any side effects and high specificity against refractory MDR bacterial infections. • Bacteriophages have fewer adverse reactions and can thus be used as monotherapy as well as in conjunction with antibiotics. • In the context of the COVID-19 pandemic, phage therapy may be a viable option. Graphical abstract

VB-ApyS-JF1, the First Trueperella pyogenes Phage, Shows Potential as an Alternative Treatment Strategy for Trueperella pyogenes Infections.

Trueperella pyogenes (T. pyogenes) is an important opportunistic animal pathogen that causes huge economic losses to the animal husbandry industry. The emergence of bacterial resistance and the unsatisfactory effect of the vaccine have prompted investigators to explore alternative strategies for controlling T. pyogenes infection. Due to the ability of phages to kill multidrug-resistant bacteria, the use of phage therapy to combat multidrug-resistant bacterial infections has attracted attention. In this study, a T. pyogenes phage, vB-ApyS-JF1 (JF1), was isolated from sewage samples, and its whole genome and biological characteristics were elucidated. Moreover, the protective effect of phage JF1 on a mouse bacteremic model caused by T. pyogenes was studied. JF1 harbors a double-stranded DNA genome with a length of 90,130 bp (30.57% G + C). The genome of JF1 lacked bacterial virulence–, antibiotic resistance– and lysogenesis-related genes. Moreover, the genome sequence of JF1 exhibited low coverage (<6%) with all published phages in the NCBI database, and a phylogenetic analysis of the terminase large subunits and capsid indicated that JF1 was evolutionarily distinct from known phages. In addition, JF1 was stable over a wide range of pH values (3 to 11) and temperatures (4 to 50°C) and exhibited strong lytic activity against T. pyogenes in vitro. In murine experiments, a single intraperitoneal administration of JF1 30 min post-inoculation provided 100% protection for mice against T. pyogenes infection. Compared to the phosphate-buffered saline (PBS) treatment group, JF1 significantly (P < 0.01) reduced the bacterial load in the blood and tissues of infected mice. Meanwhile, treatment with phage JF1 relieved the pathological symptoms observed in each tissue. Furthermore, the levels of the inflammatory cytokines tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-6 (IL-6) in the blood of infected mice were significantly (P < 0.01) decreased in the phage-treated group. Taken together, these results indicate that phage JF1 demonstrated great potential as an alternative therapeutic treatment against T. pyogenes infection.

Efficacy of Salmonella Bacteriophage S1 Delivered and Released by Alginate Beads in a Chicken Model of Infection.

Modern bacteriophage encapsulation methods based on polymers such as alginate have been developed recently for their use in phage therapy for veterinary purposes. In birds, it has been proven that using this delivery system allows the release of the bacteriophage in the small intestine, the site of infection by Salmonella spp. This work designed an approach for phage therapy using encapsulation by ionotropic gelation of the lytic bacteriophage S1 for Salmonella enterica in 2% w/v alginate beads using 2% w/v calcium chloride as crosslinking agent. This formulation resulted in beads with an average size of 3.73 ± 0.04 mm and an encapsulation efficiency of 70%. In vitro, the beads protected the bacteriophages from pH 3 and released them at higher pH. To confirm that this would protect the bacteriophages from gastrointestinal pH changes, we tested the phage infectivity in vivo assay. Using a model chicken (Gallus gallus domesticus) infected with Salmonella Enteritidis, we confirmed that after 3 h of the beads delivery, infective phages were present in the chicken’s duodenal and caecal sections. This study demonstrates that our phage formulation is an effective system for release and delivery of bacteriophage S1 against Salmonella Enteritidis with potential use in the poultry sector.