Phage-specific immunity impairs efficacy of bacteriophage targeting Vancomycin Resistant Enterococcus in a murine model

A solution to the postantibiotic era: phages as precision medicine

Antibiotic-resistant bacterial infections pose a significant global health challenge. Phage therapy provides a promising alternative to antibiotics that enables the specific targeting of pathogenic bacteria while preserving the healthy microbiome. Recent advances in genetic engineering, synthetic biology, and artificial intelligence have rekindled interest in phage therapy, as they move phages into the realm of precision medicine. Engineered phages can be customized to have a broader host range, encode counter-defenses that overcome bacterial immune systems, or express other proteins that modulate the bacterial host to their advantage. Innovations in artificial intelligence and machine learning promise to speed up the identification of optimal phage candidates and create tailored cocktails for individualized therapies - advances that will transform phage therapy and provide a solution to the antibiotic resistance crisis.

Limitation of the Lytic Effect of Bacteriophages on Salmonella and Other Enteric Bacterial Pathogens and Approaches to Overcome

Bacteriophages (phages) have emerged as promising agents for combating bacterial pathogens, including nontyphoidal Salmonella enterica (S. enterica), the most common foodborne pathogen worldwide. The emergence of antimicrobial-resistant (AMR) S. enterica poses a severe healthcare issue. Nowadays, many countries worldwide have banned antibiotics for animal feeds or additives, and various strategies have been developed and gained popularity for their potential to address S. enterica infection. Among these strategies, phage therapy shows more promise because of its ability to specifically target bacterial pathogens without disrupting the beneficial microbiota or animal/human cells. Phages are viruses that rupture host cells through the lysis of phage-encoded endolysin proteins. Nonetheless, phages also face various challenges, including phage resistance, gene transduction, serovar diversity, and the immune response of animal/human organisms, which limit the efficacy of S. enterica. Due to this limitation of phages, endolysin, as a lytic protein for bacterial cells derived from phages, has been demonstrated as another promising solution against various bacterial pathogens, including AMR. This review is aimed at discussing the benefits and limitations of phage therapies and exploring the promising potential of phage-encoded endolysins in controlling S. enterica.

Phage Therapy for Urinary Tract Infections: Progress and Challenges Ahead

INTRODUCTION AND HYPOTHESIS

Urinary tract infection (UTI) treatment is a growing public health concern owing to increasing antimicrobial resistance. Phage therapy, an alternative or adjunctive treatment to antibiotics, has the potential to address this challenge. However, clinical use of phage therapy is hindered by knowledge gaps and inconsistent reporting. The objective was to review the current state of phage therapy for UTIs and highlight research priorities that can optimize phage clinical efficacy.

METHODS

Current literature on UTI phage therapy was examined, focusing on the lack of standardized phage susceptibility testing, phage characterization, and microbiological assessments during and after treatment.

RESULTS

Critical areas requiring further investigation include appropriate phage dosing, optimal routes of administration, and the dynamics of phage-host and phage-patient interactions. The influence of the urinary microbiome, including endogenous phages, on treatment outcomes also needs to be better understood. Suggested data collection and reporting standards should be developed and implemented to improve clinical impact of studies examining phage therapy for UTI. Randomized clinical trials are needed to establish efficacy and determine the best practices for clinical use.

CONCLUSION

Phage therapy is a promising alternative to antibiotics for managing UTIs, especially in the face of rising antimicrobial resistance. To fully realize its potential, however, future research must focus on standardized protocols, dosing strategies, and the role of the urinary microbiome, with an emphasis on rigorously conducted clinical trials. These steps are essential for integrating phage therapy into mainstream UTI treatment regimens.

Advances in Engineered Phages for Disease Treatment

Phage therapy presents a promising solution for combating multidrug-resistant (MDR) bacterial infections and other bacteria-related diseases, attributed to their innate ability to target and lyse bacteria. Recent clinical successes, particularly in treating MDR-related respiratory and post-surgical infections, validated the therapeutic potential of phage therapy. However, the complex microenvironment within the human body poses significant challenges to phage activity and efficacy in vivo. To overcome these barriers, recent advances in phage engineering have aimed to enhance targeting accuracy, improve stability and survivability, and explore synergistic combinations with other therapeutic modalities. This review provides a comprehensive overview of phage therapy, emphasizing the application of engineered phages in antibacterial therapy, tumor therapy, and vaccine development. Furthermore, the review highlights the current challenges and future trends for advancing phage therapy toward broader clinical applications.

Effectiveness of newly isolated bacteriophages targeting multidrug-resistant Extraintestinal Pathogenic Escherichia coli strain (TZ1_3) in food preservation and mice health modulation

Bacteriophages are promising alternatives for combating multidrug-resistant bacterial infections. Two lytic bacteriophages, named P1 and P3, targeting pathogenic Escherichia coli (ExPEC; strain TZ1_3) were isolated and evaluated for their potential ability to control pathogenic numbers either in ExPEC-contaminated food or ExPEC-infected mice. Results showed that phages significantly reduced ExPEC numbers within 6 and 12 h in contaminated water, milk, beef, and chicken when applied at 106 plaque-forming units (PFU). Notably, phage therapy administered via intraperitoneal injection (1012 PFU) effectively reduced ExPEC numbers in the heart, liver, spleen and kidney, restored α-diversity of gut microbes, and increased levels of acetic (13.98 %-37.58 %) and valeric acid (10.27 %-31.51 %) in ExPEC-infected mice. Additionally, phage injections caused no detrimental effects on body weight (which increased by 6.49 %-8.11 %), and on gut microbes in healthy mice. Overall, this study highlights the potential of phages in controlling foodborne microorganisms.

Overcoming Pseudomonas aeruginosa in Chronic Suppurative Lung Disease: Prevalence, Treatment Challenges, and the Promise of Bacteriophage Therapy

Pseudomonas aeruginosa, a multidrug-resistant pathogen, significantly impacts patients with chronic respiratory conditions like cystic fibrosis (CF) and non-CF chronic suppurative lung disease (CSLD), contributing to progressive lung damage and poor clinical outcomes. This bacterium thrives in the airway environments of individuals with impaired mucociliary clearance, leading to persistent infections and increased morbidity and mortality. Despite advancements in management of these conditions, treatment failure remains common, emphasising the need for alternative or adjunctive treatment strategies. Bacteriophage therapy, an emerging approach utilising viruses that specifically target bacteria, offers a potential solution to combat P. aeruginosa infections resistant to conventional antibiotics. This review examines the prevalence and disease burden of P. aeruginosa in CF and CSLD, explores the mechanisms behind antibiotic resistance, the promising role of bacteriophage therapy and clinical trials in this sphere.

The future of phage therapy in the USA

Fueled by the increasing abundance of antibiotic-resistant pathogens, there has been a resurrection in the use of bacterial viruses (bacteriophages or 'phage') for therapeutic applications. Phage therapy was used in the early 20th century to limited success, which we attribute to its haphazard employment. To avoid repeating the mistakes of the past, this Opinion first evaluates the historical reasons for the failure of phage therapy, analyzes the current state of the field, and ultimately makes recommendations for how to proceed with contemporary phage therapy. Despite many advances in phage biology, crucial gaps in our knowledge persist. Our recommendations require physicians, scientists, and public-policy leaders to cooperate to bridge the outstanding gaps around phage therapy to develop phage into a useful therapeutic tool.

vB_Ent31 bacteriophage may combat Enterobacter cloacae infections with macrophage modulating activity

Multidrug-resistant organisms (MDRO), including MDR Enterobacter cloacae, may emerge due to the extensive usage of antibiotics and threaten the lives of millions of people around the world. Developing new antibiotic-free strategies to combat E. cloacae infections and curb the spread of drug-resistant genes is crucial. Bacteriophage therapy has garnered widespread attention as a promising approach to tackle bacterial infections. Herein, we isolated a specific bacteriophage (vB_Ent31) targeting E. cloacae from sewage using E. cloacae Ent31 as the host bacterium. vB_Ent31 is a tadpole-like phage with double-stranded DNA belonging to the Siphoviridae family. It exhibits narrow-spectrum activity against Enterobacter spp. and remains stable across a temperature range of 4-50 °C and pH 4 to 11. Significantly, vB_Ent31 prevents proliferation of Ent31 and inhibits inflammation, which further accelerate wound healing. Our findings suggest that bacteriophage therapy could offer an alternative to combating drug-resistant bacteria.

Enhanced suppression of Stenotrophomonas maltophilia by a three-phage cocktail: genomic insights and kinetic profiling

Stenotrophomonas maltophilia is an understudied, gram-negative, aerobic bacterium that is widespread in the environment and increasingly a cause of opportunistic infections. Treating S. maltophilia remains difficult, leading to an increase in disease severity and higher hospitalization rates in people with cystic fibrosis, cancer, and other immunocompromised health conditions. The lack of effective antibiotics has led to renewed interest in phage therapy; however, there remains a great need for well-characterized phages, especially against S. maltophilia. In response to an oncology patient with a sepsis infection, we collected 18 phages from Southern California wastewater influent that exhibit different plaque morphology against S. maltophilia host strain B28B. We hypothesized that, when combined into a cocktail, genetically diverse phages would give rise to distinct lytic infection kinetics that would enhance bacterial killing when compared to the individual phages alone. We identified three genetically distinct clusters of phages, and a representative from each group was further investigated and screened for potential therapeutic use. The results demonstrated that the three-phage cocktail significantly suppressed bacterial growth compared with individual phages when observed for 48 h. We also assessed the lytic impacts of our three-phage cocktail against a collection of 46 S. maltophilia strains to determine if a multi-phage cocktail has an expanded host range. Our phages remained strain-specific and infected >50% of tested strains. In six clinically relevant S. maltophilia strains, the multi-phage cocktail has enhanced suppression of bacterial growth. These findings suggest that specialized phage cocktails may be an effective avenue of treatment for recalcitrant S. maltophilia infections resistant to current antibiotics.

Differences in Phage Recognition and Immunogenicity Contribute to Divergent Human Immune Responses to Escherichia coli and Klebsiella pneumoniae Phages

Bacteriophages (phages) are emerging as a viable adjunct to antibiotics for the treatment of multidrug-resistant (MDR) bacterial infections. While intravenous phage therapy has proven successful in many cases, clinical outcomes remain uncertain due to a limited understanding of host response to phages. In this study, we conducted a comprehensive examination of the interaction between clinical-grade phages used to treat MDR Escherichia coli and Klebsiella pneumoniae infections, and human peripheral blood immune cells. Using whole transcriptome as well as proteomic approaches, we identified a strong inflammatory response to E. coli phage vB_EcoM-JIPh_Ec70 (herein, JIPh_Ec70) that was absent upon exposure to K. pneumoniae phage JIPh_Kp127. We confirmed that JIPh_Ec70's DNA recognition by the STING pathway was principally responsible for the activation of NF-kB and the subsequent inflammatory response. We further show that monocytes and neutrophils play a dominant role in phage uptake, primarily through complement-mediated phagocytosis. Significant differences in complement-mediated phagocytosis of JIPh_Kp127 and JIPh_Ec70 were observed, suggesting that reduced recognition, phagocytosis, and immunogenicity all contribute to the significantly decreased response to JIPh_Kp127. Our findings contribute to the progress of our understanding of the innate immune response to therapeutic phages and offer potential insights into how to improve the safety and effectiveness of phage therapy.

Phage treatment of multidrug-resistant bacterial infections in humans, animals, and plants: The current status and future prospects

Phages, including the viruses that lyse bacterial pathogens, offer unique therapeutic advantages, including their capacity to lyse antibiotic-resistant bacteria and disrupt biofilms without harming the host microbiota. The lack of new effective antibiotics and the growing limitations of existing antibiotics have refocused attention on phage therapy as an option in complex clinical cases such as burn wounds, cystic fibrosis, and pneumonia. This review describes clinical cases and preclinical studies in which phage therapy has been effective in both human and veterinary medicine, and in an agricultural context. In addition, critical challenges, such as the narrow host range of bacteriophages, the possibility of bacterial resistance, and regulatory constraints on the widespread use of phage therapy, are addressed. Future directions include optimizing phage therapy through strategies ranging from phage cocktails to broadening phage host range through genetic modification, and using phages as vaccines or biocontrol agents. In the future, if phage can be efficiently delivered, maintained in a stable state, and phage-antibiotic synergy can be achieved, phage therapy will offer much needed treatment options. However, the successful implementation of phage therapy within the current standards of practice will also require the considerable development of regulatory infrastructure and greater public acceptance. In closing, this review highlights the promise of phage therapy as a critical backup or substitute for antibiotics. It proposes a new role as a significant adjunct to, or even replacement for, antibiotics in treating multidrug-resistant bacterial infections.

Pre-exposure to phage particles reduces their antibacterial therapeutic efficacy both in vitro and in vivo

OBJECTIVES

phage therapy is a promising approach for infections caused by drug-resistant bacteria; this study evaluated the impact of pre-exposure to phage particles on subsequent therapy. Mice were exposed intradermally (i.d.) to Staphylococcus aureus wide-host-range phage JD007, a member of the Myoviridae family.

METHODS

phage-specific antibodies were detected using ELISA. Mice were infected with S. aureus in the same way to establish a dermal abscess model, and then the efficacy of phage therapy for the mice pre-exposed to JD007 was evaluated.

RESULTS

JD007 could induce their specific IgM and IgG. IgM levels peaked on the 7th day following exposure, and IgG levels peaked on the 30th day after final immunization. Neutralization assays demonstrated that specific antibodies could reduce JD007's infectivity to S. aureus in vitro. Furthermore, mice previously exposed to JD007 three times showed decreased phage therapeutic efficacies, leading to delayed recovery and even exacerbating abscesses. White blood cells and lymphocytes also increased. Despite pre-exposing the mice to JD007 once, the abscess areas following phage treatment did not differ from those of the infection group with naive mice. The western blot results showed that anti-phage antibodies could recognize the predicted major capsid protein and phage tail protein.

CONCLUSIONS

pre-exposure to phage particles may induce phage-neutralization antibodies and inhibit their therapeutic efficacies, delaying recovery or even exacerbating S. aureus-associated dermal abscesses for later treatment.

R-pyocins as targeted antimicrobials against Pseudomonas aeruginosa

R-pyocins, bacteriocin-like proteins produced by Pseudomonas aeruginosa, present a promising alternative to phage therapy and/or adjunct to currently used antimicrobials in treating bacterial infections due to their targeted specificity, lack of replication, and stability. This review explores the structural, mechanistic, and therapeutic aspects of R-pyocins, including their potential for chronic infection management, and discusses recent advances in delivery methods, paving the way for novel antimicrobial applications in clinical settings.

Prophylactic phage administration provides a time window for delayed treatment of vancomycin-resistant Enterococcus faecalis in a murine bacteremia model

Introduction

Vancomycin-resistant Enterococcus faecalis (VRE) poses a significant challenge in clinical settings due to its resistance to multiple antibiotics. Phage therapy offers a promising alternative to address this resistance crisis. However, critical gaps remain regarding optimal dosing, therapeutic design, and treatment timing for phage therapy targeting VRE-induced bacteremia.

Methods

The biological and genomic characteristics of a novel lytic phage specific to VRE were investigated. Its in vitro bactericidal and antibiofilm activities were evaluated, along with its synergy with antimicrobial agents. In vitro safety and protective efficacy were assessed using a mouse bacteremia model. The impact of phage therapy on gut microbiota was examined through 16S rDNA gene sequencing.

Results

We isolated and characterized a novel lytic phage, vB_EfaS-1017, specific to vancomycin-resistant E. faecalis. This phage features a circular, double-stranded DNA genome (40,766 bp), sharing 91.19% identity and 79% coverage with Enterococcus phage vB_EfaS_SRH2. vB_EfaS-1017 exhibited robust bactericidal and antibiofilm activity in vitro and demonstrated synergy with levofloxacin. Safety assessments confirmed its non-toxicity to mammalian cells and lack of hemolytic activity. In a mouse bacteremia model, phage treatment alone rescued 60% of infected mice, while combining phage with levofloxacin increased survival to 80%. Prophylactic administration of phage 24 hours prior to infection failed to prevent mortality. However, a combination of prophylactic phage administration and delayed treatment rescued 60% of mice, compared to 100% mortality in the delayed treatment alone group. Additionally, phage therapy helped maintain or restore gut microbiota balance.

Discussion

These findings underscore the potential of phage-antibiotic combinations as a superior therapeutic strategy against VRE infections. The observed synergy between phages and antibiotics highlights a promising approach to overcoming bacterial resistance and improving clinical outcomes. Furthermore, prophylactic phage administration may provide a critical time window for effective delayed treatment. Further preclinical research is essential to refine phage therapy protocols for clinical application.

Transcytosis of T4 Bacteriophage Through Intestinal Cells Enhances Its Immune Activation

Interactions between bacteriophages with mammalian immune cells are of great interest and most phages possess at least one molecular pattern (nucleic acid, sugar residue, or protein structure) that is recognizable to the immune system through pathogen associated molecular pattern (PAMP) receptors (i.e., TLRs). Given that phages reside in the same body niches as bacteria, they share the propensity to stimulate or quench immune responses depending on the nature of their interactions with host immune cells. While most in vitro research focuses on the outcomes of direct application of phages to immune cells of interest, the potential impact of their transcytosis through the intestinal barrier has yet to be considered. As transcytosis through intestinal cells is a necessary step in healthy systems for access by phage to the underlying immune cell populations, it is imperative to understand how this step may play a role in immune activation. We compared the activation of macrophages (as measured by TNFα secretion) following direct phage application to those stimulated by incubation with phage transcytosed through a polarized Caco2 epithelial barrier model. Our results demonstrate that phages capable of activating TNFα secretion upon direct contact maintain the stimulatory capability following transcytosis. Furthermore, activation of macrophages by a transcytosed phage is enhanced as compared to that occurring with an equivalent multiplicity of directly applied phage.

A novel broad-spectrum bacteriophage cocktail against methicillin-resistant Staphylococcus aureus: Isolation, characterization, and therapeutic potential in a mastitis mouse model

Bovine mastitis is a considerable challenge within the dairy industry, causing significant financial losses and threatening public health. The increased occurrence of methicillin-resistant Staphylococcus aureus (MRSA) has provoked difficulties in managing bovine mastitis. Bacteriophage therapy presents a novel treatment strategy to combat MRSA infections, emerging as a possible substitute for antibiotics. This study evaluated the therapeutic potency of a novel bacteriophage cocktail against MRSA mastitis. Two new bacteriophages (vB_SauR_SW21 and vB_SauR_SW25) with potent lytic activity against MRSA were isolated and characterized. The one-step growth curve displayed a rapid latent period (20-35 min) and substantial burst size (418 and 316 PFU/ cell). In silico analyses have confirmed the absence of antimicrobial resistance or virulence factor-encoding genes within their genomes. According to the results, combining these phages augmented their host range and virulence. The phage cocktail significantly reduced bacterial burden in a BALB/c mastitis model, demonstrating efficacy comparable to antibiotic treatment. Moreover, its administration led to decreased concentrations of IL-1β and TNF-α compared to the negative control group. The bacteriophage cocktail (SW21-SW25) exhibits a promising profile for therapeutic applications and may represent a novel substitute to antibiotics for managing MRSA bovine mastitis.

The Appearance of Antiphage Antibodies in Sera of Patients Treated with Phages

Background: Bacteriophages are neutralized by the sera of patients undergoing phage therapy (PT), particularly during local or concomitant local and oral phage administration in bone infections, soft tissue infections, or upper respiratory tract infections. Methods: The antiphage activity of the sera (AAS) level of 27 patients with bacterial infections such as bone infections, soft tissue infections, or upper respiratory tract infections undergoing PT was performed using the plate phage neutralization test. Results: Our preliminary results suggest that high levels of antiphage antibodies appear late in the treatment period, at the earliest in the 3rd-8th week of PT. Patients with bone infections treated locally with the S. aureus phage Staph_1N and patients with upper respiratory tract infections administered locally and orally with the S. aureus phage Staph_A5L had elevated levels of antiphage antibodies in sera during PT. In parallel to these results, it has been shown that a strong antiphage humoral response does not prevent a positive outcome of phage treatment. Conclusions: The earliest time point at which high levels of antiphage antibodies in sera appear during local and oral PT is day 21 of therapy. We noticed that the high level of antiphage antibodies in sera occurring during local or both local and oral PT was correlated with the type of infection and phage type.

Microbiome and Hemato-immune Aging

The microbiome is a highly complex and diverse symbiotic component that undergoes dynamic changes with the organismal aging. Microbial perturbations, termed dysbiosis, exert strong influence on dysregulating the bone marrow niche and subsequently promoting the aging of hematopoietic and immune system. Accumulating studies have revealed the substantial impact of intestinal microbiome on the initiation and progression of age-related hematologic alteration and diseases, such as clonal hematopoiesis and blood cancers. Current therapeutic approaches to restore the altered microbiome diversity target specific pathobionts and are demonstrated to improve clinical outcomes of antihematologic malignancy treatments. In this review, we discuss the interplay between the microbiome and the hemato-immune system during aging process. We also shed light on the emerging therapeutic strategies to tackle the dysbiosis for amelioration of aging and disease progression.

Phage-specific antibodies: are they a hurdle for the success of phage therapy?

Phage therapy has attracted attention again owing to the increasing number of drug-resistant bacteria. Although the efficacy of phage therapy has been reported, numerous studies have indicated that the generation of phage-specific antibodies resulting from phage administration might have an impact on clinical outcomes. Phage-specific antibodies promote phage uptake by macrophages and contribute to their rapid clearance from the body. In addition, phage-specific neutralizing antibodies bind to the phages and diminish their antibacterial activity. Thus, phage-specific antibody production and its role in phage therapy have been analyzed both in vitro and in vivo. Strategies for prolonging the blood circulation time of phages have also been investigated. However, despite these efforts, the results of clinical trials are still inconsistent, and a consensus on whether phage-specific antibodies influence clinical outcomes has not yet been reached. In this review, we summarize the phage-specific antibody production during phage therapy. In addition, we introduce recently performed clinical trials and discuss whether phage-specific antibodies affect clinical outcomes and what we can do to further improve phage therapy regimens.

Bacteriophages and their potential for treatment of metabolic diseases

Recent advances highlight the role of gut virome, particularly phageome, in metabolic disorders such as obesity, type 2 diabetes mellitus, metabolic dysfunction-associated fatty liver disease, and cardiovascular diseases, including hypertension, stroke, coronary heart disease, and hyperlipidemia. While alterations in gut bacteria are well-documented, emerging evidence suggests that changes in gut viruses also contribute to these disorders. Bacteriophages, the most abundant gut viruses, influence bacterial populations through their lytic and lysogenic cycles, potentially modulating the gut ecosystem and metabolic pathways. Phage therapy, previously overshadowed by antibiotics, is experiencing renewed interest due to rising antibiotic resistance. It offers a novel approach to precisely edit the gut microbiota, with promising applications in metabolic diseases. In this review, we summarize recent discoveries about gut virome in metabolic disease patients, review preclinical and clinical studies of phage therapy on metabolic diseases as well as the breakthroughs and currently faced problems and concerns.

Isolation and Characterization of a Bacteriophage with Potential for the Control of Multidrug-Resistant Salmonella Strains Encoding Virulence Factors Associated with the Promotion of Precancerous Lesions

BACKGROUND

Antimicrobial-resistant bacteria represent a serious threat to public health. Among these bacteria, Salmonella is of high priority because of its morbidity levels and its ability to induce different types of cancer.

AIM

This study aimed to identify Salmonella strains encoding genes linked to the promotion of precancerous lesions and to isolate a bacteriophage to evaluate its preclinical potential against these bacteria.

METHODOLOGY

An epidemiological approach based on wastewater analysis was employed to isolate Salmonella strains and detect genes associated with the induction of precancerous lesions. Antimicrobial susceptibility was assessed by the disk diffusion method. A bacteriophage was isolated via the double agar technique, and its morphological characteristics, stability, host range, replication dynamics, and ability to control Salmonella under different conditions were evaluated. The bacteriophage genome was sequenced and analyzed using bioinformatics tools.

RESULTS

Thirty-seven Salmonella strains were isolated, seventeen of which contained the five genes associated with precancerous lesions' induction. These strains exhibited resistance to multiple antimicrobials, including fluoroquinolones. A bacteriophage from the Autographiviridae family with lytic activity against 21 bacterial strains was isolated. This phage exhibited a 20 min replication cycle, releasing 52 ± 3 virions per infected cell. It demonstrated stability and efficacy in reducing the Salmonella concentration in simulated gastrointestinal conditions, and its genome lacked genes that represent a biosafety risk.

CONCLUSION

This bacteriophage shows promising preclinical potential as a biotherapeutic agent against Salmonella.

Characteristics of the Enterococcus Phage vB_EfS_SE, and the Properties of Its Chimeric Endolysins Harboring a PlySE-Carbohydrate-Binding Domain and a Synthetic Enzymatic Domain

Background/Objectives: The World Health Organization has selected enterococci as one of the priority multidrug-resistant microorganisms for the development of new antibacterial drugs. Bacteriophages are promising antibacterial agents, but the biology of bacteriophages requires deeper understanding. Methods: The vB_EfS_SE phage which is capable of infecting four species of the genus Enterococci was isolated from sewage plant. The complete genome of the vB_EfS_SE phage was sequenced using illumina technology. The endolysin gene was cloned into pBAD18 expression vector. Two chimeric endolysins were engineered using the vB_EfS_SE carbohydrate-binding domain (CBD) and replacing its enzymatically active domain (EAD). Results: The bacteriophage exhibits promising lytic properties and persists at temperatures of 40 °C and below, and under pH conditions ranging from 5 to 11. The genome sequence is 57,904 bp in length. The vB_EfS_SE endolysin PlySE and chimeric endolysins PlyIME-SE and PlySheep-SE were found to have the same range of specificity, but different thermostability properties and a different pH range for enzyme activity. Conclusions: Taking together the results obtained in this work and other published studies, we can highly appreciate the potential of Saphexavirus phages and their endolysins as novel antibacterial compounds.

Phage-Antibiotic Combination Therapy against Recurrent Pseudomonas Septicaemia in a Patient with an Arterial Stent

Background: Intravascular stent infections are often associated with high risks of morbidity and mortality. We report here a case of a patient with an arterial stent and recurrent Pseudomonas septicaemias successfully treated with phage-meropenem combination therapy. Methods: A 75-year-old female with arteriosclerosis and comorbidities went through a femoropopliteal bypass with prosthesis in the right inguinal area. After the bypass, she developed a recurring Pseudomonas aeruginosa infection and also neutropenia during different antibiotics. A rapidly growing pseudoaneurysm in the right inguinal area led to an emergency intra-arterial stent placement during blood stream infection, later suspected to host a P. aeruginosa biofilm. Removing the stent was deemed precarious, and phage therapy was considered as a compassionate treatment option. A three-phage cocktail infecting the P. aeruginosa strain was prepared and administered intravenously together with meropenem for two weeks, after which, a ten-month follow-up was carried out. Results: No adverse reactions occurred during the phage therapy treatment, while infection markers were normalized. In addition, recovery was seen in a PET-CT scan. During the 10-month follow-up, no further P. aeruginosa septicaemias occurred. Conclusions: Phage-meropenem combination therapy was thus found safe and effective in the treatment of recurrent Pseudomonas septicaemia in a patient with an arterial stent.

From crisis to cure: harnessing the potential of mycobacteriophages in the battle against tuberculosis

Tuberculosis (TB) is a serious and fatal disease caused by Mycobacterium tuberculosis (Mtb). The World Health Organization reported an estimated 1.30 million TB-related deaths in 2022. The escalating prevalence of Mtb strains classified as being multi-, extensively, extremely, or totally drug resistant, coupled with the decreasing efficacies of conventional therapies, necessitates the development of novel treatments. As viruses that infect Mycobacterium spp., mycobacteriophages may represent a strategy to combat and eradicate drug-resistant TB. More exploration is needed to provide a comprehensive understanding of mycobacteriophages and their genome structure, which could pave the way toward a definitive treatment for TB. This review focuses on the properties of mycobacteriophages, their potential in diagnosing and treating TB, the benefits and drawbacks of their application, and their use in human health. Specifically, we summarize recent research on mycobacteriophages targeted against Mtb infection and newly developed mycobacteriophage-based tools to diagnose and treat diseases caused by Mycobacterium spp. We underscore the urgent need for innovative approaches and highlight the potential of mycobacteriophages as a promising avenue for developing effective diagnosis and treatment to combat drug-resistant Mycobacterium strains.