Bacteriophages as potential new therapeutics to replace or supplement antibiotics

Combined antimicrobial activity of short peptide and phage-derived endolysin against antibiotic-resistant Salmonella Typhimurium

This study was designed to evaluate the combination effects of antimicrobial peptides (FK13 and FK16) and phage-encoded endolysin (LysPB32) on the inhibition of growth of polymyxin B-resistant Salmonella Typhimurium ATCC 19585 (STPMB). The inhibitory effects of FK13, FK16, and LysPB32 against STPMB were evaluated by using antimicrobial susceptibility, membrane permeability, biofilm reduction, cross-resistance, and mutant frequency assay. The minimum inhibitory concentrations (MICs) of FK13 and FK16 treated with LysPB32 (FK13+LysPB32 and FK16+LysPB32) against STPMB were decreased from more than 512 to 128 μg/ml and from 64 to 32 μg/ml, respectively. Compared to the control, the number of STPMB in the growing culture was reduced by 4.2 and 5.2 log CFU/ml, respectively, for FK13+LysPB32 and FK16+LysPB32 after 12-h incubation at 37 °C. All treatments (FK13, FK16, FK13+LysPB32, FK16+LysPB32) significantly increased the permeability of the outer membrane of STPMB. Biofilms were significantly decreased from OD600 of 0.6 to 0.16 for FK13+LysPB32 and from 0.6 to 0.13 for FK16+LysPB32. The ratios of MICs of erythromycin, ceftriaxone, polymyxin B, and ciprofloxacin to MIC of the control against STPMB were decreased to 0.50 for FK13+LysPB32 and FK16+LysPB32. The bactericidal activities of amikacin and gentamicin were enhanced for FK13+LysPB32 and FK16+LysPB32 (2-fold < MBC/MIC ratio). The mutant frequencies of STPMB to antibiotics were decreased when treated with FK13+LysPB32 and FK16+LysPB32. The results suggest that the combination of antimicrobial peptides and endolysins can be a promising strategy to control polymyxin B-resistant S. Typhimurium.

PhagoScreener: A novel phagogram platform based on a capillary-wave microbioreactor

Due to the overuse of antibiotics, the number of multidrug-resistant pathogen bacteria is rising in recent years posing a serious threat to human health. One promising alternative for treatment is the application of phage therapy using highly selective bacteriophages. Because of their selectivity, individual screens called phagograms for each patient are required to select phages from a phage library. Phagograms are mostly performed via bacterial cultivation on double layer agar plates and phage addition causing bacterial lysis. However, these assays are work-intensive and have a low ability for parallelization and automation. Hence, highly parallelizable and automatable microbioreactors in the lowest microliter scale could offer an economic solution increasing the throughput of phagograms. This paper demonstrates the applicability of a novel capillary-wave microbioreactor (cwMBR) to perform phagograms. Due to its small volume of only 7 µL and the open-droplet design, it can be easily automated and parallelized in future. Furthermore, the ability of online biomass measurement makes the cwMBR a perfect phagogram platform in the future. Herein, phagograms with E. coli and different concentrations of the phages MM02 and EASG3 were performed as proof of concept for phagograms in the cwMBR. Thereby, the cwMBR was able to measure differences in lysis kinetics of different phages. Furthermore, the phagograms were compared to those in conventional microtiter plate readers revealing the cwMBR as ideal alternative for phagograms as it combines favorable mixing conditions and a phage repellent hydrophilic glass surface with online biomass measurement in an open-droplet design for future parallelization and automation.

Phage therapy: A primer for orthopaedic trauma surgeons

Phage therapy (PT) continues to attract interest in the fight against fracture-related infection (FRI), particularly for recurring infections that have not been resolved using conventional therapeutic approaches. The journey PT has taken from early clinical application in the pre-antibiotic era to its recent reintroduction to western clinical practice has been accelerated by the increased prevalence of multi-drug resistant (MDR) pathogens in the clinic. This review will present PT's potential as a precise, adaptable, and effective treatment modality, with a focus on patient and phage selection, as well as the various administration protocols currently applied to patients. The challenges for PT, for example the most optimal application technique and dosing, are also discussed and underscore the importance of personalized approaches and the urgent need for more robust clinical evidence. Future perspectives, including phage engineering and innovative delivery systems will be discussed, as they may broaden the applicability of PT to a point where it may become a standard rather than an option of last resort for orthopedic infection management.

Bacteriophages: a potential game changer in food processing industry

In the food industry, despite the widespread use of interventions such as preservatives and thermal and non-thermal processing technologies to improve food safety, incidences of foodborne disease continue to happen worldwide, prompting the search for alternative strategies. Bacteriophages, commonly known as phages, have emerged as a promising alternative for controlling pathogenic bacteria in food. This review emphasizes the potential applications of phages in biological sciences, food processing, and preservation, with a particular focus on their role as biocontrol agents for improving food quality and preservation. By shedding light on recent developments and future possibilities, this review highlights the significance of phages in the food industry. Additionally, it addresses crucial aspects such as regulatory status and safety concerns surrounding the use of bacteriophages. The inclusion of up-to-date literature further underscores the relevance of phage-based strategies in reducing foodborne pathogenic bacteria's presence in both food and the production environment. As we look ahead, new phage products are likely to be targeted against emerging foodborne pathogens. This will further advance the efficacy of approaches that are based on phages in maintaining the safety and security of food.

A game of resistance: War between bacteria and phages and how phage cocktails can be the solution

While phages hold promise as an antibiotic alternative, they encounter significant challenges in combating bacterial infections, primarily due to the emergence of phage-resistant bacteria. Bacterial defence mechanisms like superinfection exclusion, CRISPR, and restriction-modification systems can hinder phage effectiveness. Innovative strategies, such as combining different phages into cocktails, have been explored to address these challenges. This review delves into these defence mechanisms and their impact at each stage of the infection cycle, their challenges, and the strategies phages have developed to counteract them. Additionally, we examine the role of phage cocktails in the evolving landscape of antibacterial treatments and discuss recent studies that highlight the effectiveness of diverse phage cocktails in targeting essential bacterial receptors and combating resistant strains.

Growth stage-related capsular polysaccharide translocon Wza in Vibrio splendidus modifies phage vB_VspM_VS2 susceptibility

Bacteria at different growth stages usually coordinate capsular polysaccharide (CPS) formation and may affect their susceptibility to phage. In this study, we evaluated the infection efficacy of phage vB_VspM_VS2 in V. splendidus AJ01 at different growth stages and explored the role of growth stage-related CPS translocon Wza in the susceptibility of V. splendidus to phage vB_VspM_VS2. The results showed that V. splendidus locked in the stationary growth stage (SGS) or early exponential stage (EES) infected with phage (EES-P) has a low susceptibility to phage vB_VspM_VS and exhibit a pronounced reduction in phage adsorption rate as compared to the EES bacteria. The expression of wza of CPS transport gene was significantly increased in EES bacteria compared to that bacteria locked in the SGS or EES-P. Bacteria with deleted wza (Δwza mutant) escaped phage adsorption due to absence of Wza mediated down-regulation of CPS expression, otherwise. Our results reveal that the Wza of V. splendidus can promotes phage to infect these bacteria via increasing the phage absorption, which provides important implications for using phages therapeutically target pathogenic bacteria in dynamics communities.

Detection, isolation and characterization of phage-host complexes using BONCAT and click chemistry

Introduction

Phages are viruses that infect prokaryotes and can shape microbial communities by lysis, thus offering applications in various fields. However, challenges exist in sampling, isolation and accurate prediction of the host specificity of phages as well as in the identification of newly replicated virions in response to environmental challenges.

Methods

A new workflow using biorthogonal non-canonical amino acid tagging (BONCAT) and click chemistry (CC) allowed the combined analysis of phages and their hosts, the identification of newly replicated virions, and the specific tagging of phages with biotin for affinity chromatography.

Results

Replication of phage λ in Escherichia coli was selected as a model for workflow development. Specific labeling of phage λ proteins with the non-canonical amino acid 4-azido-L-homoalanine (AHA) during phage development in E. coli was confirmed by LC-MS/MS. Subsequent tagging of AHA with fluorescent dyes via CC allowed the visualization of phages adsorbed to the cell surface by fluorescence microscopy. Flow cytometry enabled the automated detection of these fluorescent phage-host complexes. Alternatively, AHA-labeled phages were tagged with biotin for purification by affinity chromatography. Despite biotinylation the tagged phages could be purified and were infectious after purification.

Discussion

Applying this approach to environmental samples would enable host screening without cultivation. A flexible and powerful workflow for the detection and enrichment of phages and their hosts in pure cultures has been established. The developed method lays the groundwork for future workflows that could enable the isolation of phage-host complexes from diverse complex microbial communities using fluorescence-activated cell sorting or biotin purification. The ability to expand and customize the workflow through the growing range of compounds for CC offers the potential to develop a versatile toolbox in phage research. This work provides a starting point for these further studies by providing a comprehensive standard operating procedure.

Antimicrobial resistance: use of phage therapy in the management of resistant infections

The emergence and increase in antimicrobial resistance (AMR) is now widely recognized as a major public health challenge. Traditional antimicrobial drugs are becoming increasingly ineffective, while the development of new antibiotics is waning. As a result, alternative treatments for infections are garnering increased interest. Among these alternatives, bacteriophages, also known as phages, are gaining renewed attention and are reported to offer a promising solution to alleviate the burden of bacterial infections. This review discusses the current successes of phage therapy (PT) against multidrug-resistant organisms (MDROs), such as Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Enterobacter spp. The review also compares the efficacy of PT with that of chemical antibiotics, reporting on its benefits and limitations, while highlighting its impact on the human gut microbiome and immune system. Despite its potential, phage therapy is reported to face challenges such as the narrow antibacterial range, the complexity of developing phage cocktails, and the need for precise dosing and duration protocols. Nevertheless, continued research, improved regulatory frameworks, and increased public awareness are essential to realize its full potential and integration into standard medical practice, paving the way for innovative treatments that can effectively manage infections in an era of rising antimicrobial resistance.

Isolation and Characterization of Novel Lytic Bacteriophages Infecting Carbapenem-Resistant Pathogenic Diarrheagenic and Uropathogenic Escherichia Coli

Background

The evolution of antimicrobial resistance has dramatically reduced the efficacy of the first-choice and last-resort antibiotics used to treat E. coli infections. Thus, searching for novel therapeutics to treat and control the emergence of antibiotic resistance is urgent. Therefore, this study aimed to illustrate the lytic effect of phages against carbapenem-resistant pathogenic E. coli.

Methods

Phages were isolated from hospital effluents by the enrichment assay. This was followed by the evaluation of the host range of the phages by the spot assay. The time taken by phages to bind to the host bacterial cells was determined by the adsorption assay. The phage latent period and burst size were determined using a one-step growth experiment. Phage morphology was determined by the Transmission Electron Microscopy. Molecular characterization of phages was done by whole genome sequencing.

Results

Two phages named UGKSEcP1 and UGKSEcP2 were isolated from hospital effluents. The phages were professionally lytic with a broad host range. The two phages recorded an average adsorption time of 11.25 minutes, an adsorption rate of 99.3%, a latency period of 20 minutes, and a burst size of approximately 528 phages/infected cell. Phages UGKSEcP1 and UGKSEcP2 had genome lengths of 167433bp, and 167221bp with 277 and 276 predicted genes, respectively, and no undesirable genes were detected. Phylogenetic analysis revealed the two phages belonged genus Tequatrovirus. TEM micrograph showed that the two phages had a similar morphotype with icosahedral heads and contractile tails; thus, classified as members of the Myoviridae phage family.

Conclusion

The findings demonstrate that the study isolated two novel professionally lytic phages with a broad host range and thus, are candidates for phage-mediated biocontrol.

Targeted enhancement of bacteriophage activity against antibiotic-resistant Staphylococcus aureus biofilms through an evolutionary assay

Staphylococcus aureus´ biofilm-forming ability and rapid resistance development pose a significant challenge to successful treatment, particularly in postoperative complications, emphasizing the need for enhanced therapeutic strategies. Bacteriophage (phage) therapy has reemerged as a promising and safe option to combat multidrug-resistant bacteria. However, questions regarding the efficacy of phages against biofilms and the development of phage resistance require further evaluation. Expanding on the adaptable and evolutionary characteristics of phages, we introduce an evolutionary approach to enhance the activity of S. aureus phages against biofilms. Unlike other in vitro directed evolution methods performed in planktonic cultures, we employed pre-stablished biofilms to do a serial-passage assay to evolve phages monitored by real-time isothermal microcalorimetry (IMC). The evolved phages demonstrated an expanded host range, with the CUB_MRSA-COL_R9 phage infecting 83% of strains in the collection (n = 72), surpassing the ISP phage, which represented the widest host range (44%) among the ancestral phages. In terms of antimicrobial efficacy, IMC data revealed superior suppression of bacterial growth by the evolved phages compared to the ancestral CUB-M and/or ISP phages against the respective bacterial strain. The phage cocktail exhibited higher efficacy, achieving over 90% suppression relative to the growth control even after 72 h of monitoring. Biofilm cell-counts, determined by RT-qPCR, confirmed the enhanced antibiofilm performance of evolved phages with no biofilm regrowth up to 48 h in treated MRSA15 and MRSA-COL strains. Overall, our results underscore the potential of biofilm-adapted phage cocktails to improve clinical outcomes in biofilm-associated infections, minimizing the emergence of resistance and lowering the risk of infection relapse. However, further investigation is necessary to evaluate the translatability of our results from in vitro to in vivo models, especially in the context of combination therapy with the current standard of care treatment.

Three novel Enterobacter cloacae bacteriophages for therapeutic use from Ghanaian natural waters

Infections caused by multidrug-resistant (MDR) bacteria are a growing global concern. Enterobacter cloacae complex (ECC) species are particularly adept at developing antibiotic resistance. Phage therapy is proposed as an alternative treatment for pathogens that no longer respond to antibiotics. Unfortunately, ECC phages are understudied when compared to phages of many other bacterial species. In this Ghanaian-Finnish study, we isolated two ECC strains from ready-to-eat food samples and three novel phages from natural waters against these strains. We sequenced the genomic DNA of the novel Enterobacter phages, fGh-Ecl01, fGh-Ecl02, and fGh-Ecl04, and assessed their therapeutic potential. All of the phages were found to be lytic, easy to propagate, and lacking any toxic, integrase, or antibiotic resistance genes and were thus considered suitable for therapy purposes. They all were found to be related to T4-type viruses: fGh-Ecl01 and fGh-Ecl04 to karamviruses and fGh-Ecl02 to agtreviruses. Testing of Finnish clinical ECC strains showed promising susceptibility to these novel phages. As many as 61.1% of the strains were susceptible to fGh-Ecl01 and fGh-Ecl04, and 7.4% were susceptible to fGh-Ecl02. Finally, we investigated the susceptibility of the newly isolated ECC strains to three antibiotics - meropenem, ciprofloxacin, and cefepime - in combination with the novel phages. The use of phages and antibiotics together had synergistic effects. When using an antibiotic-phage combination, even low concentrations of antibiotics fully inhibited the growth of bacteria.

Characterization of Salmonella phage of the genus Kayfunavirus isolated from sewage infecting clinical strains of Salmonella enterica

The emergence of multi-drug resistance in Salmonella, causing food-borne infections, is a significant issue. With over 2,600 serovars in in Salmonella sp., it is crucial to identify specific solutions for each serovar. Phage therapy serves as an alternate treatment option. In this study, vB_SalP_792 phage was obtained from sewage, forming plaques in eight out of 13 tested clinical S. enterica isolates. Transmission electron microscopy (TEM) examination revealed a T7-like morphotype. The phage was characterized by its stability, life cycle, antibiofilm, and lytic ability in food sources. The phage remains stable throughout a range of temperatures (-20 to 70°C), pH levels (3-11), and in chloroform and ether. It also exhibited lytic activity within a range of MOIs from 0.0001 to 100. The life cycle revealed that 95% of the phages attached to their host within 3 min, followed by a 5-min latent period, resulting in a 50 PFU/cell burst size. The vB_SalP_792 phage genome has a dsDNA with a length of 37,281 bp and a GC content of 51%. There are 42 coding sequences (CDS), with 24 having putative functions and no resistance or virulence-related genes. The vB_SalP_792 phage significantly reduced the bacterial load in the established biofilms and also in egg whites. Thus, vB_SalP_792 phage can serve as an effective biocontrol agent for preventing Salmonella infections in food, and its potent lytic activity against the clinical isolates of S. enterica, sets out vB_SalP_792 phage as a successful candidate for future in vivo studies and therapeutical application against drug-resistant Salmonella infections.

Isolation, Identification, and Biological Characterization of Phage vB_KpnM_KpVB3 Targeting Carbapenem-Resistant Klebsiella pneumoniae ST11

OBJECTIVES

This study aimed to isolate a phage capable of lysing carbapenem-resistant Klebsiella pneumoniae (CRKP) and to analyse its biological characteristics and whole-genome sequence.

METHODS

The phage was isolated and purified from the sewage. Transmission electron microscopy (TEM) was employed to observe the bacteriophage's morphology. Phenotypic characterization of the bacteriophages was determined. The genomic information was analysed. Evolutionary relationships were established through comparative genomics, proteomics, and phylogenetic analysis.

RESULTS

The isolation of a virulent phage, named Klebsiella phage vB_KpnM_KpVB3, was notable for forming 6-7 mm transparent circular zones, each surrounded by a distinct halo. The phage had a head diameter of ca. 30 nm and a tail length of ca. 20 nm, being identified as a member of the Myoviridae family and the Caudovirales order. The optimal multiplicity of infection (MOI) was 0.00001, with an incubation period of 20 minutes and a lysis period of 60 minutes, and the number of released phages after lysis was 133±35 PFU/cell. The phage was relatively stable at temperatures ranging from 10°C to 40°C and at pH values ranging from 3 to 11. Its lytic efficiency against CRKP was 30.30%. It has been shown to be able to destroy the biofilm of host bacteria. The bacteriophage genome consists of double-stranded DNA (dsDNA) with a total length of 48,394 base pairs, a GC content of 48.99%, and 78 open reading frames (ORFs).

CONCLUSION

The study resulted in the isolation vB_KpnM_KpVB3, a phage demonstrating potential therapeutic efficacy against infections caused by CRKP.

Isolation and characterization of lytic bacteriophages from various sources in Addis Ababa against antimicrobial-resistant diarrheagenic Escherichia coli strains and evaluation of their therapeutic potential

BACKGROUND

Escherichia coli is a common fecal coliform, facultative aerobic, gram-negative bacterium. Pathogenic strains of such microbes have evolved to cause diarrhea, urinary tract infections, and septicemias. The emergence of antibiotic resistance urged the identification of an alternative strategy. The use of lytic bacteriophages against the control of pathogenic E. coli in clinics and different environmental setups (waste and drink water management) has become an alternative therapy to antibiotic therapy. Thus, this study aimed to isolate and characterize lytic bacteriophage from various sources in Addis Ababa, tested them against antimicrobial-resistant diarrheagenic E. coli strains and evaluated their therapeutic potential under in vitro conditions.

METHODS

A total of 14 samples were processed against six different diarrheagenic E. coli strains. The conventional culture and plaque analysis agar overlay method was used to recover lytic bacteriophage isolates. The phage isolates were characterized to determine their lytic effect, growth characteristics, host range activity, and stability under different temperature and pH conditions. Phage isolates were identified by scanning electron microscope (SEM), and molecular techniques (PCR).

RESULTS

In total, 17 phages were recovered from 84 tested plates. Of the 17 phage isolates, 11 (65%) were Myoviridae-like phages, and 6 (35%) phage isolates were Podoviridae and Siphoviridae by morphology and PCR identification. Based on the host range test, growth characteristics, and stability test 7 potent phages were selected. These phages demonstrated better growth characteristics, including short latent periods, highest burst sizes, and wider host ranges, as well as thermal stability and the ability to survive in a wide range of pH levels.

CONCLUSIONS

The promising effect of the phages isolated in this study against AMR pathogenic E. coli has raised the possibility of their use in the future treatment of E. coli infections.

A bacteriophage cocktail can efficiently reduce five important Salmonella serotypes both on chicken skin and stainless steel

Salmonella is one of the most important zoonotic pathogens and is mostly transmitted through food of animal origin. Application of bacteriophages is a promising tool to biocontrol Salmonella on both food and food contact surfaces. In this study, we evaluated the effectiveness of a six-phage cocktail for the reduction of Salmonella Enteritidis and a mixture of five major Salmonella serotypes (S. Enteritidis, Salmonella Typhimurium, Salmonella Infantis, Salmonella Paratyphi B, and Salmonella Indiana) on chicken skin and stainless steel. A phage cocktail with a final concentration of 107 PFU/cm2 was sprayed on these surfaces. After adding the phage cocktail, the samples were incubated at RT (~23°C) for different periods of time. The phage cocktail caused a significant reduction of S. Enteritidis and the mixed culture on chicken skin 30 min after phage addition, with 1.8 log10 and 1 log10 units, respectively. Reduction rates (1.2-1.7 log10 units) on stainless steel after 30 min were similar. Four hours after addition, the phage cocktail caused a significant reduction on both surfaces up to 3 log10 units on chicken skin and 2.4 log10 units on stainless steel. In a further experiment, bacteria added to stainless steel were not allowed to dry to simulate a fresh bacterial contamination. In this case, the bacterial count of S. Enteritidis was reduced below the detection limit after 2 h. The results demonstrate that this phage cocktail has potential to be used in post-harvest applications to control Salmonella contaminations.

Aggregation-Induced Emission-Armored Living Bacteriophage-DNA Nanobioconjugates for Targeting, Imaging, and Efficient Elimination of Intracellular Bacterial Infection

Intracellular bacterial infections bring a considerable risk to human life and health due to their capability to elude immune defenses and exhibit significant drug resistance. As a result, confronting and managing these infections present substantial challenges. In this study, we developed a multifunctional living phage nanoconjugate by integrating aggregation-induced emission luminogen (AIEgen) photosensitizers and nucleic acids onto a bacteriophage framework (forming MS2-DNA-AIEgen bioconjugates). These nanoconjugates can rapidly penetrate mammalian cells and specifically identify intracellular bacteria while concurrently producing a detectable fluorescent signal. By harnessing the photodynamic property of AIEgen photosensitizer and the bacteriophage's inherent targeting and lysis capability, the intracellular bacteria can be effectively eliminated and the activity of the infected cells can be restored. Moreover, our engineered phage nanoconjugates were able to expedite the healing process in bacterially infected wounds observed in diabetic mice models while simultaneously enhancing immune activity within infected cells and in vivo, without displaying noticeable toxicity. We envision that these multifunctional phage nanoconjugates, which utilize AIEgen photosensitizers and spherical nucleic acids, may present a groundbreaking strategy for combating intracellular bacteria and offer powerful avenues for theranostic applications in intracellular bacterial infection-associated diseases.

The gut microbiome and cardiac surgery an unusual symphony

The relationship between the gut microbiome and various organ systems has gained interest throughout the scientific community in recent times. The understanding of these complex relationships has greatly improved with clinical benefits now being seen. Cardiopulmonary bypass (CPB) is a form of extracorporeal circulation that provides circulatory and respiratory support during cardiac surgery. This physiological support facilitates a still and bloodless field facilitating operations on the heart to be performed. Through various mechanisms CPB results in a systemic inflammatory response syndrome (SIRS). This response can vary from mild hypotension to multiple organ failure. It remains difficult to predict the degree to which a patient will experience SIRS post-operatively. The relationship between the composition of the gut microbiome and inflammatory processes associated with disease has been seen across several fields including gastroenterology, neurology, psychiatry and cardiology. To date, minimal research has been undertaken to examine the impact the gut microbiome has on outcomes following cardiac surgery. This review paper explores the pathophysiology behind the SIRS response associated with CPB for cardiac surgery and the hypothesis that a correlation exists between a patients gut microbiome composition and the degree of inflammatory response experienced following cardiac surgery.

Expression of a recombinant endolysin from bacteriophage CAP 10-3 with lytic activity against Cutibacterium acnes

The bacteriophage CAP 10-3 forming plaques against Cutibacterium acnes which causes skin acne was previously isolated from human skin acne lesion. Incomplete whole genome sequence (WGS) of the bacteriophage CAP 10-3 was obtained and it had 29,643 bp long nucleotide with 53.86% GC content. The sequence was similar to C. acnes phage PAP 1-1 with a nucleotide sequence identity of 89.63% and the bacteriophage belonged to Pahexavirus. Bioinformatic analysis of the WGS predicted 147 ORFs and functions of 40 CDSs were identified. The predicted endolysin gene of bacteriophage CAP 10-3 was 858 bp long which was deduced as 285 amino acids (~ 31 kDa). The protein had the highest similarity with amino acid sequence of the endolysin from Propionibacterium phage PHL071N05 with 97.20% identity. The CAP 10-3 endolysin gene was amplified by PCR with primer pairs based on the gene sequence, cloned into an expression vector pET-15b and transformed into Escherichia coli BL21(DE3) strain. The predicted protein band (~ 33 kDa) for the recombinant endolysin was detected in an SDS-PAGE gel and western blot assay. The concentrated supernatant of cell lysate from E. coli BL21(DE3) (pET-15b_CAP10-3 end) and a partially purified recombinant CAP 10-3 endolysin showed antibacterial activity against C. acnes KCTC 3314 in a dose-dependent manner. In conclusion, the recombinant CAP 10-3 endolysin was successfully produced in E. coli strain and it can be considered as a therapeutic agent candidate for treatment of human skin acne.

A lytic phage to control multidrug-resistant avian pathogenic Escherichia coli (APEC) infection

The inappropriate use of antibiotics has led to the emergence of multidrug-resistant strains. Bacteriophages (phages) have gained renewed attention as promising alternatives or supplements to antibiotics. In this study, a lytic avian pathogenic Escherichia coli (APEC) phage designated as PEC9 was isolated and purified from chicken farm feces samples. The morphology, genomic information, optimal multiplicity of infection (MOI), one-step growth curve, thermal stability, pH stability, in vitro antibacterial ability and biofilm formation inhibition ability of the phage were determined. Subsequently, the therapeutic effects of the phages were investigated in the mice model. The results showed that PEC9 was a member of the siphovirus-like by electron microscopy observation. Biological characterization revealed that it could lyse two serotypes of E. coli, including O1 (9/20) and O2 (6/20). The optimal multiplicity of infection (MOI) of phage PEC9 was 0.1. Phage PEC9 had a latent period of 20 min and a burst period of 40 min, with an average burst size of 68 plaque-forming units (PFUs)/cell. It maintained good lytic activity at pH 3-11 and 4-50°C and could efficiently inhibit the bacterial planktonic cell growth and biofilm formation, and reduce bacterial counts within the biofilm, when the MOI was 0.01, 0.1, and 1, respectively. Whole-genome sequencing showed that PEC9 was a dsDNA virus with a genome of 44379 bp and GC content of 54.39%. The genome contains 56 putative ORFs and no toxin, virulence, or resistance-related genes were detected. Phylogenetic tree analysis showed that PEC9 is closely related to E. coli phages vB_EcoS_Zar3M, vB_EcoS_PTXU06, SECphi18, ZCEC10, and ZCEC11, but most of these phages exhibit different gene arrangement. The phage PEC9 could successfully protect mice against APEC infection, including improved survival rate, reduced bacterial loads, and organ lesions. To conclude, our results suggest that phage PEC9 may be a promising candidate that can be used as an alternative to antibiotics in the control of APEC infection.

Isolation, characterization and application of a lytic phage vB_VspM_VS1 against Vibrio splendidus biofilm

Vibrio splendidus is a common pathogen in the ocean that infects Apostichopus japonicus, Atlantic salmon and Crassostrea gigas, leading to a variety of diseases. In this study, a virulent phage vB_VspM_VS1, which infects V. splendidus, was isolated from aquaculture ponds in Dalian, China, and it belongs to the family Straboviridae in the order Caudoviricetes. vB_VspM_VS1 had an adsorption rate of 96% in 15 min, a latent period of 65 min, and a burst size of 140 ± 6 PFU/cell. The complete genome of phage vB_VspM_VS1 consists of a linear double-stranded DNA that is 248,270 bp in length with an average G + C content of 42.5% and 389 putative protein-coding genes; 116 genes have known functions. There are 4 tail fiber genes in the positive and negative strands of the phage vB_VspM_VS1 genome. The protein domain of the phage vB_VspM_VS1 tail fibers was obtained from the Protein Data Bank and the SMART (http://smart.embl.de) database. Bacterial challenge tests revealed that the growth of V. splendidus HS0 was apparently inhibited (OD600 < 0.01) in 12 h at an MOI of 10. In against biofilms, we also showed that the OD570 value of the vB_VspM_VS1-treated group (MOI = 1) decreased significantly to 0.04 ± 0.01 compared with that of the control group (0.48 ± 0.08) at 24 h. This study characterizes the genome of the phage vB_VspM_VS1 that infects the pathogenic bacterium V. splendidus of A. japonicus.

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

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

Phage for regenerative medicine and cosmetics

Phage or bacteriophage is a specific virus with the ability to defeat bacteria. Because of the rising prevalence of antimicrobial-resistant bacteria, the bacteriophage is now receiving interest again, with it application in skin infection or acne treatment. Moreover, bacteriophages also express their efficacy in wound healing or skin regeneration. Thanks to the development of bioengineering technology, phage display, which is a technique using bacteriophage as a tool, has recently been applied in many biotechnological and medical fields, especially in regenerative medicines. Bacteriophages can be used as nanomaterials, delivery vectors, growth factor alternatives, or in several bacteriophage display-derived therapeutics and stem cell technology. Although bacteriophage is no doubt to be a potential and effective alternative in modern medicine, there are still controversial evidence about the antibacterial efficacy as well as the affinity to expected targets of bacteriophage. Future mission is to optimize the specificity, stability, affinity and biodistribution of phage-derived substances. In this chapter, we focused on introducing several mechanisms and applications of bacteriophage and analyzing its future potential in regenerative medicines as well as cosmetics via previous research's results.

Phage Therapy Administration Route, Regimen, and Need for Supplementary Antibiotics in Patients with Chronic Suppurative Lung Disease

Antimicrobial resistance is leading to increased mortality, posing risk to those with chronic suppurative lung disease (CSLD). One therapeutic option may be to target treatment-resistant bacteria using viruses (bacteriophages [phages]). Currently, patients receiving phage therapy on compassionate grounds may not be receiving optimal treatment as there is no defined approach for phage use. This review aims to explore administration route, regimen, and need for supplementary antibiotics in phage therapy to treat bacterial infection in CSLD. Twelve articles totaling 18 participants included details of numerous phage administration routes with varying regimens. All articles reported an initial reduction of bacterial load or an improvement in patient symptoms, highlighting the potential of phage therapy in CSLD. Fifteen out of 18 used supplementary antibiotics. Standardized protocols informed by high-quality research are necessary to ensure safe and effective phage therapy. In the interim, systematic recording of information within case reports may be useful.

The Lung Microbiome in Carcinogenesis and Immunotherapy Treatment

ABSTRACT

Lung cancer is the leading cause of cancer-related deaths. Over the past 10 years, significant advances in treatment modalities, including immune checkpoint inhibitor (ICI) blockade, have led to improved outcomes. Elucidating predicative biomarkers in responders and nonresponders to ICI will lead to development of therapeutic targets that could enhance ICI efficacy. Recently, the gut microbiome was identified as a predictive biomarker for ICI in patients with multiple cancer types. However, it is unclear how other host microbiomes influence tumorigenesis and response to ICI. Other groups have explored the lung microbiome as it relates to carcinogenesis and immunotherapy efficacy. In this review, we explore the role of the lung microbiome in health and disease. We also review the current state of lung microbiome research as it relates to tumorigenesis and treatments and provide potential insights into how the lung microbiome could improve outcomes in patients with cancer.

The future of evolutionary medicine: sparking innovation in biomedicine and public health

Evolutionary medicine - i.e. the application of insights from evolution and ecology to biomedicine - has tremendous untapped potential to spark transformational innovation in biomedical research, clinical care and public health. Fundamentally, a systematic mapping across the full diversity of life is required to identify animal model systems for disease vulnerability, resistance, and counter-resistance that could lead to novel clinical treatments. Evolutionary dynamics should guide novel therapeutic approaches that target the development of treatment resistance in cancers (e.g., via adaptive or extinction therapy) and antimicrobial resistance (e.g., via innovations in chemistry, antimicrobial usage, and phage therapy). With respect to public health, the insight that many modern human pathologies (e.g., obesity) result from mismatches between the ecologies in which we evolved and our modern environments has important implications for disease prevention. Life-history evolution can also shed important light on patterns of disease burden, for example in reproductive health. Experience during the COVID-19 (SARS-CoV-2) pandemic has underlined the critical role of evolutionary dynamics (e.g., with respect to virulence and transmissibility) in predicting and managing this and future pandemics, and in using evolutionary principles to understand and address aspects of human behavior that impede biomedical innovation and public health (e.g., unhealthy behaviors and vaccine hesitancy). In conclusion, greater interdisciplinary collaboration is vital to systematically leverage the insight-generating power of evolutionary medicine to better understand, prevent, and treat existing and emerging threats to human, animal, and planetary health.

Mycobacterium abscessus Infections in Cystic Fibrosis Individuals: A Review on Therapeutic Options

Mycobacterium abscessus is an opportunistic pathogen that mainly colonizes and infects cystic fibrosis patients' lungs. M. abscessus is naturally resistant to many antibiotics such as rifamycin, tetracyclines and β-lactams. The current therapeutic regimens are not very effective and are mostly based on repurposed drugs used against Mycobacterium tuberculosis infections. Thus, new approaches and novel strategies are urgently needed. This review aims to provide an overview of the latest ongoing findings to fight M. abscessus infections by analyzing emerging and alternative treatments, novel drug delivery strategies, and innovative molecules.

The promising role of bacteriophage therapy in managing total hip and knee arthroplasty related periprosthetic joint infection, a systematic review

PURPOSE

Total hip and knee arthroplasty periprosthetic joint infection (PJI) poses a management dilemma owing to the emergence of resistant organisms. A promising option is Bacteriophage therapy (BT) was used as an adjuvant for PJI management, aiming at treating resistant infections, decreasing morbidity, and mortality. The current review aimed to demonstrate the role and safety of using BT as an adjuvant to treat PJIs.

METHODS

A systematic search was performed through four databases (Embase, PubMed, Web of Science, and Scopus) up to March 2022, according to the predetermined inclusion and exclusion criteria.

RESULTS

Our systematic review included 11 case reports of 13 patients in which 14 joints (11 TKAs and three THAs) were treated. The patients' average age was 73.7 years, underwent an average of 4.5 previous surgeries. The most common organism was the Staphylococcus aureus species. All patients underwent surgical debridement; for the 13 patients, eight received a cocktail, and five received monophage therapy. All patients received postoperative suppressive antibiotic therapy. After an average follow-up of 14.5 months, all patients had satisfactory outcomes. No recurrence of infection in any patient. Transaminitis complicating BT was developed in three patients, needed stoppage in only one, and the condition was reversible and non-life-threatening.

CONCLUSION

BT is a safe and potentially effective adjuvant therapy for treating resistant and relapsing PJIs. However, further investigations are needed to clarify some BT-related issues to create effective and reproducible therapeutics. Furthermore, new ethical regulations should be implemented to facilitate its widespread use.

Expansion of Kuravirus-like Phage Sequences within the Past Decade, including Escherichia Phage YF01 from Japan, Prompt the Creation of Three New Genera

Bacteriophages, viruses that infect bacteria, are currently receiving significant attention amid an ever-growing global antibiotic resistance crisis. In tandem, a surge in the availability and affordability of next-generation and third-generation sequencing technologies has driven the deposition of a wealth of phage sequence data. Here, we have isolated a novel Escherichia phage, YF01, from a municipal wastewater treatment plant in Yokohama, Japan. We demonstrate that the YF01 phage shares a high similarity to a collection of thirty-five Escherichia and Shigella phages found in public databases, six of which have been previously classified into the Kuravirus genus by the International Committee on Taxonomy of Viruses (ICTV). Using modern phylogenetic approaches, we demonstrate that an expansion and reshaping of the current six-membered Kuravirus genus is required to accommodate all thirty-six member phages. Ultimately, we propose the creation of three additional genera, Vellorevirus, Jinjuvirus, and Yesanvirus, which will allow a more organized approach to the addition of future Kuravirus-like phages.

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.

Natural Killers: Opportunities and Challenges for the Use of Bacteriophages in Microbial Food Safety from the One Health Perspective

Ingestion of food or water contaminated with pathogenic bacteria may cause serious diseases. The One Health approach may help to ensure food safety by anticipating, preventing, detecting, and controlling diseases that spread between animals, humans, and the environment. This concept pays special attention to the increasing spread and dissemination of antibiotic-resistant bacteria, which are considered one of the most important environment-related human and animal health hazards. In this context, the development of innovative, versatile, and effective alternatives to control bacterial infections in order to assure comprehensive food microbial safety is becoming an urgent issue. Bacteriophages (phages), viruses of bacteria, have gained significance in the last years due to the request for new effective antimicrobials for the treatment of bacterial diseases, along with many other applications, including biotechnology and food safety. This manuscript reviews the application of phages in order to prevent food- and water-borne diseases from a One Health perspective. Regarding the necessary decrease in the use of antibiotics, results taken from the literature indicate that phages are also promising tools to help to address this issue. To assist future phage-based real applications, the pending issues and main challenges to be addressed shortly by future studies are also taken into account.

Resistance-resistant antibacterial treatment strategies

Antibiotic resistance is a major danger to public health that threatens to claim the lives of millions of people per year within the next few decades. Years of necessary administration and excessive application of antibiotics have selected for strains that are resistant to many of our currently available treatments. Due to the high costs and difficulty of developing new antibiotics, the emergence of resistant bacteria is outpacing the introduction of new drugs to fight them. To overcome this problem, many researchers are focusing on developing antibacterial therapeutic strategies that are "resistance-resistant"-regimens that slow or stall resistance development in the targeted pathogens. In this mini review, we outline major examples of novel resistance-resistant therapeutic strategies. We discuss the use of compounds that reduce mutagenesis and thereby decrease the likelihood of resistance emergence. Then, we examine the effectiveness of antibiotic cycling and evolutionary steering, in which a bacterial population is forced by one antibiotic toward susceptibility to another antibiotic. We also consider combination therapies that aim to sabotage defensive mechanisms and eliminate potentially resistant pathogens by combining two antibiotics or combining an antibiotic with other therapeutics, such as antibodies or phages. Finally, we highlight promising future directions in this field, including the potential of applying machine learning and personalized medicine to fight antibiotic resistance emergence and out-maneuver adaptive pathogens.

Role of Bacteriophages for Optimized Health and Production of Poultry

The poultry sector is facing infections from Salmonella, Campylobacter, Listeria and Staphylococcus spp., and Escherichia coli, that have developed multidrug resistance aptitude. Antibiotics cause disturbances in the balance of normal microbiota leading to dysbiosis, immunosuppression, and the development of secondary infections. Bacteriophages have been reported to lower the colonization of Salmonella and Campylobacter in poultry. The specificity of bacteriophages is greater than that of antibiotics and can be used as a cocktail for enhanced antibacterial activity. Specie-specific phages have been prepared, e.g., Staphylophage (used against Staphylococcus bacteria) that specifically eliminate bacterial pathogens. Bacteriophage products, e.g., BacWash^TM and Ecolicide PX have been developed as antiseptics and disinfectants for effective biosecurity and biosafety measures. The success of phage therapy is influenced by time to use, the amount used, the delivery mechanism, and combination therapy with other therapeutics. It is a need of time to build a comprehensive understanding of the use of bacteriophages in poultry production. The current review thus focuses on mechanisms of bacteriophages against poultry pathogens, their applications in various therapeutics, impacts on the economy, and current challenges.

Comparing In Vitro Faecal Fermentation Methods as Surrogates for Phage Therapy Application

The human microbiome and its importance in health and disease have been the subject of numerous research articles. Most microbes reside in the digestive tract, with up to 10¹² cells per gram of faecal material found in the colon. In terms of gene number, it has been estimated that the gut microbiome harbours >100 times more genes than the human genome. Several human intestinal diseases are strongly associated with disruptions in gut microbiome composition. Less studied components of the gut microbiome are the bacterial viruses called bacteriophages that may be present in numbers equal to or greater than the prokaryotes. Their potential to lyse their bacterial hosts, or to act as agents of horizontal gene transfer makes them important research targets. In this study in vitro faecal fermentation systems were developed and compared for their ability to act as surrogates for the human colon. Changes in bacterial and viral composition occurred after introducing a high-titre single phage preparation both with and without a known bacterial host during the 24 h-long fermentation. We also show that during this timeframe 50 mL plastic tubes can provide data similar to that generated in a sophisticated faecal fermenter system. This knowledge can guide us to a better understanding of the short-term impact of bacteriophage transplants on the bacteriomes and viromes of human recipients.

Treatment of Pseudomonas aeruginosa infectious biofilms: Challenges and strategies

Pseudomonas aeruginosa, a Gram-negative bacterium, is one of the major pathogens implicated in human opportunistic infection and a common cause of clinically persistent infections such as cystic fibrosis, urinary tract infections, and burn infections. The main reason for the persistence of P. aeruginosa infections is due to the ability of P. aeruginosa to secrete extracellular polymeric substances such as exopolysaccharides, matrix proteins, and extracellular DNA during invasion. These substances adhere to and wrap around bacterial cells to form a biofilm. Biofilm formation leads to multiple antibiotic resistance in P. aeruginosa, posing a significant challenge to conventional single antibiotic therapeutic approaches. It has therefore become particularly important to develop anti-biofilm drugs. In recent years, a number of new alternative drugs have been developed to treat P. aeruginosa infectious biofilms, including antimicrobial peptides, quorum-sensing inhibitors, bacteriophage therapy, and antimicrobial photodynamic therapy. This article briefly introduces the process and regulation of P. aeruginosa biofilm formation and reviews several developed anti-biofilm treatment technologies to provide new directions for the treatment of P. aeruginosa biofilm infection.

Systemically targeted cancer immunotherapy and gene delivery using transmorphic particles

Immunotherapy is a powerful tool for cancer treatment, but the pleiotropic nature of cytokines and immunological agents strongly limits clinical translation and safety. To address this unmet need, we designed and characterised a systemically targeted cytokine gene delivery system through transmorphic encapsidation of human recombinant adeno-associated virus DNA using coat proteins from a tumour-targeted bacteriophage (phage). We show that Transmorphic Phage/AAV (TPA) particles provide superior delivery of transgenes over current phage-derived vectors through greater diffusion across the extracellular space and improved intracellular trafficking. We used TPA to target the delivery of cytokine-encoding transgenes for interleukin-12 (IL12), and novel isoforms of IL15 and tumour necrosis factor alpha (TNF α ) for tumour immunotherapy. Our results demonstrate selective and efficient gene delivery and immunotherapy against solid tumours in vivo, without harming healthy organs. Our transmorphic particle system provides a promising modality for safe and effective gene delivery, and cancer immunotherapies through cross-species complementation of two commonly used viruses.

Bacteriophage Cocktail Can Effectively Control Salmonella Biofilm in Poultry Housing

Salmonella enterica serovar Enteritidis (S. Enteritidis) is the major contaminant of poultry products, and its ability to form biofilms on produced food and poultry farm processing surfaces contributes to Salmonella transmission to humans. Bacteriophages have come under increasing interest for anti-Salmonella biofilm control. In this study, we used the three previously sequenced and described phages UPWr_S1, UPWr_S3, and UPWr_S4 and a phage cocktail, UPWr_S134, containing these three phages to degrade biofilms formed by two S. Enteritidis strains, 327 lux and ATCC 13076, in vitro. It was found that treatment with bacteriophages significantly reduced biofilm on a 96-well microplate (32–69%) and a stainless steel surface (52–98%) formed by S. Enteritidis 327 lux. The reduction of biofilm formed by S. Enteritidis ATCC 13076 in the 96-well microplate and on a stainless steel surface for bacteriophage treatment was in the range of 73–87% and 60–97%, respectively. Under laboratory conditions, an experimental model utilizing poultry drinkers artificially contaminated with S. Enteritidis 327 lux and treated with UPWr_S134 phage cocktail was applied. In in vitro trials, the phage cocktail significantly decreased the number of Salmonella on the surface of poultry drinkers. Moreover, the phage cocktail completely eradicated Salmonella from the abundant bacterial load on poultry drinkers in an experimentally infected chickens. Therefore, the UPWr_S134 phage cocktail is a promising candidate for Salmonella biocontrol at the farm level.

Multidrug-resistant enteric bacteria in Nigeria and potential use of bacteriophages as biocontrol

Enteric bacterial pathogens have been implicated in many cases of gastroenteritis in Nigeria, a West African country. This situation is worsened by some reports of the high prevalence of multidrug-resistant enteric bacteria. To better prepare for situations in which even antibiotics of last resort would fail to treat infections caused by these pathogens, attention should be paid to alternative antimicrobial strategies. Here, we summarize existing reports of multidrug-resistant enteric bacterial infections in Nigeria, and importantly present the use of bacteriophages (viruses of bacteria) as an attractive antimicrobial alternative to combat these pathogens. It is hoped that this review will encourage research into the use of lytic bacteriophages against multidrug-resistant enteric bacteria in Nigeria.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

The Bacteriophage vB_CbrM_HP1 Protects Crucian Carp Against Citrobacter braakii Infection

Citrobacter braakii is an opportunistic pathogen that induces aquatic infections in fish and turtles. In this study, a bacteriophage that infects C. braakii, named vB_CbrM_HP1, was isolated from sewage. This phage belongs to Myoviridae family, Ounavirinae subfamily, Mooglevirus genus. We also used the phage to treat crucian carp infection caused by C. braakii for the first time. vB_CbrM_HP1 was relatively stable at temperatures ranging from 4 to 60°C and pH values ranging from 3 to 11 but float slightly. When the multiplicities of infection (MOI) was 0.0001, the titer reached a maximum of 4.20 × 1010 PFU/ml. As revealed from the results of whole genomic sequence analysis, the total length of vB_CbrM_HP1 was 89335 bp, encoding 135 ORFs, 9 of which were &lt;75% similar to the known sequences in NCBI. The phage vB_CbrM_HP1 showed a highly efficient bactericidal effect against C. braakii both in vitro and in vivo. In vitro, vB_CbrM_HP1 was capable of effectively killing bacteria (the colony count decreased by 4.7 log units at 5 h). In vivo, administration of vB_CbrM_HP1 (1 × 109 PFU) effectively protected crucian carp against fatal infection caused by C. braakii. Phage treatment reduced the levels of inflammatory factors. All these results demonstrated the potential of vB_CbrM_HP1 as an alternative treatment strategy for infections caused by C. braakii.

Filamentous Prophage Capsid Proteins Contribute to Superinfection Exclusion and Phage Defense in Pseudomonas aeruginosa

Filamentous prophages in Pseudomonas aeruginosa PAO1 are converted to superinfective phage virions during biofilm development. Superinfection exclusion is necessary for the development of resistance against superinfective phage virions in host cells. However, the molecular mechanisms underlying the exclusion of superinfective Pf phages are unknown. In this study, we found that filamentous prophage-encoded structural proteins allow exclusion of superinfective Pf phages by interfering with type IV pilus (T4P) function. Specifically, the phage minor capsid protein pVII inhibits Pf phage adsorption by interacting with PilC and PilJ of T4P, and overproduction of pVII completely abrogates twitching motility. The minor capsid protein pIII provides partial superinfection exclusion and interacts with the PilJ and TolR/TolA proteins. Furthermore, pVII provides full host protection against infection by pilus-dependent lytic phages, and pIII provides partial protection against infection by pilus-independent lytic phages. Considering that filamentous prophages are common in clinical Pseudomonas isolates and their induction is often activated during biofilm formation, this study suggests the need to rethink the strategy of using lytic phages to treat P. aeruginosa biofilm-related infections. This article is protected by copyright. All rights reserved.

An Appraisal of Bacteriophage Isolation Techniques from Environment

Researchers have recently renewed interest in bacteriophages. Being valuable models for the study of eukaryotic viruses, and more importantly, natural killers of bacteria, bacteriophages are being tapped for their potential role in multiple applications. Bacteriophages are also being increasingly sought for bacteriophage therapy due to rising antimicrobial resistance among pathogens. Reports show that there is an increasing trend in therapeutic application of natural bacteriophages, genetically engineered bacteriophages, and bacteriophage-encoded products as antimicrobial agents. In view of these applications, the isolation and characterization of bacteriophages from the environment has caught attention. In this review, various methods for isolation of bacteriophages from environmental sources like water, soil, and air are comprehensively described. The review also draws attention towards a handful on-field bacteriophage isolation techniques and the need for their further rapid development.

Bacteriophages and antibiotic interactions in clinical practice: what we have learned so far

Bacteriophages (phages) may be used as an alternative to antibiotic therapy for combating infections caused by multidrug-resistant bacteria. In the last decades, there have been studies concerning the use of phages and antibiotics separately or in combination both in animal models as well as in humans. The phenomenon of phage–antibiotic synergy, in which antibiotics may induce the production of phages by bacterial hosts has been observed. The potential mechanisms of phage and antibiotic synergy was presented in this paper. Studies of a biofilm model showed that a combination of phages with antibiotics may increase removal of bacteria and sequential treatment, consisting of phage administration followed by an antibiotic, was most effective in eliminating biofilms. In vivo studies predominantly show the phenomenon of phage and antibiotic synergy. A few studies also describe antagonism or indifference between phages and antibiotics. Recent papers regarding the application of phages and antibiotics in patients with severe bacterial infections show the effectiveness of simultaneous treatment with both antimicrobials on the clinical outcome.

Evaluation of factors influencing expression and extraction of recombinant bacteriophage endolysins in Escherichia coli

BACKGROUND

Endolysins are peptidoglycan hydrolases with promising use as environment-friendly antibacterials mainly when used topically. However, in general, endolysin expression is hampered by its low solubility. Thus, a critical point in endolysin industrial production is optimizing their expression, including improvement of solubility and recovery from cell extracts.

RESULTS

We report the expression of two endolysins encoded in the genome of phages infecting Staphylococcus aureus. Expression was optimized through changes in the concentration of the inducer and growth temperature during the expression. Usually, only 30-40% of the total endolysin was recovered in the soluble fraction. Co-expression of molecular chaperones (DnaK, GroEL) or N-term fusion tags endowed with increased solubility (DsbC, Trx, Sumo) failed to improve that yield substantially. Inclusion of osmolytes (NaCl, CaCl2, mannitol, glycine betaine, glycerol and trehalose) or tensioactives (Triton X-100, Tween 20, Nonidet P-40, CHAPS, N-lauroylsarcosine) in the cell disruption system (in the absence of any molecular chaperone) gave meager improvements excepted by N-lauroylsarcosine which increased recovery to 54% of the total endolysin content.

CONCLUSION

This is the first attempt to systematically analyze methods for increasing yields of recombinant endolysins. We herein show that neither solubility tags nor molecular chaperones co-expression are effective to that end, while induction temperature, (His)6-tag location and lysis buffer additives (e.g. N-lauroylsarcosine), are sensible strategies to obtain higher levels of soluble S. aureus endolysins.

Oral Toxicity Study for Salmonella Killing Lytic Bacteriophage NINP13076 in BALB/c Mice and Its Effect on Probiotic Microbiota

Viruses that infect bacteria are emerging as attractive biocontrol agents and biopreservatives for foods. Since these bacteriophages kill the target pathogens by lysis and are also consumed along with food, it is essential to evaluate their collateral toxicity on the probiotic gut microbiota. In this study, we examined the acute oral toxicity of a Salmonella phage isolated from sewage in mice. Acute oral administration of the Salmonella phage for five consecutive days did not show any significant pathological changes in the vital organs like lung, kidneys, heart, liver, and intestine. In addition, growth of typical probiotic microbiota remained unaffected even after incubation up to 24 h with the Salmonella phage. The results of this study clearly showed that oral administration of the lytic Salmonella phage did not have any significant adverse effects on the animals, may not harm the probiotic gut microbiota, and are likely to be safe for use in food preservation.

Controlled release of metal phenolic network protected phage for treating bacterial infection

Phage is a promising therapeutic agent for treating antibiotic resistant bacteria. However, in the process of treatment, phage may be cleared by the immune system and cleaved by protease, which could affect the efficacy of phage. In order to solve the above problems, phage encapsulation is usually adopted. In this study, we employed metal phenolic network (MPN) for efficient phage encapsulation which could protect phage from the cleavage of protease, and keep cytotoxicity weak. In the model of skin wound infection, the encapsulated phage could be released in response to pH change to achieve good antibacterial effect. Furthermore, the MPN encapsulation could prolong the T4 phage residence time at the wound. Our findings suggest that MPN can be a promising material for phage encapsulation.

A novel method to create efficient phage cocktails via use of phage-resistant bacteria

The rapid anti-phage mutation of pathogens is a big challenge often encountered in the application of phages in aquaculture, animal husbandry and human disease prevention. A cocktail composed of phages with different infection strategies can better suppress the anti-phage resistance of pathogens. However, randomly selecting phages with different infection strategies is time-consuming and labor-intensive. Here, we verified that using a resistant pathogen quickly-evolved under single phage infection as the new host can easily obtain phages with different infection strategies. We randomly isolated two lytic phages (i.e., Va1 and Va2) that infect the opportunistic pathogen Vibrio alginolyticus. Whether they were used alone or in combination, the pathogen easily gained resistance. Using a mutated pathogen resistant to Va1 as a new host, a third lytic phage Va3 was isolated. These three phages have a similar infection cycle and lytic ability, but quite different morphologies and genome information. Notably, phage Va3 is a jumbo phage containing a larger and more complex genome (240 kb) than Va1 and Va2. Furthermore, the 34 tRNAs and multiple genes encoding receptor binding proteins and NAD⁺ synthesis proteins in the Va3 genome implicated its quite different infection strategy compared to Va1 and Va2. Although the wild-type pathogen could still readily evolve resistance under single phage infection by Va3, when Va3 was used in combination with Va1 and Va2, pathogen resistance was strongly suppressed. This study provides a novel approach for rapid isolation of phages with different infection strategies, which will be highly beneficial when designing effective phage cocktails. Importance The rapid anti-phage mutation of pathogens is a big challenge often encountered in phage therapy. Using a cocktail composed of phages with different infection strategies can better overcome this problem. However, randomly selecting phages with different infection strategies is time-consuming and labor-intensive. To address this problem, we developed a method to efficiently obtain phages with disparate infection strategies. The trick is to use the characteristics of the pathogenic bacteria that are prone to develop resistance to single phage infection, to rapidly obtain the anti-phage variant of the pathogen. Using this anti-phage variant as the host results in other phages with different infection strategies being efficiently isolated. We also verified the reliability of this method by demonstrating the ideal phage control effects on two pathogens, and thus revealed its potential importance in the development of phage therapies.