Developmental Dynamics of the Gut Virome in Tibetan Pigs at High Altitude: A Metagenomic Perspective across Age Groups

Tibetan pig is a geographically isolated pig breed that inhabits high-altitude areas of the Qinghai-Tibetan plateau. At present, there is limited research on viral diseases in Tibetan pigs. This study provides a novel metagenomic exploration of the gut virome in Tibetan pigs (altitude ≈ 3000 m) across three critical developmental stages, including lactation, nursery, and fattening. The composition of viral communities in the Tibetan pig intestine, with a dominant presence of Microviridae phages observed across all stages of development, in combination with the previous literature, suggest that it may be associated with geographical locations with high altitude. Functional annotation of viral operational taxonomic units (vOTUs) highlights that, among the constantly increasing vOTUs groups, the adaptability of viruses to environmental stressors such as salt and heat indicates an evolutionary response to high-altitude conditions. It shows that the lactation group has more abundant viral auxiliary metabolic genes (vAMGs) than the nursery and fattening groups. During the nursery and fattening stages, this leaves only DNMT1 at a high level. which may be a contributing factor in promoting gut health. The study found that viruses preferentially adopt lytic lifestyles at all three developmental stages. These findings not only elucidate the dynamic interplay between the gut virome and host development, offering novel insights into the virome ecology of Tibetan pigs and their adaptation to high-altitude environments, but also provide a theoretical basis for further studies on pig production and epidemic prevention under extreme environmental conditions.

Genomic characterization, in vitro, and preclinical evaluation of two microencapsulated lytic phages VB_ST_E15 and VB_ST_SPNIS2 against clinical multidrug-resistant Salmonella serovars

BACKGROUND

Salmonella infections continue to be one of the essential public health issues threatening millions of people. With the increasing occurrence of resistance against conventionally used antibiotics, the search for alternatives has become crucial. In this study, we aimed to isolate, characterize, and evaluate two lytic bacteriophages against clinically isolated multidrug-resistant (MDR) Salmonella serovars.

METHODS

Screening for the phage lytic activity was performed using a spot test. Characterization of the isolated phages was done by determining the host range, longevity test, and the effect of temperature, pH, organic solvents, and morphological characterization using a transmission electron microscope. Genomic analysis was performed using Oxford nanopore sequencing. The lytic activities of the free phage lysates and formulated phage as microencapsulated were evaluated both in vitro and in vivo.

RESULTS

Two phages (VB_ST_E15 and VB_ST_SPNIS2) were successfully isolated and showed lytic strong activities against MDR Salmonella (S.) Typhimurium ATCC 14,028, S. Paratyphi A, and S. Typhi. The two phages survived at the tested temperatures, maintained their infectivity for 90 days, and retained their activity until 60 °C with thermal inactivation at 65 °C. They were lytic at a pH range from 3 to 11 but lost their activities at extremely acidic or alkaline pH. The phages could withstand the organic solvents but were completely inactivated by 100% ethanol. Both phages were classified under the order Caudoviricetes, and Genus: Uetakevirus. Their genomic sequences were assembled, annotated, and submitted to the NCBI GenBank database (OR757455 and OR757456). The preclinical evaluation using the murine animal model revealed that the two-phage cocktail managed MDR Salmonella infection as evidenced by the reduction in the bacterial burden, increased animal weight, and histopathological examination.

CONCLUSION

The two encapsulated phage formulas could be considered promising candidates for the management of MDR Salmonella-associated infections and clinical analysis should be undertaken to evaluate their potential use in humans.

Paving the way forward: Escherichia coli bacteriophages in a One Health approach

Escherichia coli is one of the most notorious pathogens for its ability to adapt, colonize, and proliferate in different habitats through a multitude of acquired virulence factors. Its presence affects the food-processing industry and causes food poisoning, being also a major economic burden for the food, agriculture, and health sectors. Bacteriophages are emerging as an appealing strategy to mitigate bacterial pathogens, including specific E. coli pathovars, without exerting a deleterious effect on humans and animals. This review globally analyzes the applied research on E. coli phages for veterinary, food, and human use. It starts by describing the pathogenic E. coli pathotypes and their relevance in human and animal context. The idea that phages can be used as a One Health approach to control and interrupt the transmission routes of pathogenic E. coli is sustained through an exhaustive revision of the recent literature. The emerging phage formulations, genetic engineering and encapsulation technologies are also discussed as a means of improving phage-based control strategies, with a particular focus on E. coli pathogens.

Bacteriophages: Status quo and emerging trends toward one health approach

The alarming rise in antimicrobial resistance (AMR) among the drug-resistant pathogens has been attributed to the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, Enterobacter sp., and Escherichia coli). Recently, these AMR microbes have become difficult to treat, as they have rendered the existing therapeutics ineffective. Thus, there is an urgent need for effective alternatives to lessen or eliminate the current infections and limit the spread of emerging diseases under the "One Health" framework. Bacteriophages (phages) are naturally occurring biological resources with extraordinary potential for biomedical, agriculture/food safety, environmental protection, and energy production. Specific unique properties of phages, such as their bactericidal activity, host specificity, potency, and biocompatibility, make them desirable candidates in therapeutics. The recent biotechnological advancement has broadened the repertoire of phage applications in nanoscience, material science, physical chemistry, and soft-matter research. Herein, we present a comprehensive review, coupling the substantial aspects of phages with their applicability status and emerging opportunities in several interdependent areas under one health concept. Consolidating the recent state-of-the-art studies that integrate human, animal, plant, and environment health, the following points have been highlighted: (i) The biomedical and pharmacological advantages of phages and their antimicrobial derivatives with particular emphasis on in-vivo and clinical studies. (ii) The remarkable potential of phages to be altered, improved, and applied for drug delivery, biosensors, biomedical imaging, tissue engineering, energy, and catalysis. (iii) Resurgence of phages in biocontrol of plant, food, and animal-borne pathogens. (iv) Commercialization of phage-based products, current challenges, and perspectives.

Phage therapy: a revolutionary shift in the management of bacterial infections, pioneering new horizons in clinical practice, and reimagining the arsenal against microbial pathogens

The recent approval of experimental phage therapies by the FDA and other regulatory bodies with expanded access in cases in the United States and other nations caught the attention of the media and the general public, generating enthusiasm for phage therapy. It started to alter the situation so that more medical professionals are willing to use phage therapies with conventional antibiotics. However, more study is required to fully comprehend phage therapy's potential advantages and restrictions, which is still a relatively new field in medicine. It shows promise, nevertheless, as a secure and prosperous substitute for antibiotics when treating bacterial illnesses in animals and humans. Because of their uniqueness, phage disinfection is excellent for ready-to-eat (RTE) foods like milk, vegetables, and meat products. The traditional farm-to-fork method can be used throughout the food chain to employ bacteriophages to prevent food infections at all production stages. Phage therapy improves clinical outcomes in animal models and lowers bacterial burdens in numerous preclinical investigations. The potential of phage resistance and the need to make sure that enough phages are delivered to the infection site are obstacles to employing phages in vivo. However, according to preclinical studies, phages appear to be a promising alternative to antibiotics for treating bacterial infections in vivo. Phage therapy used with compassion (a profound understanding of and empathy for another's suffering) has recently grown with many case reports of supposedly treated patients and clinical trials. This review summarizes the knowledge on the uses of phages in various fields, such as the food industry, preclinical research, and clinical settings. It also includes a list of FDA-approved bacteriophage-based products, commercial phage products, and a global list of companies that use phages for therapeutic purposes.

The Role of Bacteriophages in the Gut Microbiota: Implications for Human Health

Bacteriophages (phages) are nano-sized viruses characterized by their inherent ability to live off bacteria. They utilize diverse mechanisms to absorb and gain entry into the bacterial cell wall via the release of viral genetic material, which uses the replication mechanisms of the host bacteria to produce and release daughter progeny virions that attack the surrounding host cells. They possess specific characteristics, including specificity for particular or closely related bacterial species. They have many applications, including as potential alternatives to antibiotics against multi-resistant bacterial pathogens and as control agents in bacteria-contaminated environments. They are ubiquitously abundant in nature and have diverse biota, including in the gut. Gut microbiota describes the community and interactions of microorganisms within the intestine. As with bacteria, parasitic bacteriophages constantly interact with the host bacterial cells within the gut system and have obvious implications for human health. However, it is imperative to understand these interactions as they open up possible applicable techniques to control gut-implicated bacterial diseases. Thus, this review aims to explore the interactions of bacteriophages with bacterial communities in the gut and their current and potential impacts on human health.

Statistical optimization of a podoviral anti-MRSA phage CCASU-L10 generated from an under sampled repository: Chicken rinse

Introduction

The insurgence of antimicrobial resistance is an imminent health danger globally. A wide range of challenging diseases are attributed to methicillin-resistant Staphylococcus aureus (MRSA) as it is weaponized with a unique array of virulence factors, and most importantly, the resistance it develops to most of the antibiotics used clinically. On that account, the present study targeted the optimization of the production of a bacteriophage active against MRSA, and evaluating some of its characters.

Methods and results

The bacteriophage originated from a quite peculiar environmental source, raw chicken rinse and was suggested to belong to Podoviridae, order Caudovirales. It withstood a variety of extreme conditions and yield optimization was accomplished via the D-optimal design by response surface methodology (RSM). A reduced quadratic model was generated, and the ideal production conditions recommended were pH 8, glycerol 0.9% v/v, peptone 0.08% w/v, and 107 CFU/ml as the host inoculum size. These conditions led to a two-log fold increase in the phage titer (1.17x10¹² PFU/ml), as compared to the regular conditions.

Discussion

To conclude, statistical optimization successfully enhanced the output of the podoviral phage titer by two-log fold and therefore, can be regarded as a potential scale-up strategy. The produced phage was able to tolerate extreme environmental condition making it suitable for topical pharmaceutical preparations. Further preclinical and clinical studies are required to ensure its suitability for use in human.

Accessing the In Vivo Efficiency of Clinically Isolated Phages against Uropathogenic and Invasive Biofilm-Forming Escherichia coli Strains for Phage Therapy

Escherichia coli is one of the most common members of the intestinal microbiota. Many of its strains are associated with various inflammatory infections, including urinary or gut infections, especially when displaying antibiotic resistance or in patients with suppressed immune systems. According to recent reports, the biofilm-forming potential of E. coli is a crucial factor for its increased resistance against antibiotics. To overcome the limitations of using antibiotics against resistant E. coli strains, the world is turning once more towards bacteriophage therapy, which is becoming a promising candidate amongst the current personalized approaches to target different bacterial infections. Although matured and persistent biofilms pose a serious challenge to phage therapy, they can still become an effective alternative to antibiotic treatment. Here, we assess the efficiency of clinically isolated phages in phage therapy against representative clinical uropathogenic and invasive biofilm-forming E. coli strains. Our results demonstrate that irrespective of host specificity, bacteriophages producing clear plaques with a high burst size, and exhibiting depolymerizing activity, are good candidates against biofilm-producing E. coli pathogens as verified from our in vitro and in vivo experiments using Galleria mellonella where survival was significantly increased for phage-therapy-treated larvae.

The Role of the Human Gut Microbiome in Inflammatory Bowel Disease and Radiation Enteropathy

The human gut microbiome plays a key role in regulating host physiology. In a stable state, both the microbiota and the gut work synergistically. The overall homeostasis of the intestinal flora can be affected by multiple factors, including disease states and the treatments given for those diseases. In this review, we examine the relatively well-characterised abnormalities that develop in the microbiome in idiopathic inflammatory bowel disease, and compare and contrast them to those that are found in radiation enteropathy. We discuss how these changes may exert their effects at a molecular level, and the possible role of manipulating the microbiome through the use of a variety of therapies to reduce the severity of the underlying condition.

An Anti-MRSA Phage From Raw Fish Rinse: Stability Evaluation and Production Optimization

Accumulating evidence has denoted the danger of resistance in tenacious organisms like methicillin-resistant Staphylococcus aureus (MRSA). MRSA, a supple bacterium that adopts a variety of antibiotic resistance mechanisms, is the cause of multiple life-threatening conditions. Approaching a post-antibiotic era, bacteria-specific natural predators, bacteriophages, are now given the chance to prove eligible for joining the antibacterial weaponry. Considering the foregoing, this study aimed at isolating bacteriophages with promising anti-MRSA lytic activity, followed by characterization and optimization of the production of the bacteriophage with the broadest host range. Five phages were isolated from different environmental sources including the rinse of raw chicken egg, raw milk, and, remarkably, the raw meat rinses of chicken and fish. Examined for lytic activity against a set of 23 MRSA isolates collected from various clinical specimens, all five phages showed relatively broad host ranges with the bacteriophage originally isolated from raw fish rinse showing lytic activity against all the isolates tested. This phage is suggested to be a member of Siphoviridae family, order Caudovirales, as revealed by electron microscopy. It also exhibited good thermal stability and viability at different pH grades. Moreover, it showed reasonable stability against UV light and all viricidal organic solvents tested. Optimization using D-optimal design by response surface methodology was carried out to enhance the phage yield. The optimum conditions suggested by the generated model were a pH value of 7, a carbon source of 0.5% w/v sucrose, and a nitrogen source of 0.1% w/v peptone, at a temperature of 28°C and a bacterial inoculum size of 107 CFU/ml, resulting in a 2 log-fold increase in the produced bacteriophage titer. Overall, the above findings indicate the lytic ability inflicted by this virus on MRSA. Apparently, its stability under some of the extreme conditions tested implies its potential to be a candidate for pharmaceutical formulation as an anti-MRSA therapeutic tool. We hope that bacteriophages could tip the balance in favor of the human front in their battle against multidrug-resistant pathogens.

Current Status of Phage Therapy against Infectious Diseases and Potential Application beyond Infectious Diseases

Intestinal microbiota plays a key role in regulating the pathogenesis of human disease and maintaining health. Many diseases, mainly induced by bacteria, are on the rise due to the emergence of antibiotic-resistant strains. Intestinal microorganisms include organisms such as bacteria, viruses, and fungi. They play an important role in maintaining human health. Among these microorganisms, phages are the main members of intestinal viromes. In particular, the viral fraction, composed essentially of phages, affects homeostasis by exerting selective pressure on bacterial communities living in the intestinal tract. In recent years, with the widespread use and even abuse of antibacterial drugs, more and more drug-resistant bacteria have been found, and they show a trend of high drug resistance and multidrug resistance. Therefore, it has also become increasingly difficult to treat serious bacterial infections. Phages, a natural antibacterial agent with strong specificity and rapid proliferation, have come back to the field of vision of clinicians and scholars. In this study, the current state of research on intestinal phages was discussed, with an exploration of the impact of phage therapy against infectious diseases, as well as potential application beyond infectious diseases.

Roles of Gut Bacteriophages in the Pathogenesis and Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, are chronic, relapsing intestinal inflammatory disorders. Although the molecular mechanisms governing the pathogenesis of IBD are not completely clear, the main factors are presumed to be a complex interaction between genetic predisposition, host immune response and environmental exposure, especially the intestinal microbiome. Currently, most studies have focused on the role of gut bacteria in the onset and development of IBD, whereas little attention has been paid to the enteroviruses. Among of them, viruses that infect prokaryotes, called bacteriophages (phages) occupy the majority (90%) in population. Moreover, several recent studies have reported the capability of regulating the bacterial population in the gut, and the direct and indirect influence on host immune response. The present review highlights the roles of gut phages in IBD pathogenesis and explores the potentiality of phages as a therapeutic target for IBD treatment.

Microbiome therapeutics: exploring the present scenario and challenges

Human gut-microbiome explorations have enriched our understanding of microbial colonization, maturation, and dysbiosis in health-and-disease subsets. The enormous metabolic potential of gut microbes and their role in the maintenance of human health is emerging, with new avenues to use them as therapeutic agents to overcome human disorders. Microbiome therapeutics are aimed at engineering the gut microbiome using additive, subtractive, or modulatory therapy with an application of native or engineered microbes, antibiotics, bacteriophages, and bacteriocins. This approach could overcome the limitation of conventional therapeutics by providing personalized, harmonized, reliable, and sustainable treatment. Its huge economic potential has been shown in the global therapeutics market. Despite the therapeutic and economical potential, microbiome therapeutics is still in the developing stage and is facing various technical and administrative issues that require research attention. This review aims to address the current knowledge and landscape of microbiome therapeutics, provides an overview of existing health-and-disease applications, and discusses the potential future directions of microbiome modulations.

Isolation and identification of specific bacteriophages against methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli, extended-spectrum beta-lactamases-producing Klebsiella pneumoniae, and multidrug-resistant Acinetobacter baumanniiin vitro

Drug resistance of methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases-producing Escherichia coli and Klebsiella pneumoniae and multidrug-resistant Acinetobacter baumannii are also cited as one of the most important causes of community and hospital acquired infections. Phage therapy can be used as a therapeutic method for the treatment of infections caused by these bacteria. The aim of this study was to isolate bacteriophages from municipal wastewater and assess their effects against drug resistant bacterial strains. The single agar layer technique was used to investigate the bacteriolytic effect of bacteriophages. Then, the double agar layer technique was used to observe phage plaques and the transmission electron microscopy was used to study the morphology of the bacteriophages. Transparent plaque formation in a double agar layer test of methicillin-resistant S. aureus and extended-spectrum beta-lactamases-producing E. coli and K. pneumoniae indicated the lysis of bacterial cells by isolated bacteriophages. No bacteriophage against A. baumannii was isolated from municipal wastewater. The morphology of these bacteriophages was also identified by electron microscopy. The results of this study showed that bacteriophages act specifically and due to the increasing level of antibiotic resistance, phage therapy as a new treatment can open a new horizon for the treatment of multidrug resistant bacteria.

Encapsulation of bacteriophage cocktail into chitosan for the treatment of bacterial diarrhea

The therapeutic effectiveness of a chitosan encapsulated bacteriophage cocktail as a smart biocontrol agent was evaluated in this study to be used as a preventative and treatment option for gastrointestinal infections. To evaluate the effect of the bacteriophage formulation on the treatment of gastrointestinal infection, rats were infected with Salmonella enterica, Shigella flexneri, and Escherichia coli. The rats were weighed and their stools cultured. The results showed that the group which had the chitosan encapsulated bacteriophage cocktail did not lose weight after 3 days and had significantly lower group weight changes. Weight loss was significant in the rats that had cefixime administered instead. Positive cultured stools were reduced after 4 days compared to 2 days in the treated group with the chitosan encapsulated bacteriophage cocktail. The chitosan encapsulated bacteriophage cocktail can therefore be effective in the treatment of gastrointestinal infections.

Bacteriophage therapy: Recent developments and applications of a renaissant weapon

Antimicrobial resistance is a global health problem and one of the leading concerns in healthcare sector. Bacteriophages are antibacterial agents ubiquitous in nature. With increase in antibiotic resistance, use of bacteriophages as therapeutics has become resurgent in recent times. This review focuses on the recent developments in phage therapy and its applications with respect to human infections, animal, food and environment. Moreover, use of phage proteins, bioengineered bacteriophages, and phage derived vaccines is also highlighted. Additionally, the limitations and challenges with regard to implementation of phage therapy, host safety and immune responses are also reviewed in this article.

Characterization of a Novel Bacteriophage swi2 Harboring Two Lysins Can Naturally Lyse Escherichia coli

The novel virulent Siphoviridae bacteriophage swi2 was isolated from a pig farm, and its biological characteristics, genome architecture, and infection-related properties were characterized. Phage swi2 has a high titer of 1.01 × 10¹² PFU/mL with good tolerance to UV rays and remains stable in the pH range of 6–10 and at temperatures less than 50°C. One-step growth analysis revealed that phage swi2 had a 25 min latent period with a large burst size (1,000 PFU/cell). The biological characteristics indicated that swi2 had good host infectivity and effective lytic activities. The genome of phage swi2 is composed of 47,611 bp with a G + C content of 46.50%. Eighty-nine orfs were predicted, and only 18 of them have known functions. No virulence genes or drug resistance genes were found in the genome. Genome sequence comparison of phage swi2 showed that there were a total of 10 homologous phages in the database with low similarity (less than 92.51% nucleotide identity and 66% query coverage). The predicted host lysis-related genes of phage swi2 consist of one holin, two endolysins, and Rz/Rz1 equivalents. Antibacterial activity assays showed that both endolysins could naturally reduce the host Escherichia coli 51 titers by -1 log unit both in vitro and in vivo, EDTA showed no obvious synergistic action, and holin had no lytic effects on the host cell. These results provide necessary information for the development of antibiotic alternatives for the treatment of multidrug-resistant Escherichia coli infection.

The clinical path to deliver encapsulated phages and lysins

The global emergence of multidrug-resistant pathogens is shaping the current dogma regarding the use of antibiotherapy. Many bacteria have evolved to become resistant to conventional antibiotherapy, representing a health and economic burden for those afflicted. The search for alternative and complementary therapeutic approaches has intensified and revived phage therapy. In recent decades, the exogenous use of lysins, encoded in phage genomes, has shown encouraging effectiveness. These two antimicrobial agents reduce bacterial populations; however, many barriers challenge their prompt delivery at the infection site. Encapsulation in delivery vehicles provides targeted therapy with a controlled compound delivery, surpassing chemical, physical and immunological barriers that can inactivate and eliminate them. This review explores phages and lysins' current use to resolve bacterial infections in the respiratory, digestive, and integumentary systems. We also highlight the different challenges they face in each of the three systems and discuss the advances towards a more expansive use of delivery vehicles.

Postbiotic-Enabled Targeting of the Host-Microbiota-Pathogen Interface: Hints of Antibiotic Decline?

Mismanagement of bacterial infection therapies has undermined the reliability and efficacy of antibiotic treatments, producing a profound crisis of the antibiotic drug market. It is by now clear that tackling deadly infections demands novel strategies not only based on the mere toxicity of anti-infective compounds. Host-directed therapies have been the first example as novel treatments with alternate success. Nevertheless, recent advances in the human microbiome research have provided evidence that compounds produced by the microbial metabolism, namely postbiotics, can have significant impact on human health. Such compounds target the host-microbe-pathogen interface rescuing biotic and immune unbalances as well as inflammation, thus providing novel therapeutic opportunities. This work discusses critically, through literature review and personal contributions, these novel nonantibiotic treatment strategies for infectious disease management and resistance prevention, which could represent a paradigm change rocking the foundation of current antibiotic therapy tenets.

Effectiveness of Bacteriophage Therapy in Field Conditions and Possible Future Applications

BACKGROUND

Bacteriophages are viruses, which are obligate parasites of specific bacteria for the completion of their lifecycle. Bacteriophages could be the possible alternative to antibioticresistant bacterial diseases. With this objective, extensive research in different fields is published which are discussed in this article.

METHODS

After a review of bacteriophage therapy, bacteriophages were found to be effective against the multidrug-resistant bacteria individually or synergistically with antibiotics. They were found to be more effective, even better than the bacteria in the development of a vaccine.

RESULTS

Apart from the bacteriophages, their cell contents like Lysin enzymes were found equally very much effective. Only the major challenge faced in phage therapy was the identification and characterization of bacteria-specific phages due to the wide genetic diversity of bacterial populations. Similarly, the threshold level of bacteriophages to act effectively was altered by ultraviolet radiation and heat exposure.

CONCLUSION

Thus, bacteriophage therapy offers promising alternatives in the treatment of antibioticresistant bacteria in different fields. However, their effectiveness is determined by a triad of bacteriophages (type & quantity), host (bacteria) and environmental factors.

Phage Types of Vibrio cholerae 01 Biotype ElTor Strains Isolated from India during 2012-2017

Background

Cholera is a primordial disease caused by Vibrio cholerae which existed from centuries in different parts of the world and still shows its periodic, endemic and epidemic presence. Thousands of cholera cases are reported from different parts of India and the disease remains endemic throughout the year. At present, we do not have enough knowledge about the phenotypic nature of the circulating V. cholerae strains in this part of the world.

Objectives

This study was carried out over a period of 6 years with the aim defer with the changes in the prevalence and distribution of biotypes, serotypes and phage types of V. cholerae clinical isolates from various endemic regions of the country to determine phenotypic characteristics of the circulating strains and also to predict the attributes of cholera strains responsible for causing significant outbreaks in future.

Materials and Methods

A total of 1882 V.cholerae O1 isolates from different cholera endemic areas of India were included in this study. V.cholerae strains which were identified as O1 biotype ElTor further analyzed for serotype and phage types using the standard methodologies. Polyvalent O1 and monospecific Inaba and Ogawa antisera were used for serotyping. A panel of five phages of Basu and Mukherjee phage typing scheme and five phages from the new phage typing scheme were used for phage typing analysis following standard methodology.

Results

Maximum numbers of strains were isolated from cholera-endemic states like Gujarat and Maharashtra. All the isolates were confirmed as V. cholerae O1 biotype ElTor and majority of them were serotype Ogawa (93.2%). New phage typing scheme resulted in almost 100% typeable V. cholerae O1 strains included in this study and phage type 27 was the predominant type. Although 80% of the strains used in this study were sensitive to all the vibrio phages, S5 phage was found most efficient in lysing cholera strains indicating its broader host range.

Conclusion

The current study identified phage type 27 as the most dominant type and serotype Ogawa was found continuous in circulation throughout the year which has caused recent cholera outbreaks in India during the past years. Phage sensitivity data propose an alternative cost-effective approach to prevent cholera outbreak by therapeutic uses of typing phages irrespective of origin or clonality of the strains.

Biological challenges of phage therapy and proposed solutions: a literature review

Introduction: In light of the emergence of antibiotic-resistant bacteria, phage (bacteriophage) therapy has been recognized as a potential alternative or addition to antibiotics in Western medicine for use in humans.Areas covered: This review assessed the scientific literature on phage therapy published between 1 January 2007 and 21 October 2019, with a focus on the successes and challenges of this prospective therapeutic.Expert opinion: Efficacy has been shown in animal models and experimental findings suggest promise for the safety of human phagotherapy. Significant challenges remain to be addressed prior to the standardization of phage therapy in the West, including the development of phage-resistant bacteria; the pharmacokinetic complexities of phage; and any potential human immune response incited by phagotherapy.

Phage-Antibiotic Combination Treatments: Antagonistic Impacts of Antibiotics on the Pharmacodynamics of Phage Therapy?

Bacteria can evolve resistance to antibiotics. Even without changing genetically, bacteria also can display tolerance to antibiotic treatments. Many antibiotics are also broadly acting, as can result in excessive modifications of body microbiomes. Particularly for antibiotics of last resort or in treating extremely ill patients, antibiotics furthermore can display excessive toxicities. Antibiotics nevertheless remain the standard of care for bacterial infections, and rightly so given their long track records of both antibacterial efficacy and infrequency of severe side effects. Antibiotics do not successfully cure all treated bacterial infections, however, thereby providing a utility to alternative antibacterial approaches. One such approach is the use of bacteriophages, the viruses of bacteria. This nearly 100-year-old bactericidal, anti-infection technology can be effective against antibiotic-resistant or -tolerant bacteria, including bacterial biofilms and persister cells. Ideally phages could be used in combination with standard antibiotics while retaining their anti-bacterial pharmacodynamic activity, this despite antibiotics interfering with aspects of bacterial metabolism that are also required for full phage infection activity. Here I examine the literature of pre-clinical phage-antibiotic combination treatments, with emphasis on antibiotic-susceptible bacterial targets. I review evidence of antibiotic interference with phage infection activity along with its converse: phage antibacterial functioning despite antibiotic presence.

Bacteriocins and Bacteriophages: Therapeutic Weapons for Gastrointestinal Diseases?

Bacteriocins are bactericidal peptides, ribosomally synthesized, with an inhibitory activity against diverse groups of undesirable microorganisms. Bacteriocins are produced by both gram-positive and gram-negative bacteria, and to a lesser extent by some archaea. Bacteriophages are viruses that are able to infect bacterial cells and force them to produce viral components, using a lytic or lysogenic cycle. They constitute a large community in the human gut called the phageome, the most abundant part of the gut virome. Bacteriocins and bacteriophages may have an influence on both human health and diseases, thanks to their ability to modulate the gut microbiota and regulate the competitive relationship among the different microorganisms, strains and cells living in the human intestine. In this review, we explore the role of bacteriocins and bacteriophages in the most frequent gastrointestinal diseases by dissecting their interaction with the complex environment of the human gut, analyzing a possible link with extra-intestinal diseases, and speculating on their possible therapeutic application with the end goal of promoting gut health.

Isolation, characterization and in vivo efficacy of Escherichia phage myPSH1131

Phage therapy is the use of lytic bacteriophages to cure infections caused by bacteria. The aim of this study is to isolate and to characterize the bacteriophages against Escherichia coli isolated from clinical samples. For isolation of bacteriophages, water samples were collected from the Ganges River, and phage enrichment method was followed for phage isolation. Microbiological, genomic and lyophilization experiments were carried out to characterize the bacteriophage. Galleria mellonella was used to study the potential of phages against E. coli infection. Escherichia phage myPSH1131 belonging to Podoviridae family and found to have broad host range infectivity (n = 31) to infect Enterohemorrhagic E. coli (n = 9), Enteropathogenic E. coli (n = 6), Enterotoxigenic E. coli (n = 3), Enteroaggregative E. coli (n = 3), Uropathogenic E. coli (n = 9) and one unknown E. coli. The genome size is 76,163 base pairs (97 coding regions) and their genes show high similarity to SU10 phage. Lyophilization studies showed that the use of 1M sucrose, 2% gelatin and the combination of both 0.5M sucrose plus 1% gelatin could restore phage viability up to 20 months at 4°C. For in vivo studies, it was observed that a single phage dose can reduce the E. coli infection but to achieve 100% survival rate the infected larvae should be treated with three phage doses (20 μL, 10³ PFU/mL) at 6 hours interval. The characterized Escherichia phage myPSH1131 was found to have broad host range activity against E. coli pathogens and in vivo studies showed that multiple doses are required for effective treatment.

Bacteriophage Therapy: Clinical Trials and Regulatory Hurdles

Increasing reports of antimicrobial resistance and limited new antibiotic discoveries and development have fuelled innovation in other research fields and led to a revitalization of bacteriophage (phage) studies in the Western world. Phage therapy mainly utilizes obligately lytic phages to kill their respective bacterial hosts, while leaving human cells intact and reducing the broader impact on commensal bacteria that often results from antibiotic use. Phage therapy is rapidly evolving and has resulted in cases of life-saving therapeutic use and multiple clinical trials. However, one of the biggest challenges this antibiotic alternative faces relates to regulations and policy surrounding clinical use and implementation beyond compassionate cases. This review discusses the multi-drug resistant Gram-negative pathogens of highest critical priority and summarizes the current state-of-the-art in phage therapy targeting these organisms. It also examines phage therapy in humans in general and the approaches different countries have taken to introduce it into clinical practice and policy. We aim to highlight the rapidly advancing field of phage therapy and the challenges that lie ahead as the world shifts away from complete reliance on antibiotics.