Isolation and Identification of Two Novel Escherichia coli Bacteriophages and Their Application in Wastewater Treatment and Coliform's Phage Therapy

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.

The role of identified and characterized bacteriophage ZCEC13 in controlling pathogenic and multidrug-resistant Escherichia coli in wastewater: in vitro study

The spread and development of Multi-Drug Resistant (MDR) bacteria in wastewater became beyond control and a global public health concern. The conventional disinfectants used in wastewater treatment methods have been becoming increasingly ineffective against a range of pathogenic and MDR bacteria. Bacteriophages are considered a novel approach to microbial control. Therefore, this study aims to explore the possibility of using phages against pathogenic and MDR Escherichia coli strains isolated from wastewater treatment plants. The wastewater samples were collected from two different treatment plants for E. coli isolation. The antibiotic sensitivity profile and occurrence of virulence and resistant genes were tested in 28 E. coli isolates. Phage ZCEC13 was selected based on its promising activity and host range to undergo identification and characterization. ZCEC13 was evaluated by transmission electron microscopy, genomic sequencing, in vitro lytic activity and tested for its stability under different conditions such as pH, Ultraviolet light exposure, and temperature. The results reported that ZCEC13 belongs to the Caudoviricetes class, with a high antibacterial dynamic. Phage ZCEC13 displayed high stability at different pH values ranging from 2 to 12, good tolerance to temperatures from -4 to 65°C, and high stability at UV exposure for 120 min. Respectively, the findings showed stability of the phage under several conditions and high efficiency in killing MDR bacteria isolated from the treatment plants. Further studies are encouraged to analyse the efficacy of phages as a microbial control agent in wastewater treatment plants.

Callistemon viminalis leaf extract phytochemicals modified silver-ruthenium bimetallic zinc oxide nanocomposite biosynthesis: application on nanocoating photocatalytic Escherichia coli disinfection

Antibiotics are of great interest due to antibiotic-resistant problems around the globe due to bacterial resistance to conventional antibiotics. In this study, a novel green biosynthesis of silver-ruthenium bimetallic zinc oxide nanocomposite using Callistemon viminalis leaf extract as a reducing agent using zinc nitrate hexahydrate, silver nitrate, and ruthenium(iii) chloride as capping agents was reported. The results demonstrated that the surface morphology of the prepared bimetallic nanocomposite by scanning electron microscopy was hexagonal in shape for zinc nanoparticle, rectangular in shape for silver nanoparticle, and tetragonal in shape for ruthenium nanoparticle, having an average surface size 25, 35, and 55 nm, respectively. Fourier transform infrared analysis confirmed the presence of compounds containing alkene, halo-, sulfoxide, phenol, nitro-, phenyl-ester, carboxylic acid, amines, and alcohols which act as functional groups attached to the surface of nanocomposites. Results from X-ray diffraction analysis found 81.12% crystallinity and hexagonal structure of zinc nanoparticles, rectangular structure of silver nanoparticles, and tetragonal structure of ruthenium nanoparticles, which are also similar to the results from transmission electron microscopy analysis. The average size distribution by dynamic light scattering of silver-ruthenium bimetallic zinc oxide nanocomposite was 255 nm, which confirms the biosynthesis of non-uniform size. Photo-disinfection activity of a silver-ruthenium bimetallic zinc oxide nanocomposite against Escherichia coli bacteria isolated from hospital wastewater under dark and ultraviolet-A irradiation conditions was observed. The antibacterial activity was calculated at 2.42704239, ensuring the silver-ruthenium bimetallic zinc oxide nanomaterials have photo-disinfection properties. The results from this study revealed that the developed novel antibacterial nanocomposite of silver-ruthenium bimetallic zinc oxide is useful in nanocoating photocatalytic Escherichia coli disinfection and can be applied to disinfect surfaces.

Characterization and synergy studies of Caudoviricete Escherichia phage FS2B infecting multi-drug resistant uropathogenic Escherichia coli isolates

Escherichia coli is one of the most common causes of urinary tract infections. However, a recent upsurge in antibiotic resistance among uropathogenic E. coli (UPEC) strains has provided an impetus to explore alternative antibacterial compounds to encounter this major issue. In this study, a lytic phage against multi-drug-resistant (MDR) UPEC strains was isolated and characterized. The isolated Escherichia phage FS2B of class Caudoviricetes exhibited high lytic activity, high burst size, and a small adsorption and latent time. The phage also exhibited a broad host range and inactivated 69.8% of the collected clinical, and 64.8% of the identified MDR UPEC strains. Further, whole genome sequencing revealed that the phage was 77,407 bp long, having a dsDNA with 124 coding regions. Annotation studies confirmed that the phage carried all the genes associated with lytic life cycle and all lysogeny related genes were absent in the genome. Further, synergism studies of the phage FS2B with antibiotics demonstrated a positive synergistic association among them. The present study therefore concluded that the phage FS2B possesses an immense potential to serve as a novel candidate for treatment of MDR UPEC strains.

Characterization of a novel genus of jumbo phages and their application in wastewater treatment

Phages widely exist in numerous environments from wastewater to deep ocean, representing a huge virus diversity, yet remain poorly characterized. Among them, jumbo phages are of particular interests due to their large genome (>200 kb) and unusual biology. To date, only six strains of jumbo phages infecting Klebsiella pneumoniae have been described. Here, we report the isolation and characterization of two jumbo phages from hospital wastewater representing the sixth genus: φKp5130 and φKp9438. Both phages showed lytic activity against broad range of clinical antibiotic-resistant K. pneumoniae strains and distinct physiology including long latent period, small burst size, and high resistance to thermal and pH stress. The treatment of sewage water with the phages cocktail resulted in dramatic decline in K. pneumoniae population. Overall, this study provides detailed molecular and genomics characterization of two novel jumbo phages, expands viral diversity, and provides novel candidate phages to facilitate environmental wastewater treatment.

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

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

Bacteriophages in wastewater treatment: can they be an approach to optimize biological treatment processes?

In this paper, we explore the applications of bacteriophages and the advantages of using these viruses to control undesirable organisms in wastewater treatment plants. Based on this, this paper reviewed the literature on the subject by performing a bibliometric and scientometric analysis of articles published in peer-reviewed journals through 2021. We obtained 806 publications, of which 40% were published in the last 5 years, demonstrating an increase in interest in the subject. These articles analyzed, bacteriophages in treatment plants were strongly linked to bacteria such as Escherichia coli and related to disinfection, inactivation, sewage, and wastewater, in addition, biocontrol studies have gained prominence in recent years, particularly due to the resistance of microorganisms to antibiotics. Studies have shown that bacteriophages have great potential for application in treatment systems to control unwanted processes and act as valuable economic and environmental tools to improve the efficiency of various treatment technologies. Although these viruses have already been studied in various applications to optimize treatment plant processes, technology transfer remains a challenge due to the limitations of the technique-such as physicochemical factors related to the environment-and the complexity of biological systems. The research focusing on application strategies in conjunction with molecular biology techniques can expand this study area, enabling the discovery of new bacteriophages.

Bacteriophages in sewage: abundance, roles, and applications

The raw sewage that flows through sewage systems contains a complex microbial community whose main source is the human gut microbiome, with bacteriophages being as abundant as bacteria or even more so. Phages that infect common strains of the human gut bacteriome and transient bacterial pathogens have been isolated in raw sewage, as have other phages corresponding to non-sewage inputs. Although human gut phages do not seem to replicate during their transit through the sewers, they predominate at the entrance of wastewater treatment plants, inside which the dominant populations of bacteria and phages undergo a swift change. The sheer abundance of phages in the sewage virome prompts several questions, some of which are addressed in this review. There is growing concern about their potential role in the horizontal transfer of genes, including those related with bacterial pathogenicity and antibiotic resistance. On the other hand, some phages that infect human gut bacteria are being used as indicators of fecal/viral water pollution and as source tracking markers and have been introduced in water quality legislation. Other potential applications of enteric phages to control bacterial pathogens in sewage or undesirable bacteria that impede the efficacy of wastewater treatments, including biofilm formation on membranes, are still being researched.

Use of bacteriophage to inactivate pathogenic bacteria from wastewater

The aim of this study was to enhance the rhizobacterium potential in horizontal subsurface flow constructed wetland (CW) system planted by Phragmites australis using specific and lytic phages. The bioinoculation of specific bacteriophage for target bacteria; Salmonella typhi, and the monitoring of bacterial inactivation under different conditions showed the effectiveness of this methodology to enhance bacteria reduction and consequentially ameliorate purification performance of this studied biological treatment system. The injection of the phage at a concentration equal to 10³ UFP/mL within the rhizosphere of the inoculated filter (F) was allowed 1 U-Log₁₀ of improvement of bacterial inactivation compared to the control filter (T) nearly 1 logarithmic unit thus, a 90% improvement of bacteria reduction. When we increased the phage titer (10⁵ UFP/mL), the bacterial reduction equal to 2.75 U-Log₁₀ (N/N₀) was registered that corresponds to a decrease of nearly 99.9%. According to the first-order model, the inactivation coefficient is equal to 2.29 min^-1 (0.88 min^-1 for the first experiment) and the bacterial reduction rate is 5 times higher than that determined for the control filter. This results show the positive impact of the phage in the bacterial inactivation and the improvement of water treatment of the biofilter C.

Bacteriophages in the Control of Aeromonas sp. in Aquaculture Systems: An Integrative View

Aeromonas species often cause disease in farmed fish and are responsible for causing significant economic losses worldwide. Although vaccination is the ideal method to prevent infectious diseases, there are still very few vaccines commercially available in the aquaculture field. Currently, aquaculture production relies heavily on antibiotics, contributing to the global issue of the emergence of antimicrobial-resistant bacteria and resistance genes. Therefore, it is essential to develop effective alternatives to antibiotics to reduce their use in aquaculture systems. Bacteriophage (or phage) therapy is a promising approach to control pathogenic bacteria in farmed fish that requires a heavy understanding of certain factors such as the selection of phages, the multiplicity of infection that produces the best bacterial inactivation, bacterial resistance, safety, the host’s immune response, administration route, phage stability and influence. This review focuses on the need to advance phage therapy research in aquaculture, its efficiency as an antimicrobial strategy and the critical aspects to successfully apply this therapy to control Aeromonas infection in fish.

Isolation and characterization of novel phage (Podoviridae ɸParuNE1) and its efficacy against multi-drug-resistant Pseudomonas aeruginosa planktonic cells and biofilm

Background

Bacterial pathogen (Pseudomonas aeruginosa) could form biofilm that conveys multi-drug resistance. Bacteriophage as an alternative to antibacterial resistance is useful against biofilm complications. This study evaluated antibacterial and biofilm removal activities of lytic phage, specific against multi-drug-resistant clinical P. aeruginosa.

Results

The phage showed a wide range of pH (5–10) and heat (7–44 °C) stability. Electron microscopy showed ɸPauNE1 phage head (60 nm in diameter) and non-contractile tail (12 nm in length by 8 nm in width); hence, the family Podoviridae and the order Caudovirales. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed structured protein of 55 kDa and double-stranded DNA of 45 kb. The phage was species specific and had broad host range activity. It inhibited bacterial growth at multiplicity of infection (MOI) 1–0.000001 pfu/ml. Inhibition was maximal at both low (1 × 105) and high (1 × 109) bacterial CFU/ml. Biofilm removal test showed that the phage removed more than 60% cell biomass within CFU/ml of 1.5 × 108, 6.0 × 108 and l.0 × 109.

Conclusion

Phage (ɸPauNE1) was unique and had broad host range activity. The phage exhibited strong bacteriolytic activity against biofilm forming multi-drug-resistant strains. It had no lytic effect on the heterogeneous strains and so a promising bioagent.

Bacteriophages PɸEn-CL and PɸEn-HO can eliminate MDR Enterobacter cloacae and Enterobacter hormaechei isolated from burn wound infections without toxicity for human skin cells

The prevalence of multidrug-resistant (MDR) strains has caused serious problems in the treatment of burn infections. MDR Enterobactercloacae and Enterobacterhormaechei have been defined as the causative agents of nosocomial infections in burn patients. In this situation, examination of phages side effects on human cell lines before any investigation on human or animal that can provide beneficial information about the safety of isolated phages. The aim of this study was to isolate and identify the specific bacteriophages on MDR E. cloacae and E. hormaechei isolated from burn wounds and to analyze the efficacy, cell viability and cell cytotoxicity of phages on A-375 and HFSF-PI cell lines by MTT (3-(4, 5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide) colorimetric assay and lactate dehydrogenase (LDH) release assay. Phages were isolated from urban sewage Isfahan, Iran. Enterobactercloacae strain Iau-EC100 (GenBank accession number: MZ314381) and E. hormaechei strain Iau-EHO100 (GenBank accession number: MZ348826) were sensitive to the isolated phages. Transmission electron microscopy (TEM) results revealed that PɸEn-CL and PɸEn-HO that were described had the morphologies of Myovirus and Inovirus, respectively. Overall, MTT and LDH assays showed moderate to excellent correlation in the evaluation of cytotoxicity of isolated phages. The results of MTT and LDH assays showed that, phages PɸEn-CL and PɸEn-HO had no significant toxicity effect on A375 and HFSF-PI 3 cells. Phage PɸEn-HO had a better efficacy on the two tested cell lines than other phage. Our results indicated that, there were significant differences between the two cytotoxicity assays in phage treatment compared to control.

Efficacious antibacterial potency of novel bacteriophages against ESBL-producing Klebsiella pneumoniae isolated from burn wound infections

BACKGROUND AND OBJECTIVES

Prevalence of extended spectrum β-lactamase (ESBL) leads to the development of antibiotic resistance and mortality in burn patients. One of the alternative strategies for controlling ESBL bacterial infections is clinical trials of bacteriophage therapy. The aim of this study was to isolate and characterize specific bacteriophages against ESBL-producing Klebsiella pneumoniae in patients with burn ulcers.

MATERIALS AND METHODS

Clinical samples were isolated from the hospitalized patient in burn medical centers, Iran. Biochemical screenings and 16S rRNA gene sequencing were determined. The phages were isolated from municipal sewerage treatment plants, Isfahan, Iran. TEM and FESEM, adsorption velocity, growth curve, host range, and the viability of the phage particles as well as proteomics and enzyme digestion patterns were examined.

RESULTS

The results showed that Klebsiella pneumoniae Iaufa_lad2 (GenBank accession number: MW836954) was confirmed as an ESBL-producing strain using combined disk method. This bacterium showed significant sensitivity to three phages including PɸBw-Kp1, PɸBw-Kp2, and PɸBw-Kp3. Morphological characterization demonstrated that the phage PɸBw-Kp3 to the Siphoviridae family (lambda-like phages) and both phages PɸBw-Kp1 and ɸBw-Kp2 to the Podoviridae family (T1-like phages). The isolated bacteriophages had a large burst size, thermal and pH viability and efficient adsorption rate to the host cells.

CONCLUSION

In present study, the efficacy of bacteriophages against ESBL pathogenic bacterium promises a remarkable achievement for phage therapy. It seems that, these isolated bacteriophages, in the form of phage cocktails, had a strong antibacterial impacts and a broad-spectrum strategy against ESBL-producing Klebsiella pneumoniae isolated from burn ulcers.

Isolation, characterization, and effectiveness of bacteriophage Pɸ-Bw-Ab against XDR Acinetobacter baumannii isolated from nosocomial burn wound infection

OBJECTIVES

With emergence of drug resistance, novel approaches such as phage therapy for treatment of bacterial infections have received significant attention. The purpose of this study was to isolate and identify effective bacteriophages on extremely drug-resistant (XDR) bacteria isolated from burn wounds.

MATERIALS AND METHODS

Pathogenic bacteria were isolated from hospitalized patient wounds in specialized burn hospitals in Iran, and their identification was performed based on biochemical testing and sequencing of the gene encoding 16S rRNA. Bacteriophages were isolated from municipal sewage, Isfahan, Iran. The phage morphology was observed by TEM. After detection of the host range, adsorption rate, and one-step growth curve, the phage proteomics pattern and restriction enzyme digestion pattern were analyzed.

RESULTS

All isolates of bacteria were highly resistant to antibiotics. Among isolates, Acinetobacter baumannii strain IAU_FAL101 (GenBank accession number: MW845680), which was an XDR bacterium, showed significant sensitivity to phage Pɸ-Bw-Ab. TEM determined the phage belongs to Siphoviridae. They had double-stranded DNA. This phage showed the highest antibacterial effect at 15 ^°C and pH 7. Analysis of the restriction enzyme digestion pattern showed Pɸ-Bw-Ab phage was sensitive to most of the used enzymes and based on SDS-PAGE, protein profiles were revealed 43 to 90 kDa.

CONCLUSION

Considering the potential ability of the isolated phage, it had an antibacterial impact on other used bacterial spp and also strong antibacterial effects on XDR A. baumannii. Also, it had long latency and low burst size. This phage can be a suitable candidate for phage therapy.

Wastewater as a fertility source for novel bacteriophages against multi-drug resistant bacteria

Antibiotic resistance is a common and serious public health worldwide. As an alternative to antibiotics, bacteriophage (phage) therapy offers one of the best solutions to antibiotic resistance. Bacteriophages survive where their bacterial hosts are found; thus, they exist in almost all environments and their applications are quite varied in the medical, environmental, and industrial fields. Moreover, a single phage or a mixture of phages can be used in phage therapy; mixed phages tend to be more effective in reducing the number and/or activity of pathogenic bacteria than that of a single phage.

Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan

The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

Bacteriophage ecology in biological wastewater treatment systems

Biological wastewater treatment (BWT) is currently the most widely applied approach for treating wastewater. The performance of BWT systems depends on the complex microbial communities they support. Although bacteriophages (phages), which are the viruses that infect prokaryotes, are recognized as the most abundant life entities, understanding of their ecological roles in BWT systems remains limited. Here, we review recent progress in phage-associated researches in BWT systems, including the interactions between phage and host, polyvalent phages, the influence of phage activity on BWT performance, and the potential applications of phage-based control for sludge bulking/foaming and pathogens. The challenges and perspectives of phage ecology are also outlined, which are expected to provide implications for future research and applications.Key points• Phage-host interactions in BWT systems are summarized• Impacts of phage activities on BWT performance• Potential applications of phages in BWT systems.

Bacteriophages in water pollution control: Advantages and limitations

Wastewater is a breeding ground for many pathogens, which may pose a threat to human health through various water transmission pathways. Therefore, a simple and effective method is urgently required to monitor and treat wastewater. As bacterial viruses, bacteriophages (phages) are the most widely distributed and abundant organisms in the biosphere. Owing to their capacity to specifically infect bacterial hosts, they have recently been used as novel tools in water pollution control. The purpose of this review is to summarize and evaluate the roles of phages in monitoring pathogens, tracking pollution sources, treating pathogenic bacteria, infecting bloom-forming cyanobacteria, and controlling bulking sludge and biofilm pollution in wastewater treatment systems. We also discuss the limitations of phage usage in water pollution control, including phage-mediated horizontal gene transfer, the evolution of bacterial resistance, and phage concentration decrease. This review provides an integrated outlook on the use of phages in water pollution control.

Phage therapy as a potential approach in the biocontrol of pathogenic bacteria associated with shellfish consumption

Infectious human diseases acquired from bivalve shellfish consumption constitute a public health threat. These health threats are largely related to the filter-feeding phenomenon, by which bivalve organisms retain and concentrate pathogenic bacteria from their surrounding waters. Even after depuration, bivalve shellfish are still involved in outbreaks caused by pathogenic bacteria, which increases the demand for new and efficient strategies to control transmission of shellfish infection. Bacteriophage (or phage) therapy represents a promising, tailor-made approach to control human pathogens in bivalves, but its success depends on a deep understanding of several factors that include the bacterial communities present in the harvesting waters, the appropriate selection of phage particles, the multiplicity of infection that produces the best bacterial inactivation, chemical and physical factors, the emergence of phage-resistant bacterial mutants and the life cycle of bivalves. This review discusses the need to advance phage therapy research for bivalve decontamination, highlighting their efficiency as an antimicrobial strategy and identifying critical aspects to successfully apply this therapy to control human pathogens associated with bivalve consumption.

Genomic characterization of a novel virulent phage infecting Shigella fiexneri and isolated from sewage

Shigella fiexneri phage SGF2 is a novel lytic phage isolated from a sewage sample. Morphological characterization indicates that phage SGF2 is a member of the Podoviridae family, producing virions with an isometric head (82.6 ± 8 nm diameter) and a short non-contractile tail (length 52 ± 8 nm). This phage specifically infected the Shigella fiexneri. One-step growth curves indicated that the burst period of phage SGF2 is 30 min, with an approximate burst size of 38. The full-length genome was sequenced and potential virulence genes were detected. We will discuss the potential application of phage SGF2 in phage therapy.

Novel lytic bacteriophages of Klebsiella oxytoca ABG-IAUF-1 as the potential agents for mastitis phage therapy

Mastitis is an inflammation of the mammary gland that occurs when pathogenic microorganisms enter the udder. Even though tremendous advancements in veterinary diagnosis and therapeutics, mastitis is still the most frequent and costly disease of dairy herds overall the world. The purpose of this research was to isolate and identify the lytic phages as a potential method for biological control of bovine mastitis. In this study Klebsiella oxytoca was isolated from contaminated milk samples of Isfahan dairy herds, Isfahan, Iran and characterized as K. oxytoca ABG-IAUF-1 and its 16s-rRNA sequence was deposited in GenBank under the accession numbers of MF175803.1. Then, the four novel specific lytic bacteriophages of K. oxytoca ABG-IAUF-1 from Isfahan public wastewater were isolated and identified. The results of transmission electron microscopy indicated that theses isolated phages were related to Myoviridae and Podoviridae families of bacteriophages. Also the analysis of the growth curve of K. oxytoca ABG-IAUF-1 before and after treatment with lytic phage showed the 97% success rate of the phages in preventing of bacterial growth. This is the first report indicating the use of bacteriophages as the potential agents for eliminating the pathogenic bacteria responsible for bovine mastitis in Iran. The applications of these lytic phages could be an asset for biocontrolling of pathogenic agents in medical and veterinary biotechnology.

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.

Genomic characterization of key bacteriophages to formulate the potential biocontrol agent to combat enteric pathogenic bacteria

Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.

Bacteriophage Procurement for Therapeutic Purposes

Bacteriophages (phages), discovered 100 years ago, are able to infect and destroy only bacterial cells. In the current crisis of antibiotic efficacy, phage therapy is considered as a supplementary or even alternative therapeutic approach. Evolution of multidrug-resistant and pandrug-resistant bacterial strains poses a real threat, so it is extremely important to have the possibility to isolate new phages for therapeutic purposes. Our phage laboratory and therapy center has extensive experience with phage isolation, characterization, and therapeutic application. In this article we present current progress in bacteriophages isolation and use for therapeutic purposes, our experience in this field and its practical implications for phage therapy. We attempt to summarize the state of the art: properties of phages, the methods for their isolation, criteria of phage selection for therapeutic purposes and limitations of their use. Perspectives for the use of genetically engineered phages to specifically target bacterial virulence-associated genes are also briefly presented.

Isolation and Characterization of a Myoviridae MJ1 Bacteriophage Against Multi-Drug Resistant Escherichia coli 3

Background:

Antibiotic resistance in Escherichia coli, a member of the Enterobacteriaceae, is of particular concern because it is the most common (Gram-negative) pathogen causing nosocomial and community infections. Researchers are now considering the use of phages for the control of various antibiotic-resistant bacterial infections.

Objectives:

The purpose of this study was to isolate and characterize a novel pathogenic/lytic phage that targets multi-drug resistant (MDR) E. coli 3, and to investigate its effectiveness at lysing this bacterium.

Materials and Methods:

A clinical strain of E. coli 3 was identified based on its 16S rRNA sequencing and its antibiotic resistance profile was determined by the disc diffusion method. A bacteriophage was isolated from wastewater and its various characteristics, such as host range, heat tolerance, pH stability, one step growth, total protein content, and genome size, were determined. The antibacterial property of the phage was determined against log-phase bacterial planktonic cells at 37°C.

Results:

The bacteriophage, designated MJ1, was isolated by testing against a clinical MDR E. coli 3 strain. The MJ1 phage showed a wide range of heat and pH stability. The phage morphology, determined by transmission electron microscopy, revealed a structure comprised of a head (108 ± 0.2 nm long by 128 ± 0.5 nm wide) and a contractile tail (123 ± 0.5 nm long by 15 - 26 nm wide). These features placed the MJ1 phage in the family Myoviridae and the order Caudovirales. Eleven structural proteins (17 to 200 kDa) for this phage were detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). A double stranded DNA, approximately 32 kb, in size was detected for this phage on agarose gels. The phage efficacy against E. coli 3 planktonic cells was also investigated. The MJ1 phage demonstrated a very good capability to reduce the numbers of E. coli 3 planktonic cells, as determined by a change in the bacterial growth (an optical density decrease at 600 nm from 0.40 to 0.12).

Conclusions:

MJ1 phage has much potential for use in phage therapy and other applications.