Effectiveness Of Phage Therapy Research Articles

The Antibacterial Activity of Novel Bacteriophages and the Emergence of Bacterial Resistance to Phage Infections: An In Vitro Study

The emergence of bacteria resistant to bacteriophage (phage) infection may compromise the success and effectiveness of phage therapy. The aim of this study was to evaluate the in vitro antibacterial activity of five novel phages, as well as the emergence of bacterial resistance to phage infections. The antibacterial activity of lytic phages was evaluated against standard strains of Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25927), Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 6538). Phages were initially grown in the presence of host bacteria in an exponential growth phase, then purified and titrated. In a second exposure, 20 μL of each phage was inoculated with 106 CFU/mL of P. aeruginosa/E. coli/E. faecalis/S. aureus, separately. In a third exposure, resistant colonies were isolated, cultivated and exposed again to the phages. Bacterial colonies resistant to phage infection after the third exposure were evaluated for their susceptibility profile to different antibiotics via the diffusion disk technique. The diameters of the inhibition halos were evaluated with Image J software (version 1.54g) and the definition of the susceptibility profile to antibiotics was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. In addition, fourteen cocktails with different phages were formulated to evaluate the emergence of a bacterial resistance to phage infections. The phages exhibited specificity for P. aeruginosa and did not infect E. coli, E. faecalis and S. aureus. The presence of bacterial colonies resistant to phage infection in the three successive exposures was identified, and the bacterial resistance to phage infection was confirmed in all phages titrated at 108 PFU/mL, in four phages titrated at 1010 PFU/mL and in one phage titrated at 1013 PFU/mL. The development of a resistance to infection by phages (~108 PFU/mL) did not change the susceptibility profile of P. aeruginosa to antibiotics and, when evaluating the emergence of a resistance to infection by phage cocktails (~108 PFU/mL, ~1010 PFU/mL, ~1013 PFU/mL), bacterial resistance to phage infection was confirmed in all cocktails with phages titrated at 108 PFU/mL, in ten cocktails with phages titrated at 1010 PFU/mL and in seven cocktails with phages titrated at 1013 PFU/mL. In conclusion, the presence of resistant P. aeruginosa colonies to phage infection after successive exposures was evidenced, although some phages at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. The development of resistance did not change the susceptibility profile of P. aeruginosa to antibiotics. Variants of P. aeruginosa that were resistant to phage infection were isolated and their resistance to infection via the phage cocktail was demonstrated regardless of the viral titer, although some cocktails at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. Despite the emergence of bacterial variants resistant to phage infection, new studies involving the applicability of phages in the control of infections must be conducted.

Effect of phage therapy on survival, histopathology, and water microbiota of Penaeus vannamei challenged with Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (AHPND)

Shrimp farming production is affected severely by the presence of toxigenic strains of Vibrio parahaemolyticus, the leading etiological agent of acute hepatopancreatic necrosis disease that causes as much as 100% mortality. To date, conventional methods have not effectively controlled AHPND, and only a few studies have reported bioassays testing phage therapy against this shrimp disease, none with a metagenomic approach. Here, Penaeus vannamei juveniles infected with AHPND-causing Vibrio parahaemolyticus were treated with phage to assess shrimp survival, tissue damage, as well as water microbiota dynamics. Phage therapy reduced by 4% shrimp mortality compared to the positive control. Histopathological analysis showed a 3 h delay in mortality of shrimp in the acute stage treated with phage therapy concerning the positive control, as well as a shortening of the terminal phase. Further, surviving shrimp in the terminal stage were only found in the positive control treatment. No significant differences were observed in the diversity of water microbiota between these treatments. Interestingly, V. parahaemolyticus caused up to 65% mortality, although its density decreased rapidly, and its relative abundance in the water microbiota ranged from 0.1% to 0.4%, while the marine bacteria that predominated in the microbiota was Donghicola eburneus (25.2%–54.6%). In addition, two copies of the pVA1 plasmid per V. parahaemolyticus genome were detected during the first 12 hpi in the positive control and phage therapy treatments. Phage therapy using a single phage could not effectively control AHPND in this investigation. Therefore, methods combining different approaches to prevent or treat the AHPND, such as a phage cocktail and a toxin binder, should be considered to increase the success rate in mitigating the disease.

Bacteriophages: The promising therapeutic approach for enhancing ciprofloxacin efficacy against bacterial infection.

The emergence of ciprofloxacin-resistant bacteria is a serious challenge worldwide, bringing the need to find new approaches to manage this bacterium. Bacteriophages (phages) have been shown inhibitory effects against ciprofloxacin-resistance bacteria; thus, ciprofloxacin resistance or tolerance may not affect the phage's infection ability. Additionally, researchers used phage-ciprofloxacin combination therapy for the inhibition of multidrug-resistant bacteria. The sublethal concentrations of ciprofloxacin could lead to an increase in progeny production. Antibiotic treatments could enhance the release of progeny phages by shortening the lytic cycle and latent period. Thus, sublethal concentrations of antibiotics combined with phages can be used for the management of bacterial infections with high antibiotic resistance. In addition, combination therapy exerts various selection pressures that can mutually decrease phage and antibiotic resistance. Moreover, phage ciprofloxacin could significantly reduce bacterial counts in the biofilm community. Immediate usage of phages after the attachment of bacteria to the surface of the flow cells, before the development of micro-colonies, could lead to the best effect of phage therapy against bacterial biofilm. Noteworthy, phage should be used before antibiotics usage because this condition may have allowed phage replication to occur first before ciprofloxacin interrupted the bacterial DNA replication process, thereby interfering with the activity of the phages. Furthermore, the phage-ciprofloxacin combination showed a promising result for the management of Pseudomonas aeruginosa infections in mouse models. Nevertheless, low data are existing about the interaction between phages and ciprofloxacin in combination therapies, especially regarding the emergence of phage-resistant mutants. Additionally, there is a challenging and important question of how the combined ciprofloxacin with phages can increase antibacterial functions. Therefore, more examinations are required to support the clinical usage of phage-ciprofloxacin combination therapy.

Микробиота при гнойных и фибринозных конъюнктивитах у собак и антибактериальная терапия фаговым средством

The article provides data on the study of the qualitative composition of the microflora in purulent and fibrinous conjunctivitis in dogs. The proportion of microbial positive samples has been determined. The biological and biochemical properties of the isolated microorganisms have been studied. Studies have shown a high role of antibiotic-resistant bacteria Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumonia, Pseudomonas aeruginosa, E. coli, Enterobacter spp. in associations. The research results showed a high comparable effectiveness of phage therapy in the treatment of infectious-inflammatory pathologies of the organ of vision in dogs.

Phage therapy in osteoarticular infections in the era of antibiotic resistance bacteria

The increase in the incidence rate of multidrug resistant strains of bacteria has prompted scientists to look for alternatives to antibiotics. One option is phage therapy. The possibility of using phages (bacteriophages) in infections of almost every organ and system is being investigated. The treatment of osteoarticular infections using antibiotics is often very problematic, which is why this is an important area of interest for phage research.As part of the bacteriophage experimental therapy conducted by Patey et al., 9 patients with osteoarticular diseases were treated. In 7 cases complete recovery was obtained. One patient achieved partial eradication of the pathogen with closure of several fistulas and stabilization of the general condition.The study was carried out on an animal model by Yilmaz et al. showed greater effectiveness in eliminating MRSA colony forming units when combining bacteriophages with antibiotics (drop to 5000 units, no biofilm) than when using antibiotics alone (17,165 units survived, biofilm present). Independent application of phage therapy brought the worst effect (30,788 surviving units).The results of the cited studies indicate the possible effectiveness of phage therapy in the case of osteoarticular infections. The potential synergy of antibiotics and bacteriophages in eradicating bacterial biofilm deserves attention.

Isolation and identification of specific bacteriophage against enteropathogenic Escherichia coli (EPEC) and in vitro and in vivo characterization of bacteriophage

In recent years, the increasing resistance of enteropathogenic Escherichia coli (EPEC) to commonly used antibiotics has made it difficult to choose the best treatment option. Bacteriophage therapy could be a potent alternative to antibiotic therapy for antibiotic-resistant bacteria. The aim of the present study was to isolate and identify a specific bacteriophage against EPEC and characterize bacteriophage in vitro and in vivo. The specific bacteriophage was isolated, and the effect of phage therapy on 48 mice (Balb/c) was investigated. Animals were divided into six groups, including A: PBS (negative control); B: bacteria (positive control); C: bacteria+ciprofloxacin (after 24 h); D: bacteria + bacteriophage (after 24 h); E: bacteria+ ciprofloxacin + bacteriophage (after 24 h) and F: bacteriophage+bacteria (after 24 h). Specific bacteriophage against EPEC was isolated from hospital sewage. The bacteriophage had an icosahedral head (120 nm) and a tail (138 nm). The single dose of the bacteriophage (2×109 pfu ml-1) was able to control the infection. Unfortunately, because of the misuse of antibiotics by EPEC infected patients, the antibiotic resistant bacteria will become prevalent in the future and the treatment of EPEC infection is going to become more difficult than ever.

Exploring potential of phage therapy for tuberculosis using model organism

Antibiotics, one of the miracle discoveries of the 20th century after world war revolutionized the treatment and prophylaxis of infectious diseases. Antibiotics led to an increase in the quality of health-care system but with the emergence of antibiotic-resistant bacterial strains compromised their very potential. The WHO calls bacterial resistance as one of the major threats to global health, food security, and development today. Antibiotic resistance poses a need of alternative therapy to conventional antibiotics. As proved in preantibiotic era phage therapy is effective against a number of successful pathogens and can be used as an alternative strategy to restrain stern infections such as antibiotic resistance tuberculosis (TB). In the present paper, effectiveness of phage therapy and use of model organisms for developing treatment strategy for antibiotic-resistant TB is discussed so as to explore new possibilities in battle against antibiotic resistance.

Characterizing the response of multidrug-resistant <i>Klebsiella pneumoniae</i> species to the application of a phage cocktail

Project Summary: The application of bacteriophages to treat bacterial infections is known as phage therapy, which takes advantage of bacteriophage’s natural ability to infect and lyse bacterial hosts. Phages have been shaped by billions of years of evolution to be highly specialized deliverers of bactericidal agents to the cytoplasm of their target bacteria. Ever since discovery of bacteriophages in 1915, phage therapy was recognized as a potentially powerful tool for eliminating bacterial infections. The effectiveness of phage therapy can be increased by creating a mixture of multiple phages to target a wider variety of bacterial strains. Furthermore, phage therapy has many advantages over antibiotics. For example, phages replicate in vivo, so a smaller effective dose can be administered. Phages will also stop reproducing once the target bacteria is destroyed. Much of the evidence strongly shows that, appropriately administered, phage therapy is effective for treatment of bacterial infectious diseases, especially those caused by multidrug-resistant bacteria. The worldwide spread of Klebsiella pneumoniae spp., which is resistance to a variety of antibiotics, threatens to revert modern medicine to a pre-antibiotic era. Infections caused by drug-resistant K. pneumoniae spp. are life threatening because of our limited ability to treat the associated disease symptoms. As a result, infections due to multidrug resistant K. pneumoniae spp. have an extremely high mortality rate. The design of a phage cocktail with potential therapeutic application against multidrug-resistant K. pneumoniae spp. may enable us to respond to a rapidly emerging generation of multidrug-resistant bacterial species.

Phage therapy reduces Campylobacter jejuni colonization in broilers

The effect of phage therapy in the control of Campylobacter jejuni colonization in young broilers, either as a preventive or a therapeutic measure, was tested. A prevention group was infected with C. jejuni at day 4 of a 10-day phage treatment. A therapeutic group was phage treated for 6 days, starting 5 days after C. jejuni colonization of the broilers had been established. Treatment was monitored by enumerating Campylobacter colony forming units (CFU) and phage plaque forming units (PFU) from caecal content. Counts were compared with control birds not receiving phage therapy. A clear 3 log decline in C. jejuni counts was initially observed in the therapeutic group, however, after 5 days bacterial counts stabilized at a level 1 log lower than that of the control group. Colonization of C. jejuni in the prevention group was delayed by the treatment and after an initial 2 log reduction, colonization stabilized within a week at levels comparable to the therapeutic group. The CFU and PFU counts displayed opposing highs and lows over time, indicative of alternating shifts in amplification of bacteria and phages. There were no adverse health effects from the phage treatment. Two different phages were combined as therapeutic treatment of Campylobacter positive chickens challenged at the age approaching broiler harvest. This again resulted in a significant decrease in Campylobacter colonization. We conclude that phage treatment is a promising alternative for reducing C. jejuni colonization in broilers.

Effect of phage therapy on the turnover and function of peripheral neutrophils

The aim of this investigation was to establish the impact of phage therapy on the turnover and function of circulating neutrophils in 37 patients with suppurative bacterial infections. We determined the levels of circulating neutrophils and their precursors before therapy, after 3 weeks of therapy, and at a distant time interval (3 months) following the beginning of therapy. In addition, we measured the ability of neutrophils to phagocytize Staphylococcus aureus in vitro. Eight healthy blood donors served as a control group. The results showed that, among the studied parameters, the significant changes involved neutrophil precursor count and the ability of neutrophils to phagocytize bacteria. The percentage of neutrophils in patients before therapy was lower than in healthy donors (mean 58.0, versus 61.4). This value dropped further in patients after 3 months of following the therapy (mean 55.6). The content of neutrophil precursors, on the other hand, was lower in healthy donors than in patients before therapy (mean 2.5, versus 3.8). After 3 weeks of the therapy and after 3 months, the levels of neutrophil precursors were significantly higher (mean 4.8 and 4.9, respectively) than in control donors. The phagocytic index was lower in patients before therapy than in control donors (mean 66.3, versus 70.1) and decreased further after 3 weeks of therapy (mean 59.0) and after 3 months (mean 59.6). The results of this investigation indicate that successful phage therapy accelerates the turnover of neutrophils, accompanied by a decrease in their ability to phagocytize bacteria.