Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms

Isolation and characterization of a relatively broad-spectrum phage against Escherichia coli

Multiple pathogenic types or serotypes restrict treatment for colibacillosis. In addition, rising antibiotic resistance has heightened public awareness to prevent and control pathogenic Escherichia coli. The bacteriophage is a viable technique to treat colibacillosis as an alternative to antibiotics. In this study, PH444, a relatively broad-spectrum obligate lytic phage, was screened from 48 Shiga toxin-producing Escherichia coli (STEC) phages isolated from farm manure samples and sewage samples in order to conduct genome-wide analysis, biological characterization, and a bacterial challenge experiment in milk. The results demonstrated that PH444 was a T7-like phage with a double-stranded DNA of 115,111 bp that belongs to the Kuravirus and was stable at temperatures between 4 and 50 °C and a pH range of 3 to 11. After adding PH444, the bacterial load in milk could be reduced from 3 × 103 PFU/ mL to zero within 1 h. In consideration of the biological properties of phage PH444, it was, therefore, demonstrated that PH444 has the potential to be used in phage biocontrol.

A systematic review and modeling of the effect of bacteriophages on E. coli O157:H7 reduction in vegetables

Prevention and control of food pathogens are important for public health and E. coli O157:H7 infections are known as one of the most important food-borne bacterial diseases transmitted to humans. Vegetables can be a major source of E. coli O157:H7 bacteria. Bacteriophages have been considered in recent years as a natural method for controlling pathogens with minimal damage to the quality of vegetables. The performance of these natural antimicrobial agents is affected by various factors including time, temperature, phage and bacterial dose, method of phage application and origin of phages. The aim of the present study was to conduct a systematic review of the works that have examined the effect of different factors to reduce E. coli O157:H7 bacteria by its specific phages and model their effect. In our study, 10 articles were chosen after applying the inclusion and exclusion criteria mentioned in the methodology. The multivariate regression results showed that time, temperature, and method of phage application revealed a positive influence on the phage function, and with each unit of increase, the E. coli O157:H7 reduction increases by 0.4 %, 3 % and 0.94 % respectively, and 6 % for phage dose, but not statistically significant (P = 0.44). In addition, commercial-type phages were more effective than wild-type phages and this result was statistically significant (Beta = 0.99; P = 0.001). The results of this study indicate that the various factors, such as temperature, time, method of phage application and type of vegetables can play an important role to reduce E. coli O157:H7 in vegetables.

Bacteriophages for the Targeted Control of Foodborne Pathogens

Foodborne illness is exacerbated by novel and emerging pathotypes, persistent contamination, antimicrobial resistance, an ever-changing environment, and the complexity of food production systems. Sporadic and outbreak events of common foodborne pathogens like Shiga toxigenic E. coli (STEC), Salmonella, Campylobacter, and Listeria monocytogenes are increasingly identified. Methods of controlling human infections linked with food products are essential to improve food safety and public health and to avoid economic losses associated with contaminated food product recalls and litigations. Bacteriophages (phages) are an attractive additional weapon in the ongoing search for preventative measures to improve food safety and public health. However, like all other antimicrobial interventions that are being employed in food production systems, phages are not a panacea to all food safety challenges. Therefore, while phage-based biocontrol can be promising in combating foodborne pathogens, their antibacterial spectrum is generally narrower than most antibiotics. The emergence of phage-insensitive single-cell variants and the formulation of effective cocktails are some of the challenges faced by phage-based biocontrol methods. This review examines phage-based applications at critical control points in food production systems with an emphasis on when and where they can be successfully applied at production and processing levels. Shortcomings associated with phage-based control measures are outlined together with strategies that can be applied to improve phage utility for current and future applications in food safety.

A systematic review and modeling of the effect of bacteriophages on Salmonella spp. Reduction in chicken meat

Prevention and control of foodborne pathogens are of vital public health importance, and poultry meat is recognized as a major source of Salmonella infection in humans. Therefore, it is necessary to reduce the presence of salmonella in poultry meat. This article provided a systematic review and modeling to assess the effect of various factors on bacteriophages' function on Salmonella spp. Reduction in poultry meat. Twenty-two studies were included based on the inclusion and exclusion criteria mentioned in the methodology. The results showed that each unit increase in bacterial dose, phage dose, and temperature increases the Salmonella reduction by about 7%, 20%, and 1%, respectively. In addition, wild-type phages were more efficient than commercial-type phages, and this result was statistically significant (β = 1.124; p-value <0.001). This multivariate analysis is a helpful tool to predict the role of various factors in the role of phage in reducing Salmonella in poultry meat.

Phage Revolution Against Multidrug-Resistant Clinical Pathogens in Southeast Asia

Southeast Asia (SEA) can be considered a hotspot of antimicrobial resistance (AMR) worldwide. As recent surveillance efforts in the region reported the emergence of multidrug-resistant (MDR) pathogens, the pursuit of therapeutic alternatives against AMR becomes a matter of utmost importance. Phage therapy, or the use of bacterial viruses called bacteriophages to kill bacterial pathogens, is among the standout therapeutic prospects. This narrative review highlights the current understanding of phages and strategies for a phage revolution in SEA. We define phage revolution as the radical use of phage therapy in infectious disease treatment against MDR infections, considering the scientific and regulatory standpoints of the region. We present a three-phase strategy to encourage a phage revolution in the SEA clinical setting, which involves: (1) enhancing phage discovery and characterization efforts, (2) creating and implementing laboratory protocols and clinical guidelines for the evaluation of phage activity, and (3) adapting regulatory standards for therapeutic phage formulations. We hope that this review will open avenues for scientific and policy-based discussions on phage therapy in SEA and eventually lead the way to its fullest potential in countering the threat of MDR pathogens in the region and worldwide.

Application of Bacteriophages on Shiga Toxin-Producing Escherichia coli (STEC) Biofilm

Shiga toxin-producing Escherichia coli are pathogenic bacteria able to form biofilms both on abiotic surfaces and on food, thus increasing risks for food consumers. Moreover, biofilms are difficult to remove and more resistant to antimicrobial agents compared to planktonic cells. Bacteriophages, natural predators of bacteria, can be used as an alternative to prevent biofilm formation or to remove pre-formed biofilm. In this work, four STEC able to produce biofilm were selected among 31 different strains and tested against single bacteriophages and two-phage cocktails. Results showed that our phages were able to reduce biofilm formation by 43.46% both when used as single phage preparation and as a cocktail formulation. Since one of the two cocktails had a slightly better performance, it was used to remove pre-existing biofilms. In this case, the phages were unable to destroy the biofilms and reduce the number of bacterial cells. Our data confirm that preventing biofilm formation in a food plant is better than trying to remove a preformed biofilm and the continuous presence of bacteriophages in the process environment could reduce the number of bacteria able to form biofilms and therefore improve the food safety.

New Phage cocktail against infantile Sepsis bacteria

A total of 54 positive blood aerobic cultures of suspected blood sepsis in neonates were purified, diagnosed and tested for antibiotic susceptibility. Six bacterial pathogens of Escherichia coli (10 isolates), Klebsiella pneumoniae (10 isolates), Haemophilus influenzae (4 isolates), Pseudomonas aeruginosa (3 isolates), Citrobacter fruendii (1 isolate) and Moraxella catarrhalis (1 isolate) were selected for preparation of phages active against all isolates of each species. Virulent phages towards bacterial isolates were isolated from sewage water by spot lysis method, and a total of 29 phages active towards selected bacterial pathogens were isolated and purified. Phage(s) active against each bacterial species showed activity spectrum within each species of 30-80%, 50-80%, 50%, 50%, 100% and 100% for isolates of Escherichia coli, Klebsiella spp., Haemophilus influenzae, Pseudomonas aeruginosa, Citrobacter fruendii and Moraxella catarrhalis, respectively. A total of 29 phages were formulated in one cocktail in a concentration of 10⁶ PFU/ml in SM buffer for each of a total of 29 phages in SM buffer and showed activity spectrum of 100% against all their bacterial hosts in vitro.

The potential of bacteriophage cocktail in eliminating Methicillin-resistant Staphylococcus aureus biofilms in terms of different extracellular matrices expressed by PIA, ciaA-D and FnBPA genes

Background

This study assessed novel approach of using highly lytic phages against methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) biofilms with and without biofilm extracellular matrix- disrupting chemical.

Method

The resultant phage-based control was assessed in relation to the type of biofilm extracellular matrix namely, polysaccharide intercellular adhesion (PIA) or proteinacious fibronectin-binding protein A (FnBPA). The biofilms were formed in vitro by 24 h incubation of bacteria in 96 wells microtiter plates at room temperature. The formed biofilms were assessed by tissue culture plate (TCP). Moreover, the nature of the biofilm was assessed by scanning electron microscopy (SEM) and PCR assay for detecting PIA genes, ciaA-D and FnBPA genes.

Results

this study showed that applied phages with 0.08 % benezenthonium chloride, for PIA biofilms, and 0.06 % ethanol, for proteinacious FnBPA biofilms, exerted 100 % eradication for MSSA biofilms and about 78 % of MRSA biofilms. The phage-based control of biofilms with chemical adjuvant showed significantly higher efficiency than that without adjuvant (P < 0.05). Moreover, FnBPA biofilms were more common in MRSA than in MSSA while PIA biofilms were more common in MSSA than in MRSA. And the most resistant type of biofilms to phage-based control was FnBPA in MRSA where 50 % of biofilms were reduced but not eradicated completely.

Conclusions

It is concluded that PIA-disturbing agent and protein denaturing alcohol can increase the efficiency of attacking phages in accessing host cell walls and lysing them which in turn lead to much more efficient MRSA and MSSA biofilm treatment and prevention.

Natural solution to antibiotic resistance: bacteriophages 'The Living Drugs'

Antibiotics have been a panacea in animal husbandry as well as in human therapy for decades. The huge amount of antibiotics used to induce the growth and protect the health of farm animals has lead to the evolution of bacteria that are resistant to the drug's effects. Today, many researchers are working with bacteriophages (phages) as an alternative to antibiotics in the control of pathogens for human therapy as well as prevention, biocontrol, and therapy in animal agriculture. Phage therapy and biocontrol have yet to fulfill their promise or potential, largely due to several key obstacles to their performance. Several suggestions are shared in order to point a direction for overcoming common obstacles in applied phage technology. The key to successful use of phages in modern scientific, farm, food processing and clinical applications is to understand the common obstacles as well as best practices and to develop answers that work in harmony with nature.

Bacteriophages for detection and control of bacterial pathogens in food and food-processing environment

This chapter presents recent advances in bacteriophage research and their application in the area of food safety. Section 1 describes general facts on phage biology that are relevant to their application for control and detection of bacterial pathogens in food and environmental samples. Section 2 summarizes the recently acquired data on application of bacteriophages to control growth of bacterial pathogens and spoilage organisms in food and food-processing environment. Section 3 deals with application of bacteriophages for detection and identification of bacterial pathogens. Advantages of bacteriophage-based methods are presented and their shortcomings are discussed. The chapter is intended for food scientist and food product developers, and people in food inspection and health agencies with the ultimate goal to attract their attention to the new developing technology that has a tremendous potential in providing means for producing wholesome and safe food.