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Bacteriophage (phage) has been reported to reduce the bacterial infection in delayed‐healing wounds and, as a result, aiding in the healing of said wounds. In this study we investigated whether the presence of phage itself could help repair delayed‐healing wounds in diabetic mice. Three strains of phage that target Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa were used. To prevent the phage liquid from running off the wound, the mixture of phage (phage‐cocktail) was encapsulated in a porous hydrogel dressing made with three‐dimensional printing. The phage‐cocktail dressing was tested for its phage preservation and release efficacy, bacterial reduction, cytotoxicity with 3T3 fibroblast, and performance in repairing a sterile full‐thickness skin wound in diabetic mice. The phage‐cocktail dressing released 1.7%–5.7% of the phages embedded in 24 h, and reduced between 37%–79% of the surface bacteria compared with the blank dressing (p <.05). The phage‐cocktail dressing exhibited no sign of cytotoxicity after 3 days (p <.05). In vivo studies showed that 14 days after incision, the full‐thickness wound treated with a phage‐cocktail dressing had a higher wound healing ratio compared with the blank dressing and control (p <.01). Histological analysis showed that the structure of the skin layers in the group treated with phage‐cocktail dressing was restored in an orderly fashion. Compared with the blank dressing and control, the repaired tissue in the phage‐cocktail dressing group had new capillary vessels and no sign of inflammation in its dermis, and its epidermis had a higher degree of re‐epithelialization (p <.05). The slow‐released phage has demonstrated positive effects in repairing diabetic skin wounds. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa and Staphylococcus aureus are opportunistic bacteria frequently linked to burn wound infections. These bacteria can grow as biofilms, which increases their level of drug resistance to current antibiotics. The purpose of the present study is to analyze the effect of biofilm formation, phage and phage cocktail action on single species and dual species biofilms I, e the coexistence of Gram positive (S. aureus) and Gram negative (P. aeruginosa). To this scenario, we employed multi-drug resistant bacteria (P. aeruginosa and S. aureus at 109 CFU/µL) biofilm as single and in combination of both Gram-positive and Gram-negative bacterial biofilms of 24 h grown with respective phage (109 PFU/µL) and phage cocktail (109 PFU/µL) at 4 h of incubation under static conditions. The bacteriolytic activity of phages vB_SAnS_SADP1 and vB_PAnP_PADP4 on 24-h-old biofilms of P. aeruginosa (0.761 ± 0.031) and S. aureus (0.856 ± 0.055), both alone and in combination (0.67 ± 0.02), was the focus of this investigation. The structural organization of biofilms in single- or dual-species combinations under in vitro conditions was validated by scanning and confocal laser scanning microscopy investigations. After 24 h of incubation, single-species biofilms are denser and more resilient whereas dual species biofilms are more loosely associated. Loose association of dual-species biofilm under scanning electron microscopic images at the same conditions, indicated the interspecies -competition of the Gram-positive and Gram-negative bacteria and dual-species biofilms (0.67 ± 0.02) have weak associations and are readily impacted by phage and a phage cocktail (0.16 ± 0.02). Dual-species biofilms were more readily impacted in in vitro settings.

Pseudomonas aeruginosa and Staphylococcus aureus are opportunistic bacteria frequently linked to burn wound infections. These bacteria can grow as biofilms, which increases their level of drug resistance to current antibiotics. The purpose of the present study is to analyze the effect of biofilm formation, phage and phage cocktail action on single species and dual species biofilms I, e the coexistence of Gram positive (S. aureus) and Gram negative (P. aeruginosa). To this scenario, we employed multi-drug resistant bacteria (P. aeruginosa and S. aureus at 109 CFU/µL) biofilm as single and in combination of both Gram-positive and Gram-negative bacterial biofilms of 24 h grown with respective phage (109 PFU/µL) and phage cocktail (109 PFU/µL) at 4 h of incubation under static conditions. The bacteriolytic activity of phages vB_SAnS_SADP1 and vB_PAnP_PADP4 on 24-h-old biofilms of P. aeruginosa (0.761 ± 0.031) and S. aureus (0.856 ± 0.055), both alone and in combination (0.67 ± 0.02), was the focus of this investigation. The structural organization of biofilms in single- or dual-species combinations under in vitro conditions was validated by scanning and confocal laser scanning microscopy investigations. After 24 h of incubation, single-species biofilms are denser and more resilient whereas dual species biofilms are more loosely associated. Loose association of dual-species biofilm under scanning electron microscopic images at the same conditions, indicated the interspecies -competition of the Gram-positive and Gram-negative bacteria and dual-species biofilms (0.67 ± 0.02) have weak associations and are readily impacted by phage and a phage cocktail (0.16 ± 0.02). Dual-species biofilms were more readily impacted in in vitro settings. [ABSTRACT FROM AUTHOR]

Pectobacterium carotovorum subsp. carotovorum is a necrotrophic plant pathogen that secretes plant cell wall-degrading enzymes (PCWDEs) that cause soft rot disease in various crops. Bacteriophages have been under consideration as harmless antibacterial agents to replace antibiotics and copper-based pesticides. However, the emergence of bacteriophage resistance is one of the main concerns that should be resolved for practical phage applications. In this study, we developed a phage cocktail with three lytic phages that recognize colanic acid (phage POP12) or flagella (phages POP15 and POP17) as phage receptors to minimize phage resistance. The phage cocktail effectively suppressed the emergence of phage-resistant P. carotovorum subsp. carotovorum compared with single phages in in vitro challenge assays. The application of the phage cocktail to napa cabbage (Brassica rapa subsp. pekinensis) resulted in significant growth retardation of P. carotovorum subsp. carotovorum (P, 0.05) and prevented the symptoms of soft rot disease. Furthermore, phage cocktail treatments of young napa cabbage leaves in a greenhouse environment indicated effective prevention of soft rot disease compared to that in the nonphage negative control. We isolated 15 phage-resistant mutants after a phage cocktail treatment to assess the virulence-associated phenotypes compared to those of wild-type (WT) strain Pcc27. All mutants showed reduced production of four different PCWDEs, leading to lower levels of tissue softening. Ten of the 15 phage-resistant mutants additionally exhibited decreased swimming motility. Taken together, these results show that the phage cocktail developed here, which targets two different types of phage receptors, provides an effective strategy for controlling P. carotovorum subsp. carotovorum in agricultural products, with a potential ability to attenuate P. carotovorum subsp. carotovorum virulence. IMPORTANCE Pectobacterium carotovorum subsp. carotovorum is a phytopathogen that causes soft rot disease in various crops by producing plant cell wall-degrading enzymes (PCWDEs). Although antibiotics and copper-based pesticides have been extensively applied to inhibit P. carotovorum subsp. carotovorum, the emergence of antibiotic-resistant bacteria and demand for harmless antimicrobial products have emphasized the necessity of finding alternative therapeutic strategies. To address this problem, we developed a phage cocktail consisting of three P. carotovorum subsp. carotovorum-specific phages that recognize colanic acids and flagella of P. carotovorum subsp. carotovorum. The phage cocktail treatments significantly decreased P. carotovorum subsp. carotovorum populations, as well as soft rot symptoms in napa cabbage. Simultaneously, they resulted in virulence attenuation in phage-resistant P. carotovorum subsp. carotovorum, which was represented by decreased PCWDE production and decreased flagellum-mediated swimming motility. These results suggested that preparations of phage cocktails targeting multiple receptors would be an effective approach to biocontrol of P. carotovorum subsp. carotovorum in crops. [ABSTRACT FROM AUTHOR]

Background & objectives: Since the bacterium, Acinetobacter baumannii (AB) has acquired resistance to almost all commercially available antibiotics, the search for alternative treatment options continues to be need of the hour. Bacteriophage therapy seems to be the most promising amongst various proposed alternatives (e.g. antimicrobial peptides, bacteriocin, probiotics, etc.). The present study, therefore, aimed to evaluate the effect of different dosages of specific phages in immunocompromised rodents in a septicaemia model caused by AB mimicking real clinical situations. Methods: The three most active and unique phages (ɸAb4, ɸAb7 and ɸAb14) were selected for this study. A constant dose (100 μl of 108 pfu/ml) of AB was given in all the experiments. Five different sets of experiments were designed: prophylactic administration of phage cocktail in the volume of 100 μl (109 pfu/ml) before and simultaneous with the bacterial challenge; and therapeutic i.e. administration of phage cocktail six, 12 and 24 h after bacterial challenge. Since there were deaths in mice when phage was given 24 h after bacterial challenge, the reduced dosage i.e. 100 μl of 107, 106, 105 pfu/ml of phage cocktail was also evaluated. Results: The administration of 100 μl (109 pfu/ml) of phage cocktail after six, 12 and 24 h of the bacterial challenge resulted in the mortality ranging between 20 to 60 per cent. However, no mortality could be observed with simultaneous or prophylactic administration of phages with the bacterial challenge. No mortality was observed with reduced doses of the cocktail (106 and105 pfu/ml). Interpretation & conclusions: As per the results of this study, it may be concluded that even if patients with acute infections report late to the hospital, a relatively low dose of the phage cocktail may be therapeutically beneficial. [ABSTRACT FROM AUTHOR]

The rise and dissemination of colistin-resistant Escherichia coli harboring mcr-1 has become a global health threat. Bacteriophage (Phage) has been considered as an alternative to antibiotics in the treatment of antibiotic-resistant bacteria. Here, we report the effective control of colistin-resistant Escherichia coli harboring mcr-1 in retail raw chicken using a phage cocktail. Three novel phages, named HEMP1, HEMP4, and HEMP5, were isolated from environmental samples using E. coli harboring mcr-1 as host bacteria. Morphological and genomic analysis revealed that HEMP1 and HEMP5 have Myovirus-like morphology, while HEMP4 has Podovirus-like morphology, without any known genes associated with lysogeny and virulence. These phages exhibited high stability across wide temperatures and pH levels and showed rapid adsorption to their host strain. The phage cocktail, composed of three phages, effectively suppressed the growth and controlled biofilm formation of E. coli harboring mcr-1. Moreover, the phage cocktail significantly inhibited the growth of the bacteria on chicken meat at room (25°C) and refrigeration (4°C) temperatures. These results indicate that the phage cocktail could serve as a biological control method for colistin-resistant E. coli strains harboring mcr-1 in the food industry. • Three lytic phages targeting E. coli harboring mcr-1 were isolated and characterized. • Phage cocktail highly controlled the growth and biofilm of E. coli harboring mcr-1. • Phage cocktail significantly inhibited the E. coli harboring mcr-1 on chicken skin. • Phage cocktail has potential as a biocontrol agent to E. coli harboring mcr-1 in food. [ABSTRACT FROM AUTHOR]

The present study was planned to evaluate the efficacy of Pseudomonas aeruginosa specific phages in immunocompromised septicemia animal model as an alternative to antibiotics. Five different sets of experiments were performed: prophylactic administration of phage cocktail (3 lytic and unique) before and simultaneous with bacterial challenge; and therapeutic, that is, administration of phage cocktail 6, 12, and 24 hours after the bacterial challenge. No mortality was observed when simultaneous and late administration of phages was done with respect to the bacterial challenge. Contrary to this, administration of phage cocktail 100 µL (1012 PFU/mL) of volume after 6 hours of the infection resulted in a mortality rate of 60%. However, no mortality could be observed with reduced dose of cocktail, that is, 108, 109, and 1010 PFU administered 6 hours after bacterial challenge. Phage therapy in acute infections initiated with very small dosage under strict supervision may give better results. However, further studies to determine the quantity and frequency of dosage of phage cocktail for septicemia of various durations is strongly indicated.

Pectobacterium carotovorum subsp. carotovorum is a necrotrophic plant pathogen that secretes plant cell wall-degrading enzymes (PCWDEs) that cause soft rot disease in various crops. Bacteriophages have been under consideration as harmless antibacterial agents to replace antibiotics and copper-based pesticides. However, the emergence of bacteriophage resistance is one of the main concerns that should be resolved for practical phage applications. In this study, we developed a phage cocktail with three lytic phages that recognize colanic acid (phage POP12) or flagella (phages POP15 and POP17) as phage receptors to minimize phage resistance. The phage cocktail effectively suppressed the emergence of phage-resistant P. carotovorum subsp. carotovorum compared with single phages in in vitro challenge assays. The application of the phage cocktail to napa cabbage (Brassica rapa subsp. pekinensis ) resulted in significant growth retardation of P. carotovorum subsp. carotovorum ( P <  0.05) and prevented the symptoms of soft rot disease. Furthermore, phage cocktail treatments of young napa cabbage leaves in a greenhouse environment indicated effective prevention of soft rot disease compared to that in the nonphage negative control. We isolated 15 phage-resistant mutants after a phage cocktail treatment to assess the virulence-associated phenotypes compared to those of wild-type (WT) strain Pcc27. All mutants showed reduced production of four different PCWDEs, leading to lower levels of tissue softening. Ten of the 15 phage-resistant mutants additionally exhibited decreased swimming motility. Taken together, these results show that the phage cocktail developed here, which targets two different types of phage receptors, provides an effective strategy for controlling P. carotovorum subsp. carotovorum in agricultural products, with a potential ability to attenuate P. carotovorum subsp. carotovorum virulence. IMPORTANCE Pectobacterium carotovorum subsp. carotovorum is a phytopathogen that causes soft rot disease in various crops by producing plant cell wall-degrading enzymes (PCWDEs). Although antibiotics and copper-based pesticides have been extensively applied to inhibit P. carotovorum subsp. carotovorum , the emergence of antibiotic-resistant bacteria and demand for harmless antimicrobial products have emphasized the necessity of finding alternative therapeutic strategies. To address this problem, we developed a phage cocktail consisting of three P. carotovorum subsp. carotovorum -specific phages that recognize colanic acids and flagella of P. carotovorum subsp. carotovorum . The phage cocktail treatments significantly decreased P. carotovorum subsp. carotovorum populations, as well as soft rot symptoms in napa cabbage. Simultaneously, they resulted in virulence attenuation in phage-resistant P. carotovorum subsp. carotovorum , which was represented by decreased PCWDE production and decreased flagellum-mediated swimming motility. These results suggested that preparations of phage cocktails targeting multiple receptors would be an effective approach to biocontrol of P. carotovorum subsp. carotovorum in crops.

The use of lytic bacteriophages for the biocontrol of food-borne pathogens in food and in the food industry is gaining increasing acceptance. In this study, the effectiveness of a bacteriophage cocktail composed of three different lytic bacteriophages (UAB_Phi 20, UAB_Phi78, and UAB_Phi87) was determined in four different food matrices (pig skin, chicken breasts, fresh eggs, and packaged lettuce) experimentally contaminated with Salmonella enterica serovar Typhimurium and S. enterica serovar Enteritidis. A significant bacterial reduction (>4 and 2log/cm2 for S. Typhimurium and S. Enteritidis, respectively; p≤0.005) was obtained in pig skin sprayed with the bacteriophage cocktail and then incubated at 33°C for 6h. Significant decreases in the concentration of S. Typhimurium and S. Enteritidis were also measured in chicken breasts dipped for 5min in a solution containing the bacteriophage cocktail and then refrigerated at 4°C for 7days (2.2 and 0.9log10 cfu/g, respectively; p≤0.0001) as well as in lettuce similarly treated for 60min at room temperature (3.9 and 2.2log10 cfu/g, respectively; p≤0.005). However, only a minor reduction of the bacterial concentration (0.9log10 cfu/cm2 of S. Enteritidis and S. Typhimurium; p≤0.005) was achieved in fresh eggs sprayed with the bacteriophage cocktail and then incubated at 25°C for 2h. These results show the potential effectiveness of this bacteriophage cocktail as a biocontrol agent of Salmonella in several food matrices under conditions similar to those used in their production. [ABSTRACT FROM AUTHOR]

Background: Poultry products are the largest food category linked to salmonellosis in Canada. Bacteriophages (phages) have been proposed as a novel antimicrobial in the poultry industry due to their documented ubiquity, efficacy, and safety benefits. Materials and Methods: A library of 78 lytic phages was rapidly screened against 50 prominent poultry-associated Salmonella enterica isolates procured from British Columbia, Canada. Results: A phage cocktail was successfully formulated using only three sewage-isolated phages (SE4, SE13, and SE20) to achieve broad-spectrum antimicrobial efficacy across all S. enterica serovars. Highly promising phages were also characterized using one-step growth curves and transmission electron microscopy. Conclusion: Relative host efficiency is a new agar-based semiquantitative metric developed here for the rapid comparison of different phages against a panel of known bacterial targets., Competing Interests: No competing financial interests exist., (Copyright 2020, Mary Ann Liebert, Inc., publishers.)