Evaluating the efficacy of a phage cocktail against Pseudomonas fluorescens group strains in raw milk: microbiological, physical, and chemical analyses.

The objective of this study was to investigate the effectiveness of a phage cocktail against Pseudomonas fluorescens group and its effect on the microbial, physical and chemical properties of raw milk during different storage conditions. A phage cocktail consisting of Pseudomonas fluorescens, Pseudomonas tolaasii, and Pseudomonas libanensis phages was prepared. As a result, reductions in fluorescent Pseudomonas counts of up to 3.44 log units for the storage at 4 °C and 2.38 log units for the storage at 25 °C were achieved. Following the phage application, it is found that there was no significant difference in the total mesophilic aerobic bacteria and Enterobacteriaceae counts. However, it was observed that the number of lactic acid bacteria was higher in phage-treated groups. The results also showed that pH values in the phage added groups were lower than the others and the highest titratable acidity was obtained only in the bacteria-inoculated group. As a future perspective, this study suggests that, while keeping the number of target microorganisms under control in the milk with the use of phages during storage, the microbiota and accordingly the quality parameters of the milk can be affected. This work contributes to the development of effective strategies for maintaining the quality and extending the shelf life of milk and dairy products.

Lysis Physiology of Pseudomonas aeruginosa Infected with ssRNA Phage PRR1.

The phage PRR1 belongs to the Leviviridae family, a group of ssRNA bacteriophages that infect Gram-negative bacteria. The variety of host cells is determined by the specificity of PRR1 to a pilus encoded by a broad host range of IncP-type plasmids that confer multiple types of antibiotic resistance to the host. Using P. aeruginosa strain PAO1 as a host, we analyzed the PRR1 infection cycle, focusing on cell lysis. PRR1 infection renders P. aeruginosa cells sensitive to lysozyme approximately 20 min before the start of a drop in suspension turbidity. At the same time, infected cells start to accumulate lipophilic anions. The on-line monitoring of the entire infection cycle showed that single-gene-mediated lysis strongly depends on the host cells' physiological state. The blockage of respiration or a reduction in the intracellular ATP concentration during the infection resulted in the inhibition of lysis. The same effect was observed when the synthesis of PRR1 lysis protein was induced in an E. coli expression system. In addition, lysis was strongly dependent on the level of aeration. Dissolved oxygen concentrations sufficient to support cell growth did not ensure efficient lysis, and a coupling between cell lysis initiation and aeration level was observed. However, the duration of the drop in suspension turbidity did not depend on the level of aeration.

Development of an enzyme-linked phage receptor-binding protein assay (ELPRA) based on a novel biorecognition molecule- receptor-binding protein Gp130 of Pseudomonas aeruginosa bacteriophage Henu5.

Pseudomonas aeruginosa is a Gram-negative bacterium associated with life-threatening healthcare-associated infections (HAIs), including burn wound infections, pneumonia and sepsis. Moreover, P. aeruginosa has been considered a pathogen of global concern due to its rising antibiotic resistance. Efficient identification of P. aeruginosa would significantly benefit the containment of bacterial infections, prevent pathogen transmission, and provide orientated treatment options. The accuracy and specificity of bacterial detection are primarily dictated by the biorecognition molecules employed. Lytic bacteriophages (or phages) could specifically attach to and lyse host bacterial cells. Phages' host specificity is typically determined by their receptor-binding proteins (RBPs), which recognize and adsorb phages to particular bacterial host receptors. This makes RBPs promising biorecognition molecules in bacterial detection. This study identified a novel RBP (Gp130) from the P. aeruginosa phage Henu5. A modified enzyme-linked phage receptor-binding protein assay (ELPRA) was developed for P. aeruginosa detection employing Gp130 as biorecognition molecules. Optimized conditions provided a calibration curve for P. aeruginosa with a range from 1.0 × 103 to 1.0 × 107 CFU/mL, with a limit of detection as low as 10 CFU/mL in phosphate-buffered saline (PBS). With VITEKⓇ 2 Compact system identification (40 positives and 21 negatives) as the gold standard, the sensitivity of ELPRA was 0.950 (0.818-0.991), and the specificity was 0.905 (0.682-0.983) within a 95 %confidence interval. Moreover, the recovery test in spiked mouse serum showed recovery rates ranging from 82.79 %to 98.17%, demonstrating the prospect of the proposed ELPRA for detecting P. aeruginosa in biological samples.

Phage-antibiotic combinations to control Pseudomonas aeruginosa-Candida two-species biofilms.

Phage-antibiotic combinations to treat bacterial infections are gaining increased attention due to the synergistic effects often observed when applying both components together. Most studies however focus on a single pathogen, although in many clinical cases multiple species are present at the site of infection. The aim of this study was to investigate the anti-biofilm activity of phage-antibiotic/antifungal combinations on single- and dual-species biofilms formed by P. aeruginosa and the fungal pathogen Candida albicans. The Pseudomonas phage Motto in combination with ciprofloxacin had significant anti-biofilm activity. We then compared biofilms formed by P. aeruginosa alone with the dual-species biofilms formed by bacteria and C. albicans. Here, we found that the phage together with the antifungal fluconazole was active against 6-h-old dual-species biofilms but showed only negligible activity against 24-h-old biofilms. This study lays the first foundation for potential therapeutic approaches to treat co-infections caused by bacteria and fungi using phage-antibiotic combinations.

Lytic bacteriophages induce the secretion of antiviral and proinflammatory cytokines from human respiratory epithelial cells.

Phage therapy is a therapeutic approach to treat multidrug-resistant (MDR) infections that employs lytic bacteriophages (phages) to eliminate bacteria. Despite the abundant evidence for its success as an antimicrobial in Eastern Europe, there is scarce data regarding its effects on the human host. Here, we aimed to understand how lytic phages interact with cells of the airway epithelium, the tissue site that is colonized by bacterial biofilms in numerous chronic respiratory disorders. Using a panel of Pseudomonas aeruginosa phages and human airway epithelial cells (AECs) derived from a person with cystic fibrosis (CF), we determined that interactions between phages and epithelial cells depend on specific phage properties as well as physiochemical features of the microenvironment. Although poor at internalizing phages, the airway epithelium responds to phage exposure by changing its transcriptional profile and secreting antiviral and proinflammatory cytokines that correlate with specific phage families. Overall, our findings indicate that mammalian responses to phages are heterogenous and could potentially alter the way that respiratory local defenses aid in bacterial clearance during phage therapy. Thus, besides phage receptor specificity in a particular bacterial isolate, the criteria to select lytic phages for therapy should be expanded to include mammalian cell responses.

Removal of Pseudomonas type IV pili by a small RNA virus.

The retractile type IV pilus (T4P) is important for virulence of the opportunistic human pathogen Pseudomonas aeruginosa. The single-stranded RNA (ssRNA) phage PP7 binds to T4P and is brought to the cell surface through pilus retraction. Using fluorescence microscopy, we discovered that PP7 detaches T4P, which impairs cell motility and restricts the pathogen's virulence. Using cryo-electron microscopy, mutagenesis, optical trapping, and Langevin dynamics simulation, we resolved the structure of PP7, T4P, and the PP7/T4P complex and showed that T4P detachment is driven by the affinity between the phage maturation protein and its bound pilin, plus the pilus retraction force and speed, and pilus bending. Pilus detachment may be widespread among other ssRNA phages and their retractile pilus systems and offers new prospects for antibacterial prophylaxis and therapeutics.

Warming alters life-history traits and competition in a phage community.

Host-parasite interactions are highly susceptible to changes in temperature due to mismatches in species thermal responses. In nature, parasites often exist in communities, and responses to temperature are expected to vary between host-parasite pairs. Temperature change thus has consequences for both host-parasite dynamics and parasite-parasite interactions. Here, we investigate the impact of warming (37°C, 40°C, and 42°C) on parasite life-history traits and competition using the opportunistic bacterial pathogen Pseudomonas aeruginosa (host) and a panel of three genetically diverse lytic bacteriophages (parasites). We show that phages vary in their responses to temperature. While 37°C and 40°C did not have a major effect on phage infectivity, infection by two phages was restricted at 42°C. This outcome was attributed to disruption of different phage life-history traits including host attachment and replication inside hosts. Furthermore, we show that temperature mediates competition between phages by altering their competitiveness. These results highlight phage trait variation across thermal regimes with the potential to drive community dynamics. Our results have important implications for eukaryotic viromes and the design of phage cocktail therapies.IMPORTANCEMammalian hosts often elevate their body temperatures through fevers to restrict the growth of bacterial infections. However, the extent to which fever temperatures affect the communities of phages with the ability to parasitize those bacteria remains unclear. In this study, we investigate the impact of warming across a fever temperature range (37°C, 40°C, and 42°C) on phage life-history traits and competition using a bacterium (host) and bacteriophage (parasite) system. We show that phages vary in their responses to temperature due to disruption of different phage life-history traits. Furthermore, we show that temperature can alter phage competitiveness and shape phage-phage competition outcomes. These results suggest that fever temperatures have the potential to restrict phage infectivity and drive phage community dynamics. We discuss implications for the role of temperature in shaping host-parasite interactions more widely.

Targeted deletion of Pf prophages from diverse Pseudomonas aeruginosa isolates has differential impacts on quorum sensing and virulence traits.

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that commonly causes medical hardware, wound, and respiratory infections. Temperate filamentous Pf phages that infect P. aeruginosa impact numerous virulence phenotypes. Most work on Pf phages has focused on Pf4 and its host P. aeruginosa PAO1. Expanding from Pf4 and PAO1, this study explores diverse Pf phages infecting P. aeruginosa clinical isolates. We describe a simple technique targeting the Pf lysogeny maintenance gene, pflM (PA0718), that enables the effective elimination of Pf prophages from diverse P. aeruginosa hosts. The pflM gene shows diversity among different Pf phage isolates; however, all examined pflM alleles encode the DUF5447 domain. We demonstrate that pflM deletion results in prophage excision but not replication, leading to total prophage loss, indicating a role for lysis/lysogeny decisions for the DUF5447 domain. This study also assesses the effects different Pf phages have on host quorum sensing, biofilm formation, pigment production, and virulence against the bacterivorous nematode Caenorhabditis elegans. We find that Pf phages have strain-specific impacts on quorum sensing and biofilm formation, but nearly all suppress pigment production and increase C. elegans avoidance behavior. Collectively, this research not only introduces a valuable tool for Pf prophage elimination from diverse P. aeruginosa isolates but also advances our understanding of the complex relationship between P. aeruginosa and filamentous Pf phages.IMPORTANCEPseudomonas aeruginosa is an opportunistic bacterial pathogen that is frequently infected by filamentous Pf phages (viruses) that integrate into its chromosome, affecting behavior. Although prior work has focused on Pf4 and PAO1, this study investigates diverse Pf in clinical isolates. A simple method targeting the deletion of the Pf lysogeny maintenance gene pflM (PA0718) effectively eliminates Pf prophages from clinical isolates. The research evaluates the impact Pf prophages have on bacterial quorum sensing, biofilm formation, and virulence phenotypes. This work introduces a valuable tool to eliminate Pf prophages from clinical isolates and advances our understanding of P. aeruginosa and filamentous Pf phage interactions.

Characteristics and whole-genome analysis of a novel Pseudomonas syringae pv. tomato bacteriophage D6 isolated from a karst cave.

Pseudomonas syringae is a gram-negative plant pathogen that infects plants such as tomato and poses a threat to global crop production. In this study, a novel lytic phage infecting P. syringae pv. tomato DC3000, named phage D6, was isolated and characterized from sediments in a karst cave. The latent period of phage D6 was found to be 60 min, with a burst size of 16 plaque-forming units per cell. Phage D6 was stable at temperatures between 4 and 40 °C but lost infectivity when heated to 70 °C. Its infectivity was unaffected at pH 6-10 but became inactivated at pH ≤ 5 or ≥ 12. The genome of phage D6 is a linear double-stranded DNA of 307,402 bp with a G + C content of 48.43%. There is a codon preference between phage D6 and its host, and the translation of phage D6 gene may not be entirely dependent on the tRNA library provided by the host. A total of 410 open reading frames (ORFs) and 14 tRNAs were predicted in its genome, with 92 ORFs encoding proteins with predicted functions. Phage D6 showed low genomic similarity to known phage genomes in the GenBank and Viral sequence databases. Genomic and phylogenetic analyses revealed that phage D6 is a novel phage. The tomato plants were first injected with phage D6, and subsequently with Pst DC3000, using the foliar spraying and root drenching inoculum approach. Results obtained after 14 days indicated that phage D6 inoculation decreased P. syringae-induced symptoms in tomato leaves and inhibited the pathogen's growth in the leaves. The amount of Pst DC3000 was reduced by 150- and 263-fold, respectively. In conclusion, the lytic phage D6 identified in this study belongs to a novel phage within the Caudoviricetes class and has potential for use in biological control of plant diseases.

Targeted Genome Editing of Virulent Pseudomonas Phages Using CRISPR-Cas3.

The vast number of unknown phage-encoded ORFan genes and limited insights into the genome organization of phages illustrate the need for efficient genome engineering tools to study bacteriophage genes in their natural context. In addition, there is an application-driven desire to alter phage properties, which is hampered by time constraints for phage genome engineering in the bacterial host. We here describe an optimized CRISPR-Cas3 system in Pseudomonas for straightforward editing of the genome of virulent bacteriophages. The two-vector system combines a broad host range CRISPR-Cas3 targeting plasmid with a SEVA plasmid for homologous directed repair, which enables the creation of clean deletions, insertions, or substitutions in the phage genome within a week. After creating the two plasmids separately, a co-transformation to P. aeruginosa cells is performed. A subsequent infection with the targeted phage allows the CRISPR-Cas3 system to cut the DNA specifically and facilitate or select for homologous recombination. This system has also been successfully applied for P. aeruginosa and Pseudomonas putida genome engineering. The method is straightforward, efficient, and universal, enabling to extrapolate the system to other phage-host pairs.

PqsA mutation-mediated enhancement of phage-mediated combat against Pseudomonas aeruginosa.

Phage therapy is a potential approach in the biocontrol of foodborne pathogens. However, the emergence of phage resistance and the narrow host range of most phage isolates continue to limit the antimicrobial efficacy of phages. Here, we investigated the potential of the pqsA gene, encoding the anthranilate-CoA ligase enzyme, as an adjuvant for phage therapy. The knockout of the pqsA gene significantly enhanced the bactericidal effect of phages vB_Pae_QDWS and vB_Pae_S1 against Pseudomonas aeruginosa. Under phage infection pressure, the growth of the PaΔpqsA was significantly inhibited within 8 h compared to the wild-type PAO1. Furthermore, we found that altering phage adsorption is not how PaΔpqsA responds to phage infection. Although pqsA represents a promising target for enhancing phage killing, it may not be applicable to all phages, such as types vB_Pae_W3 and vB_Pae_TR. Our findings provide new material reserves for the future design of novel phage-based therapeutic strategies.

Optimized preparation pipeline for emergency phage therapy against Pseudomonas aeruginosa at Yale University.

Bacteriophage therapy is one potential strategy to treat antimicrobial resistant or persistent bacterial infections, and the year 2021 marked the centennial of Felix d'Hérelle's first publication on the clinical applications of phages. At the Center for Phage Biology & Therapy at Yale University, a preparatory modular approach has been established to offer safe and potent phages for single-patient investigational new drug applications while recognizing the time constraints imposed by infection(s). This study provides a practical walkthrough of the pipeline with an Autographiviridae phage targeting Pseudomonas aeruginosa (phage vB_PaeA_SB, abbreviated to ΦSB). Notably, a thorough phage characterization and the evolutionary selection pressure exerted on bacteria by phages, analogous to antibiotics, are incorporated into the pipeline.

Bacteriophages for the treatment of pseudomonas-infected vascular prosthesis.

We present a case report detailing therapeutic application of two lytic antipseudomonal bacteriophages to treat a chronic relapsing Pseudomonas aeruginosa infection of a prosthetic aortic graft. As there are currently no Danish laboratories offering phages for clinical therapy, and this case, to our knowledge represents the first applied phage therapy in Denmark, the practical and regulatory aspects of offering this treatment option in Denmark is briefly reviewed along with the clinical case.

Accumulation of defense systems in phage-resistant strains of Pseudomonas aeruginosa.

Prokaryotes encode multiple distinct anti-phage defense systems in their genomes. However, the impact of carrying a multitude of defense systems on phage resistance remains unclear, especially in a clinical context. Using a collection of antibiotic-resistant clinical strains of Pseudomonas aeruginosa and a broad panel of phages, we demonstrate that defense systems contribute substantially to defining phage host range and that overall phage resistance scales with the number of defense systems in the bacterial genome. We show that many individual defense systems target specific phage genera and that defense systems with complementary phage specificities co-occur in P. aeruginosa genomes likely to provide benefits in phage-diverse environments. Overall, we show that phage-resistant phenotypes of P. aeruginosa with at least 19 phage defense systems exist in the populations of clinical, antibiotic-resistant P. aeruginosa strains.

Characterization of a new Pseudomonas aeruginosa Queuovirinae bacteriophage.

The ESKAPEE pathogen Pseudomonas aeruginosa is a common cause of chronic wound and cystic fibrosis lung infections, as well as acute burn and nosocomial infections. Many of these infections are recalcitrant to conventional antibiotic therapies due to both traditional antibiotic resistance mechanisms and antimicrobial tolerance. Recent successes with bacteriophage (phage) therapy to treat chronic human P. aeruginosa infections have led to a renewed interest in isolating and characterizing new P. aeruginosa phages. Here, we isolated and characterized a new lytic phage (termed PIP, pili-infecting phage) capable of infecting P. aeruginosa PA14. PIP is a tailed phage with an icosahedral head and flexible tail containing a genome that is 57,462 bp in length. Phylogenetic analysis reveals that PIP belongs to the subfamily Queuovirinae and genus Nipunavirus but is highly divergent in gene content from known Nipunaviruses. By isolating and characterizing a P. aeruginosa strain that spontaneously evolved resistance to PIP, we show that the receptor for PIP is Type IV pili. In summary, we isolated a new P. aeruginosa phage species with a unique genome, thus increasing the diversity of phages known to infect this important human pathogen.IMPORTANCEThe opportunistic pathogen Pseudomonas aeruginosa causes both acute and chronic human infections. These infections are notoriously difficult to treat due to both antibiotic resistance and antibiotic tolerance. The increasing frequency of antibiotic failure in P. aeruginosa infections has led scientists to explore other treatment options, including bacteriophage (phage) therapy. To this end, there has been a significant effort to identify new Pseudomonas phages. Here, we isolated and characterized a bacteriophage (termed PIP, pili-infecting phage) that infects P. aeruginosa PA14. Examination of the PIP genome revealed that this phage represents a new species in the subclass Queuovirinae. The isolation and characterization of spontaneous PA14 mutants that are resistant to PIP infection revealed Type IV pili as the PIP receptor. Ultimately, this study characterizes a new species of Pseudomonas phage, thus enhancing the known diversity of phages that infect this important pathogen.

Chitosan-based matrix as a carrier for bacteriophages.

Wound healing is a dynamic and complex process where infection prevention is essential. Chitosan, thanks to its bactericidal activity against gram-positive and gram-negative bacteria, as well as anti-inflammatory and hemostatic properties, is an excellent candidate to design dressings for difficult-to-heal wound treatment. The great advantage of this biopolymer is its capacity to be chemically modified, which allows for the production of various functional forms, depending on the needs and subsequent use. Moreover, chitosan can be an excellent polymer matrix for bacteriophage (phage) packing as a novel alternative/supportive antibacterial therapy approach. This study is focused on the preparation and characteristics of chitosan-based material in the form of a film with the addition of Pseudomonas lytic phages (KTN4, KT28, and LUZ19), which would exhibit antibacterial activity as a potential dressing that accelerates the wound healing. We investigated the method of producing a polymer based on microcrystalline chitosan (MKCh) to serve as the matrix for phage deposition. We described some important parameters such as average molar mass, swelling capacity, surface morphology, phage release profile, and antibacterial activity tested in the Pseudomonas aeruginosa bacterial model. The chitosan polysaccharide turned out to interact with phage particles immobilizing them within a material matrix. Nevertheless, with the high hydrophilicity and swelling features of the prepared material, the external solution of bacterial culture was absorbed and phages went in direct contact with bacteria causing their lysis in the polymer matrix. KEY POINTS: • A novel chitosan-based matrix with the addition of active phages was prepared • Phage interactions with the chitosan matrix were determined as electrostatic • Phages in the matrix work through direct contact with the bacterial cells.

A synthetic biology approach to assemble and reboot clinically relevant Pseudomonas aeruginosa tailed phages.

The rise in the frequency of antibiotic resistance has made bacterial infections, specifically Pseudomonas aeruginosa, a cause for greater concern. Phage therapy is a promising solution that uses naturally isolated phages to treat bacterial infections. Ecological limitations, which stipulate a discrete host range and the inevitable evolution of resistance, may be overcome through a better understanding of phage biology and the utilization of engineered phages. In this study, we developed a synthetic biology approach to construct tailed phages that naturally target clinically relevant strains of Pseudomonas aeruginosa. As proof of concept, we successfully cloned and assembled the JG024 and DMS3 phage genomes in yeast using transformation-associated recombination cloning and rebooted these two phage genomes in two different strains of P. aeruginosa. We identified factors that affected phage reboot efficiency like the phage species or the presence of antiviral defense systems in the bacterial strain. We have successfully extended this method to two other phage species and observed that the method enables the reboot of phages that are naturally unable to infect the strain used for reboot. This research represents a critical step toward the construction of clinically relevant, engineered P. aeruginosa phages.IMPORTANCEPseudomonas aeruginosa is a bacterium responsible for severe infections and a common major complication in cystic fibrosis. The use of antibiotics to treat bacterial infections has become increasingly difficult as antibiotic resistance has become more prevalent. Phage therapy is an alternative solution that is already being used in some European countries, but its use is limited by the narrow host range due to the phage receptor specificity, the presence of antiviral defense systems in the bacterial strain, and the possible emergence of phage resistance. In this study, we demonstrate the use of a synthetic biology approach to construct and reboot clinically relevant P. aeruginosa tailed phages. This method enables a significant expansion of possibilities through the construction of engineered phages for therapy applications.

Evaluation of the impact of repeated intravenous phage doses on mammalian host-phage interactions.

Phage therapy has shown great promise for the treatment of multidrug-resistant bacterial infections. However, the lack of a thorough and organized understanding of phage-body interactions has limited its clinical application. Here, we administered different purified phages (Salmonella phage SE_SZW1, Acinetobacter phage AB_SZ6, and Pseudomonas phage PA_LZ7) intravenously to healthy animals (rats and monkeys) to evaluate the phage-induced host responses and phage pharmacokinetics with different intravenous (IV) doses in healthy animals. The plasma and the organs were sampled after different IV doses to determine the phage biodistribution, phage-induced cytokines, and antibodies. The potential side effects of phages on animals were assessed. A non-compartment model revealed that the plasma phage titer gradually decreased over time following a single dose. Repeated doses resulted in a 2-3 Log10 decline of the plasma phage titer at 5 min compared to the first dose, regardless of the type of phage administered in rats. Host innate immune responses were activated including splenic enlargement following repeated doses. Phage-specific neutralization antibodies in animals receiving phages were detected. Similar results were obtained from monkeys. In conclusion, the mammalian bodies were well-tolerant to the administered phages. The animal responses to the phages and the phage biodistribution profiles could have a significant impact on the efficacy of phage therapy.IMPORTANCEPhage therapy has demonstrated potential in addressing multidrug-resistant bacterial infections. However, an insufficient understanding of phage-host interactions has impeded its broader clinical application. In our study, specific phages were administered intravenously (IV) to both rats and monkeys to elucidate phage-host interactions and evaluate phage pharmacokinetics (PK). Results revealed that with successive IV administrations, there was a decrease in plasma phage concentrations. Concurrently, these administrations elicited both innate and adaptive immune responses in the subjects. Notably, the observed immune responses and PK profiles exhibited variation contingent upon the phage type and the mammalian host. Despite these variations, the tested mammals exhibited a favorable tolerance to the IV-administered phages. This underscores the significance of comprehending these interactions for the optimization of phage therapy outcomes.

Pharmacokinetics and safety evaluation of intravenously administered Pseudomonas phage PA_LZ7 in a mouse model.

IMPORTANCE: Phage therapy is gaining traction as an alternative to antibiotics due to the rise of multi-drug-resistant (MDR) bacteria. This study assessed the pharmacokinetics and safety of PA_LZ7, a phage targeting MDR Pseudomonas aeruginosa, in mice. After intravenous administration, the phage showed an exponential decay in plasma and its concentration dropped significantly within 24 h for all dosage groups. Although there was a temporary increase in certain plasma cytokines and spleen weight at higher dosages, no significant toxicity was observed. Therefore, PA_LZ7 shows potential as an effective and safe candidate for future phage therapy against MDR P. aeruginosa infections.

Successful Use of Phage and Antibiotics Therapy for the Eradication of Two Bacterial Pathogens from the Respiratory Tract of an Infant.

Phage therapy can be a useful approach in a number of clinical cases associated with multidrug-resistant (MDR) bacterial infections. In this study, we describe a successful consecutive phage and antibiotic application to cure a 3-month-old girl suffering from severe bronchitis after tracheostomy. Bronchitis was associated with two bacterial agents, MDR Pseudomonas aeruginosa and a rare opportunistic pathogen Dolosigranulum pigrum. The phage cocktail "Pyobacteriophage" containing at least two different phages against isolated MDR P. aeruginosa strain was used via inhalation and nasal drops. Topical application of the phage cocktail removed most of P. aeruginosa cells and contributed to a change in the antimicrobial resistance profile of surviving P. aeruginosa cells. As a result, it became possible to choose and administer an appropriate antibiotic that was effective against both infectious agents. Complete recovery of the infant was recorded.