The rise of multi-drug-resistant (MDR) bacteria has spurred renewed interest in the use of bacteriophages in therapy. However, mechanisms contributing to phage-mediated bacterial clearance in an ...animal host remain unclear. We investigated the effects of host immunity on the efficacy of phage therapy for acute pneumonia caused by MDR Pseudomonas aeruginosa in a mouse model. Comparing efficacies of phage-curative and prophylactic treatments in healthy immunocompetent, MyD88-deficient, lymphocyte-deficient, and neutrophil-depleted murine hosts revealed that neutrophil-phage synergy is essential for the resolution of pneumonia. Population modeling of in vivo results further showed that neutrophils are required to control both phage-sensitive and emergent phage-resistant variants to clear infection. This “immunophage synergy” contrasts with the paradigm that phage therapy success is largely due to bacterial permissiveness to phage killing. Lastly, therapeutic phages were not cleared by pulmonary immune effector cells and were immunologically well tolerated by lung tissues.
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•Efficacious phage therapy to pulmonary P. aeruginosa requires innate immune components•Neutrophils are required to control phage-sensitive and emergent phage-resistant bacteria•Models predict “immunophage synergy” arises due to nonlinear feedback
The mechanisms underlying phage-mediated bacterial clearance in an animal host remain unclear. By coupling animal experiments and in silico modeling, Roach et al. show that host innate immunity is essential for the efficacy of phages in treating respiratory bacterial infections, defining the concept of “immunophage synergy.”
Widespread antibiotic-resistant bacteria are threatening the arsenal of existing antibiotics. Not only are antibiotics less likely to be effective today, but their extensive use continues to drive ...the emergence of multidrug-resistant pathogens. A new-old antibacterial strategy with bacteriophages (phages) is under development, namely, phage therapy. Phages are targeted bacterial viruses with multiple antibacterial effector functions, which can reduce multidrug-resistant infections within the human body. This review summarizes recent phage therapy clinical trials and patient cases and outlines the fundamentals behind phage treatment strategies under development, mainly through bench-to-bedside approaches. We discuss the challenges that remain in phage therapy and the role of phages when combined with antibiotic therapy.
This narrative review presents the current knowledge and latest findings regarding phage therapy. Relevant case reports and research articles available through the Scopus and PubMed databases are discussed.
Although recent clinical data suggest the tolerability and, in some cases, efficacy of phage therapy, the clinical functionality still requires careful definition. The lack of well-controlled clinical trial data and complex regulatory frameworks have driven the most recent human data generation on a single-patient compassionate use basis. These cases often include the concomitant use of antibiotics, which makes it difficult to draw conclusions regarding the effectiveness of phages alone. However, human data support using antibiotics as phage potentiators and resistance breakers; thus, phage adjuvants are a promising avenue for near-term clinical development. Current knowledge gaps exist on the appropriate routes of administration, phage selection, frequency of administration, dosage, phage resistance, and pharmacokinetic and pharmacodynamic properties of the phages. In addition, we highlight that some phage therapies have mild adverse effects in patients.
Although more translational research is needed before the clinical implementation is feasible, phage therapy may well be pivotal in safeguarding humans against antibiotic-resistant infections.
•Phage-antibiotic synergy has been reported during treatment of bacterial infections.•Phage selective pressure can re-sensitize bacteria to antibiotics.•Existing studies highlight the need for ...translational studies examining mechanisms.
Increasingly, clinical infections are becoming recalcitrant or completely resistant to antibiotics treatment and multidrug resistance is rising alarmingly. Patients suffering from infections that used to be treated successfully by antibiotic regimens are running out of the treatment options. Bacteriophage (phage) therapy, long practiced in parts of Eastern Europe and the states of the former Soviet Union, is now being reevaluated as a treatment option complementary to and synergistic with antibiotic treatments. We discuss some current studies that have addressed synergistic killing activity between phages and antibiotics, the issues of treatment order and antibiotic class, and point to considerations that will have to be addressed by future studies. Overall, co-treatments with phages and antibiotics promise to extend the utility of antibiotics in current use. Nevertheless, a lot of work, both basic and clinical, remains to be done before such co-treatments become routine options in the hospital setting.
The world is on the cusp of a post-antibiotic era, but researchers and medical doctors have found a way forward-by looking back at how infections were treated before the advent of antibiotics, namely ...using phage therapy. Although bacteriophages (phages) continue to lack drug approval in Western medicine, an increasing number of patients are being treated on an expanded-access emergency investigational new drug basis. To streamline the production of high-quality and clinically safe phage preparations, we developed a systematic procedure for medicinal phage isolation, liter-scale cultivation, concentration and purification. The 16- to 21-day procedure described in this protocol uses a combination of modified classic techniques, modern membrane filtration processes and no organic solvents to yield on average 23 mL of 10
plaque-forming units (PFUs) per milliliter for Pseudomonas, Klebsiella, and Serratia phages tested. Thus, a single production run can produce up to 64,000 treatment doses at 10
PFUs, which would be sufficient for most expanded-access phage therapy cases and potentially for clinical phase I/II applications. The protocol focuses on removing endotoxins early by conducting multiple low-speed centrifugations, microfiltration, and cross-flow ultrafiltration, which reduced endotoxins by up to 10
-fold in phage preparations. Implementation of a standardized phage cultivation and purification across research laboratories participating in phage production for expanded-access phage therapy might be pivotal to reintroduce phage therapy to Western medicine.
Immunogenicity of bacteriophages Champagne-Jorgensen, Kevin; Luong, Tiffany; Darby, Taylor ...
Trends in microbiology (Regular ed.),
10/2023, Volume:
31, Issue:
10
Journal Article
Peer reviewed
Phages are key modulators of bacterial interactions and ecosystems within microbiomes.Though phages do not infect human cells, they bear substantial similarities to eukaryotic viruses.Increasing ...evidence suggests that phages directly influence the physiology of host tissues and activate antiviral immune programs; thus, phages appear to share a double-edged sword relationship with their human host.Despite significant medical importance, the immunological influence of commensal and therapeutic phages on the human host remains sparsely understood.
Hundreds of trillions of diverse bacteriophages (phages) peacefully thrive within and on the human body. However, whether and how phages influence their mammalian hosts is poorly understood. In this review, we explore current knowledge and present growing evidence that direct interactions between phages and mammalian cells often induce host inflammatory and antiviral immune responses. We show evidence that, like viruses of the eukaryotic host, phages are actively internalized by host cells and activate conserved viral detection receptors. This interaction often generates proinflammatory cytokine secretion and recruitment of adaptive immune programs. However, significant variability exists in phage–immune interactions, suggesting an important role for structural phage characteristics. The factors leading to the differential immunogenicity of phages remain largely unknown but are highly influenced by their human and bacterial hosts.
The alarming diffusion of multidrug-resistant (MDR) bacterial strains requires investigations on nonantibiotic therapies. Among such therapies, the use of bacteriophages (phages) as antimicrobial ...agents, namely, phage therapy, is a promising treatment strategy supported by the findings of recent successful compassionate treatments in Europe and the United States. In this work, we combined host range and genomic information to design a 6-phage cocktail killing several clinical strains of
, including those collected from Italian cystic fibrosis (CF) patients, and analyzed the cocktail performance. We demonstrated that the cocktail composed of four novel phages (PYO2, DEV, E215 and E217) and two previously characterized phages (PAK_P1 and PAK_P4) was able to lyse
both in planktonic liquid cultures and in biofilms. In addition, we showed that the phage cocktail could cure acute respiratory infection in mice and treat bacteremia in wax moth (
) larvae. Furthermore, administration of the cocktail to larvae prior to bacterial infection provided prophylaxis. In this regard, the efficiency of the phage cocktail was found to be unaffected by the MDR or mucoid phenotype of the pseudomonal strain. The cocktail was found to be superior to the individual phages in destroying biofilms and providing a faster treatment in mice. We also found the
larva model to be cost-effective for testing the susceptibility of clinical strains to phages, suggesting that it could be implemented in the frame of developing personalized phage therapies.
It has been over 100 years since bacteriophages (phages) were used as a human therapeutic. Since then, phage production has dramatically evolved. Current phage preparations have fewer adverse effects ...due to their low bacterial toxin content. As a result, therapeutic phages have become a predominant class of new antimicrobials and are being widely used for compassionate treatment of multidrug-resistant (MDR) infections. We describe herein a protocol for the production and ultrapurification of phages. By this technique, it is possible for a lab experienced with the process to produce >10
plaque-forming units (PFU) per mL of Gram-negative phages that meet FDA endotoxins limits for intravenous infusions in as little as 48 hours. We provide illustrations of the process and tips on how to safely remove bacterial toxins from phage lysates. Although dependent on the phage strain, the approach described can rapidly generate and purify phages for a variety of applications.
Viruses that infect bacteria (i.e., phages) are abundant and widespread in the human body, and new anti-infective approaches such as phage therapy are essential for the future of effective medicine. ...Our understanding of microenvironmental factors such as tissue oxygen availability at the site of phage–bacteria interaction remains limited, and it is unknown whether evolved resistance is sculpted differentially under normoxia vs. hypoxia. We, therefore, analyzed the phage–bacteria interaction landscape
via
adsorption, one-step, time-kill dynamics, and genetic evolution under both normoxia and hypoxia. This revealed that adsorption of phages to
Pseudomonas aeruginosa
decreased under 14% environmental oxygen (i.e., hypoxia), but phage time-kill and one-step growth kinetics were not further influenced. Tracking the adaptation of
P. aeruginosa
to phages uncovered a higher frequency of phage resistance and constrained types of spontaneous mutation under hypoxia. Given the interest in developing phage therapies, developing our understanding of the phage–pathogen interaction under microenvironmental conditions resembling those in the body offers insight into possible strategies to overcome multidrug-resistant (MDR) bacteria.
Enteropathogenic
(EPEC) is a major pathogen for diarrheal diseases among children. Antibiotics, when used appropriately, are effective; however, their overuse and misuse have led to the rise of ...antibiotic resistance worldwide. Thus, there are renewed efforts into the development of phage therapy as an alternative antibacterial therapy. Because EPEC in vivo models have shortcomings, a surrogate is used to study the mouse pathogen
in animal models. In this study, two new phages CrRp3 and CrRp10, which infect
were isolated and characterized. CrRp3 was found to be a new species within the genus
and CrRp10 is a new strain within the species
, in the genus
Both phages appear to have independently evolved from
phages, rather than other Citrobacter spp. phages. Neither phage strain carries known genes associated with bacterial virulence, antibiotic resistance, or lysogeny. CrRp3 is more potent, having a 24-fold faster adsorption rate and shorter lytic cycle when compared to the same properties of CrRp10. However, a lysis curve analysis revealed that CrRp10 prevented growth of
for 18 h, whereas resistance developed against CrRp3 within 9 h. We also show that hypoxic (5% oxygen) conditions decreased CrRp3 ability to control bacterial densities in culture. In contrast, low oxygen conditions did not affect CrRp10 ability to replicate on
. Together, CrRp10 is likely to be the better candidate for future phage therapy investigations.
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