Non-traditional #Antibacterial #Therapeutic #Options and #Challenges (Cell Host Microbe, abstract)

[Source: Cell, Host & Microbe, full page: (LINK). Abstract, edited.]

Non-traditional Antibacterial Therapeutic Options and Challenges

Ursula Theuretzbacher, Laura J.V. Piddock




The global challenges presented by drug-resistant bacterial infections have stimulated much activity in finding new treatments. This review summarizes the progress and setbacks of non-traditional approaches intent on circumventing bacterial drug resistance. These approaches include targeting virulence via toxin production and virulence factor secretion, impeding bacterial adhesion to host cells and biofilm formation, interrupting or inhibiting bacterial communication, and downregulating virulence. Other strategies include immune evasion, microbiome-modifying therapies, and the employment of phages as treatments or carriers. Finally, the prospects of nanoparticles, immunotherapy, antisense RNA, and drug-resistance-modulation approaches are discussed. The development of non-traditional treatments suffers similar challenges faced by developers of conventional antibiotics; however, most of these new strategies have additional and considerable hurdles before it can be shown that they are safe and efficacious for patient use. For the foreseeable future, it is likely that most of these treatments, if approved, will be used in combination with antibiotics.

Keywords: anti-virulence – quorum-sensing – microbiome – phage – nanoparticles – immunotherapy – antisense RNA – non-traditional antimicrobials

Keywords: Antibiotics; Drugs Resistance; Immunotherapy; Bacteriophages.



#Phage #therapy of #pneumonia is not associated with an over stimulation of the #inflammatory response compared to #antibiotic treatment in mice (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Phage therapy of pneumonia is not associated with an over stimulation of the inflammatory response compared to antibiotic treatment in mice

Nicolas Dufour, Raphaëlle Delattre, Anne Chevallereau, Jean-Damien Ricard, Laurent Debarbieux

DOI: 10.1128/AAC.00379-19




Supported by years of clinical use in some countries and more recently by literature on experimental models as well as compassionate use in Europe and in USA, bacteriophage (phage) therapy is providing a solution for difficult to treat bacterial infections. However, studies of the impact of such treatments on the host remain scarce.


Murine acute pneumonia initiated by intranasal instillation of two pathogenic strains of Escherichia coli (536 and LM33) were treated by two specific bacteriophages (536_P1 and LM33_P1; intranasal) or antibiotics (Ceftriaxone, Cefoxitin, Imipenem-Cilastatin; intraperitoneal). Healthy mice also received phages alone. Severity of pulmonary edema, acute inflammatory cytokines (blood and lung homogenates), complete blood count, bacteria and bacteriophages counts were obtained at early (≤12h) and late (≥20h) time points.


Bacteriophage’s efficacy to decrease bacterial load was faster than antibiotics, but both displayed similar endpoints. Bacteriophage treatment was not associated with an over-inflammation but in contrast tended to lower inflammation and provided a faster correction of blood cell count abnormalities compared to antibiotics. In absence of bacterial infection, bacteriophage 536_P1 promoted a weak increase in the production of anti-viral cytokines (INF-γ and IL-12) and chemokines in the lungs, but not in the blood. However, such variations were no longer observed when bacteriophage 536_P1 was administered to treat infected animals.


The rapid lysis of bacteria by bacteriophages in vivo does not increase the innate inflammatory response compared to an antibiotic treatment.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Bacteriophages; Pneumonia; Animal models.


Specific and Selective #Bacteriophages in the Fight against #MDR #Acinetobacter baumannii (Virol Sin., abstract)

[Source: Virologica Sinica, full page: (LINK). Abstract, edited.]

Specific and Selective Bacteriophages in the Fight against Multidrug-resistant Acinetobacter baumannii

Authors: Natalia Bagińska, Anna Pichlak, Andrzej Górski, Ewa Jończyk-Matysiak

Review / First Online: 15 May 2019



Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients. Several A. baumannii strains are multidrug resistant and infect wounds, bones, and the respiratory tract. Current studies are focused on finding new effective agents against A. baumannii. Phage therapy is a promising means to fight this bacterium and many studies on procuring and applying new phages against A. baumannii are currently being conducted. As shown in animal models, phages against multidrug-resistant A. baumannii may control bacterial infections caused by this pathogen and may be a real hope to solve this dangerous health problem.

Keywords: Acinetobacter baumannii – Bacteriophages – Phage therapy – Multidrug resistance (MDR)


This work was supported by the statutory funds from the Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences. The authors also thank to Norbert Łodej for making figure to this paper.


Compliance with Ethics Standards

Conflict of interest

Andrzej Górski, is co-inventor of patents owned by the Institute and covering phage preparations. Other authors declare that they have no conflict of interest.

Animal and Human Rights Statement

This article does not contain any studies with human or animal subjects performed by any of the authors.

Keywords: Antibiotics; Drugs Resistance; Acinetobacter baumannii; Bacteriophages.


Filamentous #bacteriophages are associated with chronic #Pseudomonas #lung #infections and #antibiotic resistance in #cysticfibrosis (Sci Transl Med., abstract)

[Source: Science Translational Medicine, full page: (LINK). Abstract, edited.]

Filamentous bacteriophages are associated with chronic Pseudomonas lung infections and antibiotic resistance in cystic fibrosis

Elizabeth B. Burgener1,*, Johanna M. Sweere2,3, Michelle S. Bach2, Patrick R. Secor4, Naomi Haddock3, Laura K. Jennings4, Rasmus L. Marvig5, Helle Krogh Johansen6,7, Elio Rossi6, Xiou Cao2, Lu Tian8, Laurence Nedelec9, Søren Molin10, Paul L. Bollyky2,3,† and Carlos E. Milla1,†

1 Center for Excellence in Pulmonary Biology, Department of Pediatrics, Stanford University, Stanford, CA 94305, USA. 2 Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA 94305, USA. 3 Stanford Immunology, Stanford University, Stanford, CA 94305, USA. 4 Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA. 5 Center for Genomic Medicine, Rigshospitalet–Copenhagen University Hospital, Copenhagen, Denmark. 6 Department of Clinical Microbiology, Rigshospitalet, Copenhagen Ø, Denmark. 7 Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark. 8 Biomedical Data Science Administration and Statistics, Stanford University, Stanford, CA 94305, USA. 9 Primary Care and Population Health, Stanford University, Stanford, CA 94305, USA. 10 The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.

*Corresponding author. Email:

† Co-senior authors.

Science Translational Medicine  17 Apr 2019: Vol. 11, Issue 488, eaau9748 / DOI: 10.1126/scitranslmed.aau9748


Infection-boosting phage

Chronic Pseudomonas aeruginosa infection is common in patients with cystic fibrosis (CF). Filamentous bacteriophage (Pf phage) can infect P. aeruginosa and has been shown to contribute to the virulence of infection in animal models. However, whether Pf phage plays a role in the pathogenicity of P. aeruginosa in CF is unknown. Now, Burgener et al. showed that Pf phage was abundantly expressed in sputum samples from two large cohorts of patients with CF. The presence of Pf phage was associated with increased antibiotic resistance and reduced lung function. The results suggest that Pf phage might play a role in the pathogenicity of P. aeruginosa infection in CF.



Filamentous bacteriophage (Pf phage) contribute to the virulence of Pseudomonas aeruginosa infections in animal models, but their relevance to human disease is unclear. We sought to interrogate the prevalence and clinical relevance of Pf phage in patients with cystic fibrosis (CF) using sputum samples from two well-characterized patient cohorts. Bacterial genomic analysis in a Danish longitudinal cohort of 34 patients with CF revealed that 26.5% (n = 9) were consistently Pf phage positive. In the second cohort, a prospective cross-sectional cohort of 58 patients with CF at Stanford, sputum qPCR analysis showed that 36.2% (n = 21) of patients were Pf phage positive. In both cohorts, patients positive for Pf phage were older, and in the Stanford CF cohort, patients positive for Pf phage were more likely to have chronic P. aeruginosa infection and had greater declines in pulmonary function during exacerbations than patients negative for Pf phage presence in the sputum. Last, P. aeruginosa strains carrying Pf phage exhibited increased resistance to antipseudomonal antibiotics. Mechanistically, in vitro analysis showed that Pf phage sequesters these same antibiotics, suggesting that this mechanism may thereby contribute to the selection of antibiotic resistance over time. These data provide evidence that Pf phage may contribute to clinical outcomes in P. aeruginosa infection in CF.

Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works

This is an article distributed under the terms of the Science Journals Default License.

Keywords: Antibiotics; Drugs Resistance; Pseudomonas aeruginosa; Cystic fibrosis; Bacteriophages.


#Lysocins: Bioengineered #Antimicrobials that Deliver #Lysins Across the Outer Membrane of Gram-Negative #Bacteria (Antimicrob Agents Chemother., abstract)

[Source: Antimicrobial Agents and Chemotherapy, full page: (LINK). Abstract, edited.]

Lysocins: Bioengineered Antimicrobials that Deliver Lysins Across the Outer Membrane of Gram-Negative Bacteria

Ryan D. Heselpoth, Chad W. Euler, Raymond Schuch, Vincent A. Fischetti

DOI: 10.1128/AAC.00342-19



The prevalence of multidrug-resistant Pseudomonas aeruginosa has stimulated development of alternative therapeutics. Bacteriophage peptidoglycan hydrolases, termed lysins, represent an emerging antimicrobial option for targeting Gram-positive bacteria. However, lysins against Gram-negatives are generally deterred by the outer membrane and their inability to work in serum. One solution involves exploiting evolved delivery systems used by colicin-like bacteriocins (e.g., S-type pyocins of P. aeruginosa) to translocate through the outer membrane. Following surface receptor binding, colicin-like bacteriocins form Tol- or TonB-dependent translocons to actively import cytotoxic domains through outer membrane protein channels. With this understanding, we developed lysocins, which are bioengineered lysin-bacteriocinfusion molecules capable of periplasmic import. In our proof of concept studies, components from the P. aeruginosa bacteriocin pyocin S2 responsible for surface receptor binding and outer membrane translocation were fused to the GN4 lysin to generate the PyS2-GN4 lysocin. PyS2-GN4 delivered the GN4 lysin to the periplasm to induce peptidoglycan cleavage and log-fold P. aeruginosa death with minimal endotoxin release. While displaying narrow-spectrum antipseudomonal activity in human serum, PyS2-GN4 also efficiently disrupted biofilms, outperformed standard of care antibiotics, exhibited no cytotoxicity towards eukaryotic cells, and protected mice from P. aeruginosa challenge in a bacteremia model. In addition to P. aeruginosa, lysocins can be constructed to target other prominent Gram-negative bacterial pathogens.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Antibiotics; Drugs Resistance; Pseudomonas aeruginosa; Bacteriophages; Lysins; Bacteriocins; Lysocins.


#Enzymatic anti- #CRISPRs improve the #bacteriophage #arsenal (Nat Struct Mol Biol., abstract)

[Source: Nature Structural & Molecular Biology, full page: (LINK). Abstract, edited.]

News & Views | Published: 01 April 2019 | CRISPR

Enzymatic anti-CRISPRs improve the bacteriophage arsenal

Shravanti K. Suresh, Karthik Murugan & Dipali G. Sashital

Nature Structural & Molecular Biology (2019)


Bacteriophage-encoded anti-CRISPR (Acr) proteins were previously thought to inhibit CRISPR-mediated immunity by acting as physical barriers against the binding or cleavage of DNA. Two new studies report that recently discovered type V Acr proteins use enzymatic activities to shut down the Cas12a endonuclease, providing a multi-turnover ‘off switch’ for CRISPR-based immunity and technology.


Keywords: CRISPR; Biology; Bacteriophages.


#Bacteriophage trigger #antiviral #immunity and prevent #clearance of #bacterial infection (Science, abstract)

[Source: Science, full page: (LINK). Abstract, edited.]

Bacteriophage trigger antiviral immunity and prevent clearance of bacterial infection

Johanna M. Sweere1,2, Jonas D. Van Belleghem1, Heather Ishak1,3, Michelle S. Bach1, Medeea Popescu1,2, Vivekananda Sunkari1, Gernot Kaber1, Robert Manasherob1, Gina A. Suh1,†, Xiou Cao1, Christiaan R. de Vries1, Dung N. Lam1, Payton L. Marshall1,2, Maria Birukova1,2, Ethan Katznelson1, Daniel V. Lazzareschi1, Swathi Balaji4, Sundeep G. Keswani4, Thomas R. Hawn5, Patrick R. Secor6, Paul L. Bollyky1,*

1 Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA, USA. 2 Stanford Immunology, Stanford University, Stanford, CA, USA. 3 Palo Alto Veterans Institute of Research, Palo Alto, CA, USA. 4 Division of Pediatric Surgery, Department of Surgery, Baylor College of Medicine, Houston, TX, USA. 5 Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA. 6 Division of Biological Sciences, University of Montana, Missoula, MT, USA.

*Corresponding author. Email:

† Present address: Division of Infectious Diseases, Mayo Clinic College of Medicine, Rochester, MN, USA.

Science  29 Mar 2019: Vol. 363, Issue 6434, eaat9691 / DOI: 10.1126/science.aat9691


Phage subverts immune response

Pseudomonas aeruginosa (Pa) is a multidrug-resistant Gramnegative bacterium commonly found in health care settings. Pa infections frequently result in considerable morbidity and mortality. Sweere et al. found that a type of temperate filamentous bacteriophage that infects and integrates into Pa is associated with chronic human wound infections. Likewise, wounds in mice colonized with phage-infected Pa were more severe and longer-lasting than those colonized by Pa alone. Immune cell uptake of phage-infected Pa resulted in phage RNA production and inappropriate antiviral immune responses, impeding bacterial clearance. Both phage vaccination and transfer of antiphage antibodies were protective against Pa infection.

Science, this issue p. eaat9691


Structured Abstract


We have identified previously unsuspected, directly pathogenic roles for bacteriophage (phage) virions in bacterial infections. In particular, we report that internalization of phage by human and murine immune cells triggers maladaptive viral pattern recognition receptors and suppressed bacterial clearance from infected wounds.


Bacteriophage are abundant at sites of bacterial infection, but their effect on mammalian immunity is unclear. To investigate this, we studied Pseudomonas aeruginosa (Pa), a major human pathogen associated with chronic wounds and other infections, and Pf, a filamentous phage produced by Pa. Notably, Pf is lysogenic and its production does not typically destroy its bacterial host, unlike the lytic phage used in phage therapy for bacterial infections. Previous work had suggested that Pf phage are important in the pathogenesis of Pa infections, although the underlying mechanisms were unclear. Here, we have examined the impact of Pf on Pa wound infections in humans and in animal models.


We report that Pf bacteriophage were present in 25 of 37 (68%) Pa-infected wounds in our cohort. Furthermore, wounds infected with Pf-positive strains were significantly older than wounds infected with Pf-negative strains, and Pf was more commonly found in chronic, nonhealing wounds. Consistent with this finding, in a murine wound infection model, Pf-positive strains of Pa required an average of 50 times fewer bacteria than Pf-negative strains to establish wound infections. Additionally, mice infected with Pf-positive strains of Paexhibited greater morbidity and mortality than mice infected with Pf-negative strains.

Mechanistically, these effects were associated with endocytosis of Pf phage by mammalian immune cells, both in vivo and in vitro. We found that uptake of Pf phage resulted in the production of phage RNA, which, in turn, triggered Toll-like receptor 3 (TLR3)– and TIR domain–containing adapter-inducing interferon-β (TRIF)–dependent type I interferon production, the inhibition of tumor necrosis factor production, and the suppression of phagocytosis. These data suggest that a natural (unmodified) bacteriophage may be able to produce mRNA within human cells.

Consistent with a pathogenic role for Pf phage, we report that a vaccine against Pf phage protects against Pa wound infections. Passive immunization of mice with monoclonal antibodies against Pf was likewise effective in protecting against Pa infection by enhancing the opsonization of Pa bacteria.


These results reveal direct, pathogenic roles for phage virions in bacterial infections. Building upon these insights, we report that vaccination against phage virions represents a potential therapeutic strategy for the prevention of infections by antibiotic-resistant Pa. These findings may have broad utility and impact beyond the pathophysiology of chronic wound infections. Pa is a major pathogen in other clinical settings as well, including lung infections in cystic fibrosis. Moreover, many other Gram-negative bacteria, including Klebsiella pneumoniae,Salmonella enterica, Vibrio cholerae, and Escherichia coli, have the capacity to harbor similar filamentous phage (genus Inovirus). Indeed, several of these phage are known to contribute to the virulence potential of their host bacteria. We propose that filamentous phage may be relevant to human interactions with a broad range of pathogenic and commensal bacteria and that these viruses may have profound, direct effects on human health and disease.



Bacteriophage are abundant at sites of bacterial infection, but their effects on mammalian hosts are unclear. We have identified pathogenic roles for filamentous Pf bacteriophage produced by Pseudomonas aeruginosa (Pa) in suppression of immunity against bacterial infection. Pf promote Pa wound infection in mice and are associated with chronic human Pawound infections. Murine and human leukocytes endocytose Pf, and internalization of this single-stranded DNA virus results in phage RNA production. This triggers Toll-like receptor 3 (TLR3)– and TIR domain–containing adapter-inducing interferon-β (TRIF)–dependent type I interferon production, inhibition of tumor necrosis factor (TNF), and the suppression of phagocytosis. Conversely, immunization of mice against Pf prevents Pa wound infection. Thus, Pf triggers maladaptive innate viral pattern-recognition responses, which impair bacterial clearance. Vaccination against phage virions represents a potential strategy to prevent bacterial infection.

Keywords: Bacteriophages; Immunophatology.