scholarly journals Phage Therapy Is Effective in a Mouse Model of Bacterial Equine Keratitis

2016 ◽  
Vol 82 (17) ◽  
pp. 5332-5339 ◽  
Author(s):  
Takaaki Furusawa ◽  
Hidetomo Iwano ◽  
Yutaro Hiyashimizu ◽  
Kazuki Matsubara ◽  
Hidetoshi Higuchi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mouse Model ◽  
Phage Therapy ◽  
Host Cells ◽  
Resistant Bacteria ◽  
Broad Host Range ◽  
Bacterial Keratitis ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Content Type

ABSTRACTBacterial keratitis of the horse is mainly caused by staphylococci, streptococci, and pseudomonads. Of these bacteria,Pseudomonas aeruginosasometimes causes rapid corneal corruption and, in some cases, blindness. Antimicrobial resistance can make treatment very difficult. Therefore, new strategies to control bacterial infection are required. A bacteriophage (phage) is a virus that specifically infects and kills bacteria. Since phage often can lyse antibiotic-resistant bacteria because the killing mechanism is different, we examined the use of phage to treat horse bacterial keratitis. We isolatedMyoviridaeorPodoviridaephages, which together have a broad host range. They adsorb efficiently to host bacteria; more than 80% of the ΦR18 phage were adsorbed to host cells after 30 s. In our keratitis mouse model, the administration of phage within 3 h also could kill bacteria and suppress keratitis. A phage multiplicity of infection of 100 times the host bacterial number could kill host bacteria effectively. A cocktail of two phages suppressed bacteria in the keratitis model mouse. These data demonstrated that the phages in this study could completely prevent the keratitis caused byP. aeruginosain a keratitis mouse model. Furthermore, these results suggest that phage may be a more effective prophylaxis for horse keratitis than the current preventive use of antibiotics. Such treatment may reduce the use of antibiotics and therefore antibiotic resistance. Further studies are required to assess phage therapy as a candidate for treatment of horse keratitis.IMPORTANCEAntibiotic-resistant bacteria are emerging all over the world. Bacteriophages have great potential for resolution of this problem. A bacteriophage, or phage, is a virus that infects bacteria specifically. As a novel therapeutic strategy against racehorse keratitis caused byPseudomonas aeruginosa, we propose the application of phages for treatment. Phages isolated in this work hadin vitroeffectiveness for a broad range ofP. aeruginosastrains. Indeed, a great reduction of bacterial proliferation was shown in phage therapy for mouse models ofP. aeruginosakeratitis. Therefore, to reduce antibiotic usage, phage therapy should be investigated and developed further.

scholarly journals New Insights into Autoinducer-2 Signaling as a Virulence Regulator in a Mouse Model of Pneumonic Plague

mSphere ◽  
2016 ◽  
Vol 1 (6) ◽  
Author(s):  
Eric C. Fitts ◽  
Jourdan A. Andersson ◽  
Michelle L. Kirtley ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
...  
Keyword(s):  
Mouse Model ◽  
Yersinia Pestis ◽  
Bacterial Virulence ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Global Crisis ◽  
Antibiotic Resistant ◽  
Pneumonic Plague ◽  
Content Type ◽  
Autoinducer 2

ABSTRACT Yersinia pestis is the bacterial agent that causes the highly fatal disease plague. The organism represents a significant concern because of its potential use as a bioterror agent, beyond the several thousand naturally occurring human infection cases occurring globally each year. While there has been development of effective antibiotics, the narrow therapeutic window and challenges posed by the existence of antibiotic-resistant strains represent serious concerns. We sought to identify novel virulence factors that could potentially be incorporated into an attenuated vaccine platform or be targeted by novel therapeutics. We show here that a highly conserved quorum-sensing system, autoinducer-2, significantly affected the virulence of Y. pestis in a mouse model of pneumonic plague. We also identified steps in autoinducer-2 signaling which had confounded previous studies and demonstrated the potential for intervention in the virulence mechanism(s) of autoinducer-2. Our findings may have an impact on bacterial pathogenesis research in many other organisms and could result in identifying potential broad-spectrum therapeutic targets to combat antibiotic-resistant bacteria, which represent a global crisis of the 21st century. The Enterobacteriaceae family members, including the infamous Yersinia pestis, the causative agent of plague, have a highly conserved interbacterial signaling system that is mediated by the autoinducer-2 (AI-2) quorum-sensing molecule. The AI-2 system is implicated in regulating various bacterial virulence genes in diverse environmental niches. Deletion of the gene encoding the synthetic enzyme for the AI-2 substrate, luxS, leads to either no significant change or, paradoxically, an increase in in vivo bacterial virulence. We showed that deletion of the rbsA and lsrA genes, components of ABC transport systems that interact with AI-2, synergistically disrupted AI-2 signaling patterns and resulted in a more-than-50-fold decrease in Y. pestis strain CO92 virulence in a stringent pneumonic plague mouse model. Deletion of luxS or lsrK (encoding AI-2 kinase) from the ΔrbsA ΔlsrA background strain or complementation of the ΔrbsA ΔlsrA mutant with the corresponding gene(s) reverted the virulence phenotype to that of the wild-type Y. pestis CO92. Furthermore, the administration of synthetic AI-2 in mice infected with the ΔrbsA ΔlsrA ΔluxS mutant strain attenuated this triple mutant to a virulence phenotype similar to that of the ΔrbsA ΔlsrA strain in a pneumonic plague model. Conversely, the administration of AI-2 to mice infected with the ΔrbsA ΔlsrA ΔluxS ΔlsrK mutant did not rescue animals from lethality, indicating the importance of the AI-2–LsrK axis in regulating bacterial virulence. By performing high-throughput RNA sequencing, the potential role of some AI-2-signaling-regulated genes that modulated bacterial virulence was determined. We anticipate that the characterization of AI-2 signaling in Y. pestis will lead to reexamination of AI-2 systems in other pathogens and that AI-2 signaling may represent a broad-spectrum therapeutic target to combat antibiotic-resistant bacteria, which represent a global crisis of the 21st century. IMPORTANCE Yersinia pestis is the bacterial agent that causes the highly fatal disease plague. The organism represents a significant concern because of its potential use as a bioterror agent, beyond the several thousand naturally occurring human infection cases occurring globally each year. While there has been development of effective antibiotics, the narrow therapeutic window and challenges posed by the existence of antibiotic-resistant strains represent serious concerns. We sought to identify novel virulence factors that could potentially be incorporated into an attenuated vaccine platform or be targeted by novel therapeutics. We show here that a highly conserved quorum-sensing system, autoinducer-2, significantly affected the virulence of Y. pestis in a mouse model of pneumonic plague. We also identified steps in autoinducer-2 signaling which had confounded previous studies and demonstrated the potential for intervention in the virulence mechanism(s) of autoinducer-2. Our findings may have an impact on bacterial pathogenesis research in many other organisms and could result in identifying potential broad-spectrum therapeutic targets to combat antibiotic-resistant bacteria, which represent a global crisis of the 21st century.

scholarly journals The Concerted Action of Two B3-Like Prophage Genes Excludes Superinfecting Bacteriophages by Blocking DNA Entry into Pseudomonas aeruginosa

2020 ◽  
Vol 94 (15) ◽  
Author(s):  
Marco Antonio Carballo-Ontiveros ◽  
Adrián Cazares ◽  
Pablo Vinuesa ◽  
Luis Kameyama ◽  
Gabriel Guarneros
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pathogenic Bacteria ◽  
Phage Therapy ◽  
Alternative Therapy ◽  
Multidrug Resistant ◽  
Open Reading Frames ◽  
Resistant Bacteria ◽  
Content Type ◽  
Secondary Infections ◽  
Genes Encoding

ABSTRACT In this study, we describe seven vegetative phage genomes homologous to the historic phage B3 that infect Pseudomonas aeruginosa. Like other phage groups, the B3-like group contains conserved (core) and variable (accessory) open reading frames (ORFs) grouped at fixed regions in their genomes; however, in either case, many ORFs remain without assigned functions. We constructed lysogens of the seven B3-like phages in strain Ps33 of P. aeruginosa, a novel clinical isolate, and assayed the exclusion phenotype against a variety of temperate and virulent superinfecting phages. In addition to the classic exclusion conferred by the phage immunity repressor, the phenotype observed in B3-like lysogens suggested the presence of other exclusion genes. We set out to identify the genes responsible for this exclusion phenotype. Phage Ps56 was chosen as the study subject since it excluded numerous temperate and virulent phages. Restriction of the Ps56 genome, cloning of several fragments, and resection of the fragments that retained the exclusion phenotype allowed us to identify two core ORFs, so far without any assigned function, as responsible for a type of exclusion. Neither gene expressed separately from plasmids showed activity, but the concurrent expression of both ORFs is needed for exclusion. Our data suggest that phage adsorption occurs but that phage genome translocation to the host’s cytoplasm is defective. To our knowledge, this is the first report on this type of exclusion mediated by a prophage in P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa is a Gram-negative bacterium frequently isolated from infected immunocompromised patients, and the strains are resistant to a broad spectrum of antibiotics. Recently, the use of phages has been proposed as an alternative therapy against multidrug-resistant bacteria. However, this approach may present various hurdles. This work addresses the problem that pathogenic bacteria may be lysogenized by phages carrying genes encoding resistance against secondary infections, such as those used in phage therapy. Discovering phage genes that exclude superinfecting phages not only assigns novel functions to orphan genes in databases but also provides insight into selection of the proper phages for use in phage therapy.

Antibiotic-Resistant Bacteria in Raw Meat from Retail Markets

1976 ◽  
Vol 39 (7) ◽  
pp. 474-476 ◽  
Author(s):  
LESTER HANKIN ◽  
SANDRA L. ANAGNOSTAKIS ◽  
JOHN J. REDYS
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Putida ◽  
Pseudomonas Fluorescens ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Retail Markets ◽  
Raw Meat ◽  
Neomycin Sulfate ◽  
Meat Samples

Raw meat samples from retail markets were examined for bacteria resistant to chloramphenicol and neomycin sulfate. Total numbers of bacteria ranged from 17,000 to 30,000,000 per gram and resistant bacteria from < 100 to 450,000 per gram. Twelve isolates resistant to both antibiotics were identified as either Pseudomonas aeruginosa, Pseudomonas putida. or Pseudomonas fluorescens.

scholarly journals Coevolutionary phage training leads to greater bacterial suppression and delays the evolution of phage resistance

2020 ◽  
Author(s):  
Joshua M. Borin ◽  
Sarit Avrani ◽  
Jeffrey E. Barrick ◽  
Katherine L. Petrie ◽  
Justin R. Meyer
Keyword(s):  
Phage Therapy ◽  
Single Step ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Major Barrier ◽  
Complete Resistance ◽  
Transfer Of Information

AbstractThe evolution of antibiotic resistant bacteria threatens to become the leading cause of worldwide mortality. This crisis has renewed interest in the practice of phage therapy. Yet, bacteria’s capacity to evolve resistance is likely to debilitate this therapy as well. To combat the evolution of phage resistance and improve treatment outcomes, many have suggested leveraging phages’ ability to counter resistance by evolving phages on target hosts before using them in therapy (phage training). We found that during in vitro experiments, a phage trained for 28 days suppressed bacteria ∼1000-fold for 3-8 times longer than its untrained ancestor. This extension was due to a delay in the evolution of resistance. Several factors contributed to this prolonged suppression. Mutations that confer resistance to trained phages are ∼100× less common and, while the target bacterium can evolve complete resistance to the untrained phage in a single step, multiple mutations are required to evolve complete resistance to trained phages. Mutations that confer resistance to trained phages are more costly than mutations for untrained phage resistance. And when resistance does evolve, trained phages are better able to suppress these forms of resistance. One way the trained phage improved was through recombination with a gene in a defunct prophage in the host genome, which doubled phage fitness. This direct transfer of information encoded by the host but originating from a relict phage provides a previously unconsidered mode of training phage. Overall, we provide a case study for successful phage training and uncover mechanisms underlying its efficacy.Significance StatementThe evolution of antibiotic resistant bacteria threatens to claim over 10 million lives annually by 2050. This crisis has renewed interest in phage therapy, the use of bacterial viruses to treat infections. A major barrier to successful phage therapy is that bacteria readily evolve phage resistance. One idea proposed to combat resistance is “training” phages by using their natural capacity to evolve to counter resistance. Here, we show that training phages by coevolving them with their host for one month enhanced their capacity for suppressing bacterial growth and delayed the emergence of resistance. Enhanced suppression was caused by several mechanisms, suggesting that the coevolutionary training protocol produces a robust therapeutic that employs complementary modes of action.

scholarly journals Aerosol Phage Therapy Efficacy in Burkholderia cepacia Complex Respiratory Infections

2014 ◽  
Vol 58 (7) ◽  
pp. 4005-4013 ◽  
Author(s):  
Diana D. Semler ◽  
Amanda D. Goudie ◽  
Warren H. Finlay ◽  
Jonathan J. Dennis
Keyword(s):  
Intraperitoneal Injection ◽  
Burkholderia Cepacia ◽  
Phage Therapy ◽  
Respiratory Infections ◽  
Burkholderia Cepacia Complex ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Therapy Efficacy

ABSTRACTPhage therapy has been suggested as a potential treatment for highly antibiotic-resistant bacteria, such as the species of theBurkholderia cepaciacomplex (BCC). To address this hypothesis, experimentalB. cenocepaciarespiratory infections were established in mice using a nebulizer and a nose-only inhalation device. Following infection, the mice were treated with one of fiveB. cenocepacia-specific phages delivered as either an aerosol or intraperitoneal injection. The bacterial and phage titers within the lungs were assayed 2 days after treatment, and mice that received the aerosolized phage therapy demonstrated significant decreases in bacterial loads. Differences in phage activity were observedin vivo. Mice that received phage treatment by intraperitoneal injection did not demonstrate significantly reduced bacterial loads, although phage particles were isolated from their lung tissue. Based on these data, aerosol phage therapy appears to be an effective method for treating highly antibiotic-resistant bacterial respiratory infections, including those caused by BCC bacteria.

Phage Therapy: A Potential Solution for Antibiotic Resistance

2021 ◽  
Author(s):  
Chirag Choudhary ◽  
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Infections ◽  
Phage Therapy ◽  
Biological Agents ◽  
Resistant Bacteria ◽  
Potential Solution ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
The Future

The idea of using a virus to kill bacteria may seem counterintuitive, but it may be the future of treating bacterial infections. Before the COVID-19 pandemic, one of the most frightening biological agents were so-called “superbugs” – antibiotic resistant bacteria – which could not be treated with conventional therapeutics. When antibiotics were first developed, they were hailed as a panacea. A panacea they were not.

scholarly journals Widely Used Benzalkonium Chloride Disinfectants Can Promote Antibiotic Resistance

2018 ◽  
Vol 84 (17) ◽  
Author(s):  
Minjae Kim ◽  
Michael R. Weigand ◽  
Seungdae Oh ◽  
Janet K. Hatt ◽  
Raj Krishnan ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Microbial Communities ◽  
Gene Cloning ◽  
Benzalkonium Chloride ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Physiological Adaptations

ABSTRACTWhile the misuse of antibiotics has clearly contributed to the emergence and proliferation of resistant bacterial pathogens, with major health consequences, it remains less clear if the widespread use of disinfectants, such as benzalkonium chlorides (BAC), a different class of biocides than antibiotics, has contributed to this problem. Here, we provide evidence that exposure to BAC coselects for antibiotic-resistant bacteria and describe the underlying genetic mechanisms. After inoculation with river sediment, BAC-fed bioreactors selected for several bacterial taxa, including the opportunistic pathogenPseudomonas aeruginosa, that were more resistant to several antibiotics than their counterparts in a control (no BAC) bioreactor. A metagenomic analysis of the bioreactor microbial communities, confirmed by gene cloning experiments with the derived isolates, suggested that integrative and conjugative elements encoding a BAC efflux pump together with antibiotic resistance genes were responsible for these results. Furthermore, the exposure of theP. aeruginosaisolates to increasing concentrations of BAC selected for mutations inpmrB(polymyxin resistance) and physiological adaptations that contributed to a higher tolerance to polymyxin B and other antibiotics. The physiological adaptations included the overexpression ofmexCD-oprJmultidrug efflux pump genes when BAC was added in the growth medium at subinhibitory concentrations. Collectively, our results demonstrated that disinfectants promote antibiotic resistance via several mechanisms and highlight the need to remediate (degrade) disinfectants in nontarget environments to further restrain the spread of antibiotic-resistant bacteria.IMPORTANCEBenzalkonium chlorides (BAC) are biocides broadly used in disinfectant solutions. Disinfectants are widely used in food processing lines, domestic households, and pharmaceutical products and are typically designed to have a different mode of action than antibiotics to avoid interfering with the use of the latter. Whether exposure to BAC makes bacteria more resistant to antibiotics remains an unresolved issue of obvious practical consequences for public health. Using an integrated approach that combines metagenomics of natural microbial communities with gene cloning experiments with isolates and experimental evolution assays, we show that the widely used benzalkonium chloride disinfectants promote clinically relevant antibiotic resistance. Therefore, more attention should be given to the usage of these disinfectants, and their fate in nontarget environments should be monitored more tightly.

scholarly journals Phage Therapy: A Renewed Approach to Combat Antibiotic-Resistant Bacteria

2019 ◽  
Vol 25 (2) ◽  
pp. 219-232 ◽  
Author(s):  
Kaitlyn E. Kortright ◽  
Benjamin K. Chan ◽  
Jonathan L. Koff ◽  
Paul E. Turner
Keyword(s):  
Phage Therapy ◽  
Resistant Bacteria ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant
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