scholarly journals Phage infection restores PQS signaling and enhances growth of a Pseudomonas aeruginosa lasI quorum-sensing mutant

2021 ◽  
Author(s):  
Nina Molin Høyland-Kroghsbo ◽  
Bonnie L. Bassler
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Phage Therapy ◽  
Cell Communication ◽  
Multidrug Resistant ◽  
Phage Infection ◽  
Resistant Bacteria ◽  
Signal Molecules ◽  
Multidrug Resistant Bacteria ◽  
Communication Mechanism

AbstractBacteriophage (phage) therapy is reemerging as a valuable tool to combat multidrug resistant bacteria. A major hurdle in developing efficacious bacteriophage therapies is that bacteria acquire resistance to phage killing. In this context, it is noteworthy that quorum sensing (QS), the bacterial cell-to-cell communication mechanism that promotes collective undertaking of group behaviors including anti-phage defenses, enhances bacterial survival in the face of phage attack. QS relies on the production, release, accumulation, and detection of signal molecules called autoinducers. In the opportunistic pathogen Pseudomonas aeruginosa, the LasI/R QS system induces the RhlI/R QS system, and these two systems control, in opposing manners, the PQS QS system that relies on the autoinducer called PQS. A ΔlasI mutant is impaired in PQS synthesis, leading to accumulation of the precursor molecule HHQ. HHQ suppresses growth of the P. aeruginosa ΔlasI strain. We uncover a phage infection-induced mechanism that restores expression of the pqsH gene in the P. aeruginosa ΔlasI QS mutant. PqsH converts HHQ into PQS, preventing HHQ-mediated growth inhibition. Thus, phage-infected P. aeruginosa ΔlasI cells exhibit superior growth compared to uninfected cells. Phage infection also restores expression of virulence factors and the CRISPR-cas anti-phage defense system in the P. aeruginosa ΔlasI strain. This study highlights a challenge for phage therapy, namely that phage infection may make particular bacterial strains faster growing, more virulent, and resistant to phage killing.ImportanceThe emergence of multidrug resistant bacteria necessitates development of new antimicrobial therapies. Phage therapy relies on exploiting phages, natural enemies of bacteria, in the fight against pathogenic bacteria. For successful phage therapy development, potent phages that exhibit low propensity for acquisition of bacterial resistance are desired. Here, we show that phage infection restores QS, a cell-to-cell communication mechanism in a P. aeruginosa QS mutant, which increases its virulence and resistance to phage killing. Importantly, clinical isolates of P. aeruginosa frequently harbor mutations in particular QS genes. Thus, phage therapies against such P. aeruginosa strains may inadvertently increase bacterial virulence. Our study underscores the importance of characterizing phage-host interactions in the context of bacterial mutants that are relevant in clinical settings prior to selecting phages for therapy.

scholarly journals Pseudomonas aeruginosa PAO 1 In Vitro Time–Kill Kinetics Using Single Phages and Phage Formulations—Modulating Death, Adaptation, and Resistance

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 877
Author(s):  
Ana Mafalda Pinto ◽  
Alberta Faustino ◽  
Lorenzo M. Pastrana ◽  
Manuel Bañobre-López ◽  
Sanna Sillankorva
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Phage Therapy ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Chronic Infections ◽  
Swarming Motility ◽  
Resistance Development ◽  
Healthcare Settings ◽  
Time Kill

Pseudomonas aeruginosa is responsible for nosocomial and chronic infections in healthcare settings. The major challenge in treating P. aeruginosa-related diseases is its remarkable capacity for antibiotic resistance development. Bacteriophage (phage) therapy is regarded as a possible alternative that has, for years, attracted attention for fighting multidrug-resistant infections. In this work, we characterized five phages showing different lytic spectrums towards clinical isolates. Two of these phages were isolated from the Russian Microgen Sextaphage formulation and belong to the Phikmvviruses, while three Pbunaviruses were isolated from sewage. Different phage formulations for the treatment of P. aeruginosa PAO1 resulted in diversified time–kill outcomes. The best result was obtained with a formulation with all phages, prompting a lower frequency of resistant variants and considerable alterations in cell motility, resulting in a loss of 73.7% in swimming motility and a 79% change in swarming motility. These alterations diminished the virulence of the phage-resisting phenotypes but promoted their growth since most became insensitive to a single or even all phages. However, not all combinations drove to enhanced cell killings due to the competition and loss of receptors. This study highlights that more caution is needed when developing cocktail formulations to maximize phage therapy efficacy. Selecting phages for formulations should consider the emergence of phage-resistant bacteria and whether the formulations are intended for short-term or extended antibacterial application.

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.

scholarly journals Occurrence of NDM-1 and VIM-2 Co-Producing Escherichia coli and OprD Alteration in Pseudomonas aeruginosa Isolated from Hospital Environment Samples in Northwestern Tunisia

Diagnostics ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1617
Author(s):  
Raouaa Maaroufi ◽  
Olfa Dziri ◽  
Linda Hadjadj ◽  
Seydina M. Diene ◽  
Jean-Marc Rolain ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Resistance ◽  
Carbapenem Resistance ◽  
Multidrug Resistant ◽  
Hospital Environment ◽  
Diffusion Method ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria ◽  
Disk Diffusion Method

Hospital environments constitute the main reservoir of multidrug-resistant bacteria. In this study we aimed to investigate the presence of Gram-negative bacteria in one Northwestern Tunisian hospital environment, and characterize the genes involved in bacterial resistance. A total of 152 environmental isolates were collected from various surfaces and isolated using MacConkey medium supplemented with cefotaxime or imipenem, with 81 fermenter bacteria (27 Escherichia coli, and 54 Enterobacter spp., including 46 Enterobacter cloacae), and 71 non-fermenting bacteria (69 Pseudomonas spp., including 54 Pseudomonas aeruginosa, and 2 Stenotrophomonas maltophilia) being identified by the MALDI-TOF-MS method. Antibiotic susceptibility testing was performed by disk diffusion method and E-Test was used to determine MICs for imipenem. Several genes implicated in beta-lactams resistance were characterized by PCR and sequencing. Carbapenem resistance was detected among 12 isolates; nine E. coli (blaNDM-1 (n = 8); blaNDM-1 + blaVIM-2 (n = 1)) and three P. aeruginosa were carbapenem-resistant by loss of OprD porin. The whole-genome sequencing of P. aeruginosa 97H was determined using Illumina MiSeq sequencer, typed ST285, and harbored blaOXA-494. Other genes were also detected, notably blaTEM (n = 23), blaCTX-M-1 (n = 10) and blaCTX-M-9 (n = 6). These new epidemiological data imposed new surveillance strategies and strict hygiene rules to decrease the spread of multidrug-resistant bacteria in this area.

scholarly journals Post-antibiotic era in hemodialysis? Two case reports of simultaneous colonization and bacteremia by multidrug-resistant bacteria

2020 ◽  
Author(s):  
Johanna M. Vanegas ◽  
Lorena Salazar-Ospina ◽  
Gustavo A. Roncancio ◽  
Julián Builes ◽  
Judy Natalia Jiménez
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Case Reports ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Control Measures ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria ◽  
E Coli ◽  
Carbapenem Resistant

ABSTRACT The emergence of resistance mechanisms not only limits the therapeutic options for common bacterial infections but also worsens the prognosis in patients who have conditions that increase the risk of bacterial infections. Thus, the effectiveness of important medical advances that seek to improve the quality of life of patients with chronic diseases is threatened. We report the simultaneous colonization and bacteremia by multidrug-resistant bacteria in two hemodialysis patients. The first patient was colonized by carbapenem- and colistin-resistant Klebsiella pneumoniae, carbapenem-resistant Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus (MRSA). The patient had a bacteremia by MRSA, and molecular typing methods confirmed the colonizing isolate was the same strain that caused infection. The second case is of a patient colonized by extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli and carbapenem-resistant Pseudomonas aeruginosa. During the follow-up period, the patient presented three episodes of bacteremia, one of these caused by ESBL-producing E. coli. Molecular methods confirmed colonization by the same clone of ESBL-producing E. coli at two time points, but with a different genetic pattern to the strain isolated from the blood culture. Colonization by multidrug-resistant bacteria allows not only the spread of these microorganisms, but also increases the subsequent risk of infections with limited treatments options. In addition to infection control measures, it is important to establish policies for the prudent use of antibiotics in dialysis units.

scholarly journals Eficácia da fagoterapia para o tratamento de infecções por bactérias multirresistentes e suas aplicações / Efficacy of phage therapy for the treatment of infections caused by multidrug-resistant bacteria and its applications

2021 ◽  
Vol 4 (3) ◽  
pp. 10728-10744
Author(s):  
Gabriel Monici Vieira ◽  
Débora Oliveira Piva ◽  
Rafaela Lucas Damasceno ◽  
Ricardo de Villa Nova Japiassu ◽  
Anamaria Camargo Macedo ◽  
...  
Keyword(s):  
Phage Therapy ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria

scholarly journals Two Mechanisms of Killing of Pseudomonas aeruginosa by Tobramycin Assessed at Multiple Inocula via Mechanism-Based Modeling

2015 ◽  
Vol 59 (4) ◽  
pp. 2315-2327 ◽  
Author(s):  
Jürgen B. Bulitta ◽  
Neang S. Ly ◽  
Cornelia B. Landersdorfer ◽  
Nicholin A. Wanigaratne ◽  
Tony Velkov ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Protein Synthesis ◽  
Outer Membrane ◽  
Bacterial Resistance ◽  
Multidrug Resistant ◽  
Quantitative Model ◽  
Great Promise ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria ◽  
Bacterial Killing

ABSTRACTBacterial resistance is among the most serious threats to human health globally, and many bacterial isolates have emerged that are resistant to all antibiotics in monotherapy. Aminoglycosides are often used in combination therapies against severe infections by multidrug-resistant bacteria. However, models quantifying different antibacterial effects of aminoglycosides are lacking. While the mode of aminoglycoside action on protein synthesis has often been studied, their disruptive action on the outer membrane of Gram-negative bacteria remains poorly characterized. Here, we developed a novel quantitative model for these two mechanisms of aminoglycoside action, phenotypic tolerance at high bacterial densities, and adaptive bacterial resistance in response to an aminoglycoside (tobramycin) against threePseudomonas aeruginosastrains. At low-intermediate tobramycin concentrations (<4 mg/liter), bacterial killing due to the effect on protein synthesis was most important, whereas disruption of the outer membrane was the predominant killing mechanism at higher tobramycin concentrations (≥8 mg/liter). The extent of killing was comparable across all inocula; however, the rate of bacterial killing and growth was substantially lower at the 108.9CFU/ml inoculum than that at the lower inocula. At 1 to 4 mg/liter tobramycin for strain PAO1-RH, there was a 0.5- to 6-h lag time of killing that was modeled via the time to synthesize hypothetical lethal protein(s). Disruption of the outer bacterial membrane by tobramycin may be critical to enhance the target site penetration of antibiotics used in synergistic combinations with aminoglycosides and thereby combat multidrug-resistant bacteria. The two mechanisms of aminoglycoside action and the new quantitative model hold great promise to rationally design novel, synergistic aminoglycoside combination dosage regimens.

scholarly journals Genetically Engineered Phages: a Review of Advances over the Last Decade

2016 ◽  
Vol 80 (3) ◽  
pp. 523-543 ◽  
Author(s):  
Diana P. Pires ◽  
Sara Cleto ◽  
Sanna Sillankorva ◽  
Joana Azeredo ◽  
Timothy K. Lu
Keyword(s):  
Antimicrobial Agents ◽  
Phage Therapy ◽  
Multidrug Resistant ◽  
Genetically Engineered ◽  
Resistant Bacteria ◽  
Early 20Th Century ◽  
New Materials ◽  
Multidrug Resistant Bacteria ◽  
Challenges And Opportunities ◽  
Future Work

SUMMARYSoon after their discovery in the early 20th century, bacteriophages were recognized to have great potential as antimicrobial agents, a potential that has yet to be fully realized. The nascent field of phage therapy was adversely affected by inadequately controlled trials and the discovery of antibiotics. Although the study of phages as anti-infective agents slowed, phages played an important role in the development of molecular biology. In recent years, the increase in multidrug-resistant bacteria has renewed interest in the use of phages as antimicrobial agents. With the wide array of possibilities offered by genetic engineering, these bacterial viruses are being modified to precisely control and detect bacteria and to serve as new sources of antibacterials. In applications that go beyond their antimicrobial activity, phages are also being developed as vehicles for drug delivery and vaccines, as well as for the assembly of new materials. This review highlights advances in techniques used to engineer phages for all of these purposes and discusses existing challenges and opportunities for future work.

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