scholarly journals Filamentous Bacteriophages and the Competitive Interaction between Pseudomonas aeruginosa Strains under Antibiotic Treatment: a Modeling Study

mSystems ◽  
2021 ◽  
Author(s):  
Julie D. Pourtois ◽  
Michael J. Kratochvil ◽  
Qingquan Chen ◽  
Naomi L. Haddock ◽  
Elizabeth B. Burgener ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Treatment ◽  
Bacterial Pathogenesis ◽  
Competitive Interaction ◽  
Antibiotic Tolerance ◽  
Filamentous Bacteriophages ◽  
Bacterial Fitness ◽  
The Impact ◽  
Modeling Study ◽  
Filamentous Phages

Filamentous phages are a frontier in bacterial pathogenesis, but the impact of these phages on bacterial fitness is unclear. In particular, Pf phages produced by Pa promote antibiotic tolerance but are metabolically expensive to produce, suggesting that competing pressures may influence the prevalence of Pf+ versus Pf− strains of Pa in different settings.

scholarly journals The Impact of Pf Bacteriophages on the Fitness of Pseudomonas aeruginosa; A Mathematical Modeling Approach

2020 ◽  
Author(s):  
Julie D. Pourtois ◽  
Michael J. Kratochvil ◽  
Qingquan Chen ◽  
Naomi L. Haddock ◽  
Elizabeth B. Burgener ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Treatment Strategies ◽  
Bacterial Pathogen ◽  
Metabolic Cost ◽  
Decay Rates ◽  
Antibiotic Tolerance ◽  
Phage Production ◽  
The Impact ◽  
Filamentous Phages

AbstractPseudomonas aeruginosa (Pa) is a major bacterial pathogen responsible for chronic lung infections in cystic fibrosis patients. Recent work by ourselves and others has implicated Pf bacteriophages, non-lytic filamentous viruses produced by Pa, in the chronicity and severity of Pa infections. Pf phages act as structural elements in Pa biofilms and sequester aerosolized antibiotics, thereby contributing to antibiotic tolerance. Consistent with a selective advantage in this setting, the prevalence of Pf+ bacteria increases over time in these patients. However, the production of Pf phages comes at a metabolic cost to bacteria, such that Pf+ strains grow more slowly than Pf- strains in vitro. Here, we use a mathematical model to investigate how these competing pressures might influence the relative abundance of Pf+ versus Pf- strains in different settings. Our model predicts that Pf+ strains of Pa can only outcompete Pf- strains if the benefits of phage production falls solely onto Pf+ strains and not onto the overall bacterial community in the lung. Further, phage production only leads to a net positive gain in fitness at antibiotic concentrations slightly above the minimum inhibitory concentration (i.e., concentrations for which the benefits of antibiotic sequestration outweigh the metabolic cost of phage production), but which are not lethal for Pf+ strains. As a result, our model predicts that frequent administration of intermediate doses of antibiotics with low decay rates favors Pf+ over Pf- strains. These models inform our understanding of the ecology of Pf phages and suggest potential treatment strategies for Pf+ Pa infections.ImportanceFilamentous phages are a frontier in bacterial pathogenesis, but the impact of these phages on bacterial fitness is unclear. In particular, Pf phages produced by Pa promote antibiotic tolerance but are metabolically expensive to produce, suggesting that competing pressures may influence the prevalence of Pf+ versus Pf- strains of Pa in different settings. Our results identify conditions likely to favor Pf+ strains and thus antibiotic tolerance. This study contributes to a better understanding of the unique ecology of filamentous phages and may facilitate improved treatment strategies for combating antibiotic tolerance.

scholarly journals The high persister phenotype ofPseudomonas aeruginosais associated with increased fitness and persistence in cystic fibrosis airways

2019 ◽  
Author(s):  
Biljana Mojsoska ◽  
David R. Cameron ◽  
Jennifer A. Bartell ◽  
Janus Anders Juul Haagensen ◽  
Lea M. Sommer ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Genetic Alterations ◽  
Antibiotic Tolerance ◽  
High Throughput Screening Assay ◽  
The Impact ◽  
Over Time ◽  
Better Than

AbstractDespite intensive antibiotic treatment of cystic fibrosis (CF) patients,Pseudomonas aeruginosaoften persists in patient airways for decades, and can do so without the development of antibiotic resistance. Using a high-throughput screening assay of survival after treatment with high concentrations of ciprofloxacin, we have determined the prevalence of high-persister variants (Hip) in a large patient cohort. In a screen of 467 longitudinal clinical isolates ofP. aeruginosafrom 40 CF patients, we classified 25.7% as Hip. Hip were identified in 26 patients, but only a few bacterial lineages were dominated by Hip. Instead, the emergence of Hip increased over time, suggesting that CF airways treated with ciprofloxacin select for Hip with an increased fitness in this environment. We generally observed diverse genetic changes in the Hip isolate population (as many co-occurring routes to increased fitness exist), but interestingly elevated mutation counts in the RpoN gene of 18 Hip isolates suggest that this sigma factor plays a role in shaping levels of antibiotic tolerance. To probe the impact of the Hip phenotype in a CF-similar environment, we tested the fitness properties of otherwise genotypically and phenotypically similar low-persister (Lop) and Hip isolates in co-culture using a specialized flow-cell biofilm system mimicking pharmacokinetic/-dynamic antibiotic dosing. Hip survived ciprofloxacin treatment far better than Lop isolates. The results of this investigation provide novel insights into persister dynamics and fitness contributions to survival in the CF lung, and show that the Hip phenotype of antibiotic susceptible bacteria plays an important role in long-term infections.SignificanceAntibiotic resistance is emphasized as a rapidly increasing health threat, but antibiotic tolerance via the occurrence of persister cells in antibiotic-treated bacterial populations is clinically and publicly neglected. In 40 CF patients representing a well-established human infection model – long-term lung infections byPseudomonas aeruginosa– we show the emergence and accumulation of persister variants in a clinical population heavily reliant on antibiotic therapy. We observe that the high-persister (Hip) phenotype is independent of resistance and likely the consequence of numerous genetic alterations, complicating surveillance and inhibition in the clinic. Furthermore, we find Hip are selected for over time, survive better than ‘normal’ bacteria, and can outcompete them in CF-similar conditions, ultimately affecting 65% of patients in an early disease cohort.

scholarly journals Role of the flagellar hook in the structural development and antibiotic tolerance of Pseudomonas aeruginosa biofilms

2021 ◽  
Author(s):  
Jules D. P. Valentin ◽  
Hervé Straub ◽  
Franziska Pietsch ◽  
Marion Lemare ◽  
Christian H. Ahrens ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Structural Development ◽  
Antibiotic Tolerance ◽  
Intrinsic Resistance ◽  
Knock Out ◽  
Initial Adhesion ◽  
Flagellar Proteins ◽  
Biofilm Development ◽  
The Impact

AbstractPseudomonas aeruginosa biofilms exhibit an intrinsic resistance to antibiotics and constitute a considerable clinical threat. In cystic fibrosis, a common feature of biofilms formed by P. aeruginosa in the airway is the occurrence of mutants deficient in flagellar motility. This study investigates the impact of flagellum deletion on the structure and antibiotic tolerance of P. aeruginosa biofilms, and highlights a role for the flagellum in adaptation and cell survival during biofilm development. Mutations in the flagellar hook protein FlgE influence greatly P. aeruginosa biofilm structuring and antibiotic tolerance. Phenotypic analysis of the flgE knockout mutant compared to the wild type (WT) reveal increased fitness under planktonic conditions, reduced initial adhesion but enhanced formation of microcolony aggregates in a microfluidic environment, and decreased expression of genes involved in exopolysaccharide formation. Biofilm cells of the flgE knock-out mutant display enhanced tolerance towards multiple antibiotics, whereas its planktonic cells show similar resistance to the WT. Confocal microscopy of biofilms demonstrates that gentamicin does not affect the viability of cells located in the inner part of the flgE knock-out mutant biofilms due to reduced penetration. These findings suggest that deficiency in flagellar proteins like FlgE in biofilms and in cystic fibrosis infections represent phenotypic and evolutionary adaptations that alter the structure of P. aeruginosa biofilms conferring increased antibiotic tolerance.

scholarly journals Universal antibiotic tolerance arising from antibiotic-triggered accumulation of redox metabolites

2018 ◽  
Author(s):  
Kui Zhu ◽  
Shang Chen ◽  
Tatyana A. Sysoeva ◽  
Lingchong You
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Treatment ◽  
Opportunistic Pathogen ◽  
Antibiotic Tolerance ◽  
Treatment Protocols ◽  
Collective Behaviors ◽  
Redox Active ◽  
Redox Metabolites ◽  
The Individual ◽  
Sublethal Concentrations

AbstractPseudomonas aeruginosais an opportunistic pathogen that often infects open wounds or patients with cystic fibrosis. Once established,P. aeruginosainfections are notoriously difficult to eradicate. This difficulty is in part due to the ability ofP. aeruginosato tolerate antibiotic treatment at the individual-cell level or through collective behaviors. Here we describe a new mechanism by whichP. aeruginosatolerates antibiotic treatment by modulating its global cellular metabolism. In particular, treatment ofP. aeruginosawith sublethal concentrations of antibiotics covering all major classes promoted accumulation of the redox-sensitive phenazine - pyocyanin (PYO). PYO in turn conferred general tolerance against diverse antibiotics for bothP. aeruginosaand other Gram-negative and Gram-positive bacteria. We show that PYO promotes energy generation to enhance the activity of efflux pumps, leading to enhanced antibiotic tolerance. This property is shared by other redox-active phenazines produced byP. aeruginosa. Our discovery sheds new insights into the physiological functions of phenazines and has implications for designing effective antibiotic treatment protocols.Author SummaryAntibiotic tolerance can facilitate the evolution of resistance, and here we describe a previously unknown mechanism of collective antibiotic tolerance inPseudomonas aeruginosa. In particular,P. aeruginosatreated with sublethal concentrations of antibiotics covering all major classes promotes accumulation of pyocyanin (PYO), an important virulence factor. In turn, PYO confers general tolerance against diverse antibiotics for bothP. aeruginosaand other bacteria. Our discovery is a perfect example of what Nietzsche once said:That which does not kill me makes me stronger.

Confocal and SEM imaging to demonstrate food pathogen- biofilm biocontrol by pyocyanin from Pseudomonas aeruginosa BTRY1

2016 ◽  
Vol 6 (01) ◽  
pp. 5218
Author(s):  
Laxmi Mohandas ◽  
Anju T. R. ◽  
Sarita G. Bhat*
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Antibiofilm Activity ◽  
Opportunistic Pathogens ◽  
Redox Active ◽  
Sem Imaging ◽  
The Impact

An assortment of redox-active phenazine compounds like pyocyanin with their characteristic blue-green colour are synthesized by Pseudomonas aeruginosa, Gram-negative opportunistic pathogens, which are also considered one of the most commercially valuable microorganisms. In this study, pyocyanin from Pseudomonas aeruginosa BTRY1 from food sample was assessed for its antibiofilm activity by micro titer plate assay against strong biofilm producers belonging to the genera Bacillus, Staphylococcus, Brevibacterium and Micrococcus. Pyocyanin inhibited biofilm activity in very minute concentrations. This was also confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Both SEM and CLSM helped to visualize the biocontrol of biofilm formation by eight pathogens. The imaging and quantification by CLSM also established the impact of pyocyanin on biofilm-biocontrol mainly in the food industry.

scholarly journals 288. Follow-Up Blood Cultures in Gram-Negative Bacteremia: How Do They Impact Outcomes

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S144-S144
Author(s):  
Azza Elamin ◽  
Faisal Khan ◽  
Ali Abunayla ◽  
Rajasekhar Jagarlamudi ◽  
aditee Dash
Keyword(s):  
Clinical Outcomes ◽  
Antibiotic Treatment ◽  
Readmission Rate ◽  
Blood Cultures ◽  
Categorical Variables ◽  
Gram Negative ◽  
Number Of Patients ◽  
Significant Difference ◽  
The Impact

Abstract Background As opposed to Staphylococcus. aureus bacteremia, there are no guidelines to recommend repeating blood cultures in Gram-negative bacilli bacteremia (GNB). Several studies have questioned the utility of follow-up blood cultures (FUBCs) in GNB, but the impact of this practice on clinical outcomes is not fully understood. Our aim was to study the practice of obtaining FUBCs in GNB at our institution and to assess it’s impact on clinical outcomes. Methods We conducted a retrospective, single-center study of adult patients, ≥ 18 years of age admitted with GNB between January 2017 and December 2018. We aimed to compare clinical outcomes in those with and without FUBCs. Data collected included demographics, comorbidities, presumed source of bacteremia and need for intensive care unit (ICU) admission. Presence of fever, hypotension /shock and white blood cell (WBC) count on the day of FUBC was recorded. The primary objective was to compare 30-day mortality between the two groups. Secondary objectives were to compare differences in 30-day readmission rate, hospital length of stay (LOS) and duration of antibiotic treatment. Mean and standard deviation were used for continuous variables, frequency and proportion were used for categorical variables. P-value < 0.05 was defined as statistically significant. Results 482 patients were included, and of these, 321 (67%) had FUBCs. 96% of FUBCs were negative and 2.8% had persistent bacteremia. There was no significant difference in 30-day mortality between those with and without FUBCs (2.9% and 2.7% respectively), or in 30-day readmission rate (21.4% and 23.4% respectively). In patients with FUBCs compared to those without FUBCs, hospital LOS was longer (7 days vs 5 days, P < 0.001), and mean duration of antibiotic treatment was longer (14 days vs 11 days, P < 0.001). A higher number of patients with FUBCs needed ICU care compared to those without FUBCs (41.4% and 25.5% respectively, P < 0.001) Microbiology of index blood culture in those with and without FUBCs Outcomes in those with and without FUBCs FUBCs characteristics Conclusion Obtaining FUBCs in GNB had no impact on 30-day mortality or 30-day readmission rate. It was associated with longer LOS and antibiotic duration. Our findings suggest that FUBCs in GNB are low yield and may not be recommended in all patients. Prospective studies are needed to further examine the utility of this practice in GNB. Disclosures All Authors: No reported disclosures

scholarly journals An Eschar-like souvenir from a journey to Colombia: Ecthyma gangrenosum as a differential diagnosis of tropical diseases in immunocompromised patients – a case report

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gabriela M. Wiedemann ◽  
Jochen Schneider ◽  
Mareike Verbeek ◽  
Björn Konukiewitz ◽  
Christoph D. Spinner ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Differential Diagnosis ◽  
Antibiotic Treatment ◽  
Partial Remission ◽  
Combined Treatment ◽  
Lymphocytic Leukemia ◽  
Entire Body ◽  
Tropical Diseases ◽  
Ecthyma Gangrenosum ◽  
Skin Ulcers

Abstract Background Ecthyma gangrenosum (EG) is a cutaneous infectious disease characterized by eschar-like skin ulcers typically caused by Pseudomonas aeruginosa. Here, we report a case of relapsing EG in a patient who had returned from a trip to Colombia, thus establishing EG as an important differential diagnosis of tropical diseases, and demonstrating that even long-term antibiotic treatment can result in only partial remission of EG. Case presentation A 77-year-old man with underlying chronic lymphocytic leukemia (CLL) on ibrutinib treatment was admitted because of a superinfected mosquito bite on the left ear and multiple partially necrotic skin lesions disseminated all over the entire body five days after returning from a trip to Colombia. The initial clinical suspicion of a tropical disease (leishmaniosis, systemic mycosis, or others) could not be confirmed. During the diagnostic workup, microbiological cultures of the skin biopsies and bronchoalveolar lavage revealed Pseudomonas aeruginosa, leading to a diagnosis of EG. Initial antibiotic treatment resulted in partial remission. However, the patient had to be re-admitted due to a relapse 3–4 weeks after the first episode. Finally, the patient was successfully treated with a combined approach consisting of antibiotics, recurrent surgical incisions, and administration of immunoglobulins. Conclusions In conclusion, EG should be considered as a differential diagnosis in immunosuppressed patients presenting with eschar-like skin ulcers. A combined treatment approach seems to be the best choice to achieve clinical cure and avoid relapse.

scholarly journals The Impact of an Efflux Pump Inhibitor on the Activity of Free and Liposomal Antibiotics against Pseudomonas aeruginosa

Pharmaceutics ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 577
Author(s):  
Douweh Leyla Gbian ◽  
Abdelwahab Omri
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Antimicrobial Activities ◽  
Dilution Method ◽  
Efflux Pump Inhibitor ◽  
Signal Production ◽  
Lung Infections ◽  
The Impact ◽  
Microbroth Dilution

The eradication of Pseudomonas aeruginosa in cystic fibrosis patients has become continuously difficult due to its increased resistance to treatments. This study assessed the efficacy of free and liposomal gentamicin and erythromycin, combined with Phenylalanine arginine beta-naphthylamide (PABN), a broad-spectrum efflux pump inhibitor, against P. aeruginosa isolates. Liposomes were prepared and characterized for their sizes and encapsulation efficiencies. The antimicrobial activities of formulations were determined by the microbroth dilution method. Their activity on P. aeruginosa biofilms was assessed, and the effect of sub-inhibitory concentrations on bacterial virulence factors, quorum sensing (QS) signals and bacterial motility was also evaluated. The average diameters of liposomes were 562.67 ± 33.74 nm for gentamicin and 3086.35 ± 553.95 nm for erythromycin, with encapsulation efficiencies of 13.89 ± 1.54% and 51.58 ± 2.84%, respectively. Liposomes and PABN combinations potentiated antibiotics by reducing minimum inhibitory and bactericidal concentrations by 4–32 fold overall. The formulations significantly inhibited biofilm formation and differentially attenuated virulence factor production as well as motility. Unexpectedly, QS signal production was not affected by treatments. Taken together, the results indicate that PABN shows potential as an adjuvant of liposomal macrolides and aminoglycosides in the management of lung infections in cystic fibrosis patients.

scholarly journals Baicalin Represses Type Three Secretion System of Pseudomonas aeruginosa through PQS System

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1497
Author(s):  
Pansong Zhang ◽  
Qiao Guo ◽  
Zhihua Wei ◽  
Qin Yang ◽  
Zisheng Guo ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Mammalian Cells ◽  
Secretion System ◽  
Chinese Herbs ◽  
Infection Model ◽  
Lung Pathology ◽  
Promising Alternative ◽  
The Impact

Therapeutics that target the virulence of pathogens rather than their viability offer a promising alternative for treating infectious diseases and circumventing antibiotic resistance. In this study, we searched for anti-virulence compounds against Pseudomonas aeruginosa from Chinese herbs and investigated baicalin from Scutellariae radix as such an active anti-virulence compound. The effect of baicalin on a range of important virulence factors in P. aeruginosa was assessed using luxCDABE-based reporters and by phenotypical assays. The molecular mechanism of the virulence inhibition by baicalin was investigated using genetic approaches. The impact of baicalin on P. aeruginosa pathogenicity was evaluated by both in vitro assays and in vivo animal models. The results show that baicalin diminished a plenty of important virulence factors in P. aeruginosa, including the Type III secretion system (T3SS). Baicalin treatment reduced the cellular toxicity of P. aeruginosa on the mammalian cells and attenuated in vivo pathogenicity in a Drosophila melanogaster infection model. In a rat pulmonary infection model, baicalin significantly reduced the severity of lung pathology and accelerated lung bacterial clearance. The PqsR of the Pseudomonas quinolone signal (PQS) system was found to be required for baicalin’s impact on T3SS. These findings indicate that baicalin is a promising therapeutic candidate for treating P. aeruginosa infections.

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