Virulence of Pseudomonas aeruginosa strains with mechanisms of microbial persistence for β-lactam and aminoglycoside antibiotics in a mouse infection model

1985 ◽  
Vol 31 (4) ◽  
pp. 377-380 ◽  
Author(s):  
L. E. Bryan ◽  
A. J. Godfrey ◽  
T. Schollardt
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Therapeutic Failure ◽  
Infection Model ◽  
Iron Dextran ◽  
Mechanisms Of Resistance ◽  
Penicillin Binding Proteins ◽  
Mouse Infection Model ◽  
Lactam Antibiotic ◽  
Resistant Mutants ◽  
Mechanisms Of Persistence

A series of mutations and transductants producing low-level aminoglycoside and β-lactam antibiotic resistance of Pseudomonas aeruginosa have been constructed in an isogenic background. The phenotypes of these mutations are identical to or closely resemble those of clinical isolates of P. aeruginosa associated with therapeutic failure or microbial persistence in the presence of members of one or both groups of drugs. Virulence of the mutants was examined in an infection model using iron–dextran treated mice and bacteria grown in low-iron medium. All β-lactam resistant mutants affecting affinity of penicillin-binding proteins for β-lactams, constitutive β-lactamase, or permeability of β-lactams retained parental levels of virulence. Aminoglycoside-resistant mutants with defective energy generation or transductants with modified lipopolysaccharide showed reduced virulence. Strains with the preceding forms of resistance are likely to account for therapeutic failure or microbial persistence with antibiotic treatment. We propose that mechanisms of low or unstable forms of resistance should be designated mechanisms of persistence to differentiate them from more classical mechanisms of resistance.

scholarly journals In vitro dynamics and mechanisms of resistance development to imipenem and imipenem/relebactam in Pseudomonas aeruginosa

2020 ◽  
Vol 75 (9) ◽  
pp. 2508-2515 ◽  
Author(s):  
María A Gomis-Font ◽  
Gabriel Cabot ◽  
Irina Sánchez-Diener ◽  
Pablo A Fraile-Ribot ◽  
Carlos Juan ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Infection Model ◽  
Mechanisms Of Resistance ◽  
Resistance Development ◽  
C Elegans ◽  
Imipenem Resistance ◽  
High Level

Abstract Objectives We analysed the dynamics and mechanisms of resistance development to imipenem alone or combined with relebactam in Pseudomonas aeruginosa WT (PAO1) and mutator (PAOMS; ΔmutS) strains. Methods PAO1 or PAOMS strains were incubated for 24 h in Mueller–Hinton Broth with 0.125–64 mg/L of imipenem ± relebactam 4 mg/L. Tubes from the highest antibiotic concentration showing growth were reinoculated in fresh medium containing concentrations up to 64 mg/L of imipenem ± relebactam for 7 days. Two colonies per strain, replicate experiment and antibiotic from early (Day 1) and late (Day 7) cultures were characterized by determining the susceptibility profiles, WGS and determination of the expression of ampC and efflux-pump-coding genes. Virulence was studied in a Caenorhabditis elegans infection model. Results Relebactam reduced imipenem resistance development for both strains, although resistance emerged much faster for PAOMS. WGS indicated that imipenem resistance was associated with mutations in the porin OprD and regulators of ampC, while the mutations in imipenem/relebactam-resistant mutants were located in oprD and regulatoras of MexAB-OprM. High-level imipenem/relebactam resistance was only documented in the PAOMS strain and was associated with an additional specific (T680A) mutation located in the catalytic pocket of ponA (PBP1a) and with reduced virulence in the C. elegans model. Conclusions Imipenem/relebactam could be a useful alternative for the treatment of MDR P. aeruginosa infections, potentially reducing resistance development during treatment. Moreover, this work deciphers the potential resistance mechanisms that may emerge upon the introduction of this novel combination into clinical practice.

scholarly journals Pseudomonas aeruginosa: Mechanisms of resistance to antibiotics and case analysis

2021 ◽  
Vol 14 (3) ◽  
pp. 179-188
Author(s):  
Verónica Jocelyne Flores-Velázquez ◽  
Rocío Pérez-y-Terrón
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Case Analysis ◽  
Opportunistic Pathogen ◽  
Resistance Mechanisms ◽  
Downward Trend ◽  
Low Permeability ◽  
Mechanisms Of Resistance ◽  
Digital Resources ◽  
Penicillin Binding Proteins ◽  
Resistance To Antibiotics

Pseudomonas aeruginosa is an opportunistic pathogen, causing great concern due to the rapid increase in its resistance to antibiotics. The objective of the research was to describe the resistance mechanisms that P. aeruginosa possesses, as well as to report its behavior against antibiotics in the years 2003 to 2018 in Mexico. A retrospective and longitudinal documentary research was carried out in different digital resources referring to antibiotic resistance in P. aeruginosa. The results showed that the main resistance mechanisms of P. aeruginosa are β-lactamases, ejection pumps, mutations in porins, acquisition of plasmids, low permeability, formation of biofilms, alterations in penicillin-binding proteins, modifying enzymes of aminoglycosides and mutations in the active site. The antibiotics with the highest percentage of resistance presented between the years 2003 to 2018 were imipenen IMP, gentamicin GEN, ticarcillin / clavulanate TIC, trimethoprim / sulfamethoxazole TMS, ticarcillin TC, ceftriaxone CRO, aztreonam AZT, ceftazidime CAZ, cefepime FEP, levofloxacin LEV, chloramphenicol CL, tigecilcin TIG and ciprofloxacin CIP, with a peak of resistance between the years 2007 to 2008 and a possible downward trend in 2018. The behavior of resistance between the years 2003 to 2018 report a downward trend in the last two years.

scholarly journals Pseudomonas Aeruginosa Antibiotic Efflux Pump Variants Exhibit Increased Virulence

2021 ◽  
Author(s):  
Mylene Vaillancourt ◽  
Sam P. Limsuwannarot ◽  
Catherine Bresee ◽  
Rahgavi Poopalarajah ◽  
Peter Jorth
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Infection Model ◽  
Dependent Manner ◽  
Resistance Mutations ◽  
Efflux Pump Inhibitor ◽  
Pump System ◽  
Mouse Infection Model ◽  
Epithelial Barriers

Antibiotic resistant Pseudomonas aeruginosa infections are the primary cause of mortality in people with cystic fibrosis (CF). Yet it has only recently become appreciated that resistance mutations can also increase P. aeruginosa virulence, even in the absence of antibiotics. Moreover, the mechanisms by which resistance mutations increase virulence are poorly understood. In this study we tested the hypothesis that mutations affecting efflux pumps can directly increase P. aeruginosa virulence. Using genetics, physiological assays, and model infections, we show that efflux pump mutations can increase virulence. Mutations of the mexEF efflux pump system increased swarming, rhamnolipid production, and lethality in a mouse infection model, while mutations in mexR that increased expression of the mexAB-oprM efflux system increased virulence during an acute murine lung infection without affecting swarming or rhamnolipid gene expression. Finally, we show that an efflux pump inhibitor, which represents a proposed novel treatment approach for P. aeruginosa, increased rhamnolipid gene expression in a dose-dependent manner. This finding is important because rhamnolipids are key virulence factors involved in dissemination through epithelial barriers and cause neutrophil necrosis. Together, these data show how current and proposed future anti-Pseudomonal treatments may unintentionally make infections worse by increasing virulence. Therefore, treatments that target efflux should be pursued with caution.

scholarly journals Evolved Aztreonam Resistance Is Multifactorial and Can Produce Hypervirulence in Pseudomonas aeruginosa

mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
Peter Jorth ◽  
Kathryn McLean ◽  
Anina Ratjen ◽  
Patrick R. Secor ◽  
Gilbert E. Bautista ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Experimental Evolution ◽  
Antimicrobial Agents ◽  
Cumulative Effect ◽  
Infection Model ◽  
Secondary Effects ◽  
Resistance Mutations ◽  
Mouse Infection Model ◽  
Airway Infections

ABSTRACT While much attention has been focused on acquired antibiotic resistance genes, chromosomal mutations may be most important in chronic infections where isolated, persistently infecting lineages experience repeated antibiotic exposure. Here, we used experimental evolution and whole-genome sequencing to investigate chromosomally encoded mutations causing aztreonam resistance in Pseudomonas aeruginosa and characterized the secondary consequences of resistance development. We identified 19 recurrently mutated genes associated with aztreonam resistance. The most frequently observed mutations affected negative transcriptional regulators of the mexAB-oprM efflux system and the target of aztreonam, ftsI. While individual mutations conferred modest resistance gains, high-level resistance (1,024 µg/ml) was achieved through the accumulation of multiple variants. Despite being largely stable when strains were passaged in the absence of antibiotics, aztreonam resistance was associated with decreased in vitro growth rates, indicating an associated fitness cost. In some instances, evolved aztreonam-resistant strains exhibited increased resistance to structurally unrelated antipseudomonal antibiotics. Surprisingly, strains carrying evolved mutations which affected negative regulators of mexAB-oprM (mexR and nalD) demonstrated enhanced virulence in a murine pneumonia infection model. Mutations in these genes, and other genes that we associated with aztreonam resistance, were common in P. aeruginosa isolates from chronically infected patients with cystic fibrosis. These findings illuminate mechanisms of P. aeruginosa aztreonam resistance and raise the possibility that antibiotic treatment could inadvertently select for hypervirulence phenotypes. IMPORTANCE Inhaled aztreonam is a relatively new antibiotic which is being increasingly used to treat cystic fibrosis patients with Pseudomonas aeruginosa airway infections. As for all antimicrobial agents, bacteria can evolve resistance that decreases the effectiveness of the drug; however, the mechanisms and consequences of aztreonam resistance are incompletely understood. Here, using experimental evolution, we have cataloged spontaneous mutations conferring aztreonam resistance and have explored their effects. We found that a diverse collection of genes contributes to aztreonam resistance, each with a small but cumulative effect. Surprisingly, we found that selection for aztreonam resistance mutations could confer increased resistance to other antibiotics and promote hypervirulence in a mouse infection model. Our study reveals inherent mechanisms of aztreonam resistance and indicates that aztreonam exposure can have unintended secondary effects. IMPORTANCE Inhaled aztreonam is a relatively new antibiotic which is being increasingly used to treat cystic fibrosis patients with Pseudomonas aeruginosa airway infections. As for all antimicrobial agents, bacteria can evolve resistance that decreases the effectiveness of the drug; however, the mechanisms and consequences of aztreonam resistance are incompletely understood. Here, using experimental evolution, we have cataloged spontaneous mutations conferring aztreonam resistance and have explored their effects. We found that a diverse collection of genes contributes to aztreonam resistance, each with a small but cumulative effect. Surprisingly, we found that selection for aztreonam resistance mutations could confer increased resistance to other antibiotics and promote hypervirulence in a mouse infection model. Our study reveals inherent mechanisms of aztreonam resistance and indicates that aztreonam exposure can have unintended secondary effects.

Roles of Ohr (a Cys based peroxidase) and OhrR (a redox regulated transcription factor) from Pseudomonas aeruginosa in a mouse infection model

2018 ◽  
Vol 128 ◽  
pp. S106-S107
Author(s):  
Anita Martins Fontes Del Guercio ◽  
Grasielle Januzzi ◽  
Gilberto Kaihami ◽  
Thiago Alegria ◽  
Diogo Meireles ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Mouse Infection

Antivirulence Activity of a Dietary Phytochemical: Hibiscus Acid Isolated from Hibiscus sabdariffa L. Reduces the Virulence of Pseudomonas aeruginosa in a Mouse Infection Model

2021 ◽  
Author(s):  
Humberto Cortes-López ◽  
Javier Castro-Rosas ◽  
Rodolfo García-Contreras ◽  
José Salud Rodríguez-Zavala ◽  
Bertha González-Pedrajo ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Infection Model ◽  
Hibiscus Sabdariffa ◽  
Mouse Infection Model ◽  
Mouse Infection

scholarly journals Pseudomonas aeruginosa mexR and mexEF Antibiotic Efflux Pump Variants Exhibit Increased Virulence

Antibiotics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1164
Author(s):  
Mylene Vaillancourt ◽  
Sam P. Limsuwannarot ◽  
Catherine Bresee ◽  
Rahgavi Poopalarajah ◽  
Peter Jorth
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Infection Model ◽  
Dependent Manner ◽  
Resistance Mutations ◽  
Efflux Pump Inhibitor ◽  
Pump System ◽  
Mouse Infection Model ◽  
Epithelial Barriers

Antibiotic-resistant Pseudomonas aeruginosa infections are the primary cause of mortality in people with cystic fibrosis (CF). Yet, it has only recently become appreciated that resistance mutations can also increase P. aeruginosa virulence, even in the absence of antibiotics. Moreover, the mechanisms by which resistance mutations increase virulence are poorly understood. In this study we tested the hypothesis that mutations affecting efflux pumps can directly increase P. aeruginosa virulence. Using genetics, physiological assays, and model infections, we show that efflux pump mutations can increase virulence. Mutations of the mexEF efflux pump system increased swarming, rhamnolipid production, and lethality in a mouse infection model, while mutations in mexR that increased expression of the mexAB-oprM efflux system increased virulence during an acute murine lung infection without affecting swarming or rhamnolipid gene expression. Finally, we show that an efflux pump inhibitor, which represents a proposed novel treatment approach for P. aeruginosa, increased rhamnolipid gene expression in a dose-dependent manner. This finding is important because rhamnolipids are key virulence factors involved in dissemination through epithelial barriers and cause neutrophil necrosis. Together, these data show how current and proposed future anti-Pseudomonal treatments may unintentionally make infections worse by increasing virulence. Therefore, treatments that target efflux should be pursued with caution.

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

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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