Characterization of acquired β-lactamases in and quantification of their contributions to resistance.

is a highly problematic opportunistic pathogen that causes a range of different infections. Infections are commonly treated with β-lactam antibiotics, including cephalosporins, monobactams, penicillins, and carbapenems, with carbapenems regarded as antibiotics of last resort. Isolates of can contain horizontally acquired genes encoding β-lactamase enzymes, but the extent to which these contribute to β-lactam resistance in this species has not been systematically quantified.

Penicillin-binding protein 3 sequence variations reduce susceptibility of Pseudomonas aeruginosa to β-lactams but inhibit cell division.

Background: β-lactam antibiotics, which inhibit penicillin-binding protein 3 (PBP3) that is required for cell division, play a key role in treating P. aeruginosa infections. Some sequence variations in PBP3 have been associated with β-lactam resistance but the effects of variations on antibiotic susceptibility and on cell division have not been quantified.

Using host-mimicking conditions and a murine cutaneous abscess model to identify synergistic antibiotic combinations effective against .

Antibiotic drug combination therapy is critical for the successful treatment of infections caused by multidrug resistant pathogens. We investigated the efficacy of β-lactam and β-lactam/β-lactamase inhibitor combinations with other antibiotics, against the hypervirulent, ceftazidime/avibactam resistant Liverpool epidemic strain (LES) B58. Although minimum inhibitory concentrations differed by up to eighty-fold between standard and host-mimicking media, combinatorial effects only marginally changed between conditions for some combinations.

Murepavadin promotes the killing efficacies of aminoglycoside antibiotics against by enhancing membrane potential.

Murepavadin is a peptidomimetic that specifically targets the lipopolysaccharide transport protein LptD of . Here, we found that murepavadin enhances the bactericidal efficacies of tobramycin and amikacin. We further demonstrated that murepavadin enhances bacterial respiration activity and subsequent membrane potential, which promotes intracellular uptake of aminoglycoside antibiotics.

The PitA protein contributes to colistin susceptibility in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of problematic infections in individuals with predisposing conditions. Infections can be treated with colistin but some isolates are resistant to this antibiotic. To better understand the genetic basis of resistance, we experimentally evolved 19 independent resistant mutants from the susceptible laboratory strain PAO1.

Murepavadin induces envelope stress response and enhances the killing efficacies of β-lactam antibiotics by impairing the outer membrane integrity of .

is a ubiquitous opportunistic pathogen that can cause a variety of acute and chronic infections. The bacterium is highly resistant to numerous antibiotics. Murepavadin is a peptidomimetic antibiotic that blocks the function of lipopolysaccharide (LPS) transport protein D (LptD), thus inhibiting the insertion of LPS into the outer membrane.

Pseudomonas aeruginosa is oxygen-deprived during infection in cystic fibrosis lungs, reducing the effectiveness of antibiotics.

Pseudomonas aeruginosa infects the lungs of patients with cystic fibrosis. Sputum expectorated from the lungs of patients contains low levels of oxygen, indicating that P. aeruginosa may be oxygen-deprived during infection.

Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex.

Pseudomonas aeruginosa causes a wide range of severe infections. Ceftazidime, a cephalosporin, is a key antibiotic for treating infections but a significant proportion of isolates are ceftazidime-resistant. The aim of this research was to identify mutations that contribute to resistance, and to quantify the impacts of individual mutations and mutation combinations.

Gene-Gene Interactions Reduce Aminoglycoside Susceptibility of through Efflux Pump-Dependent and -Independent Mechanisms.

causes a wide range of acute and chronic infections. Aminoglycosides are a cornerstone of treatment, but isolates are often resistant. The purpose of this research was to better understand the genetic basis of aminoglycoside resistance in .

Inhalable ceftazidime-roflumilast powder targeting infection and inflammation: Influence of incorporating roflumilast into ceftazidime-leucine co-amorphous formulation.

Co-amorphization of a single drug with amino acid is a technique to improve aerosolization of inhalable spray-dried formulation for inhalation therapy. However, the incorporation of a second drug molecule into drug-amino acid co-amorphous particles to prepare combination formulations has not been explored. Here, we prepared combination powders using two model drugs, ceftazidime and roflumilast, which when concurrently used can potentially improve therapeutic outcome in non-cystic fibrosis bronchiectasis by counteracting both infection and inflammation.

Aminoglycoside-Modifying Enzymes Are Sufficient to Make Clinically Resistant to Key Antibiotics.

Aminoglycosides are widely used to treat infections of . Genes encoding aminoglycoside-modifying enzymes (AMEs), acquired by horizontal gene transfer, are commonly associated with aminoglycoside resistance, but their effects have not been quantified. The aim of this research was to determine the extent to which AMEs increase the antibiotic tolerance of .

Aminoglycoside resistance in : the contribution of the MexXY-OprM efflux pump varies between isolates.

Aminoglycoside antibiotics are widely used to treat infections of . The MexXY-OprM efflux pump is an important contributor to aminoglycoside tolerance in reference strains and expression of the genes is repressed by the MexZ repressor protein. Direct investigation of the role of this efflux pump in clinical isolates is relatively limited.

The Effects of Sub-inhibitory Antibiotic Concentrations on : Reduced Susceptibility Due to Mutations.

chronically infects in the lungs of people with cystic fibrosis and other forms of lung disease. Infections are treated with antibiotics, but over time, the bacteria acquire mutations that reduce their antibiotic susceptibility. The effects of inhibitory amounts of antibiotics in selecting for antibiotic-resistant mutants have been well studied.

β-lactam Resistance in : Current Status, Future Prospects.

is a major opportunistic pathogen, causing a wide range of acute and chronic infections. β-lactam antibiotics including penicillins, carbapenems, monobactams, and cephalosporins play a key role in the treatment of infections. However, a significant number of isolates of these bacteria are resistant to β-lactams, complicating treatment of infections and leading to worse outcomes for patients.

The Pseudomonas aeruginosa whole genome sequence: A 20th anniversary celebration.

Toward the end of August 2000, the 6.3 Mbp whole genome sequence of Pseudomonas aeruginosa strain PAO1 was published. With 5570 open reading frames (ORFs), PAO1 had the largest microbial genome sequenced up to that point in time-including a large proportion of metabolic, transport and antimicrobial resistance genes supporting its ability to colonize diverse environments.

Genome evolution drives transcriptomic and phenotypic adaptation in during 20 years of infection.

The opportunistic pathogen chronically infects the lungs of patients with cystic fibrosis (CF). During infection the bacteria evolve and adapt to the lung environment. Here we use genomic, transcriptomic and phenotypic approaches to compare multiple isolates of collected more than 20 years apart during a chronic infection in a CF patient.

Gene-Gene Interactions Dictate Ciprofloxacin Resistance in Pseudomonas aeruginosa and Facilitate Prediction of Resistance Phenotype from Genome Sequence Data.

Ciprofloxacin is one of the most widely used antibiotics for treating Pseudomonas aeruginosa infections. However, P. aeruginosa acquires mutations that confer ciprofloxacin resistance, making treatment more difficult.

Transmission, adaptation and geographical spread of the Liverpool epidemic strain.

The Liverpool epidemic strain (LES) is an important transmissible clonal lineage of that chronically infects the lungs of people with cystic fibrosis (CF). Previous studies have focused on the genomics of the LES in a limited number of isolates, mostly from one CF centre in the UK, and from studies highlighting identification of the LES in Canada. Here we significantly extend the current LES genome database by genome sequencing 91 isolates from multiple CF centres across the UK, and we describe the comparative genomics of this large collection of LES isolates from the UK and Canada.

Identification of Active Site Residues of the Siderophore Synthesis Enzyme PvdF and Evidence for Interaction of PvdF with a Substrate-Providing Enzyme.

The problematic opportunistic pathogen secretes a siderophore, pyoverdine. Pyoverdine scavenges iron needed by the bacteria for growth and for pathogenicity in a range of different infection models. PvdF, a hydroxyornithine transformylase enzyme, is essential for pyoverdine synthesis, catalysing synthesis of formylhydroxyornithine (fOHOrn) that forms part of the pyoverdine molecule and provides iron-chelating hydroxamate ligands.

Role of Tris-CaEDTA as an adjuvant with nebulised tobramycin in cystic fibrosis patients with Pseudomonas aeruginosa lung infections: A randomised controlled trial.

Background: We tested if disrupting iron utilisation by P. aeruginosa by adding the Tris-buffered chelating agent CaEDTA to nebulised tobramycin would enhance bacterial clearance and improve lung function in CF patients.

Methods: In this double-blind, randomised controlled trial, 26 episodes (25 patients) with P.

One Health Aotearoa: a transdisciplinary initiative to improve human, animal and environmental health in New Zealand.

There is increased recognition that complex health challenges at the human-animal-environmental interface require a transdisciplinary, "" approach. This philosophy is particularly pertinent in Aotearoa-New Zealand because of the country's relatively isolated island ecosystem, economic reliance on agriculture and its intensification, and existing indigenous worldview that emphasises holism and interconnectivity between humans, animals and the environment. In New Zealand, the One Health Aotearoa (OHA) alliance was established in order to better connect researchers and to address a growing number of infectious diseases challenges.

Cell envelope proteases and peptidases of Pseudomonas aeruginosa: multiple roles, multiple mechanisms.

Pseudomonas aeruginosa is a Gram-negative bacterium that is commonly isolated from damp environments. It is also a major opportunistic pathogen, causing a wide range of problematic infections. The cell envelope of P.

The Iron-chelator, N,N'-bis (2-hydroxybenzyl) Ethylenediamine-N,N'-Diacetic acid is an Effective Colistin Adjunct against Clinical Strains of Biofilm-Dwelling .

Targeting the iron requirement of may be an effective adjunctive for conventional antibiotic treatment against biofilm-dwelling . We, therefore, assessed the anti-biofilm activity of N,N'-bis (2-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid (HBED), which is a synthetic hexadentate iron chelator. The effect of HBED was studied using short-term (microtitre plate) and longer-term (flow-cell) biofilm models, under aerobic, anaerobic, and microaerobic (flow-cell) conditions and in combination with the polymyxin antibiotic colistimethate sodium (colistin).

A large-scale whole-genome comparison shows that experimental evolution in response to antibiotics predicts changes in naturally evolved clinical .

is an opportunistic pathogen that causes a wide range of acute and chronic infections. An increasing number of isolates have mutations that make them antibiotic resistant, making treatment difficult. To identify resistance-associated mutations we experimentally evolved the antibiotic sensitive strain PAO1 to become resistant to three widely used anti-pseudomonal antibiotics, ciprofloxacin, meropenem and tobramycin.