Search results for "Antibiotic resistance"
showing 10 items of 243 documents
Conjugation is necessary for a bacterial plasmid to survive under protozoan predation
2016
Horizontal gene transfer by conjugative plasmids plays a critical role in the evolution of antibiotic resistance. Interactions between bacteria and other organisms can affect the persistence and spread of conjugative plasmids. Here we show that protozoan predation increased the persistence and spread of the antibiotic resistance plasmid RP4 in populations of the opportunist bacterial pathogenSerratia marcescens. A conjugation-defective mutant plasmid was unable to survive under predation, suggesting that conjugative transfer is required for plasmid persistence under the realistic condition of predation. These results indicate that multi-trophic interactions can affect the maintenance of con…
Evolutionary Changes after Translational Challenges Imposed by Horizontal Gene Transfer
2019
International audience; Genes acquired by horizontal gene transfer (HGT) may provide the recipient organism with potentially new functions, but proper expression level and integration of the transferred genes in the novel environment are not granted. Notably, transferred genes can differ from the receiving genome in codon usage preferences, leading to impaired translation and reduced functionality. Here, we characterize the genomic and proteomic changes undergone during experimental evolution of Escherichia coli after HGT of three synonymous versions, presenting very different codon usage preference, of an antibiotic resistance gene. The experimental evolution was conducted with and without…
Constitutive activation of MexT by amino acid substitutions results in MexEF-OprN overproduction in clinical isolates of Pseudomonas aeruginosa
2018
ABSTRACT When overproduced, the multidrug efflux system MexEF-OprN increases the resistance of Pseudomonas aeruginosa to fluoroquinolones, chloramphenicol, and trimethoprim. In this work, we demonstrate that gain-of-function mutations in the regulatory gene mexT result in oligomerization of the LysR regulator MexT, constitutive upregulation of the efflux pump, and increased resistance in clinical isolates.
Role of AxyZ Transcriptional Regulator in Overproduction of AxyXY-OprZ Multidrug Efflux System in Achromobacter Species Mutants Selected by Tobramycin
2017
ABSTRACT AxyXY-OprZ is an RND-type efflux system that confers innate aminoglycoside resistance to Achromobacter spp. We investigated here a putative TetR family transcriptional regulator encoded by the axyZ gene located upstream of axyXY-oprZ . An in-frame axyZ gene deletion assay led to increased MICs of antibiotic substrates of the efflux system, including aminoglycosides, cefepime, fluoroquinolones, tetracyclines, and erythromycin, indicating that the product of axyZ negatively regulates expression of axyXY-oprZ . Moreover, we identified an amino acid substitution at position 29 of AxyZ (V29G) in a clinical Achromobacter strain that occurred during the course of chronic respiratory tract…
It is Time for Action in the Struggle against Antibiotic-Resistance, Let’s Start Reducing or Replacing Antibiotics in Agriculture
2016
Million people around the world are infected each year and thousands of them die from pathogens that are resistant to the treatment by any of known antibiotics [1]. The excessive use and abuse of antibiotics in clinical setting and in agriculture, added to the great ability of microorganisms to evolve, are the causes of the wide spread of isolates resistant to all major classes of current antibiotics. It is time for action in order to tackle antimicrobial-resistance (AMR), which can be considered a major threat to global health care and security. While we are waiting for new antimicrobial molecules and strategies, shorter-term approaches are needed to address the menace of AMR and preserve …
A Comparative Analysis of Aquatic and Polyethylene-Associated Antibiotic-Resistant Microbiota in the Mediterranean Sea
2021
Simple Summary In recent years, a growing interest has been devoted to the bacterial characterization of marine plastic debris. So far, a few publications have explored the composition of microbial communities on polyethylene (PE) waste items and the occurrence of antibiotic-resistant bacteria (ARB). The occurrence of ARB in natural matrices can contribute to the spread of antibiotic resistance genes (ARGs) among environmental bacteria. In this study, we compared the microbial composition and the presence of ARGs in water and PE fragments collected from a stream and the seawater in a coastal area of Northwestern Sicily. Our findings showed more ARGs on PE fragments than the corresponding wa…
Resistance profiles and risk factors of resistant microorganisms in bacteraemia of abdominal origin
2017
Abstract Objective The presence of resistant microorganisms is a major cause of failure in initial empirical antimicrobial therapy. The objectives of this study are to determine the resistance profile of microorganisms that cause bacteraemia of abdominal origin and to identify whether the previous use of antibiotics and the place of acquisition of bacteraemia are risk factors associated with the presence of resistant organisms. Material and methods A clinical, observational, epidemiological, retrospective cohort study was conducted with all the adult patients admitted to a university hospital from 2011 to 2013. Antimicrobial resistance profiles were described and a 95% confidence interval c…
Antibiotics Resistance in Enterococcus Isolates from Poultry Waste
2020
Abstract The aim of the study was to evaluate the drug resistance of Enterococcus faecalis and Enterococcus faecium isolated from different types of poultry waste. The study material consisted of feather samples (duck, turkey, chicken), sludge and centrifuge sediment, originating from three poultry farms. The study was conducted in two stages; isolation and identification of Enterococcus bacteria from the waste and evaluation of their drug resistance using Kirby-Bauer method. Contamination of the poultry waste with Enterococcus isolates included E. faecium species (79 %) and E. faecalis (21 %). The most contaminated were sludge and sediment from the centrifuge as well as chicken feathers, i…
Pharmaceutical Approaches to Target Antibiotic Resistance Mechanisms
2017
There is urgent need for new therapeutic strategies to fight the global threat of antibiotic resistance. The focus of this Perspective is on chemical agents that target the most common mechanisms of antibiotic resistance such as enzymatic inactivation of antibiotics, changes in cell permeability, and induction/activation of efflux pumps. Here we assess the current landscape and challenges in the treatment of antibiotic resistance mechanisms at both bacterial cell and community levels. We also discuss the potential clinical application of chemical inhibitors of antibiotic resistance mechanisms as add-on treatments for serious drug-resistant infections. Enzymatic inhibitors, such as the deriv…
Antibiotic resistance and population structure of cystic fibrosis Pseudomonas aeruginosa isolates from a Spanish multi-centre study
2017
The first Spanish multi-centre study on the microbiology of cystic fibrosis (CF) was conducted from 2013 to 2014. The study involved 24 CF units from 17 hospitals, and recruited 341 patients. The aim of this study was to characterise Pseudomonas aeruginosa isolates, 79 of which were recovered from 75 (22%) patients. The study determined the population structure, antibiotic susceptibility profile and genetic background of the strains. Fifty-five percent of the isolates were multi-drug-resistant, and 16% were extensively drug-resistant. Defective mutS and mutL genes were observed in mutator isolates (15.2%). Considerable genetic diversity was observed by pulsed-field gel electrophoresis (70 p…