scholarly journals Mutation-Driven Evolution ofPseudomonas aeruginosain the Presence of either Ceftazidime or Ceftazidime-Avibactam

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Fernando Sanz-García ◽  
Sara Hernando-Amado ◽  
José Luis Martínez
Keyword(s):  
Experimental Evolution ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Two Component System ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
Chromosomal Deletions ◽  
Two Component ◽  
Main Driver ◽  
Selection Of

ABSTRACTCeftazidime-avibactam is a combination of β-lactam/β-lactamase inhibitor, the use of which is restricted to some clinical cases, including cystic fibrosis patients infected with multidrug-resistantPseudomonas aeruginosa, in which mutation is the main driver of resistance. This study aims to predict the mechanisms of mutation-driven resistance that are selected for whenP. aeruginosais challenged with either ceftazidime or ceftazidime-avibactam. For this purpose,P. aeruginosaPA14 was submitted to experimental evolution in the absence of antibiotics and in the presence of increasing concentrations of ceftazidime or ceftazidime-avibactam for 30 consecutive days. Final populations were analyzed by whole-genome sequencing. All evolved populations reached similar levels of ceftazidime resistance. In addition, they were more susceptible to amikacin and produced pyomelanin. A first event in this evolution was the selection of large chromosomal deletions containinghmgA(involved in pyomelanin production),galU(involved in β-lactams resistance), andmexXY-oprM(involved in aminoglycoside resistance). Besides mutations inmplanddacBthat regulate β-lactamase expression, mutations related to MexAB-OprM overexpression were prevalent. Ceftazidime-avibactam challenge selected mutants in the putative efflux pumpPA14_45890andPA14_45910and in a two-component system (PA14_45870andPA14_45880), likely regulating its expression. All populations produced pyomelanin and were more susceptible to aminoglycosides, likely due to the selection of large chromosomal deletions. Since pyomelanin-producing mutants presenting similar deletions are regularly isolated from infections, the potential aminoglycoside hypersusceptiblity and reduced β-lactam susceptibility of pyomelanin-producingP. aeruginosashould be taken into consideration for treating infections caused by these isolates.

scholarly journals Mutation-driven evolution of Pseudomonas aeruginosa in the presence of either ceftazidime or ceftazidime/avibactam

2018 ◽  
Author(s):  
Fernando Sanz-García ◽  
Sara Hernando-Amado ◽  
José Luis Martínez
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Beta Lactam ◽  
Two Component System ◽  
Aminoglycoside Resistance ◽  
Beta Lactamases ◽  
Chromosomal Deletions ◽  
Main Driver ◽  
Selection Of

ABSTRACTCeftazidime/avibactam is a combination of beta-lactam/beta-lactamases inhibitor, which use is restricted to some clinical cases including cystic fibrosis patients infected with multidrug resistant Pseudomonas aeruginosa, in which mutation is the main driver of resistance. This study aims to predict the mechanisms of mutation-driven resistance that are selected for when P. aeruginosa is challenged with either ceftazidime or ceftazidime/avibactam. For this purpose, P. aeruginosa PA14 was submitted to experimental evolution in the absence of antibiotics and in the presence of increasing concentrations of ceftazidime or ceftazidime/avibactam for 30 consecutive days. Final populations were analysed by whole-genome sequencing. All evolved populations reached similar levels of ceftazidime resistance. Besides, all of them were more susceptible to amikacin and produced pyomelanin. A first event in the evolution was the selection of large chromosomal deletions containing hmgA (involved in pyomelanin production), galU (involved in β-lactams resistance) and mexXY-oprM (involved in aminoglycoside resistance). Besides mutations in mpl and dacB that regulate β-lactamase expression, mutations related to MexAB-OprM overexpression were prevalent. Ceftazidime/avibactam challenge selected mutants in the putative efflux pump PA14_45890-45910 and in a two-component system (PA14_45870-45880), likely regulating its expression. All populations produce pyomelanin and were more susceptible to aminoglycosides likely due to the selection of large chromosomal deletions. Since pyomelanin-producing mutants, presenting similar deletions are regularly isolated from infections, the potential aminoglycosides hyper-susceptiblity and reduced β-lactams susceptibility of pyomelanin-producing P. aeruginosa should be taken into consideration for treating infections by these isolates.

scholarly journals RND-Type Efflux Pumps in Multidrug-Resistant Clinical Isolates of Acinetobacter baumannii: Major Role for AdeABC Overexpression and AdeRS Mutations

2013 ◽  
Vol 57 (7) ◽  
pp. 2989-2995 ◽  
Author(s):  
Eun-Jeong Yoon ◽  
Patrice Courvalin ◽  
Catherine Grillot-Courvalin
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Clinical Settings ◽  
Two Component System ◽  
Content Type ◽  
High Incidence ◽  
Two Component

ABSTRACTIncreased expression of chromosomal genes for resistance-nodulation-cell division (RND)-type efflux systems plays a major role in the multidrug resistance (MDR) ofAcinetobacter baumannii. However, the relative contributions of the three most prevalent pumps, AdeABC, AdeFGH, and AdeIJK, have not been evaluated in clinical settings. We have screened 14 MDR clinical isolates shown to be distinct on the basis of multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) for the presence and overexpression of the three Ade efflux systems and analyzed the sequences of the regulators AdeRS, a two-component system, for AdeABC and AdeL, a LysR-type regulator, for AdeFGH. GeneadeBwas detected in 13 of 14 isolates, andadeGand the intrinsicadeJgene were detected in all strains. Significant overexpression ofadeBwas observed in 10 strains, whereas only 7 had moderately increased levels of expression of AdeFGH, and none overexpressed AdeIJK. Thirteen strains had reduced susceptibility to tigecycline, but there was no correlation between tigecycline MICs and the levels of AdeABC expression, suggesting the presence of other mechanisms for tigecycline resistance. No mutations were found in the highly conserved LysR regulator of the nine strains expressing AdeFGH. In contrast, functional mutations were found in conserved domains of AdeRS in all the strains that overexpressed AdeABC with two mutational hot spots, one in AdeS near histidine 149 suggesting convergent evolution and the other in the DNA binding domain of AdeR compatible with horizontal gene transfer. This report outlines the high incidence of AdeABC efflux pump overexpression in MDRA. baumanniias a result of a variety of single mutations in the corresponding two-component regulatory system.

scholarly journals Expression of the MexXY Aminoglycoside Efflux Pump and Presence of an Aminoglycoside-Modifying Enzyme in Clinical Pseudomonas aeruginosa Isolates Are Highly Correlated

2020 ◽  
Vol 65 (1) ◽  
pp. e01166-20
Author(s):  
Alexander Seupt ◽  
Monika Schniederjans ◽  
Jürgen Tomasch ◽  
Susanne Häussler
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
Main Driver ◽  
Gentamicin Resistance ◽  
Bacterial Cell Membrane ◽  
Highly Correlated ◽  
The Impact ◽  
Gene Expression Levels

ABSTRACTThe impact of MexXY efflux pump expression on aminoglycoside resistance in clinical Pseudomonas aeruginosa isolates has been debated. In this study, we found that, in general, elevated mexXY gene expression levels in clinical P. aeruginosa isolates confer to slight increases in aminoglycoside MIC levels; however, those levels rarely lead to clinically relevant resistance phenotypes. The main driver of resistance in the clinical isolates studied here was the acquisition of aminoglycoside-modifying enzymes (AMEs). Nevertheless, acquisition of an AME was strongly associated with mexY overexpression. In line with this observation, we demonstrate that the introduction of a gentamicin acetyltransferase confers to full gentamicin resistance levels in a P. aeruginosa type strain only if the MexXY efflux pump was active. We discuss that increased mexXY activity in clinical AME-harboring P. aeruginosa isolates might affect ion fluxes at the bacterial cell membrane and thus might play a role in the establishment of enhanced fitness that extends beyond aminoglycoside resistance.

scholarly journals Real-Time Sequencing To Decipher the Molecular Mechanism of Resistance of a Clinical Pan-Drug-Resistant Acinetobacter baumannii Isolate from Marseille, France

2012 ◽  
Vol 57 (1) ◽  
pp. 592-596 ◽  
Author(s):  
Jean-Marc Rolain ◽  
Seydina M. Diene ◽  
Marie Kempf ◽  
Gregory Gimenez ◽  
Catherine Robert ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Molecular Mechanisms ◽  
Multidrug Resistant ◽  
Drug Resistant ◽  
Two Component System ◽  
Genome Sequences ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Baumannii Isolate

ABSTRACTWe compare the whole-genome sequences of two multidrug-resistant clinicalAcinetobacter baumanniiisolates recovered in the same patient before (ABIsac_ColiS susceptible to colistin and rifampin only) and after (ABIsac_ColiR resistant to colistin and rifampin) treatment with colistin and rifampin. We decipher all the molecular mechanisms of antibiotic resistance, and we found mutations in therpoBgene and in the PmrAB two-component system explaining resistance to rifampin and colistin in ABIsac_ColiR, respectively.

scholarly journals Mutational Activation of the AmgRS Two-Component System in Aminoglycoside-Resistant Pseudomonas aeruginosa

2013 ◽  
Vol 57 (5) ◽  
pp. 2243-2251 ◽  
Author(s):  
Calvin Ho-Fung Lau ◽  
Sebastien Fraud ◽  
Marcus Jones ◽  
Scott N. Peterson ◽  
Keith Poole
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Fold Increase ◽  
Wild Type ◽  
Two Component System ◽  
Aminoglycoside Resistance ◽  
Gain Of Function ◽  
Component System ◽  
Content Type ◽  
Resistance Phenotype ◽  
Two Component

ABSTRACTTheamgRSoperon encodes a presumed membrane stress-responsive two-component system linked to intrinsic aminoglycoside resistance inPseudomonas aeruginosa. Genome sequencing of a lab isolate showing modest pan-aminoglycoside resistance, strain K2979, revealed a number of mutations, including a substitution inamgSthat produced an R182C change in the AmgS sensor kinase product of this gene. Introduction of this mutation into an otherwise wild-type strain recapitulated the resistance phenotype, while correcting the mutation in the resistant mutant abrogated the resistant phenotype, confirming that theamgSmutation is responsible for the aminoglycoside resistance of strain K2979. TheamgSR182mutation promoted an AmgR-dependent, 2- to 3-fold increase in expression of the AmgRS target geneshtpXand PA5528, mirroring the impact of aminoglycoside exposure of wild-type cells onhtpXand PA5528 expression. This suggests thatamgSR182is a gain-of-function mutation that activates AmgS and the AmgRS two-component system in promoting modest resistance to aminoglycosides. Screening of several pan-aminoglycoside-resistant clinical isolates ofP. aeruginosarevealed three that showed elevatedhtpXand PA5528 expression and harbored single amino acid-altering mutations inamgS(V121G or D106N) and no mutations inamgR. Introduction of theamgSV121Gmutation into wild-typeP. aeruginosagenerated a resistance phenotype reminiscent of theamgSR182mutant and produced a 2- to 3-fold increase inhtpXand PA5528 expression, confirming that it, too, is a gain-of-function aminoglycoside resistance-promoting mutation. These results highlight the contribution ofamgSmutations and activation of the AmgRS two-component system to acquired aminoglycoside resistance in lab and clinical isolates ofP. aeruginosa.

scholarly journals Overexpression of SmeDEF Efflux Pump Decreases Aminoglycoside Resistance in Stenotrophomonas maltophilia

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Yi-Wei Huang ◽  
Cheng-Wen Lin ◽  
Hsiao-Chen Ning ◽  
Yi-Tsung Lin ◽  
Yi-Chih Chang ◽  
...  
Keyword(s):  
Binding Site ◽  
Nalidixic Acid ◽  
Stenotrophomonas Maltophilia ◽  
Deletion Mutant ◽  
Efflux Pump ◽  
Regulatory System ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
Regulatory Circuit ◽  
Two Component

ABSTRACT The SmeDEF pump of Stenotrophomonas maltophilia is negatively regulated by SmeT. In this study, strains KJΔT (smeT deletion mutant) and KJT-Dm (mutant with a defective SmeT-binding site) showed increased resistance to chloramphenicol/nalidixic acid/macrolides and susceptibility to aminoglycoside. Overexpression of the SmeDEF pump, in either KJΔT or KJT-Dm, downregulated smeYZ expression, which is responsible for the reduced aminoglycoside resistance. Furthermore, the SmeRySy two-component regulatory system was downregulated in response to SmeDEF overexpression, which supports its involvement in the regulatory circuit.

scholarly journals The Two-Component System ChtRS Contributes to Chlorhexidine Tolerance in Enterococcus faecium

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Ana M. Guzmán Prieto ◽  
Jessica Wijngaarden ◽  
Johanna C. Braat ◽  
Malbert R. C. Rogers ◽  
Eline Majoor ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Response Regulator ◽  
Normal Growth ◽  
Multidrug Resistant ◽  
Cross Tolerance ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
A Genome ◽  
Two Component

ABSTRACT Enterococcus faecium is one of the primary causes of nosocomial infections. Disinfectants are commonly used to prevent infections with multidrug-resistant E. faecium in hospitals. Worryingly, E. faecium strains that exhibit tolerance to disinfectants have already been described. We aimed to identify and characterize E. faecium genes that contribute to tolerance to the disinfectant chlorhexidine (CHX). We used a transposon mutant library, constructed in a multidrug-resistant E. faecium bloodstream isolate, to perform a genome-wide screen to identify genetic determinants involved in tolerance to CHX. We identified a putative two-component system (2CS), composed of a putative sensor histidine kinase (ChtS) and a cognate DNA-binding response regulator (ChtR), which contributed to CHX tolerance in E. faecium. Targeted chtR and chtS deletion mutants exhibited compromised growth in the presence of CHX. Growth of the chtR and chtS mutants was also affected in the presence of the antibiotic bacitracin. The CHX- and bacitracin-tolerant phenotype of E. faecium E1162 was linked to a unique, nonsynonymous single nucleotide polymorphism in chtR. Transmission electron microscopy showed that upon challenge with CHX, the ΔchtR and ΔchtS mutants failed to divide properly and formed long chains. Normal growth and cell morphology were restored when the mutations were complemented in trans. Morphological abnormalities were also observed upon exposure of the ΔchtR and ΔchtS mutants to bacitracin. The tolerance to both chlorhexidine and bacitracin provided by ChtRS in E. faecium highlights the overlap between responses to disinfectants and antibiotics and the potential for the development of cross-tolerance for these classes of antimicrobials.

scholarly journals Innate Aminoglycoside Resistance of Achromobacter xylosoxidans Is Due to AxyXY-OprZ, an RND-Type Multidrug Efflux Pump

2012 ◽  
Vol 57 (1) ◽  
pp. 603-605 ◽  
Author(s):  
Julien Bador ◽  
Lucie Amoureux ◽  
Emmanuel Blanc ◽  
Catherine Neuwirth
Keyword(s):  
Efflux Pump ◽  
Multidrug Resistant ◽  
Achromobacter Xylosoxidans ◽  
Pulmonary Infections ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
High Level ◽  
Level Resistance

ABSTRACTAchromobacter xylosoxidansis an innately multidrug-resistant pathogen which is emerging in cystic fibrosis (CF) patients. We characterized a new resistance-nodulation-cell division (RND)-type multidrug efflux pump, AxyXY-OprZ. This system is responsible for the intrinsic high-level resistance ofA. xylosoxidansto aminoglycosides (tobramycin, amikacin, and gentamicin). Furthermore, it can extrude cefepime, carbapenems, some fluoroquinolones, tetracyclines, and erythromycin. Some of the AxyXY-OprZ substrates are major components widely used to treat pulmonary infections in CF patients.

scholarly journals Nutritional Regulation of the Sae Two-Component System by CodY inStaphylococcus aureus

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Kevin D. Mlynek ◽  
William E. Sause ◽  
Derek E. Moormeier ◽  
Marat R. Sadykov ◽  
Kurt R. Hill ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Factors ◽  
Virulence Gene ◽  
Nutrient Depletion ◽  
Global Regulator ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Two Component

ABSTRACTStaphylococcus aureussubverts innate defenses during infection in part by killing host immune cells to exacerbate disease. This human pathogen intercepts host cues and activates a transcriptional response via theS. aureusexoprotein expression (SaeR/SaeS [SaeR/S]) two-component system to secrete virulence factors critical for pathogenesis. We recently showed that the transcriptional repressor CodY adjusts nuclease (nuc) gene expression via SaeR/S, but the mechanism remained unknown. Here, we identified two CodY binding motifs upstream of thesaeP1 promoter, which suggested direct regulation by this global regulator. We show that CodY shares a binding site with the positive activator SaeR and that alleviating direct CodY repression at this site is sufficient to abrogate stochastic expression, suggesting that CodY repressessaeexpression by blocking SaeR binding. Epistasis experiments support a model that CodY also controlssaeindirectly through Agr and Rot-mediated repression of thesaeP1 promoter. We also demonstrate that CodY repression ofsaerestrains production of secreted cytotoxins that kill human neutrophils. We conclude that CodY plays a previously unrecognized role in controlling virulence gene expression via SaeR/S and suggest a mechanism by which CodY acts as a master regulator of pathogenesis by tying nutrient availability to virulence gene expression.IMPORTANCEBacterial mechanisms that mediate the switch from a commensal to pathogenic lifestyle are among the biggest unanswered questions in infectious disease research. Since the expression of most virulence genes is often correlated with nutrient depletion, this implies that virulence is a response to the lack of nourishment in host tissues and that pathogens likeS. aureusproduce virulence factors in order to gain access to nutrients in the host. Here, we show that specific nutrient depletion signals appear to be funneled to the SaeR/S system through the global regulator CodY. Our findings reveal a strategy by whichS. aureusdelays the production of immune evasion and immune-cell-killing proteins until key nutrients are depleted.

Resistance to nitrofurantoin is an indicator of extensive drug-resistant (XDR) Enterobacteriaceae

2021 ◽  
Vol 70 (4) ◽  
Author(s):  
Balaram Khamari ◽  
Prakash Kumar ◽  
Bulagonda Eswarappa Pradeep
Keyword(s):  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Treatment Options ◽  
Strong Association ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Content Type ◽  
Link Type

Introduction. Nitrofurantoin is one of the preferred antibiotics in the treatment of uropathogenic multidrug-resistant (MDR) infections. However, resistance to nitrofurantoin in extensively drug-resistant (XDR) bacteria has severely limited the treatment options. Gap statement. Information related to co-resistance or collateral sensitivity (CS) with reference to nitrofurantoin resistant bacteria is limited. Aim. To study the potential of nitrofurantoin resistance as an indicator of the XDR phenotype in Enterobacteriaceae . Methods. One hundred (45 nitrofurantoin-resistant, 21 intermediately resistant and 34 nitrofurantoin-susceptible) Enterobacteriaceae were analysed in this study. Antibiotic susceptibility testing (AST) against nitrofurantoin and 17 other antimicrobial agents across eight different classes was performed by using the Vitek 2.0 system. The isolates were screened for the prevalence of acquired antimicrobial resistance (AMR) and efflux pump genes by PCR. Results. In total, 51 % of nitrofurantoin-resistant and 28 % of intermediately nitrofurantoin resistant isolates exhibited XDR characteristics, while only 3 % of nitrofurantoin-sensitive isolates were XDR (P=0.0001). Significant co-resistance was observed between nitrofurantoin and other tested antibiotics (β-lactam, cephalosporin, carbapenem, aminoglycoside and tetracycline). Further, the prevalence of AMR and efflux pump genes was higher in the nitrofurantoin-resistant strains compared to the susceptible isolates. A strong association was observed between nitrofurantoin resistance and the presence of bla PER-1, bla NDM-1, bla OXA-48, ant(2) and oqxA-oqxB genes. Tigecycline (84 %) and colistin (95 %) were the only antibiotics to which the majority of the isolates were susceptible. Conclusion. Nitrofurantoin resistance could be an indicator of the XDR phenotype among Enterobacteriaceae , harbouring multiple AMR and efflux pump genes. Tigecycline and colistin are the only antibiotics that could be used in the treatment of such XDR infections. A deeper understanding of the co-resistance mechanisms in XDR pathogens and prescription of AST-based appropriate combination therapy may help mitigate this problem.

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