The multidrug resistance efflux pump MexCD-OprJ is a switcher of thePseudomonas aeruginosaquorum sensing response

AbstractMost antibiotic resistance genes acquired by human pathogens originate from environmental microorganisms. Therefore, understanding the additional functions of these genes, other than conferring antibiotic resistance, is relevant from an ecological point of view. We examined the effect that overexpression of the MexCD-OprJ multidrug efflux pump has in the physiology of the environmental opportunistic pathogenPseudomonas aeruginosa. Overexpression of this intrinsic resistance determinant shuts down theP. aeruginosaquorum sensing (QS) response. Impaired QS response is due to the extrusion of 4-hydroxy-2-heptylquinoline (HHQ), the precursor of thePseudomonasQuinolone Signal (PQS), leading to low PQS intracellular levels and reduced production of QS signal molecules. TheP. aeruginosaQS response induces the expression of hundreds of genes, which can be costly unless such activation becomes beneficial for the bacterial population. While it is known that the QS response is modulated by population density, information on additional signals/cues that may alert the cells about the benefits of mounting the response is still scarce. It is possible that MexCD-OprJ plays a role in this particular aspect; our results indicate that, upon overexpression, MexCD-OprJ can act as a switcher in the QS population response. If MexCD-OprJ alleviate the cost associated to trigger the QS response when un-needed, it could be possible that MexCD-OprJ overproducer strains might be eventually selected even in the absence of antibiotic selective pressure, acting as antibiotic resistant cheaters in heterogeneousP. aeruginosapopulations. This possibility may have potential implications for the treatment ofP. aeruginosachronic infections.

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Correlation between the Antibiotic Resistance Genes and Susceptibility to Antibiotics among the Carbapenem-Resistant Gram-Negative Pathogens

Antibiotics ◽

10.3390/antibiotics10030255 ◽

2021 ◽

Vol 10 (3) ◽

pp. 255

Author(s):

Salma M. Abdelaziz ◽

Khaled M. Aboshanab ◽

Ibrahim S. Yahia ◽

Mahmoud A. Yassien ◽

Nadia A. Hassouna

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Efflux Pump ◽

Antibiotic Resistance Genes ◽

Multiple Drug ◽

P Value ◽

Multidrug Efflux ◽

Multidrug Efflux Pump ◽

Gram Negative ◽

Carbapenem Resistant

In this study, the correlation between the antibiotic resistance genes and antibiotic susceptibility among the carbapenem-resistant Gram-negative pathogens (CRGNPs) recovered from patients diagnosed with acute pneumonia in Egypt was found. A total of 194 isolates including Klebsiella pneumoniae (89; 46%), Escherichia coli (47; 24%) and Pseudomonas aeruginosa (58; 30%) were recovered. Of these, 34 (18%) isolates were multiple drug resistant (MDR) and carbapenem resistant. For the K. pneumoniae MDR isolates (n = 22), blaNDM (14; 64%) was the most prevalent carbapenemase, followed by blaOXA-48 (11; 50%) and blaVIM (4; 18%). A significant association (p value < 0.05) was observed between the multidrug efflux pump (AcrA) and resistance to β-lactams and the aminoglycoside acetyl transferase gene (aac-6’-Ib) gene and resistance to ciprofloxacin, azithromycin and β-lactams (except for aztreonam). For P. aeruginosa, a significant association was noticed between the presence of the blaSHV gene and the multidrug efflux pump (MexA) and resistance to fluoroquinolones, amikacin, tobramycin, co-trimoxazole and β-lactams and between the aac-6’-Ib gene and resistance to aminoglycosides. All P. aeruginosa isolates (100%) harbored the MexAB-OprM multidrug efflux pump while 86% of the K. pneumoniae isolates harbored the AcrAB-TolC pump. Our results are of great medical importance for the guidance of healthcare practitioners for effective antibiotic prescription.

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Bacterial defenses against a natural antibiotic promote collateral resilience to clinical antibiotics

10.1101/2020.04.20.049437 ◽

2020 ◽

Author(s):

Lucas A. Meirelles ◽

Elena K. Perry ◽

Megan Bergkessel ◽

Dianne K. Newman

Keyword(s):

Antibiotic Resistance ◽

Opportunistic Pathogen ◽

Antimicrobial Treatment ◽

Bacterial Survival ◽

Human Pathogens ◽

Opportunistic Pathogens ◽

Chronic Infections ◽

Antibiotic Resistant ◽

Lung Infections ◽

Environmental Microbes

SummaryAs antibiotic-resistant infections become increasingly prevalent worldwide, understanding the factors that lead to antimicrobial treatment failure is essential to optimizing the use of existing drugs. Opportunistic human pathogens in particular typically exhibit high levels of intrinsic antibiotic resistance and tolerance1, leading to chronic infections that can be nearly impossible to eradicate2. We asked whether the recalcitrance of these organisms to antibiotic treatment could be driven in part by their evolutionary history as environmental microbes, which frequently produce or encounter natural antibiotics3,4. Using the opportunistic pathogen Pseudomonas aeruginosa as a model, we demonstrate that the self-produced natural antibiotic pyocyanin (PYO) activates bacterial defenses that confer collateral tolerance to certain synthetic antibiotics, including in a clinically-relevant growth medium. Non-PYO-producing opportunistic pathogens isolated from lung infections similarly display increased antibiotic tolerance when they are co-cultured with PYO-producing P. aeruginosa. Furthermore, we show that beyond promoting bacterial survival in the presence of antibiotics, PYO can increase the apparent rate of mutation to antibiotic resistance by up to two orders of magnitude. Our work thus suggests that bacterial production of natural antibiotics in infections could play an important role in modulating not only the immediate efficacy of clinical antibiotics, but also the rate at which antibiotic resistance arises in multispecies bacterial communities.

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Pseudomonas aeruginosa Polynucleotide Phosphorylase Controls Tolerance to Aminoglycoside Antibiotics by Regulating the MexXY Multidrug Efflux Pump

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01846-20 ◽

2020 ◽

Author(s):

Zheng Fan ◽

Xiaolei Pan ◽

Dan Wang ◽

Ronghao Chen ◽

Tongtong Fu ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Bacterial Resistance ◽

Efflux Pump ◽

Opportunistic Pathogen ◽

Aminoglycoside Antibiotics ◽

Polynucleotide Phosphorylase ◽

Multidrug Efflux ◽

Intrinsic Resistance ◽

Multidrug Efflux Pump ◽

Fluoroquinolone Antibiotics

Pseudomonas aeruginosa is an opportunistic pathogen that shows high intrinsic resistance to a variety of antibiotics. The MexX-MexY-OprM efflux pump plays an important role in the bacterial resistance to aminoglycoside antibiotics. Polynucleotide phosphorylase (PNPase) is a highly conserved exonuclease that plays important roles in RNA processing and bacterial response to environmental stresses. Previously, we demonstrated that PNPase controls the tolerance to fluoroquinolone antibiotics by influencing the production of pyocin in P. aeruginosa. In this study, we found that mutation of the PNPase coding gene (pnp) in P. aeruginosa increases the bacterial tolerance to aminoglycoside antibiotics. We further demonstrate that upregulation of the mexXY genes is responsible for the increased tolerance in the pnp mutant. Furthermore, our experimental results revealed that PNPase controls translation of the armZ mRNA through its 5′ untranslated region (5′-UTR). ArmZ had previously been shown to positively regulate the expression of mexXY. Therefore, our results revealed a novel role of PNPase in the regulation of armZ and subsequently the MexXY efflux pump.

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GENERAL PRINCIPLES OF ANTIBIOTIC RESISTANCE EVOLUTION IN BACTERIA (REVIEW OF LITERATURE)

Russian Clinical Laboratory Diagnostics ◽

10.18821/0869-2084-2020-65-6-387-393 ◽

2020 ◽

Vol 65 (6) ◽

pp. 387-393

Author(s):

N. V. Davidovich ◽

Natalya Nilolaevna Kukalevskaya ◽

E. N. Bashilova ◽

T. A. Bazhukova

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Molecular Genetic ◽

Antibiotic Resistance Genes ◽

Human Pathogens ◽

Intrinsic Resistance ◽

Resistance Evolution ◽

Genes Encoding ◽

The Impact

Currently, the impact of antibiotic resistance on human health is a worldwide problem and its study is of great interest from a molecular genetic, environmental and clinical view-point. This review summarizes the latest data about antibiotic resistance, the classification of microorganisms as sensitive and resistant to the action of antibiotics, reveals the concept of minimum inhibitory concentration from modern positions. The resistance of microorganisms to antibacterial agents can be intrinsic and acquired, as well as being one of the examples of evolution that are currently available for study. Modern methods of whole-genome sequencing and complex databases of nucleotide-tagged libraries give an idea of the multifaceted nature of the mechanisms of intrinsic resistance to antibiotics and are able to provide information on genes encoding metabolic enzymes and proteins that regulate the basic processes of the physiology of bacteria. The article describes the main ways of spreading the resistance of microorganisms, reflects the concepts of “founder effect” and the fitness cost of bacteria, which underlie the emergence and evolution of antibiotic resistance. It is shown that the origin of antibiotic resistance genes that human pathogens currently possess can be traced by studying the surrounding not only clinical, but also non-clinical (ecological) habitats. As well as microorganisms of the surrounding ecosystems are the donors of resistance genes in horizontal gene transfer.

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The resistome of common human pathogens

10.1101/140194 ◽

2017 ◽

Cited By ~ 4

Author(s):

Christian Munck ◽

Mostafa M. Hashim Ellabaan ◽

Michael Schantz Klausen ◽

Morten O.A. Sommer

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Bacterial Pathogens ◽

Antibiotic Resistance Genes ◽

Gene Clusters ◽

Species Level ◽

Natural Environments ◽

Human Pathogens ◽

Bacterial Genomes ◽

Risk Ranking

AbstractGenes capable of conferring resistance to clinically used antibiotics have been found in many different natural environments. However, a concise overview of the resistance genes found in common human bacterial pathogens is lacking, which complicates risk ranking of environmental reservoirs. Here, we present an analysis of potential antibiotic resistance genes in the 17 most common bacterial pathogens isolated from humans. We analyzed more than 20,000 bacterial genomes and defined a clinical resistome as the set of resistance genes found across these genomes. Using this database, we uncovered the co-occurrence frequencies of the resistance gene clusters within each species enabling identification of co-dissemination and co-selection patterns. The resistance genes identified in this study represent the subset of the environmental resistome that is clinically relevant and the dataset and approach provides a baseline for further investigations into the abundance of clinically relevant resistance genes across different environments. To facilitate an easy overview the data is presented at the species level at www.resistome.biosustain.dtu.dk.

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Improved Electrotransformation and Decreased Antibiotic Resistance of the Cystic Fibrosis Pathogen Burkholderia cenocepacia Strain J2315

Applied and Environmental Microbiology ◽

10.1128/aem.02123-09 ◽

2009 ◽

Vol 76 (4) ◽

pp. 1095-1102 ◽

Cited By ~ 15

Author(s):

Nelly Dubarry ◽

Wenli Du ◽

David Lane ◽

Franck Pasta

Keyword(s):

Cystic Fibrosis ◽

Antibiotic Resistance ◽

Resistance Genes ◽

Efflux Pump ◽

Antibiotic Resistance Genes ◽

Burkholderia Cenocepacia ◽

The Poor ◽

High Level

ABSTRACT The bacterium Burkholderia cenocepacia is pathogenic for sufferers from cystic fibrosis (CF) and certain immunocompromised conditions. The B. cenocepacia strain most frequently isolated from CF patients, and which serves as the reference for CF epidemiology, is J2315. The J2315 genome is split into three chromosomes and one plasmid. The strain was sequenced several years ago, and its annotation has been released recently. This information should allow genetic experimentation with J2315, but two major impediments appear: the poor potential of J2315 to act as a recipient in transformation and conjugation and the high level of resistance it mounts to nearly all antibiotics. Here, we describe modifications to the standard electroporation procedure that allow routine transformation of J2315 by DNA. In addition, we show that deletion of an efflux pump gene and addition of spermine to the medium enhance the sensitivity of J2315 to certain commonly used antibiotics and so allow a wider range of antibiotic resistance genes to be used for selection.

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Antibacterial and antibiofilm effects of α-humulene against Bacteroides fragilis

Canadian Journal of Microbiology ◽

10.1139/cjm-2020-0004 ◽

2020 ◽

Vol 66 (6) ◽

pp. 389-399 ◽

Cited By ~ 4

Author(s):

Hye-In Jang ◽

Ki-Jong Rhee ◽

Yong-Bin Eom

Keyword(s):

Antibiotic Resistance ◽

Laser Scanning ◽

Inhibitory Concentration ◽

Efflux Pump ◽

Bacteroides Fragilis ◽

New Drugs ◽

Confocal Laser ◽

Multidrug Efflux Pump ◽

Biofilm Inhibition ◽

Potential Therapeutic Application

The rapid increase in antibiotic resistance has prompted the discovery of drugs that reduce antibiotic resistance or new drugs that are an alternative to antibiotics. Plant extracts have health benefits and may also exhibit antibacterial and antibiofilm activities against pathogens. This study determined the antibacterial and antibiofilm effects of α-humulene extracted from plants against enterotoxigenic Bacteroides fragilis, which causes inflammatory bowel disease. The minimum inhibitory concentration and biofilm inhibitory concentration of α-humulene for B. fragilis were 2 μg/mL, and the biofilm eradication concentration was in the range of 8–32 μg/mL. The XTT reduction assay confirmed that the cellular metabolic activity in biofilm rarely occurred at the concentration of 8–16 μg/mL. In addition, biofilm inhibition by α-humulene was also detected via confocal laser scanning microcopy. Quantitative real-time polymerase chain reaction (qPCR) was also used to investigate the effect of α-humulene on the expression of resistance–nodulation–cell division type multidrug efflux pump genes (bmeB1 and bmeB3). According to the results of qPCR, α-humulene significantly reduced the expression of bmeB1 and bmeB3 genes. This study demonstrates the potential therapeutic application of α-humulene for inhibiting the growth of B. fragilis cells and biofilms, and it expands the knowledge about biofilm medicine.

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Ultraviolet irradiation sensitizes Pseudomonas aeruginosa PAO1 to multiple antibiotics

Environmental Science Water Research & Technology ◽

10.1039/c8ew00293b ◽

2018 ◽

Vol 4 (12) ◽

pp. 2051-2057 ◽

Cited By ~ 1

Author(s):

Fuzheng Zhao ◽

Qing Hu ◽

Hongqiang Ren ◽

Xu-Xiang Zhang

Keyword(s):

Pseudomonas Aeruginosa ◽

Antibiotic Resistance ◽

Uv Irradiation ◽

Resistance Genes ◽

Ultraviolet Irradiation ◽

Efflux Pump ◽

Antibiotic Resistance Genes ◽

Regulatory System ◽

Pseudomonas Aeruginosa Pao1 ◽

Multiple Antibiotics

UV irradiation disturbs the regulatory system of efflux pump proteins to sensitize P. aeruginosa to multiple antibiotics. The increasing susceptibility to rifampicin and vancomycin might be caused by UV-mediated mutations in antibiotic resistance genes.

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Studies on Bd0934 and Bd3507, Two Secreted Nucleases from Bdellovibrio bacteriovorus, Reveal Sequential Release of Nucleases during the Predatory Cycle

Journal of Bacteriology ◽

10.1128/jb.00150-20 ◽

2020 ◽

Vol 202 (18) ◽

Author(s):

Ewa Bukowska-Faniband ◽

Tilde Andersson ◽

Rolf Lood

Keyword(s):

Antibiotic Resistance ◽

Life Cycle ◽

Antibiotic Resistance Genes ◽

Human Pathogens ◽

Temporal Expression ◽

Bdellovibrio Bacteriovorus ◽

Exogenous Dna ◽

Content Type ◽

Genes Encoding ◽

Predatory Bacteria

ABSTRACT Bdellovibrio bacteriovorus is an obligate predatory bacterium that invades and kills a broad range of Gram-negative prey cells, including human pathogens. Its potential therapeutic application has been the subject of increased research interest in recent years. However, an improved understanding of the fundamental molecular aspects of the predatory life cycle is crucial for developing this bacterium as a “living antibiotic.” During intracellular growth, B. bacteriovorus secretes an arsenal of hydrolases, which digest the content of the host cell to provide growth nutrients for the predator, e.g., prey DNA is completely degraded by the nucleases. Here, we have, on a genetic and molecular level, characterized two secreted DNases from B. bacteriovorus, Bd0934 and Bd3507, and determined the temporal expression profile of other putative secreted nucleases. We conclude that Bd0934 and Bd3507 are likely a part of the predatosome but are not essential for the predation, host-independent growth, prey biofilm degradation, and self-biofilm formation. The detailed temporal expression analysis of genes encoding secreted nucleases revealed that these enzymes are produced in a sequential orchestrated manner. This work contributes to our understanding of the sequential breakdown of the prey nucleic acid by the nucleases secreted during the predatory life cycle of B. bacteriovorus. IMPORTANCE Antibiotic resistance is a major global concern with few available new means to combat it. From a therapeutic perspective, predatory bacteria constitute an interesting tool. They not only eliminate the pathogen but also reduce the overall pool of antibiotic resistance genes through secretion of nucleases and complete degradation of exogenous DNA. Molecular knowledge of how these secreted DNases act will give us further insight into how antibiotic resistance, and the spread thereof, can be limited through the action of predatory bacteria.

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Understanding the basis of antibiotic resistance: a platform for drug discovery

Microbiology ◽

10.1099/mic.0.082412-0 ◽

2014 ◽

Vol 160 (11) ◽

pp. 2366-2373 ◽

Cited By ~ 28

Author(s):

Laura J. V. Piddock

Keyword(s):

Antibiotic Resistance ◽

Salmonella Enterica ◽

Efflux Pump ◽

Antibiotic Resistance Genes ◽

Multi Drug Resistance ◽

Annual Conference ◽

Altered Expression ◽

Genetic Inactivation ◽

Fluoroquinolone Antibiotics ◽

Serovar Typhimurium

There are numerous genes in Salmonella enterica serovar Typhimurium that can confer resistance to fluoroquinolone antibiotics, including those that encode topoisomerase proteins, the primary targets of this class of drugs. However, resistance is often multifactorial in clinical isolates and it is not uncommon to also detect mutations in genes that affect the expression of proteins involved in permeability and multi-drug efflux. The latter mechanism, mediated by tripartite efflux systems, such as that formed by the AcrAB–TolC system, confers inherent resistance to many antibiotics, detergents and biocides. Genetic inactivation of efflux genes gives multi-drug hyper-susceptibility, and in the absence of an intact AcrAB–TolC system some chromosomal and transmissible antibiotic resistance genes no longer confer clinically relevant levels of resistance. Furthermore, a functional multi-drug resistance efflux pump, such as AcrAB–TolC, is required for virulence and the ability to form a biofilm. In part, this is due to altered expression of virulence and biofilm genes being sensitive to efflux status. Efflux pump expression can be increased, usually due to mutations in regulatory genes, and this confers resistance to clinically useful drugs such as fluoroquinolones and β-lactams. Here, I discuss some of the work my team has carried out characterizing the mechanisms of antibiotic resistance in Salmonella enterica serovar Typhimurium from the late 1980s to 2014. A video of this Prize Lecture, presented at the Society for General Microbiology Annual Conference 2014, can be viewed via this link: https://www.youtube.com/watch?v=MCRumMV99Yw.

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