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Gravey F, Michel A, Langlois B, Gérard M, Galopin S, Gakuba C, Du Cheyron D, Fazilleau L, Brossier D, Guérin F, Giard JC, Le Hello S. Central role of the ramAR locus in the multidrug resistance in ESBL -Enterobacterales. Microbiol Spectr 2024:e0354823. [PMID: 38916360 DOI: 10.1128/spectrum.03548-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 05/17/2024] [Indexed: 06/26/2024] Open
Abstract
The aim of this study was to evaluate the proportion of resistance to a temocillin, tigecycline, ciprofloxacin, and chloramphenicol phenotype called t2c2 that resulted from mutations within the ramAR locus among extended-spectrum β-lactamases-Enterobacterales (ESBL-E) isolated in three intensive care units for 3 years in a French university hospital. Two parallel approaches were performed on all 443 ESBL-E included: (i) the minimal inhibitory concentrations of temocillin, tigecycline, ciprofloxacin, and chloramphenicol were determined and (ii) the genomes obtained from the Illumina sequencing platform were analyzed to determine multilocus sequence types, resistomes, and diversity of several tetR-associated genes including ramAR operon. Among the 443 ESBL-E strains included, isolates of Escherichia coli (n = 194), Klebsiella pneumoniae (n = 122), and Enterobacter cloacae complex (Ecc) (n = 127) were found. Thirty-one ESBL-E strains (7%), 16 K. pneumoniae (13.1%), and 15 Ecc (11.8%) presented the t2c2 phenotype in addition to their ESBL profile, whereas no E. coli presented these resistances. The t2c2 phenotype was invariably reversible by the addition of Phe-Arg-β-naphthylamide, indicating a role of resistance-nodulation-division pumps in these observations. Mutations associated with the t2c2 phenotype were restricted to RamR, the ramAR intergenic region (IR), and AcrR. Mutations in RamR consisted of C- or N-terminal deletions and amino acid substitutions inside its DNA-binding domain or within key sites of protein-substrate interactions. The ramAR IR showed nucleotide substitutions involved in the RamR DNA-binding domain. This diversity of sequences suggested that RamR and the ramAR IR represent major genetic events for bacterial antimicrobial resistance.IMPORTANCEMorbimortality caused by infectious diseases is very high among patients hospitalized in intensive care units (ICUs). A part of these outcomes can be explained by antibiotic resistance, which delays the appropriate therapy. The transferable antibiotic resistance gene is a well-known mechanism to explain the high rate of multidrug resistance (MDR) bacteria in ICUs. This study describes the prevalence of chromosomal mutations, which led to additional antibiotic resistance among MDR bacteria. More than 12% of Klebsiella pneumoniae and Enterobacter cloacae complex strains presented mutations within the ramAR locus associated with a dysregulation of an efflux pump called AcrAB-TolC and a porin: OmpF. These dysregulations led to an increase in antibiotic output notably tigecycline, ciprofloxacin, and chloramphenicol associated with a decrease of input for beta-lactam, especially temocillin. Mutations within transcriptional regulators such as ramAR locus played a major role in antibiotic resistance dissemination and need to be further explored.
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Affiliation(s)
- François Gravey
- Department of Infectious Agents, Bacteriology, Université de Caen Normandie, Univ Rouen Normandie, INSERM, Normandie Univ, DYNAMICURE UMR 1311, CHU Caen Normandie, Caen, France
| | - Alice Michel
- Univ de Caen Normandie, Univ Rouen Normandie, INSERM, DYNAMICURE UMR 1311, Caen, France
| | - Bénédicte Langlois
- Department of Infectious Agents, Bacteriology, Université de Caen Normandie, Univ Rouen Normandie, INSERM, Normandie Univ, DYNAMICURE UMR 1311, CHU Caen Normandie, Caen, France
| | - Mattéo Gérard
- Univ de Caen Normandie, Univ Rouen Normandie, INSERM, DYNAMICURE UMR 1311, Caen, France
| | - Sébastien Galopin
- Univ de Caen Normandie, Univ Rouen Normandie, INSERM, DYNAMICURE UMR 1311, Caen, France
| | - Clément Gakuba
- Service de Réanimation Chirurgicale, Univ de Caen Normandie, CHU de Caen Normandie, Caen, France
| | - Damien Du Cheyron
- Service de Réanimation Médicale, Univ de Caen Normandie, CHU de Caen Normandie, Caen, France
| | - Laura Fazilleau
- Service de Réanimation Néonatale, Univ de Caen Normandie, CHU de Caen Normandie, Caen, France
| | - David Brossier
- Service de Réanimation Pédiatrique, Univ de Caen Normandie, CHU de Caen Normandie, Caen, France
| | - François Guérin
- Service de Bactériologie, CHU de Rennes Pontchaillou, Rennes, France
| | - Jean-Christophe Giard
- Univ de Caen Normandie, Univ Rouen Normandie, INSERM, DYNAMICURE UMR 1311, Caen, France
| | - Simon Le Hello
- Department of Infectious Agents, Bacteriology, Université de Caen Normandie, Univ Rouen Normandie, INSERM, Normandie Univ, DYNAMICURE UMR 1311, CHU Caen Normandie, Caen, France
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Karlowsky JA, Hackel MA, Wise MG, Six DA, Uehara T, Daigle DM, Cusick SM, Pevear DC, Moeck G, Sahm DF. In Vitro Activity of Cefepime-Taniborbactam and Comparators against Clinical Isolates of Gram-Negative Bacilli from 2018 to 2020: Results from the Global Evaluation of Antimicrobial Resistance via Surveillance (GEARS) Program. Antimicrob Agents Chemother 2023; 67:e0128122. [PMID: 36541767 PMCID: PMC9872668 DOI: 10.1128/aac.01281-22] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
Taniborbactam is a novel cyclic boronate β-lactamase inhibitor in clinical development in combination with cefepime. We assessed the in vitro activity of cefepime-taniborbactam and comparators against a 2018-2020 collection of Enterobacterales (n = 13,731) and Pseudomonas aeruginosa (n = 4,619) isolates cultured from infected patients attending hospitals in 56 countries. MICs were determined by CLSI broth microdilution. Taniborbactam was tested at a fixed concentration of 4 μg/mL. Isolates with cefepime-taniborbactam MICs of ≥16 μg/mL underwent whole-genome sequencing. β-lactamase genes were identified in meropenem-resistant isolates by PCR/Sanger sequencing. Against Enterobacterales, taniborbactam reduced the cefepime MIC90 value by >64-fold (from >16 to 0.25 μg/mL). At ≤16 μg/mL, cefepime-taniborbactam inhibited 99.7% of all Enterobacterales isolates; >97% of isolates with multidrug-resistant (MDR) and ceftolozane-tazobactam-resistant phenotypes; ≥90% of isolates with meropenem-resistant, difficult-to-treat-resistant (DTR), meropenem-vaborbactam-resistant, and ceftazidime-avibactam-resistant phenotypes; 100% of VIM-positive, AmpC-positive, and KPC-positive isolates; 98.7% of extended-spectrum β-lactamase (ESBL)-positive; 98.8% of OXA-48-like-positive; and 84.6% of NDM-positive isolates. Against P. aeruginosa, taniborbactam reduced the cefepime MIC90 value by 4-fold (from 32 to 8 μg/mL). At ≤16 μg/mL, cefepime-taniborbactam inhibited 97.4% of all P. aeruginosa isolates; ≥85% of isolates with meropenem-resistant, MDR, and meropenem-vaborbactam-resistant phenotypes; >75% of isolates with DTR, ceftazidime-avibactam-resistant, and ceftolozane-tazobactam-resistant phenotypes; and 87.4% of VIM-positive isolates. Multiple potential mechanisms, including carriage of IMP, certain alterations in PBP3, permeability (porin) defects, and possibly, upregulation of efflux were present in most isolates with cefepime-taniborbactam MICs of ≥16 μg/mL. We conclude that cefepime-taniborbactam exhibited potent in vitro activity against Enterobacterales and P. aeruginosa and inhibited most carbapenem-resistant isolates, including those carrying serine carbapenemases or NDM/VIM metallo-β-lactamases (MBLs).
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Affiliation(s)
- James A. Karlowsky
- IHMA, Schaumburg, Illinois, USA
- Department of Medical Microbiology and Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | | | - David A. Six
- Venatorx Pharmaceuticals, Inc., Malvern, Pennsylvania, USA
| | | | | | | | | | - Greg Moeck
- Venatorx Pharmaceuticals, Inc., Malvern, Pennsylvania, USA
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Molecular characterization of Enterobacter aerogenes isolated from urinary tract infections in Iran. Acta Trop 2022; 232:106485. [PMID: 35487296 DOI: 10.1016/j.actatropica.2022.106485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/20/2022] [Accepted: 04/24/2022] [Indexed: 11/24/2022]
Abstract
The prevalence of multidrug-resistant Enterobacter aerogenes strains in UTIs is increasing. Therefore, the purpose of this study was to examine the mechanisms of resistance in Enterobacter aerogenes strains isolated from the urinary tract of infected patients. To achieve this goal, 786 urine samples from Shahrekord, Iran, were collected from June 2019 to February 2020. After isolating and identifying E. aerogenes samples, antibiotic susceptibility testing was done on the strains using Kirby-Bauer's disk diffusion method. The biofilm formation assays were performed to study the link between antibiotic resistance and biofilm formation and virulence genes. As a result, amongst the 786 urine samples, 50 strains were identified as E. aerogenes. The lowest rate of resistance was observed with imipenem (30%). This study also reports that all the strains of E. aerogenes are biofilm producers, with 50% of isolates producing a large amount, 30% a moderate amount, and 20% a small amount of biofilm. 42% were identified in the phenotypic study of ESBLs. In the PCR test, (64%) produced broad-spectrum beta-lactamases. Prevalence of qnrC, qnrB, qnrA, tetA, tet B, acc(3)IIa, acc(2)IIa, ant(2)Ia and Sul1 in strong producing isolates reported 100%, 80.95%,% 58.14, 87.5%, 81.58%, 86.67%, 82.14, 81.48% and 90% respectively. In the statistical analysis based on the chi-square test, a statistically significant relationship was reported between qnrA, qnrB, tetA, tetB, Sul1, ant(2)Ia, ant(3)I, aac(3)II, and biofilm formation. Resistance to cephalothin, ceftriaxone, cefotaxime and ceftazidime were reported 40%, 34%, 30% and 30%, respectively. Out of 50 Enterobacter aerogenes, 32 isolates (64%) were identified in the phenotypic study of ESBLS, prevalence of blaCTX-M, blaTEM and blaSHV reported 30%, 20% and 14% respectively. There is a significant relationship between resistance to ceftriaxone and blaCTX-M. Prevalence of csgA, ybtS, markD, rmpA, csgD and fimH in strong biofilm formation isolates reported 84%, 83.33%, 80%, 80%, 80% and 66% respectively. The chi-square test showed a statistically significant relationship between biofilm production and resistance genes fimH, csgA, csgD, ybtS, and mrkD. The findings of this study indicate that the ability to produce biofilms is associated with the increase of antibiotic resistance and virulence genes. These agents enable bacteria to produce biofilms that ultimately lead to colonization and bacterial survival in the body.
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Majewski P, Gutowska A, Sacha P, Schneiders T, Talalaj M, Majewska P, Zebrowska A, Ojdana D, Wieczorek P, Hauschild T, Kowalczuk O, Niklinski J, Radziwon P, Tryniszewska E. Expression of AraC/XylS stress response regulators in two distinct carbapenem-resistant Enterobacter cloacae ST89 biotypes. J Antimicrob Chemother 2021; 75:1146-1150. [PMID: 31960042 DOI: 10.1093/jac/dkz569] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 12/09/2019] [Accepted: 12/20/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The growing incidence of MDR Gram-negative bacteria is a rapidly emerging challenge in modern medicine. OBJECTIVES We sought to establish the role of intrinsic drug-resistance regulators in combination with specific genetic mutations in 11 Enterobacter cloacae isolates obtained from a single patient within a 7 week period. METHODS The molecular characterization of eight carbapenem-resistant and three carbapenem-susceptible E. cloacae ST89 isolates included expression-level analysis and WGS. Quantitative PCR included: (i) chromosomal cephalosporinase gene (ampC); (ii) membrane permeability factor genes, e.g. ompF, ompC, acrA, acrB and tolC; and (iii) intrinsic regulatory genes, e.g. ramA, ampR, rob, marA and soxS, which confer reductions in antibiotic susceptibility. RESULTS In this study we describe the influence of the alterations in membrane permeability (ompF and ompC levels), intrinsic regulatory genes (ramA, marA, soxS) and intrinsic chromosomal cephalosporinase AmpC on reductions in carbapenem susceptibility of E. cloacae clinical isolates. Interestingly, only the first isolate possessed the acquired VIM-4 carbapenemase, which has been lost in subsequent isolates. The remaining XDR E. cloacae ST89 isolates presented complex carbapenem-resistance pathways, which included perturbations in permeability of bacterial membranes mediated by overexpression of ramA, encoding an AraC/XylS global regulator. Moreover, susceptible isolates differed significantly from other isolates in terms of marA down-regulation and soxS up-regulation. CONCLUSIONS Molecular mechanisms of resistance among carbapenem-resistant E. cloacae included production of acquired VIM-4 carbapenemase, significant alterations in membrane permeability due to increased expression of ramA, encoding an AraC/XylS global regulator, and the overproduction of chromosomal AmpC cephalosporinase.
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Affiliation(s)
- Piotr Majewski
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Anna Gutowska
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Pawel Sacha
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | | | - Mariola Talalaj
- Department of Anaesthesiology and Intensive Care with Postoperative Unit, University Children's Clinical Hospital, Bialystok, Poland
| | | | | | - Dominika Ojdana
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Wieczorek
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
| | - Tomasz Hauschild
- Department of Microbiology, Institute of Biology, University of Bialystok, Bialystok, Poland
| | - Oksana Kowalczuk
- Department of Clinical Molecular Biology, Medical University of Bialystok, Bialystok, Poland
| | - Jacek Niklinski
- Department of Clinical Molecular Biology, Medical University of Bialystok, Bialystok, Poland
| | - Piotr Radziwon
- Regional Centre for Transfusion Medicine, Bialystok, Poland.,Department of Hematology, Medical University of Bialystok, Bialystok, Poland
| | - Elzbieta Tryniszewska
- Department of Microbiological Diagnostics and Infectious Immunology, Medical University of Bialystok, Bialystok, Poland
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Serratia marcescens RamA Expression Is under PhoP-Dependent Control and Modulates Lipid A-Related Gene Transcription and Antibiotic Resistance Phenotypes. J Bacteriol 2021; 203:e0052320. [PMID: 33927048 DOI: 10.1128/jb.00523-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Serratia marcescens is an enteric bacterium that can function as an opportunistic pathogen with increasing incidence in clinical settings. This is mainly due to the ability to express a wide range of virulence factors and the acquisition of antibiotic resistance mechanisms. For these reasons, S. marcescens has been declared by the World Health Organization (WHO) as a research priority to develop alternative antimicrobial strategies. In this study, we found a PhoP-binding motif in the promoter region of transcriptional regulator RamA of S. marcescens RM66262. We demonstrated that the expression of ramA is autoregulated and that ramA is also part of the PhoP/PhoQ regulon. We have also shown that PhoP binds directly and specifically to ramA, mgtE1, mgtE2, lpxO1, and lpxO2 promoter regions and that RamA binds to ramA and lpxO1 but not to mgtE1 and lpxO2, suggesting an indirect control for the latter genes. Finally, we have demonstrated that in S. marcescens, RamA overexpression induces the AcrAB-TolC efflux pump, required to reduce the susceptibility of the bacteria to tetracycline and nalidixic acid. In sum, we here provide the first report describing the regulation of ramA under the control of the PhoP/PhoQ regulon and the regulatory role of RamA in S. marcescens. IMPORTANCE We demonstrate that in S. marcescens, the transcriptional regulator RamA is autoregulated and also controlled by the PhoP/PhoQ signal transduction system. We show that PhoP is able to directly and specifically bind to ramA, mgtE1, mgtE2, lpxO1, and lpxO2 promoter regions. In addition, RamA is able to directly interact with the promoter regions of ramA and lpxO1 but indirectly regulates mgtE1 and lpxO2. Finally, we found that in S. marcescens, RamA overexpression induces the AcrAB-TolC efflux pump, required to reduce susceptibility to tetracycline and nalidixic acid. Collectively, these results further our understanding of the PhoP/PhoQ regulon in S. marcescens and demonstrate the involvement of RamA in the protection against antibiotic challenges.
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ramR Deletion in an Enterobacter hormaechei Isolate as a Consequence of Therapeutic Failure of Key Antibiotics in a Long-Term Hospitalized Patient. Antimicrob Agents Chemother 2020; 64:AAC.00962-20. [PMID: 32778545 DOI: 10.1128/aac.00962-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/22/2020] [Indexed: 11/20/2022] Open
Abstract
Genome changes are central to the adaptation of bacteria, especially under antibiotic pressure. The aim of this study was to report phenotypic and genomic adaptations undergone by an Enterobacter hormaechei clinical strain that became highly resistant to key antimicrobials during a 4-month period in a patient hospitalized in an intensive care unit (ICU). All six clinical E. hormaechei strains isolated in one ICU-hospitalized patient have been studied. MICs regarding 17 antimicrobial molecules have been measured. Single nucleotide polymorphisms (SNPs) were determined on the sequenced genomes. The expression of genes involved in antibiotic resistance among Enterobacter cloacae complex strains were determined by reverse transcription-quantitative PCR (qRT-PCR). All the strains belonged to sequence type 66 and were distant by a maximum of nine SNPs. After 3 months of hospitalization, three strains presented a significant increase in MICs for ceftazidime, cefepime, temocillin, ertapenem, tigecycline, ciprofloxacin, and chloramphenicol. Those resistant strains did not acquire additional antibiotic resistance genes but harbored a 16-bp deletion in the ramR gene. This deletion led to upregulated expression of RamA, AcrA, AcrB, and TolC and downregulated expression of OmpF. The ΔramR mutant harbored the same phenotype as the resistant clinical strains regarding tigecycline, chloramphenicol, and ciprofloxacin. The increased expression of RamA due to partial deletion in the ramR gene led to a cross-resistance phenotype by an increase of antibiotic efflux through the AcrAB-TolC pump and a decrease of antibiotic permeability by porin OmpF. ramR appears to be an important adaptative trait for E. hormaechei strains.
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Ferrand A, Vergalli J, Pagès JM, Davin-Regli A. An Intertwined Network of Regulation Controls Membrane Permeability Including Drug Influx and Efflux in Enterobacteriaceae. Microorganisms 2020; 8:E833. [PMID: 32492979 PMCID: PMC7355843 DOI: 10.3390/microorganisms8060833] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 12/19/2022] Open
Abstract
The transport of small molecules across membranes is a pivotal step for controlling the drug concentration into the bacterial cell and it efficiently contributes to the antibiotic susceptibility in Enterobacteriaceae. Two types of membrane transports, passive and active, usually represented by porins and efflux pumps, are involved in this process. Importantly, the expression of these transporters and channels are modulated by an armamentarium of tangled regulatory systems. Among them, Helix-turn-Helix (HTH) family regulators (including the AraC/XylS family) and the two-component systems (TCS) play a key role in bacterial adaptation to environmental stresses and can manage a decrease of porin expression associated with an increase of efflux transporters expression. In the present review, we highlight some recent genetic and functional studies that have substantially contributed to our better understanding of the sophisticated mechanisms controlling the transport of small solutes (antibiotics) across the membrane of Enterobacteriaceae. This information is discussed, taking into account the worrying context of clinical antibiotic resistance and fitness of bacterial pathogens. The localization and relevance of mutations identified in the respective regulation cascades in clinical resistant strains are discussed. The possible way to bypass the membrane/transport barriers is described in the perspective of developing new therapeutic targets to combat bacterial resistance.
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Affiliation(s)
| | | | | | - Anne Davin-Regli
- UMR_MD1, U-1261, Aix-Marseille University, INSERM, SSA, IRBA, MCT, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille CEDEX 05, France; (A.F.); (J.V.); (J.-M.P.)
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Davin-Regli A, Lavigne JP, Pagès JM. Enterobacter spp.: Update on Taxonomy, Clinical Aspects, and Emerging Antimicrobial Resistance. Clin Microbiol Rev 2019; 32:e00002-19. [PMID: 31315895 PMCID: PMC6750132 DOI: 10.1128/cmr.00002-19] [Citation(s) in RCA: 249] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The genus Enterobacter is a member of the ESKAPE group, which contains the major resistant bacterial pathogens. First described in 1960, this group member has proven to be more complex as a result of the exponential evolution of phenotypic and genotypic methods. Today, 22 species belong to the Enterobacter genus. These species are described in the environment and have been reported as opportunistic pathogens in plants, animals, and humans. The pathogenicity/virulence of this bacterium remains rather unclear due to the limited amount of work performed to date in this field. In contrast, its resistance against antibacterial agents has been extensively studied. In the face of antibiotic treatment, it is able to manage different mechanisms of resistance via various local and global regulator genes and the modulation of the expression of different proteins, including enzymes (β-lactamases, etc.) or membrane transporters, such as porins and efflux pumps. During various hospital outbreaks, the Enterobacter aerogenes and E. cloacae complex exhibited a multidrug-resistant phenotype, which has stimulated questions about the role of cascade regulation in the emergence of these well-adapted clones.
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Affiliation(s)
- Anne Davin-Regli
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
| | - Jean-Philippe Lavigne
- Department of Microbiology, U1047, INSERM, University Montpellier and University Hospital Nîmes, Nîmes, France
| | - Jean-Marie Pagès
- INSERM, SSA, IRBA, MCT, Aix Marseille University, Marseille, France
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Vatlin AA, Bekker OB, Lysenkova LN, Shchekotikhin AE, Danilenko VN. A functional study of the global transcriptional regulator PadR from a strain Streptomyces fradiae-nitR+bld, resistant to nitrone-oligomycin. J Basic Microbiol 2018; 58:739-746. [PMID: 29963725 DOI: 10.1002/jobm.201800095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/20/2018] [Accepted: 06/09/2018] [Indexed: 01/30/2023]
Abstract
We describe Streptomyces fradiae mechanisms of sensitivity to nitrone-oligomycin A, a derivative of oligomycin A. We obtained S. fradiae-nitR+ bld, a nitrone-oligomycin A resistant mutant with a «bald» phenotype. Comparative genomic analysis of the wild-type S. fradiae ATCC19609 and S. fradiae-nitR+ bld revealed a mutation in padR - a gene encoding a multifunction transcription regulator, which resulted in the amino acid replacement in a highly conserved DNA-binding domain. Bioinformatics genome analysis of S. fradiae ATCC19609 discovered a PadR binding site 13 bp upstream the start codon of the marR transcription factor gene. Induction of S. fradiaenitR+ bld and w.t. strains with nitrone-oligomycin A lead to a significant increase in expression level of the marR gene in the w.t. strain, but no change observed in mutant strain. We identified differences between DNA-protein interactions of the mutant and native PadR proteins with its putative binding site in S. fradiae ATCC19609. This allowed us to suggest that the padR gene, that harbored a single nucleotide mutation in the S. fradiaenitR+ bld strain, might be involved in the mechanism of resistance to nitrone-oligomycin A. We assume the participation of the transcriptional factorpadR in the formation of the bald phenotype.
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Affiliation(s)
- Aleksey A Vatlin
- Vavilov Institute of General Genetics Russian Academy of Sciences, Moscow, Russia
| | - Olga B Bekker
- Vavilov Institute of General Genetics Russian Academy of Sciences, Moscow, Russia
| | | | | | - Valery N Danilenko
- Vavilov Institute of General Genetics Russian Academy of Sciences, Moscow, Russia
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