Different effects of transcriptional regulators MarA, SoxS and Rob on susceptibility of Escherichia coli to cationic antimicrobial peptides (CAMPs): Rob-dependent CAMP induction of the marRAB operon

Cationic antimicrobial peptides (CAMPs), a component of the mammalian immune system, protect the host from bacterial infections. The roles of the Escherichia coli transcriptional regulators MarA, SoxS and Rob in susceptibility to these peptides were examined. Overexpression of marA, either in an antibiotic-resistant marR mutant or from a plasmid, decreased bacterial susceptibility to CAMPs. Overexpression of the soxS gene from a plasmid, which decreased susceptibility to antibiotics, unexpectedly caused no decrease in CAMP susceptibility; instead it produced increased susceptibility to different CAMPs. Deletion or overexpression of rob had little effect on CAMP susceptibility. The marRAB operon was upregulated when E. coli was incubated in sublethal amounts of CAMPs polymyxin B, LL-37 or human β-defensin-1; however, this upregulation required Rob. Deletion of acrAB increased bacterial susceptibility to polymyxin B, LL-37 and human β-defensin-1 peptides. Deletion of tolC yielded an even greater increase in susceptibility to these peptides and also led to increased susceptibility to human α-defensin-2. Inhibition of cellular proton-motive force increased peptide susceptibility for wild-type and acrAB deletion strains; however, it decreased susceptibility of tolC mutants. These findings demonstrate that CAMPs are both inducers of marA-mediated drug resistance through interaction with Rob and also substrates for efflux in E. coli. The three related transcriptional regulators show different effects on bacterial cell susceptibility to CAMPs.

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Induction of the Cpx Envelope Stress Pathway Contributes to Escherichia coli Tolerance to Antimicrobial Peptides

Applied and Environmental Microbiology ◽

10.1128/aem.02593-13 ◽

2013 ◽

Vol 79 (24) ◽

pp. 7770-7779 ◽

Cited By ~ 21

Author(s):

Bianca Audrain ◽

Lionel Ferrières ◽

Amira Zairi ◽

Guillaume Soubigou ◽

Curtis Dobson ◽

...

Keyword(s):

Escherichia Coli ◽

Antimicrobial Peptides ◽

Antimicrobial Peptide ◽

Polymyxin B ◽

Genetic Response ◽

Content Type ◽

E Coli ◽

Multiresistant Bacteria ◽

Envelope Stress ◽

Stress Pathway

ABSTRACTAntimicrobial peptides produced by multicellular organisms as part of their innate system of defense against microorganisms are currently considered potential alternatives to conventional antibiotics in case of infection by multiresistant bacteria. However, while the mode of action of antimicrobial peptides is relatively well described, resistance mechanisms potentially induced or selected by these peptides are still poorly understood. In this work, we studied the mechanisms of action and resistance potentially induced by ApoEdpL-W, a new antimicrobial peptide derived from human apolipoprotein E. Investigation of the genetic response ofEscherichia coliupon exposure to sublethal concentrations of ApoEdpL-W revealed that this antimicrobial peptide triggers activation of RcsCDB, CpxAR, and σEenvelope stress pathways. This genetic response is not restricted to ApoEdpL-W, since several other antimicrobial peptides, including polymyxin B, melittin, LL-37, and modified S4dermaseptin, also activate severalE. colienvelope stress pathways. Finally, we demonstrate that induction of the CpxAR two-component system directly contributes toE. colitolerance toward ApoEdpL-W, polymyxin B, and melittin. These results therefore show thatE. colisenses and responds to different antimicrobial peptides by activation of the CpxAR pathway. While this study further extends the understanding of the array of peptide-induced stress signaling systems, it also provides insight into the contribution of Cpx envelope stress pathway toE. colitolerance to antimicrobial peptides.

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Transcriptome changes and polymyxin resistance of acid-adapted Escherichia coli O157:H7 ATCC 43889

Gut Pathogens ◽

10.1186/s13099-020-00390-5 ◽

2020 ◽

Vol 12 (1) ◽

Author(s):

Daekeun Hwang ◽

Seung Min Kim ◽

Hyun Jung Kim

Keyword(s):

Escherichia Coli ◽

Acid Treatment ◽

Bacterial Infections ◽

Acid Tolerance ◽

Polymyxin B ◽

Multidrug Resistant ◽

Health Concern ◽

E Coli ◽

Tolerance Response ◽

Acid Tolerant

Abstract Background Acid treatment is commonly used for controlling or killing pathogenic microorganisms on medical devices and environments; however, inadequate acid treatment may cause acid tolerance response (ATR) and offer cross-protection against environmental stresses, including antimicrobials. This study aimed to characterise an Escherichia coli strain that can survive in the acidic gastrointestinal environment. Results We developed an acid-tolerant E. coli O157:H7 ATCC 43889 (ATCC 43889) strain that can survive at pH 2.75 via cell adaptation in low pH conditions. We also performed RNA sequencing and qRT-PCR to compare differentially expressed transcripts between acid-adapted and non-adapted cells. Genes related to stress resistance, including kdpA and bshA were upregulated in the acid-adapted ATCC 43889 strain. Furthermore, the polymyxin resistance gene arnA was upregulated in the acid-adapted cells, and resistance against polymyxin B and colistin (polymyxin E) was observed. As polymyxins are important antibiotics, effective against multidrug-resistant gram-negative bacterial infections, the emergence of polymyxin resistance in acid-adapted E. coli is a serious public health concern. Conclusion The transcriptomic and phenotypic changes analysed in this study during the adaptation of E. coli to acid environments can provide useful information for developing intervention technologies and mitigating the risk associated with the emergence and spread of antimicrobial resistance.

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Comparison of Polymyxin E and Polymyxin B as an Additive to Pulmonary Surfactant in Escherichia coli Pneumonia of Ventilated Neonatal Rabbits

Biomedicine Hub ◽

10.1159/000475877 ◽

2017 ◽

Vol 2 (2) ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

Guido Stichtenoth ◽

Marie Haegerstrand-Björkman ◽

Gabi Walter ◽

Bim Linderholm ◽

Egbert Herting ◽

...

Keyword(s):

Escherichia Coli ◽

Bacterial Growth ◽

Pulmonary Surfactant ◽

Bacterial Infections ◽

Bacterial Load ◽

Polymyxin B ◽

Lung Compliance ◽

Antimicrobial Treatment ◽

E Coli ◽

Polymyxin E

Background: Ascending maternofetal bacterial infections often result in premature birth and neonatal respiratory distress. These neonates are treated with exogenous pulmonary surfactant (SF) and systemic antibiotics. Polymyxins are antimicrobiotic peptides that may bind to SF phospholipids. Objectives: Does topical administration of SF/polymyxin reduce bacterial growth in neonatal rabbit pneumonia and improve pulmonary function? Methods: Neonatal rabbits were tracheotomized and treated intratracheally with mixtures of porcine SF, SF/polymyxin E (PxE), or polymyxin B (PxB). Control animals received saline. Animals were then inoculated with Escherichia coli and ventilated for 4 h. During the experiment, peak insufflation pressures, dynamic lung compliance, and ECG were recorded. Pulmonary and renal bacterial load were determined. Lung histology was performed. Lung and kidney IL-8 were measured in subgroups. Results: Eighty-five animals were included in 2 experimental series, of which 78% survived 4 h of ventilation. E. coli inoculation caused severe neonatal pneumonia with median IL-8 levels of 2.2 ng/g in the lungs compared to a median of 0.2 ng/g in the lungs of the saline controls (p < 0.01). Lung compliance after 4 h was significantly increased at a mean of 0.48 ml/(kg·cm H2O) in the SF group and 0.43 in the SF + PxE group compared to 0.35 in the E. coli group (p < 0.01). In direct comparison, bacterial growth found in the E. coli group was reduced 20-fold in the SF + PxB group compared to 75-fold in the SF + PxE group. Conclusion: Addition of polymyxin to SF effectively promotes antimicrobial treatment and improves lung function in neonatal pneumonia of rabbits.

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Transcriptomics and methylomics study on the effect of iodine-containing drug FS-1 on Escherichia coli ATCC BAA-196

10.1101/2020.05.15.097816 ◽

2020 ◽

Cited By ~ 3

Author(s):

Ilya S. Korotetskiy ◽

Ardak B. Jumagaziyeva ◽

Sergey V. Shilov ◽

Tatyana V. Kuznetsova ◽

Auyes N. Myrzabayeva ◽

...

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Antibiotic Therapy ◽

Nutrient Uptake ◽

Anaerobic Respiration ◽

Mechanisms Of Action ◽

Antibiotic Resistant ◽

E Coli ◽

Gene Expression Alterations ◽

Increased Susceptibility

AbstractBackgroundRecent studies showed promising results on application of iodine-containing nanomicelles, FS-1, against antibiotic resistant pathogens. The effect was studied on Escherichia coli ATCC BAA-196.Materials & methodsRNA sequencing for transcriptomics and the complete genome sequencing by SMRT PacBio RS II technology followed by genome assembly and methylomics study were performed.Results & conclusionsFS-1 treated E. coli showed an increased susceptibility to antibiotics ampicillin and gentamicin. The analysis of differential gene regulation showed that possible targets of iodine-containing particles are cell membrane fatty acids and proteins, particularly cytochromes, that leads to oxidative, osmotic and acidic stresses. Cultivation with FS-1 caused gene expression alterations towards anaerobic respiration, increased anabolism and inhibition of many nutrient uptake systems. Identification of methylated nucleotides showed an altered pattern in the FS-1 treated culture. Possible role of transcriptional and epigenetic modifications in the observed increase in susceptibility to gentamicin and ampicillin were discussed.Lay abstractNew approaches of combatting drug resistance infections are in demand as the development of new antibiotics is in a deep crisis. This study was set out to investigate molecular mechanisms of action of new iodine-containing nano-micelle drug FS-1, which potentially may improve the antibiotic therapy of drug resistant infections. Iodine is one of the oldest antimicrobials and until now there were no reports on development of resistance to iodine. Recent studies showed promising results on application of iodine-containing nano-micelles against antibiotic resistant pathogens as a supplement to antibiotic therapy. The mechanisms of action, however, remain unclear. The collection strain Escherichia coli ATCC BAA-196 showing an extended spectrum of resistance to beta-lactam and aminoglycoside antibiotics was used in this study as a model organism. Antibiotic resistance patterns, whole genomes and total RNA sequences of the FS-1 treated (FS) and negative control (NC) variants of E. coli BAA-196 were obtained and analyzed. FS culture showed an increased susceptibility to antibiotics associated with profound gene expression alterations switching the bacterial metabolism to anaerobic respiration, increased anabolism, osmotic stress response and inhibition of many nutrient uptake systems. Nucleotide methylation pattern were identified in FS and NC cultures. While the numbers of methylated sites in both genomes remained similar, some peculiar alterations were observed in their distribution along chromosomal and plasmid sequences.

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An Undecaprenyl Phosphate-Aminoarabinose Flippase Required for Polymyxin Resistance in Escherichia coli

Journal of Biological Chemistry ◽

10.1074/jbc.m706172200 ◽

2007 ◽

Vol 282 (49) ◽

pp. 36077-36089 ◽

Cited By ~ 83

Author(s):

Aixin Yan ◽

Ziqiang Guan ◽

Christian R. H. Raetz

Keyword(s):

Escherichia Coli ◽

Transcription Factor ◽

Antimicrobial Peptides ◽

Salmonella Typhimurium ◽

Lipid A ◽

Inner Membrane ◽

Cationic Antimicrobial Peptides ◽

E Coli ◽

Undecaprenyl Phosphate

Modification of lipid A with the 4-amino-4-deoxy-l-arabinose (l-Ara4N) moiety is required for resistance to polymyxin and cationic antimicrobial peptides in Escherichia coli and Salmonella typhimurium. An operon of seven genes (designated pmrHFIJKLM in S. typhimurium), which is regulated by the PmrA transcription factor and is also present in E. coli, is necessary for the maintenance of polymyxin resistance. We previously elucidated the roles of pmrHFIJK in the biosynthesis and attachment of l-Ara4N to lipid A and renamed these genes arn-BCADT, respectively. We now propose functions for the last two genes of the operon, pmrL and pmrM. Chromosomal inactivation of each of these genes in an E. coli pmrAc parent switched its phenotype from polymyxin-resistant to polymyxin-sensitive. Lipid A was no longer modified with l-Ara4N, even though the levels of the lipid-linked donor of the l-Ara4N moiety, undecaprenyl phosphate-α-l-Ara4N, were not reduced in the mutants. However, the undecaprenyl phosphate-α-l-Ara4N present in the mutants was less concentrated on the periplasmic surface of the inner membrane, as judged by 4-5-fold reduced labeling with the inner membrane-impermeable amine reagent N-hydroxysulfosuccin-imidobiotin. In an arnT mutant of the same pmrAc parent, which lacks the enzyme that transfers the l-Ara4N unit to lipid A but retains the same high levels of undecaprenyl phosphate-α-l-Ara4N as the parent, N-hydroxysulfosuccinimidobiotin labeling was not reduced. These results implicate pmrL and pmrM, but not arnT, in transporting undecaprenyl phosphate-α-l-Ara4N across the inner membrane. PmrM and PmrL, now renamed ArnE and ArnF because of their involvement in l-Ara4N modification of lipid A, may be subunits of an undecaprenyl phosphate-α-l-Ara4N flippase.

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Evaluation of the Antimicrobial Activity of Olive and Rosemary Leave Extracts Prepared with Different Solvents Against Antibiotic-Resistant Escherichia coli

International Journal of Infection ◽

10.5812/iji.114498 ◽

2021 ◽

Vol In Press (In Press) ◽

Author(s):

Bahman Fazeli-Nasab ◽

Moharam Valizadeh ◽

Mohammad Amir Hassanzadeh ◽

Maryam Beigomi

Keyword(s):

Escherichia Coli ◽

Antimicrobial Activity ◽

Bacterial Infections ◽

Inhibitory Concentration ◽

Methanolic Extract ◽

Ethanolic Extract ◽

Antibiotic Resistant ◽

E Coli ◽

Microdilution Method ◽

Methanolic Extracts

Background: This study was done to investigate the antimicrobial activity of rosemary and olive extracts on antibiotic-resistant Escherichia coli isolated from quail feces in Zabol city. Methods: Ethanolic and methanolic extracts of rosemary (leaf) and olive (leaf) plants were prepared using a rotary apparatus. Also, E. coli strains were isolated from poultry feces samples, the minimum inhibitory concentration and the minimum bactericidal concentration were determined by the microdilution method. Results: The lowest values of MIC and MBC against E. coli were 12.5 ppm and 25 ppm for rosemary ethanolic extract and 25 ppm and 50 ppm for rosemary methanolic extract, respectively. The lowest values of MIC and MBC against E. coli were 12.5 ppm and 25 ppm for olive ethanolic extract and 6.25 ppm and 12.5 ppm for olive methanolic extract, respectively. Conclusions: In general, methanol solvent and olive extract are highly effective against E. coli. Due to the obtained results and increasing resistance of bacteria to chemical antibiotics, it is suggested that with further studies on olives and the use of methanol solvent in the extraction of plant extracts, antibacterial compounds of olives and other plants be used in the treatment of bacterial infections.

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Identification of EnvC and Its Cognate Amidases as Novel Determinants of Intrinsic Resistance to Cationic Antimicrobial Peptides

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02699-15 ◽

2016 ◽

Vol 60 (4) ◽

pp. 2222-2231 ◽

Cited By ~ 4

Author(s):

Tamiko Oguri ◽

Won-Sik Yeo ◽

Taeok Bae ◽

Hyunwoo Lee

Keyword(s):

Antimicrobial Peptides ◽

Common Factor ◽

Animal Experiments ◽

Enteric Bacteria ◽

Polymyxin B ◽

Intrinsic Resistance ◽

Cationic Antimicrobial Peptides ◽

Gram Negative ◽

Content Type ◽

E Coli

ABSTRACTCationic antimicrobial peptides (CAMPs) are an essential part of the innate immune system. Some Gram-negative enteric pathogens, such asSalmonella enterica, show intrinsic resistance to CAMPs. However, the molecular basis of intrinsic resistance is poorly understood, largely due to a lack of information about the genes involved. In this study, using a microarray-based genomic technique, we screened the Keio collection of 3,985Escherichia colimutants for altered susceptibility to human neutrophil peptide 1 (HNP-1) and identifiedenvCandzapBas novel genetic determinants of intrinsic CAMP resistance. In CAMP killing assays, anE. coliΔenvCEcor ΔzapBEcmutant displayed a distinct profile of increased susceptibility to both LL-37 and HNP-1. Both mutants, however, displayed wild-type resistance to polymyxin B and human β-defensin 3 (HBD3), suggesting that the intrinsic resistance mediated by EnvC or ZapB is specific to certain CAMPs. A correspondingSalmonellaΔenvCSemutant showed similarly increased CAMP susceptibility. TheenvCmutants of bothE. coliandS. entericadisplayed increased surface negativity and hydrophobicity, which partly explained the increased CAMP susceptibility. However, the ΔenvCEcmutant, but not the ΔenvCSemutant, was defective in outer membrane permeability, excluding this defect as a common factor contributing to the increased CAMP susceptibility. Animal experiments showed that theSalmonellaΔenvCSemutant had attenuated virulence. Taken together, our results indicate that the role ofenvCin intrinsic CAMP resistance is likely conserved among Gram-negative enteric bacteria, demonstrate the importance of intrinsic CAMP resistance for full virulence ofS. enterica, and provide insight into distinct mechanisms of action of CAMPs.

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Critical Role of 3′-Downstream Region of pmrB in Polymyxin Resistance in Escherichia coli BL21(DE3)

Microorganisms ◽

10.3390/microorganisms9030655 ◽

2021 ◽

Vol 9 (3) ◽

pp. 655

Author(s):

Fuzhou Xu ◽

Atsushi Hinenoya ◽

Ximin Zeng ◽

Xing-Ping Li ◽

Ziqiang Guan ◽

...

Keyword(s):

Escherichia Coli ◽

Bacterial Infections ◽

Lipid A ◽

Mrna Level ◽

Critical Role ◽

Polymyxin B ◽

Colistin Resistance ◽

E Coli ◽

Escherichia Coli Bl21 ◽

Downstream Region

Polymyxins, such as colistin and polymyxin B, are the drugs used as a last resort to treat multidrug-resistant Gram-negative bacterial infections in humans. Increasing colistin resistance has posed a serious threat to human health, warranting in-depth mechanistic research. In this study, using a functional cloning approach, we examined the molecular basis of colistin resistance in Escherichia coli BL21(DE3). Five transformants with inserts ranging from 3.8 to 10.7 kb displayed significantly increased colistin resistance, three of which containing pmrB locus and two containing pmrD locus. Stepwise subcloning indicated that both the pmrB with a single G361A mutation and at least a 103 bp downstream region of pmrB are essential for conferring colistin resistance. Analysis of the mRNA level and stability showed that the length of the downstream region drastically affected the pmrB mRNA level but not its half-life. Lipid A analysis, by mass spectrometry, revealed that the constructs containing pmrB with a longer downstream region (103 or 126 bp) have charge-altering l-4-aminoarabinose (Ara4N) and phosphoethanolamine (pEtN) modifications in lipid A, which were not observed in both vector control and the construct containing pmrB with an 86 bp downstream region. Together, the findings from this study indicate that the 3′-downstream region of pmrB is critical for the PmrB-mediated lipid A modifications and colistin resistance in E. coli BL21(DE3), suggesting a novel regulatory mechanism of PmrB-mediated colistin resistance in E. coli.

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A New Surface Charge Neutralizing Nano-Adjuvant to Potentiate Polymyxins in Killing Mcr-1 Mediated Drug-Resistant Escherichia coli

Pharmaceutics ◽

10.3390/pharmaceutics13020250 ◽

2021 ◽

Vol 13 (2) ◽

pp. 250

Author(s):

Hyejin Cho ◽

Atanu Naskar ◽

Sohee Lee ◽

Semi Kim ◽

Kwang-Sun Kim

Keyword(s):

Escherichia Coli ◽

Bacterial Infections ◽

Underlying Mechanism ◽

Polymyxin B ◽

Multidrug Resistant ◽

Gene Products ◽

Physical Status ◽

Cellular Gene ◽

Gram Negative ◽

E Coli

Resistance to polymyxins when treating multidrug-resistant (MDR) Gram-negative bacterial infections limit therapeutic options. Here, we report the synthesis of a nickel (Ni) doped Zinc oxide (NZO) combined with black phosphorus (BP) (NZB) nanocomposite and its synergistic action with polymyxin B (PolB) against polymyxin-resistant Escherichia coli harboring mobilized colistin resistance (mcr-1) gene. NZB and PolB combination therapy expressed a specific and strong synergy against Mcr-1 expressing E. coli cells. The underlying mechanism of the synergy is the charge neutralization of the E. coli cell surface by NZB, resulting in a more feasible incorporation of PolB to E. coli. The synergistic concentration of NZB with PolB was proved biocompatible. Thus, the NZB is the first biocompatible nano-adjuvant to polymyxins against polymyxin-resistant E. coli cells, recognizing the physical status of bacteria instead of known adjuvants targeting cellular gene products. Therefore, NZB has the potential to revive polymyxins as leading last-resort antibiotics to combat polymyxin-resistant Gram-negative bacterial infections.

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Prevalence and Characterization of Extended-Spectrum β-Lactamase-Producing Antibiotic-Resistant Escherichia coli and Klebsiella pneumoniae in Ready-to-Eat Street Foods

Antibiotics ◽

10.3390/antibiotics10070850 ◽

2021 ◽

Vol 10 (7) ◽

pp. 850

Author(s):

Shobha Giri ◽

Vaishnavi Kudva ◽

Kalidas Shetty ◽

Veena Shetty

Keyword(s):

Escherichia Coli ◽

Food Safety ◽

Klebsiella Pneumoniae ◽

Rural Areas ◽

Significant Risk ◽

Microbiological Quality ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

E Coli ◽

Extended Spectrum

As the global urban populations increase with rapid migration from rural areas, ready-to-eat (RTE) street foods are posing food safety challenges where street foods are prepared with less structured food safety guidelines in small and roadside outlets. The increased presence of extended-spectrum-β-lactamase (ESBL) producing bacteria in street foods is a significant risk for human health because of its epidemiological significance. Escherichia coli and Klebsiella pneumoniae have become important and dangerous foodborne pathogens globally for their relevance to antibiotic resistance. The present study was undertaken to evaluate the potential burden of antibiotic-resistant E. coli and K. pneumoniae contaminating RTE street foods and to assess the microbiological quality of foods in a typical emerging and growing urban suburb of India where RTE street foods are rapidly establishing with public health implications. A total of 100 RTE food samples were collected of which, 22.88% were E. coli and 27.12% K. pneumoniae. The prevalence of ESBL-producing E. coli and K. pneumoniae was 25.42%, isolated mostly from chutneys, salads, paani puri, and chicken. Antimicrobial resistance was observed towards cefepime (72.9%), imipenem (55.9%), cefotaxime (52.5%), and meropenem (16.9%) with 86.44% of the isolates with MAR index above 0.22. Among β-lactamase encoding genes, blaTEM (40.68%) was the most prevalent followed by blaCTX (32.20%) and blaSHV (10.17%). blaNDM gene was detected in 20.34% of the isolates. This study indicated that contaminated RTE street foods present health risks to consumers and there is a high potential of transferring multi-drug-resistant bacteria from foods to humans and from person to person as pathogens or as commensal residents of the human gut leading to challenges for subsequent therapeutic treatments.

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