1
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Ruest MK, Supina BSI, Dennis JJ. Bacteriophage steering of Burkholderia cenocepacia toward reduced virulence and increased antibiotic sensitivity. J Bacteriol 2023; 205:e0019623. [PMID: 37791751 PMCID: PMC10601696 DOI: 10.1128/jb.00196-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 09/06/2023] [Indexed: 10/05/2023] Open
Abstract
Antibiotic resistance in bacteria is a growing global concern and has spurred increasing efforts to find alternative therapeutics, such as the use of bacterial viruses, or bacteriophages. One promising approach is to use phages that not only kill pathogenic bacteria but also select phage-resistant survivors that are newly sensitized to traditional antibiotics, in a process called "phage steering." Members of the bacterial genus Burkholderia, which includes various human pathogens, are highly resistant to most antimicrobial agents, including serum immune components, antimicrobial peptides, and polymixin-class antibiotics. However, the application of phages in combination with certain antibiotics can produce synergistic effects that more effectively kill pathogenic bacteria. Herein, we demonstrate that Burkholderia cenocepacia serum resistance is due to intact lipopolysaccharide (LPS) and membranes, and phage-induced resistance altering LPS structure can enhance bacterial sensitivity not only to immune components in serum but also to membrane-associated antibiotics such as colistin. IMPORTANCE Bacteria frequently encounter selection pressure from both antibiotics and lytic phages, but little is known about the interactions between antibiotics and phages. This study provides new insights into the evolutionary trade-offs between phage resistance and antibiotic sensitivity. The creation of phage resistance through changes in membrane structure or lipopolysaccharide composition can simultaneously be a major cause of antibiotic sensitivity. Our results provide evidence of synergistic therapeutic efficacy in phage-antibiotic interactions and have implications for the future clinical use of phage steering in phage therapy applications.
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Affiliation(s)
- Marta K. Ruest
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | | | - Jonathan J. Dennis
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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2
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Panta PR, Doerrler WT. A link between pH homeostasis and colistin resistance in bacteria. Sci Rep 2021; 11:13230. [PMID: 34168215 PMCID: PMC8225787 DOI: 10.1038/s41598-021-92718-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/14/2021] [Indexed: 12/15/2022] Open
Abstract
Colistin resistance is complex and multifactorial. DbcA is an inner membrane protein belonging to the DedA superfamily required for maintaining extreme colistin resistance of Burkholderia thailandensis. The molecular mechanisms behind this remain unclear. Here, we report that ∆dbcA displays alkaline pH/bicarbonate sensitivity and propose a role of DbcA in extreme colistin resistance of B. thailandensis by maintaining cytoplasmic pH homeostasis. We found that alkaline pH or presence of sodium bicarbonate displays a synergistic effect with colistin against not only extremely colistin resistant species like B. thailandensis and Serratia marcescens, but also a majority of Gram-negative and Gram-positive bacteria tested, suggesting a link between cytoplasmic pH homeostasis and colistin resistance across species. We found that lowering the level of oxygen in the growth media or supplementation of fermentable sugars such as glucose not only alleviated alkaline pH stress, but also increased colistin resistance in most bacteria tested, likely by avoiding cytoplasmic alkalinization. Our observations suggest a previously unreported link between pH, oxygen, and colistin resistance. We propose that maintaining optimal cytoplasmic pH is required for colistin resistance in a majority of bacterial species, consistent with the emerging link between cytoplasmic pH homeostasis and antibiotic resistance.
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Affiliation(s)
- Pradip R Panta
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - William T Doerrler
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
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3
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Gunardi WD, Timotius KH, Natasha A, Evriarti PR. Biofilm Targeting Strategy in the Eradication of Burkholderia Infections: A Mini-Review. Open Microbiol J 2021. [DOI: 10.2174/1874285802115010051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Burkholderia are intracellular pathogenic bacteria which can produce biofilm. This biofilm protects the intracellular pathogenic bacteria from antibiotic treatment and the immunological system of the host. Therefore, this review aims to describe the capacity of Burkholderia to form a biofilm, the regulation of its biofilm formation, the efficacy of antibiotics to eradicate biofilm, and the novel therapy which targets its biofilm. Burkholderia's biofilm is characterized by its lipopolysaccharides, exopolysaccharides (EPSs), biofilm-associated proteins, and eDNA. Its regulation is made by quorum sensing, c-di-AMP, sRNA, and two component systems. Many antibiotics have been used as sole or mixture agents; however, they are not always effective in eradicating the biofilm-forming Burkholderia. Inhibitors of quorum sensing and other non-conventional antibiotic approaches are promising to discover effective treatment of Burkholderia infections.
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4
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Troudi A, Pagès JM, Brunel JM. Chemical Highlights Supporting the Role of Lipid A in Efficient Biological Adaptation of Gram-Negative Bacteria to External Stresses. J Med Chem 2021; 64:1816-1834. [PMID: 33538159 DOI: 10.1021/acs.jmedchem.0c02185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria provides an efficient barrier against external noxious compounds such as antimicrobial agents. Associated with drug target modification, it contributes to the overall failure of chemotherapy. In the complex OM architecture, Lipid A plays an essential role by anchoring the lipopolysaccharide in the membrane and ensuring the spatial organization between lipids, proteins, and sugars. Currently, the targets of almost all antibiotics are intracellularly located and require translocation across membranes. We report herein an integrated view of Lipid A synthesis, membrane assembly, a structure comparison at the molecular structure level of numerous Gram-negative bacterial species, as well as its recent use as a target for original antibacterial molecules. This review paves the way for a new vision of a key membrane component that acts during bacterial adaptation to environmental stresses and for the development of new weapons against microbial resistance to usual antibiotics.
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Affiliation(s)
- Azza Troudi
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France.,Laboratory of Microorganisms and Active Biomolecules, Department of Biology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis 1008, Tunisia
| | - Jean Marie Pagès
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
| | - Jean Michel Brunel
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
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5
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Adak T, Morales DL, Cook AJ, Grigg JC, Murphy MEP, Tanner ME. ArnD is a deformylase involved in polymyxin resistance. Chem Commun (Camb) 2020; 56:6830-6833. [PMID: 32432293 DOI: 10.1039/d0cc02241a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The modification of lipid A with cationic 4-amino-4-deoxy-l-arabinose residues serves to confer resistance against cationic peptide antibiotics in Gram-negative bacteria. In this work, the enzyme ArnD is shown to act as a metal-dependent deformylase in the biosynthesis of this carbohydrate.
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Affiliation(s)
- Taniya Adak
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada.
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6
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Abstract
The regulation and timely expression of bacterial genes during infection is critical for a pathogen to cause an infection. Bacteria have multiple mechanisms to regulate gene expression in response to their environment, one of which is two-component systems (TCS). TCS have two components. One component is a sensory histidine kinase (HK) that autophosphorylates when activated by a signal. The activated sensory histidine kinase then transfers the phosphoryl group to the second component, the response regulator, which activates transcription of target genes. The genus Burkholderia contains members that cause human disease and are often extensively resistant to many antibiotics. The Burkholderia cepacia complex (BCC) can cause severe lung infections in patients with cystic fibrosis (CF) or chronic granulomatous disease (CGD). BCC members have also recently been associated with several outbreaks of bacteremia from contaminated pharmaceutical products. Separate from the BCC is Burkholderia pseudomallei, which is the causative agent of melioidosis, a serious disease that occurs in the tropics, and a potential bioterrorism weapon. Bioinformatic analysis of sequenced Burkholderia isolates predicts that most strains have at least 40 TCS. The vast majority of these TCS are uncharacterized both in terms of the signals that activate them and the genes that are regulated by them. This review will highlight TCS that have been described to play a role in virulence in either the BCC or B. pseudomallei Since many of these TCS are involved in virulence, TCS are potential novel therapeutic targets, and elucidating their function is critical for understanding Burkholderia pathogenesis.
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7
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Panta PR, Kumar S, Stafford CF, Billiot CE, Douglass MV, Herrera CM, Trent MS, Doerrler WT. A DedA Family Membrane Protein Is Required for Burkholderia thailandensis Colistin Resistance. Front Microbiol 2019; 10:2532. [PMID: 31827463 PMCID: PMC6849406 DOI: 10.3389/fmicb.2019.02532] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/21/2019] [Indexed: 12/15/2022] Open
Abstract
Colistin is a “last resort” antibiotic for treatment of infections caused by some multidrug resistant Gram-negative bacterial pathogens. Resistance to colistin varies between bacterial species. Some Gram-negative bacteria such as Burkholderia spp. are intrinsically resistant to very high levels of colistin with minimal inhibitory concentrations (MIC) often above 0.5 mg/ml. We have previously shown DedA family proteins YqjA and YghB are conserved membrane transporters required for alkaline tolerance and resistance to several classes of dyes and antibiotics in Escherichia coli. Here, we show that a DedA family protein in Burkholderia thailandensis (DbcA; DedA of Burkholderia required for colistin resistance) is a membrane transporter required for resistance to colistin. Mutation of dbcA results in >100-fold greater sensitivity to colistin. Colistin resistance is often conferred via covalent modification of lipopolysaccharide (LPS) lipid A. Mass spectrometry of lipid A of ΔdbcA showed a sharp reduction of aminoarabinose in lipid A compared to wild type. Complementation of colistin sensitivity of B. thailandensis ΔdbcA was observed by expression of dbcA, E. coli yghB or E. coli yqjA. Many proton-dependent transporters possess charged amino acids in transmembrane domains that take part in the transport mechanism and are essential for function. Site directed mutagenesis of conserved and predicted membrane embedded charged amino acids suggest that DbcA functions as a proton-dependent transporter. Direct measurement of membrane potential shows that B. thailandensis ΔdbcA is partially depolarized suggesting that loss of protonmotive force can lead to alterations in LPS structure and severe colistin sensitivity in this species.
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Affiliation(s)
- Pradip R Panta
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Sujeet Kumar
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Caroline F Stafford
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Caitlin E Billiot
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
| | - Martin V Douglass
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, United States.,Center for Vaccines and Immunology, University of Georgia College of Veterinary Medicine, Athens, GA, United States
| | - Carmen M Herrera
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, United States.,Center for Vaccines and Immunology, University of Georgia College of Veterinary Medicine, Athens, GA, United States
| | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, United States.,Center for Vaccines and Immunology, University of Georgia College of Veterinary Medicine, Athens, GA, United States
| | - William T Doerrler
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
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8
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Su M, Wang M, Hong Y, Nimmagadda A, Shen N, Shi Y, Gao R, Zhang E, Cao C, Cai J. Polymyxin derivatives as broad-spectrum antibiotic agents. Chem Commun (Camb) 2019; 55:13104-13107. [PMID: 31612170 PMCID: PMC10484568 DOI: 10.1039/c9cc06908a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
We designed a few polymyxin derivatives which exhibit broad-spectrum antimicrobial activity. Lead compound P1 could disrupt bacterial membranes rapidly without developing resistance, inhibit biofilms formed by E. coli, and exhibit excellent in vivo activity in an MRSA-infected thigh burden mouse model.
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Affiliation(s)
- Ma Su
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
| | - Minghui Wang
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
| | - Yuzhu Hong
- College of Pharmacy, University of South Florida, Tampa, FL 33620, USA.
| | - Alekhya Nimmagadda
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
| | - Ning Shen
- College of Pharmacy, University of South Florida, Tampa, FL 33620, USA.
| | - Yan Shi
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
| | - Ruixuan Gao
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
| | - En Zhang
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA. and School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Chuanhai Cao
- College of Pharmacy, University of South Florida, Tampa, FL 33620, USA.
| | - Jianfeng Cai
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA.
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9
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Lee W, Cai Y, Lim TP, Teo J, Chua SC, Kwa ALH. In vitro Pharmacodynamics and PK/PD in Animals. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1145:105-116. [PMID: 31364074 DOI: 10.1007/978-3-030-16373-0_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
In the last decade, considerable advancements have been made to identify the pharmacokinetic/pharmacodynamic (PK/PD) index that defines the antimicrobial activity of polymyxins. Dose-fractionation studies performed in hollow-fiber models found that altering the dosing schedule had little impact on the killing or suppression of resistance emergence, alluding to AUC/MIC as the pharmacodynamic index that best describes polymyxin's activity. For in vivo efficacy, the PK/PD index that was the most predictive of the antibacterial effect of colistin against P. aeruginosa and A. baumannii was ƒAUC/MIC.
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Affiliation(s)
- Winnie Lee
- Singapore General Hospital, Singapore, Singapore
| | - Yiying Cai
- Singapore General Hospital, Singapore, Singapore
| | - Tze-Peng Lim
- Singapore General Hospital, Singapore, Singapore
| | - Jocelyn Teo
- Singapore General Hospital, Singapore, Singapore
| | - Sonja Courtney Chua
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Andrea Lay-Hoon Kwa
- Singapore General Hospital, Singapore, Singapore. .,Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore. .,Emerging Infectious Diseases, Duke-National University of Singapore Medical School, Singapore, Singapore.
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10
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Molecular mechanisms of polymyxin resistance and detection of mcr genes. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2018; 163:28-38. [PMID: 30439931 DOI: 10.5507/bp.2018.070] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/26/2018] [Indexed: 12/12/2022] Open
Abstract
Antibiotic resistance is an ever-increasing global problem. Major commercial antibiotics often fail to fight common bacteria, and some pathogens have become multi-resistant. Polymyxins are potent bactericidal antibiotics against gram-negative bacteria. Known resistance to polymyxin includes intrinsic, mutational and adaptive mechanisms, with the recently described horizontally acquired resistance mechanisms. In this review, we present several strategies for bacteria to develop enhanced resistance to polymyxins, focusing on changes in the outer membrane, efflux and other resistance determinants. Better understanding of the genes involved in polymyxin resistance may pave the way for the development of new and effective antimicrobial agents. We also report novel in silico tested primers for PCR assay that may be able distinguish colistin-resistant isolates carrying the plasmid-encoded mcr genes and will assist in combating the spread of colistin resistance in bacteria.
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11
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Scoffone VC, Chiarelli LR, Trespidi G, Mentasti M, Riccardi G, Buroni S. Burkholderia cenocepacia Infections in Cystic Fibrosis Patients: Drug Resistance and Therapeutic Approaches. Front Microbiol 2017; 8:1592. [PMID: 28878751 PMCID: PMC5572248 DOI: 10.3389/fmicb.2017.01592] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/04/2017] [Indexed: 12/29/2022] Open
Abstract
Burkholderia cenocepacia is an opportunistic pathogen particularly dangerous for cystic fibrosis (CF) patients. It can cause a severe decline in CF lung function possibly developing into a life-threatening systemic infection known as cepacia syndrome. Antibiotic resistance and presence of numerous virulence determinants in the genome make B. cenocepacia extremely difficult to treat. Better understanding of its resistance profiles and mechanisms is crucial to improve management of these infections. Here, we present the clinical distribution of B. cenocepacia described in the last 6 years and methods for identification and classification of epidemic strains. We also detail new antibiotics, clinical trials, and alternative approaches reported in the literature in the last 5 years to tackle B. cenocepacia resistance issue. All together these findings point out the urgent need of new and alternative therapies to improve CF patients’ life expectancy.
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Affiliation(s)
- Viola C Scoffone
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | | | - Gabriele Trespidi
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | - Massimo Mentasti
- Respiratory and Vaccine Preventable Bacteria Reference Unit, Public Health EnglandLondon, United Kingdom.,Department of Microbiology, Royal Cornwall HospitalTruro, United Kingdom
| | - Giovanna Riccardi
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
| | - Silvia Buroni
- Department of Biology and Biotechnology, University of PaviaPavia, Italy
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12
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Dutta D, Zhao T, Cheah KB, Holmlund L, Willcox MD. Activity of a melimine derived peptide Mel4 against Stenotrophomonas, Delftia, Elizabethkingia, Burkholderia and biocompatibility as a contact lens coating. Cont Lens Anterior Eye 2017; 40:175-183. [DOI: 10.1016/j.clae.2017.01.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/12/2016] [Accepted: 01/10/2017] [Indexed: 02/07/2023]
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13
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Abstract
Antimicrobial peptides (AMPs), also known as host defense peptides, are small naturally occurring microbicidal molecules produced by the host innate immune response that function as a first line of defense to kill pathogenic microorganisms by inducing deleterious cell membrane damage. AMPs also possess signaling and chemoattractant activities and can modulate the innate immune response to enhance protective immunity or suppress inflammation. Human pathogens have evolved defense molecules and strategies to counter and survive the AMPs released by host immune cells such as neutrophils and macrophages. Here, we review the various mechanisms used by human bacterial pathogens to resist AMP-mediated killing, including surface charge modification, active efflux, alteration of membrane fluidity, inactivation by proteolytic digestion, and entrapment by surface proteins and polysaccharides. Enhanced understanding of AMP resistance at the molecular level may offer insight into the mechanisms of bacterial pathogenesis and augment the discovery of novel therapeutic targets and drug design for the treatment of recalcitrant multidrug-resistant bacterial infections.
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14
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Lim MP, Firdaus-Raih M, Nathan S. Nematode Peptides with Host-Directed Anti-inflammatory Activity Rescue Caenorhabditis elegans from a Burkholderia pseudomallei Infection. Front Microbiol 2016; 7:1436. [PMID: 27672387 PMCID: PMC5019075 DOI: 10.3389/fmicb.2016.01436] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/30/2016] [Indexed: 01/10/2023] Open
Abstract
Burkholderia pseudomallei, the causative agent of melioidosis, is among a growing number of bacterial pathogens that are increasingly antibiotic resistant. Antimicrobial peptides (AMPs) have been investigated as an alternative approach to treat microbial infections, as generally, there is a lower likelihood that a pathogen will develop resistance to AMPs. In this study, 36 candidate Caenorhabditis elegans genes that encode secreted peptides of <150 amino acids and previously shown to be overexpressed during infection by B. pseudomallei were identified from the expression profile of infected nematodes. RNA interference (RNAi)-based knockdown of 12/34 peptide-encoding genes resulted in enhanced nematode susceptibility to B. pseudomallei without affecting worm fitness. A microdilution test demonstrated that two peptides, NLP-31 and Y43C5A.3, exhibited anti-B. pseudomallei activity in a dose dependent manner on different pathogens. Time kill analysis proposed that these peptides were bacteriostatic against B. pseudomallei at concentrations up to 8× MIC90. The SYTOX green assay demonstrated that NLP-31 and Y43C5A.3 did not disrupt the B. pseudomallei membrane. Instead, gel retardation assays revealed that both peptides were able to bind to DNA and interfere with bacterial viability. In parallel, microscopic examination showed induction of cellular filamentation, a hallmark of DNA synthesis inhibition, of NLP-31 and Y43C5A.3 treated cells. In addition, the peptides also regulated the expression of inflammatory cytokines in B. pseudomallei infected macrophage cells. Collectively, these findings demonstrate the potential of NLP-31 and Y43C5A.3 as anti-B. pseudomallei peptides based on their function as immune modulators.
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Affiliation(s)
- Mei-Perng Lim
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia Bangi, Malaysia
| | - Mohd Firdaus-Raih
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia Bangi, Malaysia
| | - Sheila Nathan
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan MalaysiaBangi, Malaysia; Malaysia Genome InstituteKajang, Malaysia
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15
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Tavares-Carreón F, Patel KB, Valvano MA. Burkholderia cenocepacia and Salmonella enterica ArnT proteins that transfer 4-amino-4-deoxy-l-arabinose to lipopolysaccharide share membrane topology and functional amino acids. Sci Rep 2015; 5:10773. [PMID: 26030265 PMCID: PMC5377068 DOI: 10.1038/srep10773] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/01/2015] [Indexed: 12/27/2022] Open
Abstract
We recently demonstrated that incorporation of 4-amino-4-deoxy-l-arabinose (l-Ara4N) to the lipid A moiety of lipopolysaccharide (LPS) is required for transport of LPS to the outer membrane and viability of the Gram-negative bacterium Burkholderia cenocepacia. ArnT is a membrane protein catalyzing the transfer of l-Ara4N to the LPS molecule at the periplasmic face of the inner membrane, but its topology and mechanism of action are not well characterized. Here, we elucidate the topology of ArnT and identify key amino acids that likely contribute to its enzymatic function. PEGylation assays using a cysteineless version of ArnT support a model of 13 transmembrane helices and a large C-terminal region exposed to the periplasm. The same topological configuration is proposed for the Salmonella enterica serovar Typhimurium ArnT. Four highly conserved periplasmic residues in B. cenocepacia ArnT, tyrosine-43, lysine-69, arginine-254 and glutamic acid-493, were required for activity. Tyrosine-43 and lysine-69 span two highly conserved motifs, 42RYA44 and 66YFEKP70, that are found in ArnT homologues from other species. The same residues in S. enterica ArnT are also needed for function. We propose these aromatic and charged amino acids participate in either undecaprenyl phosphate-l-Ara4N substrate recognition or transfer of l-Ara4N to the LPS.
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Affiliation(s)
- Faviola Tavares-Carreón
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Kinnari B Patel
- Centre for Infection and Immunity, Queen's University Belfast, Belfast, BT9 7AE, United Kingdom
| | - Miguel A Valvano
- 1] Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, N6A 5C1, Canada [2] Centre for Infection and Immunity, Queen's University Belfast, Belfast, BT9 7AE, United Kingdom
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16
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Antibacterial mechanisms of polymyxin and bacterial resistance. BIOMED RESEARCH INTERNATIONAL 2015; 2015:679109. [PMID: 25664322 PMCID: PMC4312571 DOI: 10.1155/2015/679109] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/10/2014] [Indexed: 11/18/2022]
Abstract
Multidrug resistance in pathogens is an increasingly significant threat for human health. Indeed, some strains are resistant to almost all currently available antibiotics, leaving very limited choices for antimicrobial clinical therapy. In many such cases, polymyxins are the last option available, although their use increases the risk of developing resistant strains. This review mainly aims to discuss advances in unraveling the mechanisms of antibacterial activity of polymyxins and bacterial tolerance together with the description of polymyxin structure, synthesis, and structural modification. These are expected to help researchers not only develop a series of new polymyxin derivatives necessary for future medical care, but also optimize the clinical use of polymyxins with minimal resistance development.
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17
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Schmerk CL, Welander PV, Hamad MA, Bain KL, Bernards MA, Summons RE, Valvano MA. Elucidation of theBurkholderia cenocepaciahopanoid biosynthesis pathway uncovers functions for conserved proteins in hopanoid-producing bacteria. Environ Microbiol 2014; 17:735-50. [DOI: 10.1111/1462-2920.12509] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 05/09/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Crystal L. Schmerk
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Paula V. Welander
- Department of Environmental Earth System Science; Stanford University; Stanford CA USA
| | - Mohamad A. Hamad
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Katie L. Bain
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Mark A. Bernards
- Department of Biology; University of Western Ontario; London Ontario N6A 5C1 Canada
| | - Roger E. Summons
- Department of Earth, Atmospheric, and Planetary Sciences; Massachusetts Institute of Technology; Cambridge MA USA
| | - Miguel A. Valvano
- Department of Microbiology and Immunology; University of Western Ontario; London Ontario N6A 5C1 Canada
- Centre for Infection and Immunity; Queen's University Belfast; Belfast BT9 5AE UK
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18
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Fosmidomycin decreases membrane hopanoids and potentiates the effects of colistin on Burkholderia multivorans clinical isolates. Antimicrob Agents Chemother 2014; 58:5211-9. [PMID: 24957830 DOI: 10.1128/aac.02705-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cepacia complex (Bcc) pulmonary infections in people living with cystic fibrosis (CF) are difficult to treat because of the extreme intrinsic resistance of most isolates to a broad range of antimicrobials. Fosmidomycin is an antibacterial and antiparasitic agent that disrupts the isoprenoid biosynthesis pathway, a precursor to hopanoid biosynthesis. Hopanoids are involved in membrane stability and contribute to polymyxin resistance in Bcc bacteria. Checkerboard MIC assays determined that although isolates of the Bcc species B. multivorans were highly resistant to treatment with fosmidomycin or colistin (polymyxin E), antimicrobial synergy was observed in certain isolates when the antimicrobials were used in combination. Treatment with fosmidomycin decreased the MIC of colistin for isolates as much as 64-fold to as low as 8 μg/ml, a concentration achievable with colistin inhalation therapy. A liquid chromatography-tandem mass spectrometry technique was developed for the accurate quantitative determination of underivatized hopanoids in total lipid extracts, and bacteriohopanetetrol cyclitol ether (BHT-CE) was found to be the dominant hopanoid made by B. multivorans. The amount of BHT-CE made was significantly reduced upon fosmidomycin treatment of the bacteria. Uptake assays with 1-N-phenylnaphthylamine were used to determine that dual treatment with fosmidomycin and colistin increases membrane permeability, while binding assays with boron-dipyrromethene-conjugated polymyxin B illustrated that the addition of fosmidomycin had no impact on polymyxin binding. This work indicates that pharmacological suppression of membrane hopanoids with fosmidomycin treatment can increase the susceptibility of certain clinical B. multivorans isolates to colistin, an agent currently in use to treat pulmonary infections in CF patients.
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Guilhelmelli F, Vilela N, Albuquerque P, Derengowski LDS, Silva-Pereira I, Kyaw CM. Antibiotic development challenges: the various mechanisms of action of antimicrobial peptides and of bacterial resistance. Front Microbiol 2013; 4:353. [PMID: 24367355 PMCID: PMC3856679 DOI: 10.3389/fmicb.2013.00353] [Citation(s) in RCA: 334] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/06/2013] [Indexed: 12/15/2022] Open
Abstract
Antimicrobial peptides (AMPs) are natural antibiotics produced by various organisms such as mammals, arthropods, plants, and bacteria. In addition to antimicrobial activity, AMPs can induce chemokine production, accelerate angiogenesis, and wound healing and modulate apoptosis in multicellular organisms. Originally, their antimicrobial mechanism of action was thought to consist solely of an increase in pathogen cell membrane permeability, but it has already been shown that several AMPs do not modulate membrane permeability in the minimal lethal concentration. Instead, they exert their effects by inhibiting processes such as protein and cell wall synthesis, as well as enzyme activity, among others. Although resistance to these molecules is uncommon several pathogens developed different strategies to overcome AMPs killing such as surface modification, expression of efflux pumps, and secretion of proteases among others. This review describes the various mechanisms of action of AMPs and how pathogens evolve resistance to them.
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Affiliation(s)
- Fernanda Guilhelmelli
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Nathália Vilela
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Patrícia Albuquerque
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Lorena da S Derengowski
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Ildinete Silva-Pereira
- Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
| | - Cynthia M Kyaw
- Laboratório de Microbiologia, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília Brasília, Brazil
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Velkov T, Roberts KD, Nation RL, Thompson PE, Li J. Pharmacology of polymyxins: new insights into an 'old' class of antibiotics. Future Microbiol 2013; 8:711-24. [PMID: 23701329 DOI: 10.2217/fmb.13.39] [Citation(s) in RCA: 326] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Increasing antibiotic resistance in Gram-negative bacteria, particularly in Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae, presents a global medical challenge. No new antibiotics will be available for these 'superbugs' in the near future due to the dry antibiotic discovery pipeline. Colistin and polymyxin B are increasingly used as the last-line therapeutic options for treatment of infections caused by multidrug-resistant Gram-negative bacteria. This article surveys the significant progress over the last decade in understanding polymyxin chemistry, mechanisms of antibacterial activity and resistance, structure-activity relationships and pharmacokinetics/pharmacodynamics. In the 'Bad Bugs, No Drugs' era, we must pursue structure-activity relationship-based approaches to develop novel polymyxin-like lipopeptides targeting polymyxin-resistant Gram-negative 'superbugs'. Before new antibiotics become available, we must optimize the clinical use of polymyxins through the application of pharmacokinetic/pharmacodynamic principles, thereby minimizing the development of resistance.
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Affiliation(s)
- Tony Velkov
- Drug Delivery, Disposition & Dynamics, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade Parkville 3052, Victoria, Australia
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Chemical communication of antibiotic resistance by a highly resistant subpopulation of bacterial cells. PLoS One 2013; 8:e68874. [PMID: 23844246 PMCID: PMC3700957 DOI: 10.1371/journal.pone.0068874] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/03/2013] [Indexed: 01/05/2023] Open
Abstract
The overall antibiotic resistance of a bacterial population results from the combination of a wide range of susceptibilities displayed by subsets of bacterial cells. Bacterial heteroresistance to antibiotics has been documented for several opportunistic Gram-negative bacteria, but the mechanism of heteroresistance is unclear. We use Burkholderia cenocepacia as a model opportunistic bacterium to investigate the implications of heterogeneity in the response to the antimicrobial peptide polymyxin B (PmB) and also other bactericidal antibiotics. Here, we report that B. cenocepacia is heteroresistant to PmB. Population analysis profiling also identified B. cenocepacia subpopulations arising from a seemingly homogenous culture that are resistant to higher levels of polymyxin B than the rest of the cells in the culture, and can protect the more sensitive cells from killing, as well as sensitive bacteria from other species, such as Pseudomonas aeruginosa and Escherichia coli. Communication of resistance depended on upregulation of putrescine synthesis and YceI, a widely conserved low-molecular weight secreted protein. Deletion of genes for the synthesis of putrescine and YceI abrogate protection, while pharmacologic inhibition of putrescine synthesis reduced resistance to polymyxin B. Polyamines and YceI were also required for heteroresistance of B. cenocepacia to various bactericidal antibiotics. We propose that putrescine and YceI resemble "danger" infochemicals whose increased production by a bacterial subpopulation, becoming more resistant to bactericidal antibiotics, communicates higher level of resistance to more sensitive members of the population of the same or different species.
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Madhongsa K, Pasan S, Phophetleb O, Nasompag S, Thammasirirak S, Daduang S, Taweechaisupapong S, Lomize AL, Patramanon R. Antimicrobial action of the cyclic peptide bactenecin on Burkholderia pseudomallei correlates with efficient membrane permeabilization. PLoS Negl Trop Dis 2013; 7:e2267. [PMID: 23785532 PMCID: PMC3681726 DOI: 10.1371/journal.pntd.0002267] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/01/2013] [Indexed: 01/05/2023] Open
Abstract
Burkholderia pseudomallei is a category B agent that causes Melioidosis, an acute and chronic disease with septicemia. The current treatment regimen is a heavy dose of antibiotics such as ceftazidime (CAZ); however, the risk of a relapse is possible. Peptide antibiotics are an alternative to classical antibiotics as they exhibit rapid action and are less likely to result in the development of resistance. The aim of this study was to determine the bactericidal activity against B. pseudomallei and examine the membrane disrupting abilities of the potent antimicrobial peptides: bactenecin, RTA3, BMAP-18 and CA-MA. All peptides exhibited >97% bactericidal activity at 20 µM, with bactenecin having slightly higher activity. Long term time-kill assays revealed a complete inhibition of cell growth at 50 µM bactenecin and CA-MA. All peptides inhibited biofilm formation comparable to CAZ, but exhibited faster kinetics (within 1 h). Bactenecin exhibited stronger binding to LPS and induced perturbation of the inner membrane of live cells. Interaction of bactenecin with model membranes resulted in changes in membrane fluidity and permeability, leading to leakage of dye across the membrane at levels two-fold greater than that of other peptides. Modeling of peptide binding on the membrane showed stable and deep insertion of bactenecin into the membrane (up to 9 Å). We propose that bactenecin is able to form dimers or large β-sheet structures in a concentration dependent manner and subsequently rapidly permeabilize the membrane, leading to cytosolic leakage and cell death in a shorter period of time compared to CAZ. Bactenecin might be considered as a potent antimicrobial agent for use against B. pseudomallei. Burkholderia pseudomallei is a category B agent that causes Melioidosis, an acute and chronic disease with septicemia. The current treatment regimen is a heavy dose of antibiotics such as ceftazidime (CAZ), however, the risk of a relapse is possible. In this study we demonstrate that bactenecin, CA-MA, RTA3 and BMAP-18 are able to inhibit the growth and biofilm formation of B. pseudomallei. The strong bactericidal activity of bactenecin is attributed to its greater ability to permeabilize the membrane. Computational modeling of these peptide-membrane interactions provide support for a model in which bactenecin is able to penetrate the membrane most effectively due to its cyclical structure. The peptide, bactenecin has the potential to act as a highly effective alternative to CAZ, or as a combination therapy with CAZ in the treatment of melioidosis. Furthermore, understanding the mechanism of bactenecin may help us better design more effective peptides therapeutics of choice for melioidosis.
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Affiliation(s)
- Kanjana Madhongsa
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Supaluk Pasan
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Onanong Phophetleb
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Sawinee Nasompag
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Sompong Thammasirirak
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Sakda Daduang
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
| | - Suwimol Taweechaisupapong
- Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand
- Biofilm Research Group, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
| | - Andrei L. Lomize
- College of Pharmacy, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Rina Patramanon
- Protein and Proteomics Research Center for Commercial and Industrial Purposes (ProCCI), Khon Kaen University, Khon Kaen, Thailand
- Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, Thailand
- * E-mail:
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Hamad MA, Di Lorenzo F, Molinaro A, Valvano MA. Aminoarabinose is essential for lipopolysaccharide export and intrinsic antimicrobial peptide resistance inBurkholderia cenocepacia†. Mol Microbiol 2012; 85:962-74. [DOI: 10.1111/j.1365-2958.2012.08154.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Porter LA, Goldberg JB. Influence of neutrophil defects on Burkholderia cepacia complex pathogenesis. Front Cell Infect Microbiol 2011; 1:9. [PMID: 22919575 PMCID: PMC3417359 DOI: 10.3389/fcimb.2011.00009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 11/01/2011] [Indexed: 12/16/2022] Open
Abstract
The Burkholderia cepacia complex (Bcc) is a group of Gram-negative bacteria that are ubiquitous in the environment and have emerged as opportunistic pathogens in immunocompromised patients. The primary patient populations infected with Bcc include individuals with cystic fibrosis (CF), as well as those with chronic granulomatous disease (CGD). While Bcc infection in CF is better characterized than in CGD, these two genetic diseases are not obviously similar and it is currently unknown if there is any commonality in host immune defects that is responsible for the susceptibility to Bcc. CF is caused by mutations in the CF transmembrane conductance regulator, resulting in manifestations in various organ systems, however the major cause of morbidity and mortality is currently due to bacterial respiratory infections. CGD, on the other hand, is a genetic disorder that is caused by defects in phagocyte NADPH oxidase. Because of the defect in CGD, phagocytes in these patients are unable to produce reactive oxygen species, which results in increased susceptibility to bacterial and fungal infections. Despite this significant defect in microbial clearance, the spectrum of pathogens frequently implicated in infections in CGD is relatively narrow and includes some bacterial species that are considered almost pathognomonic for this disorder. Very little is known about the cause of the specific susceptibility to Bcc over other potential pathogens more prevalent in the environment, and a better understanding of specific mechanisms required for bacterial virulence has become a high priority. This review will summarize both the current knowledge and future directions related to Bcc virulence in immunocompromised individuals with a focus on the roles of bacterial factors and neutrophil defects in pathogenesis.
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Affiliation(s)
- Laura A Porter
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia Health System, Charlottesville, VA, USA
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El-Halfawy OM, Valvano MA. Heteroresistance of opportunistic bacteria to antimicrobial peptides: a new challenge to antimicrobial therapy of cystic fibrosis infections. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/thy.11.69] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Identification of hopanoid biosynthesis genes involved in polymyxin resistance in Burkholderia multivorans. Antimicrob Agents Chemother 2011; 56:464-71. [PMID: 22006009 DOI: 10.1128/aac.00602-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major challenge to clinical therapy of Burkholderia cepacia complex (Bcc) pulmonary infections is their innate resistance to a broad range of antimicrobials, including polycationic agents such as aminoglycosides, polymyxins, and cationic peptides. To identify genetic loci associated with this phenotype, a transposon mutant library was constructed in B. multivorans ATCC 17616 and screened for increased susceptibility to polymyxin B. Compared to the parent strain, mutant 26D7 exhibited 8- and 16-fold increases in susceptibility to polymyxin B and colistin, respectively. Genetic analysis of mutant 26D7 indicated that the transposon inserted into open reading frame (ORF) Bmul_2133, part of a putative hopanoid biosynthesis gene cluster. A strain with a mutation in another ORF in this cluster, Bmul_2134, was constructed and named RMI19. Mutant RMI19 also had increased polymyxin susceptibility. Hopanoids are analogues of eukaryotic sterols involved in membrane stability and barrier function. Strains with mutations in Bmul_2133 and Bmul_2134 showed increased permeability to 1-N-phenylnaphthylamine in the presence of increasing concentrations of polymyxin, suggesting that the putative hopanoid biosynthesis genes are involved in stabilizing outer membrane permeability, contributing to polymyxin resistance. Results from a dansyl-polymyxin binding assay demonstrated that polymyxin B does not bind well to the parent or mutant strains, suggesting that Bmul_2133 and Bmul_2134 contribute to polymyxin B resistance by a mechanism that is independent of lipopolysaccharide (LPS) binding. Through this work, we propose a role for hopanoid biosynthesis as part of the multiple antimicrobial resistance phenotype in Bcc bacteria.
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Loutet SA, Di Lorenzo F, Clarke C, Molinaro A, Valvano MA. Transcriptional responses of Burkholderia cenocepacia to polymyxin B in isogenic strains with diverse polymyxin B resistance phenotypes. BMC Genomics 2011; 12:472. [PMID: 21955326 PMCID: PMC3190405 DOI: 10.1186/1471-2164-12-472] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 09/29/2011] [Indexed: 12/04/2022] Open
Abstract
Background Burkholderia cenocepacia is a Gram-negative opportunistic pathogen displaying high resistance to antimicrobial peptides and polymyxins. We identified mechanisms of resistance by analyzing transcriptional changes to polymyxin B treatment in three isogenic B. cenocepacia strains with diverse polymyxin B resistance phenotypes: the polymyxin B-resistant parental strain K56-2, a polymyxin B-sensitive K56-2 mutant strain with heptoseless lipopolysaccharide (LPS) (RSF34), and a derivative of RSF34 (RSF34 4000B) isolated through multiple rounds of selection in polymyxin B that despite having a heptoseless LPS is highly polymyxin B-resistant. Results A heptoseless LPS mutant of B. cenocepacia was passaged through multiple rounds of selection to regain high levels of polymyxin B-resistance. This process resulted in various phenotypic changes in the isolate that could contribute to polymyxin B resistance and are consistent with LPS-independent changes in the outer membrane. The transcriptional response of three B. cenocepacia strains to subinhibitory concentrations of polymyxin B was analyzed using microarray analysis and validated by quantitative Real Time-PCR. There were numerous baseline changes in expression between the three strains in the absence of polymyxin B. In both K56-2 and RSF34, similar transcriptional changes upon treatment with polymyxin B were found and included upregulation of various genes that may be involved in polymyxin B resistance and downregulation of genes required for the synthesis and operation of flagella. This last result was validated phenotypically as both swimming and swarming motility were impaired in the presence of polymyxin B. RSF34 4000B had altered the expression in a larger number of genes upon treatment with polymyxin B than either K56-2 or RSF34, but the relative fold-changes in expression were lower. Conclusions It is possible to generate polymyxin B-resistant isolates from polymyxin B-sensitive mutant strains of B. cenocepacia, likely due to the multifactorial nature of polymyxin B resistance of this bacterium. Microarray analysis showed that B. cenocepacia mounts multiple transcriptional responses following exposure to polymyxin B. Polymyxin B-regulated genes identified in this study may be required for polymyxin B resistance, which must be tested experimentally. Exposure to polymyxin B also decreases expression of flagellar genes resulting in reduced swimming and swarming motility.
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Affiliation(s)
- Slade A Loutet
- Centre for Human Immunology, Department of Microbiology and Immunology, the University of Western Ontario, London, Ontario, Canada
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Loutet SA, Valvano MA. Extreme antimicrobial peptide and polymyxin B resistance in the genus Burkholderia. Front Cell Infect Microbiol 2011; 1:6. [PMID: 22919572 PMCID: PMC3417367 DOI: 10.3389/fcimb.2011.00006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 07/12/2011] [Indexed: 12/12/2022] Open
Abstract
Cationic antimicrobial peptides and polymyxins are a group of naturally occurring antibiotics that can also possess immunomodulatory activities. They are considered a new source of antibiotics for treating infections by bacteria that are resistant to conventional antibiotics. Members of the genus Burkholderia, which includes various human pathogens, are inherently resistant to antimicrobial peptides. The resistance is several orders of magnitude higher than that of other Gram-negative bacteria such as Escherichia coli, Salmonella enterica, or Pseudomonas aeruginosa. This review summarizes our current understanding of antimicrobial peptide and polymyxin B resistance in the genus Burkholderia. These bacteria possess major and minor resistance mechanisms that will be described in detail. Recent studies have revealed that many other emerging Gram-negative opportunistic pathogens may also be inherently resistant to antimicrobial peptides and polymyxins and we propose that Burkholderia sp. are a model system to investigate the molecular basis of the resistance in extremely resistant bacteria. Understanding resistance in these types of bacteria will be important if antimicrobial peptides come to be used regularly for the treatment of infections by susceptible bacteria because this may lead to increased resistance in the species that are currently susceptible and may also open up new niches for opportunistic pathogens with high inherent resistance.
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Affiliation(s)
- Slade A Loutet
- Centre for Human Immunology, University of Western Ontario London, Ontario, Canada
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Loutet SA, Valvano MA. Extreme antimicrobial Peptide and polymyxin B resistance in the genus burkholderia. Front Microbiol 2011; 2:159. [PMID: 21811491 PMCID: PMC3143681 DOI: 10.3389/fmicb.2011.00159] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 07/12/2011] [Indexed: 01/04/2023] Open
Abstract
Cationic antimicrobial peptides and polymyxins are a group of naturally occurring antibiotics that can also possess immunomodulatory activities. They are considered a new source of antibiotics for treating infections by bacteria that are resistant to conventional antibiotics. Members of the genus Burkholderia, which includes various human pathogens, are inherently resistant to antimicrobial peptides. The resistance is several orders of magnitude higher than that of other Gram-negative bacteria such as Escherichia coli, Salmonella enterica, or Pseudomonas aeruginosa. This review summarizes our current understanding of antimicrobial peptide and polymyxin B resistance in the genus Burkholderia. These bacteria possess major and minor resistance mechanisms that will be described in detail. Recent studies have revealed that many other emerging Gram-negative opportunistic pathogens may also be inherently resistant to antimicrobial peptides and polymyxins and we propose that Burkholderia sp. are a model system to investigate the molecular basis of the resistance in extremely resistant bacteria. Understanding resistance in these types of bacteria will be important if antimicrobial peptides come to be used regularly for the treatment of infections by susceptible bacteria because this may lead to increased resistance in the species that are currently susceptible and may also open up new niches for opportunistic pathogens with high inherent resistance.
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Affiliation(s)
- Slade A Loutet
- Centre for Human Immunology, University of Western Ontario London, ON, Canada
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