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Han J, Zhao X, Zhao X, Li P, Gu Q. Insight into the structure, biosynthesis, isolation method and biological function of teichoic acid in different gram-positive microorganisms: A review. Int J Biol Macromol 2023; 253:126825. [PMID: 37696369 DOI: 10.1016/j.ijbiomac.2023.126825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/07/2023] [Accepted: 09/07/2023] [Indexed: 09/13/2023]
Abstract
Teichoic acid (TA) is a weakly anionic polymer present in the cell walls of Gram-positive bacteria. It can be classified into wall teichoic acid (WTA) and lipoteichoic acid (LTA) based on its localization in the cell wall. The structure and biosynthetic pathway of TAs are strain-specific and have a significant role in maintaining cell wall stability. TAs have various beneficial functions, such as immunomodulatory, anticancer and antioxidant activities. However, the purity and yield of TAs are generally not high, and different isolation methods may even affect their structural integrity, which limits the research progress on the probiotic functions of TA. This paper reviews an overview of the structure and biosynthetic pathway of TAs in different strains, as well as the research progress of the isolation and purification methods of TAs. Furthermore, this review also highlights the current research status on the biological functions of TAs. Through a comprehensive understanding of this review, it is expected to pave the way for advancements in isolating and purifying high-quality TAs and, in turn, lay a foundation for contributing to the development of targeted probiotic therapies.
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Affiliation(s)
- Jiarun Han
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Xin Zhao
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Xilian Zhao
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Ping Li
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, People's Republic of China
| | - Qing Gu
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, People's Republic of China.
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2
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Boutet-Dubois A, Magnan C, Lienard A, Pouget C, Bouchet F, Marchandin H, Larcher R, Lavigne JP, Pantel A. In Vivo-Acquired Resistance to Daptomycin during Methicillin-Resistant Staphylococcus aureus Bacteremia. Antibiotics (Basel) 2023; 12:1647. [PMID: 38136681 PMCID: PMC10740961 DOI: 10.3390/antibiotics12121647] [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: 09/28/2023] [Revised: 11/11/2023] [Accepted: 11/16/2023] [Indexed: 12/24/2023] Open
Abstract
Daptomycin (DAP) represents an interesting alternative to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. Different mechanisms of DAP resistance have been described; however, in vivo-acquired resistance is uncharacterized. This study described the phenotypic and genotypic evolution of MRSA strains that became resistant to DAP in two unrelated patients with bacteremia under DAP treatment, in two hospitals in the South of France. DAP MICs were determined using broth microdilution method on the pairs of isogenic (DAP-S/DAP-R) S. aureus isolated from bloodstream cultures. Whole genome sequencing was carried out using Illumina MiSeq Sequencing system. The two cases revealed DAP-R acquisition by MRSA strains within three weeks in patients treated by DAP. The isolates belonged to the widespread ST5 (patient A) and ST8 (patient B) lineages and were of spa-type t777 and t622, respectively. SNP analysis comparing each DAP-S/DAP-R pair confirmed that the isolates were isogenic. The causative mutations were identified in MprF (Multiple peptide resistance Factor) protein: L826F (Patient A) and S295L (Patient B), and in Cls protein: R228H (Patient B). These proteins encoded both proteins of the lipid biosynthetic enzymes. The resistance to DAP is particularly poorly described whereas DAP is highly prescribed to treat MRSA. Our study highlights the non-systematic cross-resistance between DAP and glycopeptides and the importance of monitoring DAP MIC in persistent MRSA bacteremia.
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Affiliation(s)
- Adeline Boutet-Dubois
- VBIC, INSERM U1047, Department of Microbiology and Hospital Hygiene, University of Montpellier, CHU Nîmes, 30029 Nîmes, France; (A.B.-D.); (C.M.); (C.P.); (A.P.)
| | - Chloé Magnan
- VBIC, INSERM U1047, Department of Microbiology and Hospital Hygiene, University of Montpellier, CHU Nîmes, 30029 Nîmes, France; (A.B.-D.); (C.M.); (C.P.); (A.P.)
| | - Alexi Lienard
- Laboratory of Medical Biology, CH Bassin de Thau, 34207 Sète, France;
| | - Cassandra Pouget
- VBIC, INSERM U1047, Department of Microbiology and Hospital Hygiene, University of Montpellier, CHU Nîmes, 30029 Nîmes, France; (A.B.-D.); (C.M.); (C.P.); (A.P.)
| | - Flavien Bouchet
- Department of Internal Medicine-Infectiology, CH Bassin de Thau, 34207 Sète, France;
| | - Hélène Marchandin
- HydroSciences Montpellier, Department of Microbiology and Hospital Hygiene, University of Montpellier, CNRS, IRD, CHU Nîmes, 30029 Nîmes, France;
| | - Romaric Larcher
- Department of Infectious Diseases, CHU Nîmes, 30029 Nîmes, France;
| | - Jean-Philippe Lavigne
- VBIC, INSERM U1047, Department of Microbiology and Hospital Hygiene, University of Montpellier, CHU Nîmes, 30029 Nîmes, France; (A.B.-D.); (C.M.); (C.P.); (A.P.)
| | - Alix Pantel
- VBIC, INSERM U1047, Department of Microbiology and Hospital Hygiene, University of Montpellier, CHU Nîmes, 30029 Nîmes, France; (A.B.-D.); (C.M.); (C.P.); (A.P.)
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Douglas EJ, Laabei M. Staph wars: the antibiotic pipeline strikes back. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001387. [PMID: 37656158 PMCID: PMC10569064 DOI: 10.1099/mic.0.001387] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/14/2023] [Indexed: 09/02/2023]
Abstract
Antibiotic chemotherapy is widely regarded as one of the most significant medical advancements in history. However, the continued misuse of antibiotics has contributed to the rapid rise of antimicrobial resistance (AMR) globally. Staphylococcus aureus, a major human pathogen, has become synonymous with multidrug resistance and is a leading antimicrobial-resistant pathogen causing significant morbidity and mortality worldwide. This review focuses on (1) the targets of current anti-staphylococcal antibiotics and the specific mechanisms that confirm resistance; (2) an in-depth analysis of recently licensed antibiotics approved for the treatment of S. aureus infections; and (3) an examination of the pre-clinical pipeline of anti-staphylococcal compounds. In addition, we examine the molecular mechanism of action of novel antimicrobials and derivatives of existing classes of antibiotics, collate data on the emergence of resistance to new compounds and provide an overview of key data from clinical trials evaluating anti-staphylococcal compounds. We present several successful cases in the development of alternative forms of existing antibiotics that have activity against multidrug-resistant S. aureus. Pre-clinical antimicrobials show promise, but more focus and funding are required to develop novel classes of compounds that can curtail the spread of and sustainably control antimicrobial-resistant S. aureus infections.
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Affiliation(s)
| | - Maisem Laabei
- Department of Life Sciences, University of Bath, Bath BA2 7AY, UK
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4
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Poshvina DV, Dilbaryan DS, Vasilchenko AS. Gausemycin A-Resistant Staphylococcus aureus Demonstrates Affected Cell Membrane and Cell Wall Homeostasis. Microorganisms 2023; 11:1330. [PMID: 37317304 DOI: 10.3390/microorganisms11051330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 06/16/2023] Open
Abstract
Antibiotic resistance is a significant and pressing issue in the medical field, as numerous strains of infectious bacteria have become resistant to commonly prescribed antibiotics. Staphylococcus aureus is a bacterium that poses a grave threat, as it is responsible for a large number of nosocomial infections and has high mortality rates worldwide. Gausemycin A is a new lipoglycopeptide antibiotic that has considerable efficacy against multidrug-resistant S. aureus strains. Although the cellular targets of gausemycin A have been previously identified, detailing the molecular processes of action is still needed. We performed gene expression analysis to identify molecular mechanisms that may be involved in bacterial resistance to gausemycin A. In the present study, we observed that gausemycin A-resistant S. aureus in the late-exponential phase showed an increased expression of genes involved in cell wall turnover (sceD), membrane charge (dltA), phospholipid metabolism (pgsA), the two-component stress-response system (vraS), and the Clp proteolytic system (clpX). The increased expression of these genes implies that changes in the cell wall and cell membrane are essential for the bacterial resistance to gausemycin A. In the stationary phase, we observed a decrease in the expression of genes involved in the phospholipid metabolism (mprF) and Clp proteolytic system (clpX).
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Affiliation(s)
- Darya V Poshvina
- Laboratory of Antimicrobial Resistance, Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
| | - Diana S Dilbaryan
- Laboratory of Antimicrobial Resistance, Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
| | - Alexey S Vasilchenko
- Laboratory of Antimicrobial Resistance, Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
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Ali Alghamdi B, Al-Johani I, Al-Shamrani JM, Musamed Alshamrani H, Al-Otaibi BG, Almazmomi K, Yusnoraini Yusof N. Antimicrobial resistance in methicillin-resistant staphylococcus aureus. Saudi J Biol Sci 2023; 30:103604. [PMID: 36936699 PMCID: PMC10018568 DOI: 10.1016/j.sjbs.2023.103604] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/02/2023] [Accepted: 02/19/2023] [Indexed: 03/02/2023] Open
Abstract
In the medical community, antibiotics are revered as a miracle because they stop diseases brought on by pathogenic bacteria. Antibiotics have become the cornerstone of contemporary medical advancements ever since penicillin was discovered. Antibiotic resistance developed among germs quickly, placing a strain in the medical field. Methicillin-resistant Staphylococcus aureus (MRSA), Since 1961, has emerged as the major general antimicrobial resistant bacteria (AMR) worldwide. MRSA can easily transmit across the hospital system and has mostly gained resistance to medications called beta-lactamases. This enzyme destroys the cell wall of beta-lactam antibiotics resulting in resistance against that respective antibiotic. Daptomycin, linezolid and vancomycin were previously used to treat MRSA infections. However, due to mutations and Single nucleotide polymorphisms (SNPs) in Open reading frames (ORFs) and SCCmec machinery of respective antibody, MRSA developed resistance against those antibiotics. The MRSA strains (USA300, CC398, CC130 etc.), when their pan-genomes were analyzed were found the genes involved in invoking resistance against the antibiotics as well as the epidemiology of that respective strain. PENC (penicillin plus potassium clavulanate) is the new antibiotic showing potential in treatment of MRSA though it is itself resistant against penicillin alone. In this review, our main focus is on mechanism of development of AMR in MRSA, how different ORFs are involved in evoking resistance in MRSA and what is the core-genome of different antimicrobial resistant MRSA.
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Affiliation(s)
- Bandar Ali Alghamdi
- Department of Cardiac Surgery, King Fahad Armed Forces Hospital, Jeddah, Saudi Arabia
| | - Intisar Al-Johani
- Department of Biotechnology, Taif University, Taif City, Saudi Arabia
| | | | - Hussein Musamed Alshamrani
- Directorate of Health Affairs in Qunfudah Center (Namerah Primary Health care) Pharmacy Department, Saudi Arabia
| | | | - Kholod Almazmomi
- Department of Biotechnology, Taif University, Taif City, Saudi Arabia
| | - Nik Yusnoraini Yusof
- Institute for Research in Molecular Medicine (INFORMM), Health Campus, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia
- Corresponding author at.: Institute for Research in Molecular Medicine (INFORMM) Universiti Sains Malaysia Kubang Kerian, Kelantan 16150, Malaysia.
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Abstract
Gram-positive bacterial cells are protected from the environment by a cell envelope that is comprised of a thick layer of peptidoglycan that maintains cell shape and teichoic acid polymers whose biological function remains unclear. In Bacillus subtilis, the loss of all class A penicillin-binding proteins (aPBPs), which function in peptidoglycan synthesis, is conditionally lethal. Here, we show that this lethality is associated with an alteration of lipoteichoic acids (LTAs) and the accumulation of the major autolysin LytE in the cell wall. Our analysis provides further evidence that the length and abundance of LTAs act to regulate the cellular level and activity of autolytic enzymes, specifically LytE. Importantly, we identify a novel function for the aminoacyl-phosphatidylglycerol synthase MprF in the modulation of LTA biosynthesis in both B. subtilis and Staphylococcus aureus. This finding has implications for our understanding of antimicrobial resistance (particularly to daptomycin) in clinically relevant bacteria and the involvement of MprF in the virulence of pathogens such as methicillin-resistant S. aureus (MRSA). IMPORTANCE In Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus, the cell envelope is a structure that protects the cells from the environment but is also dynamic in that it must be modified in a controlled way to allow cell growth. In this study, we show that lipoteichoic acids (LTAs), which are anionic polymers attached to the membrane, have a direct role in modulating the cellular abundance of cell wall-degrading enzymes. We also find that the apparent length of the LTA is modulated by the activity of the enzyme MprF, previously implicated in modifications of the cell membrane leading to resistance to antimicrobial peptides. These findings are important contributions to our understanding of how bacteria balance cell wall synthesis and degradation to permit controlled growth and division. These results also have implications for the interpretation of antibiotic resistance, particularly for the clinical treatment of MRSA infections.
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Abstract
Almost all bactericidal drugs require bacterial replication and/or metabolic activity for their killing activity. When these processes are inhibited by bacteriostatic antibiotics, bacterial killing is significantly reduced. One notable exception is the lipopeptide antibiotic daptomycin, which has been reported to efficiently kill growth-arrested bacteria. However, these studies employed only short periods of growth arrest (<1 h), which may not fully represent the duration of growth arrest that can occur in vivo. We found that a growth inhibitory concentration of the protein synthesis inhibitor tetracycline led to a time-dependent induction of daptomycin tolerance in S. aureus, with an approximately 100,000-fold increase in survival after 16 h of growth arrest, relative to exponential-phase bacteria. Daptomycin tolerance required glucose and was associated with increased production of the cell wall polymers peptidoglycan and wall-teichoic acids. However, while the accumulation of peptidoglycan was required for daptomycin tolerance, only a low abundance of wall teichoic acid was necessary. Therefore, whereas tolerance to most antibiotics occurs passively due to a lack of metabolic activity and/or replication, daptomycin tolerance arises via active cell wall remodelling. IMPORTANCE Understanding why antibiotics sometimes fail to cure infections is fundamental to improving treatment outcomes. This is a major challenge when it comes to Staphylococcus aureus because this pathogen causes several different chronic or recurrent infections. Previous work has shown that a lack of replication, as often occurs during infection, makes bacteria tolerant of most bactericidal antibiotics. However, one antibiotic that has been reported to kill nonreplicating bacteria is daptomycin. In this work, we show that the growth arrest of S. aureus does in fact lead to daptomycin tolerance, but it requires time, nutrients, and biosynthetic pathways, making it distinct from other types of antibiotic tolerance that occur in nonreplicating bacteria.
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Mahjabeen F, Saha U, Mostafa MN, Siddique F, Ahsan E, Fathma S, Tasnim A, Rahman T, Faruq R, Sakibuzzaman M, Dilnaz F, Ashraf A. An Update on Treatment Options for Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia: A Systematic Review. Cureus 2022; 14:e31486. [DOI: 10.7759/cureus.31486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2022] [Indexed: 11/16/2022] Open
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9
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Chang AW, Dowd SE, Brackee G, Fralick JA, Vediyappan G. Inhibition of Staphylococcus aureus biofilm formation by gurmarin, a plant-derived cyclic peptide. Front Cell Infect Microbiol 2022; 12:1017545. [PMID: 36268224 PMCID: PMC9578378 DOI: 10.3389/fcimb.2022.1017545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus (Sa) is an opportunistic pathogen capable of causing various infections ranging from superficial skin infections to life-threatening severe diseases including pneumonia and sepsis. Sa produces biofilms readily on biotic and abiotic surfaces. Biofilm cells are embedded in a protective polysaccharide matrix and show an innate resistance to antibiotics, disinfectants, and clearance by host defenses. Additionally, biofilms serve as a source for systemic dissemination. Moreover, infections associated with biofilms may result in longer hospitalizations, a need for surgery, and may even result in death. Agents that inhibit the formation of biofilms and virulence without affecting bacterial growth to avoid the development of drug resistance could be useful for therapeutic purposes. In this regard, we identified and purified a small cyclic peptide, gurmarin, from a plant source that inhibited the formation of Sa biofilm under in vitro growth conditions without affecting the viability of the bacterium. The purified peptide showed a predicted molecular size of ~4.2 kDa on SDS-PAGE. Transcriptomic analysis of Sa biofilm treated with peptide showed 161 differentially affected genes at a 2-fold change, and some of them include upregulation of genes involved in oxidoreductases and downregulation of genes involved in transferases and hydrolases. To determine the inhibitory effect of the peptide against Sa biofilm formation and virulence in vivo, we used a rat-implant biofilm model. Sa infected implants with or without peptide were placed under the neck skin of rats for seven days. Implants treated with peptide showed a reduction of CFU and lack of edema and sepsis when compared to that of control animals without peptide. Taken together, gurmarin peptide blocks Sa biofilm formation in vitro and in vivo and can be further developed for therapeutic use.
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Affiliation(s)
- Adeline W. Chang
- Division of Biology, Kansas State University, Manhattan, KS, United States
| | - Scot E. Dowd
- MR DNA (Molecular Research), Shallowater, TX, United States
| | - Gordon Brackee
- Laboratory Animal Resources Center, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Joe A. Fralick
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Govindsamy Vediyappan
- Division of Biology, Kansas State University, Manhattan, KS, United States
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- *Correspondence: Govindsamy Vediyappan,
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Panda G, Dash S, Sahu SK. Harnessing the Role of Bacterial Plasma Membrane Modifications for the Development of Sustainable Membranotropic Phytotherapeutics. MEMBRANES 2022; 12:914. [PMID: 36295673 PMCID: PMC9612325 DOI: 10.3390/membranes12100914] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/08/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Membrane-targeted molecules such as cationic antimicrobial peptides (CAMPs) are amongst the most advanced group of antibiotics used against drug-resistant bacteria due to their conserved and accessible targets. However, multi-drug-resistant bacteria alter their plasma membrane (PM) lipids, such as lipopolysaccharides (LPS) and phospholipids (PLs), to evade membrane-targeted antibiotics. Investigations reveal that in addition to LPS, the varying composition and spatiotemporal organization of PLs in the bacterial PM are currently being explored as novel drug targets. Additionally, PM proteins such as Mla complex, MPRF, Lpts, lipid II flippase, PL synthases, and PL flippases that maintain PM integrity are the most sought-after targets for development of new-generation drugs. However, most of their structural details and mechanism of action remains elusive. Exploration of the role of bacterial membrane lipidome and proteome in addition to their organization is the key to developing novel membrane-targeted antibiotics. In addition, membranotropic phytochemicals and their synthetic derivatives have gained attractiveness as popular herbal alternatives against bacterial multi-drug resistance. This review provides the current understanding on the role of bacterial PM components on multidrug resistance and their targeting with membranotropic phytochemicals.
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Affiliation(s)
- Gayatree Panda
- Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University (Erstwhile: North Orissa University), Baripada 757003, India
| | - Sabyasachi Dash
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065, USA
| | - Santosh Kumar Sahu
- Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University (Erstwhile: North Orissa University), Baripada 757003, India
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Ledger EVK, Mesnage S, Edwards AM. Human serum triggers antibiotic tolerance in Staphylococcus aureus. Nat Commun 2022; 13:2041. [PMID: 35440121 PMCID: PMC9018823 DOI: 10.1038/s41467-022-29717-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 03/30/2022] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus frequently causes infections that are challenging to treat, leading to high rates of persistent and relapsing infection. Here, to understand how the host environment influences treatment outcomes, we study the impact of human serum on staphylococcal antibiotic susceptibility. We show that serum triggers a high degree of tolerance to the lipopeptide antibiotic daptomycin and several other classes of antibiotic. Serum-induced daptomycin tolerance is due to two independent mechanisms. Firstly, the host defence peptide LL-37 induces tolerance by triggering the staphylococcal GraRS two-component system, leading to increased peptidoglycan accumulation. Secondly, GraRS-independent increases in membrane cardiolipin abundance are required for full tolerance. When both mechanisms are blocked, S. aureus incubated in serum is as susceptible to daptomycin as when grown in laboratory media. Our work demonstrates that host factors can significantly modulate antibiotic susceptibility via diverse mechanisms, and combination therapy may provide a way to mitigate this.
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Affiliation(s)
- Elizabeth V K Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Stéphane Mesnage
- School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK.
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12
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Ledger EVK, Sabnis A, Edwards AM. Polymyxin and lipopeptide antibiotics: membrane-targeting drugs of last resort. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35118938 PMCID: PMC8941995 DOI: 10.1099/mic.0.001136] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The polymyxin and lipopeptide classes of antibiotics are membrane-targeting drugs of last resort used to treat infections caused by multi-drug-resistant pathogens. Despite similar structures, these two antibiotic classes have distinct modes of action and clinical uses. The polymyxins target lipopolysaccharide in the membranes of most Gram-negative species and are often used to treat infections caused by carbapenem-resistant species such as Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. By contrast, the lipopeptide daptomycin requires membrane phosphatidylglycerol for activity and is only used to treat infections caused by drug-resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. However, despite having distinct targets, both antibiotic classes cause membrane disruption, are potently bactericidal in vitro and share similarities in resistance mechanisms. Furthermore, there are concerns about the efficacy of these antibiotics, and there is increasing interest in using both polymyxins and daptomycin in combination therapies to improve patient outcomes. In this review article, we will explore what is known about these distinct but structurally similar classes of antibiotics, discuss recent advances in the field and highlight remaining gaps in our knowledge.
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Affiliation(s)
- Elizabeth V K Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
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13
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Phenotypic and genetic changes associated with the seesaw effect in MRSA strain N315 in a bioreactor model. J Glob Antimicrob Resist 2022; 28:249-253. [PMID: 35085792 PMCID: PMC9576143 DOI: 10.1016/j.jgar.2022.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 11/20/2022] Open
Abstract
Objectives: Over the past decade, daptomycin treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections has led to the emergence of daptomycin nonsusceptible (DAP-NS) MRSA strains and a subsequent interest in combinatorial antibiotic therapies. We investigated the phenotypic and genetic changes associated with the seesaw effect, which describes the correlation between daptomycin resistance and increased β-lactam susceptibility in DAP-NS MRSA and the reverse phenomenon of DAP-NS strains acquiring renewed susceptibility to daptomycin after β-lactam exposure. Methods: A continuous bioreactor model was used to study the effects of incremental doses of daptomycin followed by oxacillin on MRSA strain N315. Minimum inhibitory concentrations for daptomycin and oxacillin were determined for the bioreactor-derived samples. Transmission electron microscopy and cytochrome C binding assays were used to measure cell wall thickness and cell membrane charge, respectively, in the bioreactor-derived samples. Whole-genome sequencing was used to identify mutations associated with the seesaw effect. Results: Although daptomycin resistance conferred enhanced susceptibility to oxacillin, oxacillin treatment of DAP-NS strains was accompanied by a lowered minimum inhibitory concentration for daptomycin. Additionally, there was a reduction in relative positive cell surface charge and cell wall thickness. However, the mutations acquired in our DAP-NS populations were not accompanied by additional genomic changes after treatment with oxacillin, implicating alternative mechanisms for the seesaw effect. Conclusion: In this study, we successfully produced and characterized the seesaw effect in MRSA strain N315 in a unique bioreactor model.
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Cai Y, Zheng L, Lu Y, Zhao X, Sun Y, Tang X, Xiao J, Wang C, Tong C, Zhao L, Xiao Y, Zhao X, Xue H. Inducible Resistance to β-Lactams in Oxacillin-Susceptible mecA1-Positive Staphylococcus sciuri Isolated From Retail Pork. Front Microbiol 2021; 12:721426. [PMID: 34745029 PMCID: PMC8564388 DOI: 10.3389/fmicb.2021.721426] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/27/2021] [Indexed: 11/20/2022] Open
Abstract
Most isolated strains of Staphylococcus sciuri contain mecA1, the evolutionary origin of mecA, but are sensitive to β-lactams (OS-MRSS, oxacillin-susceptible mecA1-positive S. sciuri). In order to improve the efficacy of antibiotic treatment, it is important to clarify whether the resistance of OS-MRSS to β-lactams is an inducible phenotype. In this study, three OS-MRSS strains with oxacillin MIC = 1 μg/ml were isolated from 29 retail pork samples. The resistance of OS-MRSS to β-lactams (MIC > 256 μg/ml) was found to be induced by oxacillin, and the induced resistance was observed to remain stable within a certain period of time. Interestingly, the induced β-lactam resistance was not caused by mecA1, heterogeneous resistance, or any genetic mutation, but mainly due to increased wall teichoic acid (WTA) synthesis that thickened the cell wall. The induced strains also showed slower growth rate, as well as decreased adhesion ability and biofilm thickness. These phenotypes were found to be achieved through altered gene expression in associated pathways, such as the citrate cycle and pentose phosphate pathway. The results challenge the traditional antibiotic sensitivity test. In the presence of β-lactam antibiotics, OS-MRSS that was initially sensitive to β-lactams was observed to gradually develop β-lactam resistance in several days. This often-neglected phenomenon in antibiotic sensitivity tests requires further research attention.
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Affiliation(s)
- Yifei Cai
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Liangjun Zheng
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Yao Lu
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Xu Zhao
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Yanting Sun
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Xingyuan Tang
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Jinhe Xiao
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Chen Wang
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Chao Tong
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Lili Zhao
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
| | - Yingping Xiao
- Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Xin Zhao
- Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Huping Xue
- College of Animal Science and Technology, Northwest A&F University, Xianyang, China
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15
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Spengler C, Nolle F, Thewes N, Wieland B, Jung P, Bischoff M, Jacobs K. Using Knock-Out Mutants to Investigate the Adhesion of Staphylococcus aureus to Abiotic Surfaces. Int J Mol Sci 2021; 22:11952. [PMID: 34769382 PMCID: PMC8584566 DOI: 10.3390/ijms222111952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 10/29/2021] [Accepted: 10/30/2021] [Indexed: 12/19/2022] Open
Abstract
The adhesion of Staphylococcus aureus to abiotic surfaces is crucial for establishing device-related infections. With a high number of single-cell force spectroscopy measurements with genetically modified S. aureus cells, this study provides insights into the adhesion process of the pathogen to abiotic surfaces of different wettability. Our results show that S. aureus utilizes different cell wall molecules and interaction mechanisms when binding to hydrophobic and hydrophilic surfaces. We found that covalently bound cell wall proteins strongly interact with hydrophobic substrates, while their contribution to the overall adhesion force is smaller on hydrophilic substrates. Teichoic acids promote adhesion to hydrophobic surfaces as well as to hydrophilic surfaces. This, however, is to a lesser extent. An interplay of electrostatic effects of charges and protein composition on bacterial surfaces is predominant on hydrophilic surfaces, while it is overshadowed on hydrophobic surfaces by the influence of the high number of binding proteins. Our results can help to design new models of bacterial adhesion and may be used to interpret the adhesion of other microorganisms with similar surface properties.
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Affiliation(s)
- Christian Spengler
- Experimental Physics and Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany; (C.S.); (F.N.); (N.T.)
| | - Friederike Nolle
- Experimental Physics and Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany; (C.S.); (F.N.); (N.T.)
| | - Nicolas Thewes
- Experimental Physics and Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany; (C.S.); (F.N.); (N.T.)
| | - Ben Wieland
- Institute of Medical Microbiology and Hygiene and Center for Biophysics, Saarland University, 66421 Homburg, Germany; (B.W.); (P.J.); (M.B.)
| | - Philipp Jung
- Institute of Medical Microbiology and Hygiene and Center for Biophysics, Saarland University, 66421 Homburg, Germany; (B.W.); (P.J.); (M.B.)
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene and Center for Biophysics, Saarland University, 66421 Homburg, Germany; (B.W.); (P.J.); (M.B.)
| | - Karin Jacobs
- Experimental Physics and Center for Biophysics, Saarland University, 66123 Saarbrücken, Germany; (C.S.); (F.N.); (N.T.)
- Max Planck School Matter to Life, Jahnstraße 29, 69120 Heidelberg, Germany
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16
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Hort M, Bertsche U, Nozinovic S, Dietrich A, Schrötter AS, Mildenberger L, Axtmann K, Berscheid A, Bierbaum G. The Role of β-Glycosylated Wall Teichoic Acids in the Reduction of Vancomycin Susceptibility in Vancomycin-Intermediate Staphylococcus aureus. Microbiol Spectr 2021; 9:e0052821. [PMID: 34668723 PMCID: PMC8528128 DOI: 10.1128/spectrum.00528-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/12/2021] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen that causes a wide range of infections. Due to the rapid evolution of antibiotic resistance that leads to treatment failure, it is important to understand the underlying mechanisms. Here, the cell wall structures of several laboratory vancomycin-intermediate S. aureus (VISA) strains were analyzed. Among the VISA strains were S. aureus VC40, which accumulated 79 mutations, including most importantly 2 exchanges in the histidine-kinase VraS, and developed full resistance against vancomycin (MIC, 64 μg/ml); a revertant S. aureus VC40R, which has an additional mutation in vraR (MIC, 4 μg/ml); and S. aureus VraS(VC40), in which the 2 vraS mutations were reconstituted into a susceptible background (MIC, 4 μg/ml). A ultraperformance liquid chromatography (UPLC) analysis showed that S. aureus VC40 had a significantly decreased cross-linking of the peptidoglycan. Both S. aureus VC40 and S. aureus VraS(VC40) displayed reduced autolysis and an altered autolysin profile in a zymogram. Most striking was the significant increase in d-alanine and N-acetyl-d-glucosamine (GlcNAc) substitution of the wall teichoic acids (WTAs) in S. aureus VC40. Nuclear magnetic resonance (NMR) analysis revealed that this strain had mostly β-glycosylated WTAs in contrast to the other strains, which showed only the α-glycosylation peak. Salt stress induced the incorporation of β-GlcNAc anomers and drastically increased the vancomycin MIC for S. aureus VC40R. In addition, β-glycosylated WTAs decreased the binding affinity of AtlA, the major autolysin of S. aureus, to the cell wall, compared with α-glycosylated WTAs. In conclusion, there is a novel connection between wall teichoic acids, autolysis, and vancomycin susceptibility in S. aureus. IMPORTANCE Infections with methicillin-resistant Staphylococcus aureus are commonly treated with vancomycin. This antibiotic inhibits cell wall biosynthesis by binding to the cell wall building block lipid II. We set out to characterize the mechanisms leading to decreased vancomycin susceptibility in a laboratory-generated strain, S. aureus VC40. This strain has an altered cell wall architecture with a thick cell wall with low cross-linking, which provides decoy binding sites for vancomycin. The low cross-linking, necessary for this resistance mechanism, decreases the stability of the cell wall against lytic enzymes, which separate the daughter cells. Protection against these enzymes is provided by another cell wall polymer, the teichoic acids, which contain an unusually high substitution with sugars in the β-conformation. By experimentally increasing the proportion of β-N-acetyl-d-glucosamine in a closely related isolate through the induction of salt stress, we could show that the β-conformation of the sugars plays a vital role in the resistance of S. aureus VC40.
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Affiliation(s)
- Michael Hort
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Ute Bertsche
- Department of Infection Biology, University of Tuebingen, Tuebingen, Germany
| | | | - Alina Dietrich
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Anne Sophie Schrötter
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Laura Mildenberger
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Katharina Axtmann
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Anne Berscheid
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, University Clinics of Bonn, Bonn, Germany
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17
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Liu WT, Chen EZ, Yang L, Peng C, Wang Q, Xu Z, Chen DQ. Emerging resistance mechanisms for 4 types of common anti-MRSA antibiotics in Staphylococcus aureus: A comprehensive review. Microb Pathog 2021; 156:104915. [PMID: 33930416 DOI: 10.1016/j.micpath.2021.104915] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/02/2021] [Accepted: 04/06/2021] [Indexed: 01/10/2023]
Abstract
Staphylococcus aureus is one of the leading hospital-associated and community-associated pathogens, which has caused a global public health concern. The emergence of methicillin-resistant S. aureus (MRSA) along with the widespread use of different classes of antibiotics has become a significant therapeutic challenge. Antibiotic resistance is a disturbing problem that poses a threat to humans. Treatment options for S. aureus resistant to β-lactam antibiotics include glycopeptide antibiotic, cyclic lipopeptide antibiotic, cephalosporins and oxazolidinone antibiotic. The most representative types of these antibiotics are vancomycin, daptomycin, ceftaroline and linezolid. The frequent use of the first-line drug vancomycin for MRSA treatment has increased the number of resistant strains, namely vancomycin intermediate resistant S. aureus (VISA) and vancomycin resistant S. aureus (VRSA). A systematic literature review of relevant published studies in PubMed before 2020 was conducted. In recent years, there have been some reports on the relevant resistant mechanisms of vancomycin, daptomycin, ceftaroline and linezolid. In this review, we have summarized the antibiotic molecular modes of action and different gene mutants at the whole-genome level, which will aid in further development on new drugs for effective MRSA treatment based on describing different resistance mechanisms of classic antibiotics.
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Affiliation(s)
- Wan-Ting Liu
- Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510282, China
| | - En-Zhong Chen
- Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510282, China
| | - Ling Yang
- Department of Laboratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510120, China
| | - Chen Peng
- Department of Laboratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510120, China
| | - Qun Wang
- Department of Laboratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510120, China
| | - Zhenbo Xu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China; College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN38163, USA; Research Institute for Food Nutrition and Human Health, Guangzhou, 510640, China; Home Economics Technology, Rajamangala University of Technology Phra Nakhon, Bangkok, Thailand.
| | - Ding-Qiang Chen
- Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, 510282, China.
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18
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Fisher JF, Mobashery S. β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium. Chem Rev 2021; 121:3412-3463. [PMID: 33373523 PMCID: PMC8653850 DOI: 10.1021/acs.chemrev.0c01010] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
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19
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Hou Q, Kolodkin-Gal I. Harvesting the complex pathways of antibiotic production and resistance of soil bacilli for optimizing plant microbiome. FEMS Microbiol Ecol 2021; 96:5872479. [PMID: 32672816 DOI: 10.1093/femsec/fiaa142] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/13/2020] [Indexed: 01/04/2023] Open
Abstract
A sustainable future increasing depends on our capacity to utilize beneficial plant microbiomes to meet our growing needs. Plant microbiome symbiosis is a hallmark of the beneficial interactions between bacteria and their host. Specifically, colonization of plant roots by biocontrol agents and plant growth-promoting bacteria can play an important role in maintaining the optimal rhizosphere environment, supporting plant growth and promoting its fitness. Rhizosphere communities confer immunity against a wide range of foliar diseases by secreting antibiotics and activating plant defences. At the same time, the rhizosphere is a highly competitive niche, with multiple microbial species competing for space and resources, engaged in an arms race involving the production of a vast array of antibiotics and utilization of a variety of antibiotic resistance mechanisms. Therefore, elucidating the mechanisms that govern antibiotic production and resistance in the rhizosphere is of great significance for designing beneficial communities with enhanced biocontrol properties. In this review, we used Bacillus subtilis and B. amyloliquefaciens as models to investigate the genetics of antibiosis and the potential for its translation of into improved plant microbiome performance.
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Affiliation(s)
- Qihui Hou
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ilana Kolodkin-Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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20
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Guo Y, Pfahler NM, Völpel SL, Stehle T. Cell wall glycosylation in Staphylococcus aureus: targeting the tar glycosyltransferases. Curr Opin Struct Biol 2021; 68:166-174. [PMID: 33540375 DOI: 10.1016/j.sbi.2021.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/14/2020] [Accepted: 01/07/2021] [Indexed: 11/26/2022]
Abstract
Peptidoglycan (PG) is the major structural polymer of the bacterial cell wall. The PG layer of gram-positive bacterial pathogens such as Staphylococcus aureus (S. aureus) is permeated with anionic glycopolymers known as wall teichoic acids (WTAs) and lipoteichoic acids (LTAs). In S. aureus, the WTA backbone typically consists of repeating ribitol-5-phosphate units, which are modified by enzymes that introduce glycosylation as well as amino acids at different locations. These modifications are key determinants of phage adhesion, bacterial biofilm formation and virulence of S. aureus. In this review, we examine differences in WTA structures in gram-positive bacteria, focusing in particular on three enzymes, TarM, TarS, and TarP that glycosylate the WTA of S. aureus at different locations. Infections with S. aureus pose an increasing threat to human health, particularly through the emergence of multidrug-resistant strains. Recently obtained structural information on TarM, TarS and TarP has helped to better understand the strategies used by S. aureus to establish resistance and to evade host defense mechanisms. Moreover, structures of complexes with poly-RboP and its analogs can serve as a platform for the development of new inhibitors that could form a basis for the development of antibiotic agents.
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Affiliation(s)
- Yinglan Guo
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany
| | - Nina M Pfahler
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany
| | - Simon L Völpel
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany; Vanderbilt University School of Medicine, Nashville, USA.
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21
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Thitiananpakorn K, Aiba Y, Tan XE, Watanabe S, Kiga K, Sato'o Y, Boonsiri T, Li FY, Sasahara T, Taki Y, Azam AH, Zhang Y, Cui L. Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA). Sci Rep 2020; 10:16107. [PMID: 32999359 PMCID: PMC7527455 DOI: 10.1038/s41598-020-73108-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
Abstract
We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAPS) and DAP non-susceptible (DAPR) MRSA isolates from 12 patients who had DAP therapy, we (i) assessed susceptibility to DAP and VCM, (ii) compared whole-genome sequences, (iii) identified mutations associated with cross-resistance to DAP and VCM, and (iv) investigated the impact of altered gene expression and metabolic pathway relevant to the cross-resistance. We found that all 12 DAPR strains exhibiting cross-resistance to DAP and VCM carried mutations in mprF, while one DAPR strain with reduced susceptibility to only DAP carried a lacF mutation. On the other hand, among the 32 vancomycin-intermediate S. aureus (VISA) strains isolated from patients treated with VCM, five out of the 18 strains showing cross-resistance to DAP and VCM carried a mprF mutation, while 14 strains resistant to only VCM had no mprF mutation. Moreover, substitution of mprF in a DAPS strain with mutated mprF resulted in cross-resistance and vice versa. The elevated lysyl-phosphatidylglycerol (L-PG) production, increased positive bacterial surface charges and activated cell wall (CW) synthetic pathways were commonly found in both clinical isolates and laboratory-developed mutants that carry mprF mutations. We conclude that mprF mutation is responsible for the cross-resistance of MRSA to DAP and VCM, and treatment with DAP is more likely to select for mprF-mediated cross-resistance than is with VCM.
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Affiliation(s)
- Kanate Thitiananpakorn
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yoshifumi Aiba
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Xin-Ee Tan
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Shinya Watanabe
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Kotaro Kiga
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yusuke Sato'o
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Tanit Boonsiri
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Feng-Yu Li
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Teppei Sasahara
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yusuke Taki
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Aa Haeruman Azam
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yuancheng Zhang
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Longzhu Cui
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan.
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22
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Ushino T, Jin W, Wachino JI, Arakawa Y, Kimura K. Daptomycin Susceptibility of Group B Streptococcus. Jpn J Infect Dis 2020; 74:233-235. [PMID: 32999183 DOI: 10.7883/yoken.jjid.2020.371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We previously reported the emergence and high prevalence of group B streptococci (GBS) with reduced penicillin susceptibility (PRGBS) clinical isolates in Japan. PRGBS tend to be non-susceptible to macrolides and fluoroquinolones. In our previous study, we found that the minimum inhibitory concentration (MIC) of daptomycin for one clinical isolate of GBS was above the susceptible breakpoint settled by the Clinical and Laboratory Standards Institute (CLSI). This suggests the possibility of the unrecognized spread of daptomycin-non-susceptible clinical GBS isolates in Japan. This study aimed to analyze the daptomycin susceptibility in 1,046 clinical GBS isolates that were recovered after the approval of daptomycin in Japan. MICs of daptomycin for the 1,046 clinical isolates were determined by the microdilution method recommended by the CLSI. The MIC range was 0.12-1 µg/mL, and the MIC50 and MIC90 were 0.5 µg/mL and 1 µg/mL, respectively. All the GBS isolates evaluated in this study were susceptible to daptomycin. Therefore, at present, daptomycin might be considered as a new option to treat GBS infections, especially multidrug-resistant PRGBS infections.
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Affiliation(s)
- Takumi Ushino
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Japan
| | - Wanchun Jin
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Japan
| | - Jun-Ichi Wachino
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Japan
| | - Yoshichika Arakawa
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Japan
| | - Kouji Kimura
- Department of Bacteriology, Nagoya University Graduate School of Medicine, Japan
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23
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Mellergaard M, Høgh RI, Lund A, Aldana BI, Guérillot R, Møller SH, Hayes AS, Panagiotopoulou N, Frimand Z, Jepsen SD, Hansen CHF, Andresen L, Larsen AR, Peleg AY, Stinear TP, Howden BP, Waagepetersen HS, Frees D, Skov S. Staphylococcus aureus induces cell-surface expression of immune stimulatory NKG2D ligands on human monocytes. J Biol Chem 2020; 295:11803-11821. [PMID: 32605922 PMCID: PMC7450114 DOI: 10.1074/jbc.ra120.012673] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 06/24/2020] [Indexed: 12/24/2022] Open
Abstract
Staphylococcus aureus is among the leading causes of bacterial infections worldwide. The pathogenicity and establishment of S. aureus infections are tightly linked to its ability to modulate host immunity. Persistent infections are often associated with mutant staphylococcal strains that have decreased susceptibility to antibiotics; however, little is known about how these mutations influence bacterial interaction with the host immune system. Here, we discovered that clinical S. aureus isolates activate human monocytes, leading to cell-surface expression of immune stimulatory natural killer group 2D (NKG2D) ligands on the monocytes. We found that expression of the NKG2D ligand ULBP2 (UL16-binding protein 2) is associated with bacterial degradability and phagolysosomal activity. Moreover, S. aureus-induced ULBP2 expression was linked to altered host cell metabolism, including increased cytoplasmic (iso)citrate levels, reduced glycolytic flux, and functional mitochondrial activity. Interestingly, we found that the ability of S. aureus to induce ULBP2 and proinflammatory cytokines in human monocytes depends on a functional ClpP protease in S. aureus These findings indicate that S. aureus activates ULBP2 in human monocytes through immunometabolic mechanisms and reveal that clpP inactivation may function as a potential immune evasion mechanism. Our results provide critical insight into the interplay between the host immune system and S. aureus that has evolved under the dual selective pressure of host immune responses and antibiotic treatment. Our discovery of an immune stimulatory pathway consisting of human monocyte-based defense against S. aureus suggests that targeting the NKG2D pathway holds potential for managing persistent staphylococcal infections.
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Affiliation(s)
- Maiken Mellergaard
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Illum Høgh
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Astrid Lund
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Romain Guérillot
- Department of Microbiology and Immunology, University of Melbourne at the Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Sofie Hedlund Møller
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ashleigh S Hayes
- Department of Microbiology and Immunology, University of Melbourne at the Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Nafsika Panagiotopoulou
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Zofija Frimand
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stine Dam Jepsen
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Camilla Hartmann Friis Hansen
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars Andresen
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders Rhod Larsen
- Statens Serum Institut, Microbiology and Infection Control, Copenhagen, Denmark
| | - Anton Y Peleg
- Department of Infectious Diseases, Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology, University of Melbourne at the Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Benjamin P Howden
- Department of Microbiology and Immunology, University of Melbourne at the Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dorte Frees
- Food Safety and Zoonosis, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Skov
- Experimental Animal Models, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Karas JA, Carter GP, Howden BP, Turner AM, Paulin OKA, Swarbrick JD, Baker MA, Li J, Velkov T. Structure–Activity Relationships of Daptomycin Lipopeptides. J Med Chem 2020; 63:13266-13290. [DOI: 10.1021/acs.jmedchem.0c00780] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John A. Karas
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Glen P. Carter
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia
| | - Benjamin P. Howden
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia
| | - Adrianna M. Turner
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC 3000, Australia
| | - Olivia K. A. Paulin
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - James D. Swarbrick
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Mark. A. Baker
- Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Jian Li
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Tony Velkov
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia
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Savijoki K, Miettinen I, Nyman TA, Kortesoja M, Hanski L, Varmanen P, Fallarero A. Growth Mode and Physiological State of Cells Prior to Biofilm Formation Affect Immune Evasion and Persistence of Staphylococcus aureus. Microorganisms 2020; 8:E106. [PMID: 31940921 PMCID: PMC7023439 DOI: 10.3390/microorganisms8010106] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 01/01/2023] Open
Abstract
The present study investigated Staphylococcus aureus ATCC25923 surfaceomes (cell surface proteins) during prolonged growth by subjecting planktonic and biofilm cultures (initiated from exponential or stationary cells) to label-free quantitative surfaceomics and phenotypic confirmations. The abundance of adhesion, autolytic, hemolytic, and lipolytic proteins decreased over time in both growth modes, while an opposite trend was detected for many tricarboxylic acid (TCA) cycle, reactive oxygen species (ROS) scavenging, Fe-S repair, and peptidolytic moonlighters. In planktonic cells, these changes were accompanied by decreasing and increasing adherence to hydrophobic surface and fibronectin, respectively. Specific RNA/DNA binding (cold-shock protein CspD and ribosomal proteins) and the immune evasion (SpA, ClfA, and IsaB) proteins were notably more abundant on fully mature biofilms initiated with stationary-phase cells (SDBF) compared to biofilms derived from exponential cells (EDBF) or equivalent planktonic cells. The fully matured SDBF cells demonstrated higher viability in THP-1 monocyte/macrophage cells compared to the EDBF cells. Peptidoglycan strengthening, specific urea-cycle, and detoxification enzymes were more abundant on planktonic than biofilm cells, indicating the activation of growth-mode specific pathways during prolonged cultivation. Thus, we show that S. aureus shapes its surfaceome in a growth mode-dependent manner to reach high levofloxacin tolerance (>200-times the minimum biofilm inhibitory concentration). This study also demonstrates that the phenotypic state of the cells prior to biofilm formation affects the immune-evasion and persistence-related traits of S. aureus.
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Affiliation(s)
- Kirsi Savijoki
- Pharmaceutical Design and Discovery (PharmDD) Group, Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, 00014 Helsinki, Finland; (I.M.); (M.K.); (L.H.); (A.F.)
| | - Ilkka Miettinen
- Pharmaceutical Design and Discovery (PharmDD) Group, Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, 00014 Helsinki, Finland; (I.M.); (M.K.); (L.H.); (A.F.)
| | - Tuula A. Nyman
- Department of Immunology, Institute of Clinical Medicine, University of Oslo and Rikshospitalet Oslo, 0372 Oslo, Norway; or
| | - Maarit Kortesoja
- Pharmaceutical Design and Discovery (PharmDD) Group, Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, 00014 Helsinki, Finland; (I.M.); (M.K.); (L.H.); (A.F.)
| | - Leena Hanski
- Pharmaceutical Design and Discovery (PharmDD) Group, Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, 00014 Helsinki, Finland; (I.M.); (M.K.); (L.H.); (A.F.)
| | - Pekka Varmanen
- Department of Food and Nutrition, University of Helsinki, 00014 Helsinki, Finland;
| | - Adyary Fallarero
- Pharmaceutical Design and Discovery (PharmDD) Group, Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5, 00014 Helsinki, Finland; (I.M.); (M.K.); (L.H.); (A.F.)
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Gray DA, Wenzel M. More Than a Pore: A Current Perspective on the In Vivo Mode of Action of the Lipopeptide Antibiotic Daptomycin. Antibiotics (Basel) 2020; 9:E17. [PMID: 31947747 PMCID: PMC7168178 DOI: 10.3390/antibiotics9010017] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 12/29/2019] [Accepted: 12/31/2019] [Indexed: 12/19/2022] Open
Abstract
Daptomycin is a cyclic lipopeptide antibiotic, which was discovered in 1987 and entered the market in 2003. To date, it serves as last resort antibiotic to treat complicated skin infections, bacteremia, and right-sided endocarditis caused by Gram-positive pathogens, most prominently methicillin-resistant Staphylococcus aureus. Daptomycin was the last representative of a novel antibiotic class that was introduced to the clinic. It is also one of the few membrane-active compounds that can be applied systemically. While membrane-active antibiotics have long been limited to topical applications and were generally excluded from systemic drug development, they promise slower resistance development than many classical drugs that target single proteins. The success of daptomycin together with the emergence of more and more multi-resistant superbugs attracted renewed interest in this compound class. Studying daptomycin as a pioneering systemic membrane-active compound might help to pave the way for future membrane-targeting antibiotics. However, more than 30 years after its discovery, the exact mechanism of action of daptomycin is still debated. In particular, there is a prominent discrepancy between in vivo and in vitro studies. In this review, we discuss the current knowledge on the mechanism of daptomycin against Gram-positive bacteria and try to offer explanations for these conflicting observations.
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Affiliation(s)
- Declan Alan Gray
- Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Michaela Wenzel
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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Unknown Risk on the Farm: Does Agricultural Use of Ionophores Contribute to the Burden of Antimicrobial Resistance? mSphere 2019; 4:4/5/e00433-19. [PMID: 31554722 PMCID: PMC6763768 DOI: 10.1128/msphere.00433-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ionophores are the second most widely used class of antibiotic in agriculture, with over 4 million kilograms sold in the United States in 2016. Because ionophores are not used in humans, it is widely assumed that their agricultural use will not impact human health. Consequently, these drugs have not been subject to the same regulations as medically important antibiotics. Ionophores are the second most widely used class of antibiotic in agriculture, with over 4 million kilograms sold in the United States in 2016. Because ionophores are not used in humans, it is widely assumed that their agricultural use will not impact human health. Consequently, these drugs have not been subject to the same regulations as medically important antibiotics. Here, I argue that the current evidence base is insufficient to conclude that ionophores do not contribute to human relevant antimicrobial resistance. It is unclear whether ionophore resistance can result in cross-resistance to medically important antibiotics. Moreover, recent evidence suggests that ionophore use may coselect for resistance to vancomycin in some cases. Systematic investigation of the consequences of agricultural ionophore use for human health is therefore imperative.
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28
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Keinhörster D, George SE, Weidenmaier C, Wolz C. Function and regulation of Staphylococcus aureus wall teichoic acids and capsular polysaccharides. Int J Med Microbiol 2019; 309:151333. [DOI: 10.1016/j.ijmm.2019.151333] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 07/09/2019] [Accepted: 07/17/2019] [Indexed: 01/05/2023] Open
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29
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Porfírio S, Carlson RW, Azadi P. Elucidating Peptidoglycan Structure: An Analytical Toolset. Trends Microbiol 2019; 27:607-622. [DOI: 10.1016/j.tim.2019.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/16/2019] [Accepted: 01/29/2019] [Indexed: 01/04/2023]
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30
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Jeong S, Kim HY, Kim AR, Yun CH, Han SH. Propionate Ameliorates Staphylococcus aureus Skin Infection by Attenuating Bacterial Growth. Front Microbiol 2019; 10:1363. [PMID: 31275281 PMCID: PMC6591440 DOI: 10.3389/fmicb.2019.01363] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/31/2019] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus causes various diseases including skin and soft tissue infections, pneumonia, gastroenteritis, and sepsis. Antibiotic-resistant S. aureus such as methicillin-resistant S. aureus (MRSA) and multidrug-resistant S. aureus is a serious threat in healthcare-associated settings and in the communities. In this study, we investigated the effects of short-chain fatty acids, metabolites produced by commensal bacteria, on the growth of S. aureus both in vitro and in vivo. Sodium propionate (NaP) most potently inhibited the growth of MRSA and multidrug-resistant clinical isolates. Of note, only NaP, but not sodium acetate (NaA) or sodium butyrate (NaB), ameliorated MRSA skin infection, significantly lowering bacterial load, excessive cytokine production, and the size and weight of abscesses approximately by twofold. In addition, interestingly, S. aureus deficient of lipoteichoic acids (LTA) or wall teichoic acids (WTA), which are important in bacterial physiology and antimicrobial susceptibility, was more susceptible to NaP than the wild-type. Furthermore, S. aureus deficient of D-alanine motifs common in LTA and WTA was more susceptible to NaP, its growth being almost completely inhibited. Concordantly, MRSA treated with an inhibitor of D-alanylation on LTA and WTA was more susceptible to NaP, and co-treatment of NaP and a D-alanylation inhibitor further decreased the pathology of MRSA skin infection. Collectively, these results demonstrate that NaP ameliorates MRSA skin infection by attenuating the growth of S. aureus, and suggest an alternative combination treatment strategy against S. aureus infection.
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Affiliation(s)
- Soyoung Jeong
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Hyun Young Kim
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
| | - A Reum Kim
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Cheol-Heui Yun
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Seung Hyun Han
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
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31
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Ernst CM, Peschel A. MprF-mediated daptomycin resistance. Int J Med Microbiol 2019; 309:359-363. [PMID: 31182276 DOI: 10.1016/j.ijmm.2019.05.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/23/2019] [Accepted: 05/31/2019] [Indexed: 12/11/2022] Open
Abstract
Daptomycin has become an important antibiotic for the treatment of serious Methicillin-Resistant Staphylococcus aureus (MRSA) infections. Unlike other approved antibiotics, its mode of action is still under active investigation, as well as the molecular basis of daptomycin resistance, which emerges in some cases during daptomycin treatment. Small nucleotide polymorphisms (SNPs) in the Multiple Peptide Resistance Factor (MprF) appear to play a major role in the resistance mechanism. Until recently, the impact of the SNPs on MprF activity has remained unclear, which is due to conflicting reports on resistance-associated phenotypes and an incomplete understanding of the mode of action of MprF. However, recent structural insights into MprF and studies with isogenic mutants have now led to a new model of MprF-mediated daptomycin resistance, which harmonizes most of the observed phenotypes and provides a basis for challenging biochemical investigations.
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Affiliation(s)
- Christoph M Ernst
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
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32
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Abstract
Staphylococcus aureus is capable of becoming resistant to all classes of antibiotics clinically available and resistance can develop through de novo mutations in chromosomal genes or through acquisition of horizontally transferred resistance determinants. This review covers the most important antibiotics available for treatment of S. aureus infections and a special emphasis is dedicated to the current knowledge of the wide variety of resistance mechanisms that S. aureus employ to withstand antibiotics. Since resistance development has been inevitable for all currently available antibiotics, new therapies are continuously under development. Besides development of new small molecules affecting cell viability, alternative approaches including anti-virulence and bacteriophage therapeutics are being investigated and may become important tools to combat staphylococcal infections in the future.
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Mistretta N, Brossaud M, Telles F, Sanchez V, Talaga P, Rokbi B. Glycosylation of Staphylococcus aureus cell wall teichoic acid is influenced by environmental conditions. Sci Rep 2019; 9:3212. [PMID: 30824758 PMCID: PMC6397182 DOI: 10.1038/s41598-019-39929-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/31/2019] [Indexed: 01/26/2023] Open
Abstract
Wall teichoic acid (WTA) are major constituents of Staphylococcus aureus (S. aureus) cell envelopes with important roles in the bacteria's physiology, resistance to antimicrobial molecules, host interaction, virulence and biofilm formation. They consist of ribitol phosphate repeat units in which the ribitol residue is substituted with D-alanine (D-Ala) and N-acetyl-D-glucosamine (GlcNAc). The complete S. aureus WTA biosynthesis pathways was recently revealed with the identification of the two glycosyltransferases, TarM and TarS, respectively responsible for the α- and β-GlcNAc anomeric substitutions. We performed structural analyses to characterize WTAs from a panel of 24 S. aureus strains responsible for invasive infections. A majority of the S. aureus strains produced the β-GlcNAc WTA form in accordance with the presence of the tarS gene in all strains assessed. The β-GlcNAc anomer was preferentially expressed at the expense of the α-GlcNAc anomer when grown on stress-inducing culture medium containing high NaCl concentration. Furthermore, WTA glycosylation of the prototype S. aureus Newman strain was characterized in vivo in two different animal models, namely peritonitis and deep wound infection. While the inoculum used to infect animals produced almost exclusively α-GlcNAc WTA, a complete switch to β-glycosylation was observed in infected kidneys, livers and muscles. Overall, our data demonstrate that S. aureus WTA glycosylation is strongly influenced by environmental conditions and suggest that β-GlcNAc WTA may bring competitive advantage in vivo.
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Affiliation(s)
- Noëlle Mistretta
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France.
| | - Marina Brossaud
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France
| | - Fabienne Telles
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France
| | - Violette Sanchez
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France
| | - Philippe Talaga
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France
| | - Bachra Rokbi
- Research and Development, Sanofi Pasteur, Marcy l'Etoile, France
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34
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Daptomycin Resistance and Tolerance Due to Loss of Function in Staphylococcus aureus dsp1 and asp23. Antimicrob Agents Chemother 2018; 63:AAC.01542-18. [PMID: 30397055 DOI: 10.1128/aac.01542-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/23/2018] [Indexed: 02/07/2023] Open
Abstract
Lipopeptide daptomycin is a last-line cell-membrane-targeting antibiotic to treat multidrug-resistant Staphylococcus aureus Alarmingly, daptomycin-resistant S. aureus isolates have emerged. The mechanisms underlying daptomycin resistance are diverse and share similarities with resistances to cationic antimicrobial peptides and other lipopeptides, but they remain to be fully elucidated. We selected mutants with increased resistance to daptomycin from a library of transposon insertions in sequent type 8 (ST8) S. aureus HG003. Insertions conferring increased daptomycin resistance were localized to two genes, one coding for a hypothetical lipoprotein (SAOUHSC_00362, Dsp1), and the other for an alkaline shock protein (SAOUHSC_02441, Asp23). Markerless loss-of-function mutants were then generated for comparison. All transposon mutants and knockout strains exhibited increased daptomycin resistance compared to those of wild-type and complemented strains. Null and transposon insertion mutants also exhibited increased resistance to cationic antimicrobial peptides. Interestingly, the Δdsp1 mutant also showed increased resistance to vancomycin, a cell-wall-targeting drug with a different mode of action. Null mutations in both dsp1 and asp23 resulted in increased tolerance as reflected by reduced killing to both daptomycin and vancomycin, as well as an increased tolerance to surfactant (Triton X-100). Neither mutant exhibited increased resistance to lysostaphin, a cell-wall-targeting endopeptidase. These findings identified two genes core to the S. aureus species that make previously uncharacterized contributions to antimicrobial resistance and tolerance in S. aureus.
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35
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Sabat AJ, Tinelli M, Grundmann H, Akkerboom V, Monaco M, Del Grosso M, Errico G, Pantosti A, Friedrich AW. Daptomycin Resistant Staphylococcus aureus Clinical Strain With Novel Non-synonymous Mutations in the mprF and vraS Genes: A New Insight Into Daptomycin Resistance. Front Microbiol 2018; 9:2705. [PMID: 30459746 PMCID: PMC6232378 DOI: 10.3389/fmicb.2018.02705] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/23/2018] [Indexed: 11/25/2022] Open
Abstract
Objectives: Daptomycin (DAP) resistance in Staphylococcus aureus is uncommon but there are increasing reports of the emergence of resistance during DAP therapy. Most clinical DAP-resistant S. aureus isolates investigated carried mutations in the mprF gene. The aim of this study was to identify mutations between a clinical pair of methicillin-susceptible S. aureus (MSSA) isolates (DAP-susceptible and DAP-resistant). Additionally, the activity of genes previously associated with DAP resistance was assessed. Materials and Methods: Two MSSA isolates from patient with left-sided endocarditis were analyzed by whole genome sequencing (WGS) and reverse transcription-quantitative real-time PCR (RT-qPCR). The first isolate, DAP-susceptible, was obtained before initiation of treatment and the second isolate, DAP-resistant, was recovered after 4 weeks of DAP therapy. Results: Comparison of complete genomes of DAP-susceptible and its DAP-resistant variant identified two non-synonymous and one synonymous mutations. The non-synonymous mutations consisted of a S829L substitution in mprF and a T331I substitution in vraS. The RT-qPCR experiments revealed an increased expression of vraS, dltA, mprF, and sceD genes in DAP-resistant variant. Strikingly, the expression of dltA and mprF genes was significantly downregulated by DAP. Conclusion: The mprF and vraS genes were previously associated with DAP resistance, however, none of the mutations described in this study had been previously identified and linked to DAP resistance. Moreover, we provide a new insight into the DAP action on S. aureus, in which the expression of key genes in DAP resistance is decreased by the antibiotic.
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Affiliation(s)
- Artur J Sabat
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Marco Tinelli
- Division of Infectious and Tropical Diseases, Hospital of Lodi, Lodi, Italy
| | - Hajo Grundmann
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.,Institute for Infection Prevention and Hospital Epidemiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Viktoria Akkerboom
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Monica Monaco
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Maria Del Grosso
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Giulia Errico
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Annalisa Pantosti
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Alexander W Friedrich
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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Romaniuk JAH, Cegelski L. Peptidoglycan and Teichoic Acid Levels and Alterations in Staphylococcus aureus by Cell-Wall and Whole-Cell Nuclear Magnetic Resonance. Biochemistry 2018; 57:3966-3975. [PMID: 29806458 PMCID: PMC6309457 DOI: 10.1021/acs.biochem.8b00495] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gram-positive bacteria surround themselves with a multilayered macromolecular cell wall that is essential to cell survival and serves as a major target for antibiotics. The cell wall of Staphylococcus aureus is composed of two major structural components, peptidoglycan (PG) and wall teichoic acid (WTA), together creating a heterogeneous and insoluble matrix that poses a challenge to quantitative compositional analysis. Here, we present 13C cross polarization magic angle spinning solid-state nuclear magnetic resonance (NMR) spectra of intact cell walls, purified PG, and purified WTA. The spectra reveal the clear molecular differences in the two polymers and enable quantification of PG and WTA in isolated cell walls, an attractive alternative to estimating teichoic acid content from a phosphate analysis of completely pyrolyzed cell walls. Furthermore, we discovered that unique PG and WTA spectral signatures could be identified in whole-cell NMR spectra and used to compare PG and WTA levels among intact bacterial cell samples. The distinguishing whole-cell 13C NMR contributions associated with PG include the GlcNAc-MurNAc sugar carbons and glycyl α-carbons. WTA contributes carbons from the phosphoribitol backbone. Distinguishing 15N spectral signatures include glycyl amide nitrogens in PG and the esterified d-alanyl amine nitrogens in WTA. 13C NMR analysis was performed with samples at natural abundance and included 10 whole-cell sample comparisons. Changes consistent with altered PG and WTA content were detected in whole-cell spectra of bacteria harvested at different growth times and in cells treated with tunicamycin. This use of whole-cell NMR provides quantitative parameters of composition in the context of whole-cell activity.
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Affiliation(s)
| | - Lynette Cegelski
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford CA 94305
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37
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Lee GY, Kang KM, Back SH, Baek JY, Kim SH, Park JH, Yang SJ. Adaptations of Vancomycin-Intermediate Sequence Type 72 Methicillin-Resistant Staphylococcus aureus for Daptomycin Nonsusceptibility. Microb Drug Resist 2018; 24:1489-1496. [PMID: 29927700 DOI: 10.1089/mdr.2018.0112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In Korea, the major clonal type of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is sequence type 72 (ST72) with staphylococcal cassette chromosome mec (SCCmec) type IV (ST72-MRSA-IV). In this study, we used a previously well-characterized isogenic pair of ST72 vancomycin (VAN) susceptible-and VAN intermediate-MRSA strains (VSSA303 and VISA072) and several VSSA strains complemented with plasmids expressing single-point mutated genes (dprAG196C, femAF92C, vraRE127K, and vraSRE127K) identified in the VISA strain. Using the strain set, we assessed the (1) susceptibilities to daptomycin (DAP) and cationic antimicrobial peptides (CAMPs), (2) alterations in cell envelope phenotypes, such as cell wall autolysis, surface positive charge, and membrane potential (ΔΨ), (3) transcriptional expression profiles of genes involved in surface charge regulation and changes of ΔΨ, and (4) cytokine stimulation profiles in murine macrophages. The vraRE127K mutation could enhance surface positive charge through mprF- and dltABCD-independent mechanisms with thickened cell wall. However, none of the single-point mutated genes increased DAP resistance. The DAP nonsusceptible (DAP-NS) phenotype observed in VISA072 strain likely resulted from the combined effects of low ΔΨ and increased positive surface charge. These results suggest that physicochemical alterations in cell envelope are involved in the survival response of DAP-NS VISA072 in sites of infections.
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Affiliation(s)
- Gi Yong Lee
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Kyung Mi Kang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Seung Hyun Back
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Jin Yang Baek
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - So Hyun Kim
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - Jong-Hwan Park
- 4 Laboratory Animal Medicine, College of Veterinary Medicine, Chonnam National University , Gwangju, Korea
| | - Soo-Jin Yang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
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Ma Z, Lasek-Nesselquist E, Lu J, Schneider R, Shah R, Oliva G, Pata J, McDonough K, Pai MP, Rose WE, Sakoulas G, Malik M. Characterization of genetic changes associated with daptomycin nonsusceptibility in Staphylococcus aureus. PLoS One 2018; 13:e0198366. [PMID: 29879195 PMCID: PMC5991675 DOI: 10.1371/journal.pone.0198366] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 05/17/2018] [Indexed: 11/25/2022] Open
Abstract
The extensive use of daptomycin (DAP) for treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the last decade has led to the emergence of DAP non-susceptible (DNS) Staphylococcus aureus strains. A better understanding of the molecular changes underlying DAP-non-susceptibility is required for early diagnosis and intervention with alternate combination therapies. The phenotypic changes associated with DNS strains have been well established. However, the genotypic changes—especially the kinetics of expression of the genes responsible for DAP-non-susceptibility are not well understood. In this study, we used three clinically derived isogenic pairs of DAP-susceptible (DAP-S) and DNS S. aureus strains to study gene expression profiles with the objective of identifying the potential genotypic changes associated with DAP-nonsusceptibility. We determined the expression profiles of genes involved in cell membrane (CM) charge, autolysis, cell wall (CW) synthesis, and penicillin binding proteins in DAP-S and DNS isogenic pairs. Our results demonstrate characteristic expression profiles for mprF, dltABCD, vraS, femB, and pbp2a genes, which are common to all the DNS S. aureus strains tested. Whole genome sequencing of DAP-S and DNS clinical isolates of S. aureus showed non-synonymous mutations in all DNS strains in genes involved in CM charge, CM composition, CW thickness and CW composition. To conclude, this study unravels some of the complex molecular changes involved in the development of DAP-nonsusceptibility by demonstrating distinct differences in gene expression profiles and mutations in the DNS S. aureus strains. This knowledge will aid in rapid identification of DNS S. aureus in clinical settings.
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Affiliation(s)
- Zhuo Ma
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Erica Lasek-Nesselquist
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Jackson Lu
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Ryan Schneider
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Riddhi Shah
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - George Oliva
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Janice Pata
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Kathleen McDonough
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Manjunath P. Pai
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
| | - Warren E. Rose
- Universtiy of Wisconsin-Madison, School of Pharmacy, Madison, Wisconsin, United States of America
| | - George Sakoulas
- Center for Immunity, Infection & Inflammation, UCSD School of Medicine, La Jolla, California, United States of America
| | - Meenakshi Malik
- Albany College of Pharmacy and Health Sciences, Albany, New York, United States of America
- * E-mail:
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Müller A, Grein F, Otto A, Gries K, Orlov D, Zarubaev V, Girard M, Sher X, Shamova O, Roemer T, François P, Becher D, Schneider T, Sahl HG. Differential daptomycin resistance development in Staphylococcus aureus strains with active and mutated gra regulatory systems. Int J Med Microbiol 2017; 308:335-348. [PMID: 29429584 DOI: 10.1016/j.ijmm.2017.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 12/13/2017] [Accepted: 12/18/2017] [Indexed: 02/03/2023] Open
Abstract
The first-in-class lipopeptide antibiotic daptomycin (DAP) is highly active against Gram-positive pathogens including ß-lactam and glycopeptide resistant strains. Its molecular mode of action remains enigmatic, since a defined target has not been identified so far and multiple effects, primarily on the cell envelope have been observed. Reduced DAP susceptibility has been described in S. aureus and enterococci after prolonged treatment courses. In line with its pleiotropic antibiotic activities, a unique, defined molecular mechanism of resistance has not emerged, instead non-susceptibility appears often accompanied by alterations in membrane composition and changes in cell wall homeostasis. We compared S. aureus strains HG001 and SG511, which differ primarily in the functionality of the histidine kinase GraS, to evaluate the impact of the GraRS regulatory system on the development of DAP non-susceptibility. After extensive serial passing, both DAPR variants reached a minimal inhibitory concentration of 31 μg/ml and shared some phenotypic characteristics (e.g. thicker cell wall, reduced autolysis). However, based on comprehensive analysis of the underlying genetic, transcriptomic and proteomic changes, we found that both strains took different routes to achieve DAP resistance. Our study highlights the impressive genetic and physiological capacity of S. aureus to counteract pleiotropic activities of cell wall- and membrane-active compounds even when a major cell wall regulatory system is dysfunctional.
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Affiliation(s)
- Anna Müller
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn.
| | - Fabian Grein
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn
| | - Andreas Otto
- Institute for Microbiology, University of Greifswald, Greifswald, Germany
| | - Kathrin Gries
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Dmitriy Orlov
- Institute for Experimental Medicine, Saint Petersburg, Russia; Saint Petersburg University, Saint Petersburg, Russia
| | - Vladimir Zarubaev
- Pasteur Institute of Epidemiology and Microbiology, Saint Petersburg Russia
| | - Myriam Girard
- Genomic Research Laboratory, Department of Medical Specialties, University Hospitals of Geneva, University of Geneva, Geneva, Switzerland
| | - Xinwei Sher
- Merck & Co., Infectious Diseases, Kenilworth, NJ, USA
| | - Olga Shamova
- Institute for Experimental Medicine, Saint Petersburg, Russia; Saint Petersburg University, Saint Petersburg, Russia
| | | | - Patrice François
- Genomic Research Laboratory, Department of Medical Specialties, University Hospitals of Geneva, University of Geneva, Geneva, Switzerland
| | - Dörte Becher
- Institute for Microbiology, University of Greifswald, Greifswald, Germany
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn
| | - Hans-Georg Sahl
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn; Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, University of Bonn, Bonn, Germany
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Characterization of the Mechanisms of Daptomycin Resistance among Gram-Positive Bacterial Pathogens by Multidimensional Lipidomics. mSphere 2017; 2:mSphere00492-17. [PMID: 29242835 PMCID: PMC5729219 DOI: 10.1128/msphere.00492-17] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 11/16/2017] [Indexed: 12/22/2022] Open
Abstract
Previous work suggests that altered lipid metabolism may be associated with daptomycin resistance in Gram-positive pathogens, but lipidomic changes underlying resistance are not fully understood. We performed untargeted lipidomics by using three-dimensional hydrophilic interaction liquid chromatography-ion mobility-mass spectrometry (HILIC-IM-MS) to characterize alterations in the lipidomes of daptomycin-susceptible and -resistant isogenic strain pairs of Enterococcus faecalis, Staphylococcus aureus, and Corynebacterium striatum. We first validated the HILIC-IM-MS method by replicating the expected alterations of phospholipid metabolism in the previously studied E. faecalis strain pairs, such as reduced phosphatidylglycerols (PGs), while also revealing additional changes in cardiolipins (CLs), lysyl-PGs, and glycolipids. Whole-genome sequencing of the S. aureus and C. striatum strains found that daptomycin resistance was associated with mutations in pgsA, which encodes phosphatidylglycerophosphate synthase, as well as mutations in genes affecting fatty acid biosynthesis and cell wall metabolism. Lipidomics revealed significantly decreased levels of PGs, CLs, and amino acid-modified PGs, as well as accumulation of lipids upstream of PGs, such as glycolipids and phosphatidic acids, in the resistant strains. Notably, the glycolipids, diglucosyldiacylglycerols, were significantly elevated in a fatty acid-dependent manner in the daptomycin-resistant S. aureus strain. In daptomycin-resistant C. striatum, which has a unique cell envelope architecture, the glycolipids, glucuronosyldiacylglycerols, and phosphatidylinositols were significantly elevated. These results demonstrate that alteration of lipid metabolism via mutations in pgsA is a common mechanism of daptomycin resistance in two distinct species of Gram-positive bacteria and point to the potential contribution of altered glycolipid and fatty acid compositions to daptomycin resistance. IMPORTANCE This work comprehensively characterizes lipidomic changes underlying daptomycin resistance in three Gram-positive bacterial species, E. faecalis, S. aureus, and C. striatum, by using a novel three-dimensional lipidomics methodology based on advanced mass spectrometry. We demonstrated a number of advantages of our method in comparison with other methods commonly used in the field, such as high molecular specificity, sensitivity, and throughput. Whole-genome sequencing of the S. aureus and C. striatum strains identified mutations in pgsA, which encodes phosphatidylglycerophosphate synthase, in both resistant strains. Lipidomics revealed significantly decreased levels of lipids downstream of PgsA, as well as accumulation of lipids upstream of PgsA in the resistant strains. Furthermore, we found that changes in individual molecular species of each lipid class depend on the their specific fatty acid compositions. The characteristic changes in individual lipid species could be used as biomarkers for identifying underlying resistance mechanisms and for evaluating potential therapies.
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García AB, Viñuela-Prieto JM, López-González L, Candel FJ. Correlation between resistance mechanisms in Staphylococcus aureus and cell wall and septum thickening. Infect Drug Resist 2017; 10:353-356. [PMID: 29089777 PMCID: PMC5655128 DOI: 10.2147/idr.s146748] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose The aim of the present study is to examine cell wall and septum thickening of methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and methicillin- and linezolid-resistant S. aureus (MLRSA) isolates by transmission electron microscopy to correlate the association of resistance mechanisms with major changes in the morphology of membrane or septum. Materials and methods MSSA, MRSA, and MLRSA strains obtained from clinical samples of an outbreak that occurred in 2010 at the Intensive Care Unit of our Hospital were thawed and sown at 37°C in blood agar overnight. After that, they were washed, pelleted, and treated with a fixer solution. Pellets were dehydrated and finally embedded in resin. Transmission electron microscopy was used to characterize cell wall and septum thickening in all isolates. The comparison between the measurements obtained for each group was performed by a Kruskal–Wallis test and a post hoc Dunn–Bonferroni’s pairwise comparison method. Results Differences in cell wall and septum thickness were statistically significant (P<0.001 and P<0.001, respectively) between the three groups. Moreover, significant differences were detected in wall and septum thickness between the MSSA and MRSA strains (P<0.001 and P<0.001, respectively) and between the MSSA and MLRSA strains (P<0.001 and P<0.001, respectively) but not between the MRSA and MLRSA strains (P=0.386 and P=0.117). Conclusion In this analysis, we correlate the resistance mediated by alterations in the cell membrane of S. aureus (methicillin-resistant, for example) with a greater thickness of the wall or septum. The resistance added to linezolid did not determine significant changes in the characteristics of the wall or septum with respect to those strains resistant only to methicillin.
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Affiliation(s)
- Ana Belén García
- Department of Clinical Microbiology, Hospital Clínico San Carlos, Complutense University, Madrid, Spain
| | | | - Laura López-González
- Department of Clinical Microbiology, Hospital Clínico San Carlos, Complutense University, Madrid, Spain
| | - Francisco Javier Candel
- Department of Clinical Microbiology, Hospital Clínico San Carlos, Complutense University, Madrid, Spain.,Health Research Institute, Hospital Universitario San Carlos, Madrid, Spain
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Inhibition of the ATP Synthase Eliminates the Intrinsic Resistance of Staphylococcus aureus towards Polymyxins. mBio 2017; 8:mBio.01114-17. [PMID: 28874470 PMCID: PMC5587909 DOI: 10.1128/mbio.01114-17] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Staphylococcus aureus is intrinsically resistant to polymyxins (polymyxin B and colistin), an important class of cationic antimicrobial peptides used in treatment of Gram-negative bacterial infections. To understand the mechanisms underlying intrinsic polymyxin resistance in S. aureus, we screened the Nebraska Transposon Mutant Library established in S. aureus strain JE2 for increased susceptibility to polymyxin B. Nineteen mutants displayed at least 2-fold reductions in MIC, while the greatest reductions (8-fold) were observed for mutants with inactivation of either graS, graR, vraF, or vraG or the subunits of the ATP synthase (atpA, atpB, atpG, or atpH), which during respiration is the main source of energy. Inactivation of atpA also conferred hypersusceptibility to colistin and the aminoglycoside gentamicin, whereas susceptibilities to nisin, gallidermin, bacitracin, vancomycin, ciprofloxacin, linezolid, daptomycin, and oxacillin were unchanged. ATP synthase activity is known to be inhibited by oligomycin A, and the presence of this compound increased polymyxin B-mediated killing of S. aureus Our results demonstrate that the ATP synthase contributes to intrinsic resistance of S. aureus towards polymyxins and that inhibition of the ATP synthase sensitizes S. aureus to this group of compounds. These findings show that by modulation of bacterial metabolism, new classes of antibiotics may show efficacy against pathogens towards which they were previously considered inapplicable. In light of the need for new treatment options for infections with serious pathogens like S. aureus, this approach may pave the way for novel applications of existing antibiotics.IMPORTANCE Bacterial pathogens that cause disease in humans remain a serious threat to public health, and antibiotics are still our primary weapon in treating bacterial diseases. The ability to eradicate bacterial infections is critically challenged by development of resistance to all clinically available antibiotics. Polymyxins constitute an important class of antibiotics for treatment of infections caused by Gram-negative pathogens, whereas Gram-positive bacteria remain largely insusceptible towards class of antibiotics. Here we performed a whole-genome screen among nonessential genes for polymyxin intrinsic resistance determinants in Staphylococcus aureus We found that the ATP synthase is important for polymyxin susceptibility and that inhibition of the ATP synthase sensitizes S. aureus towards polymyxins. Our study provides novel insights into the mechanisms that limit polymyxin activity against S. aureus and provides valuable targets for inhibitors to potentially enable the use of polymyxins against S. aureus and other Gram-positive pathogens.
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43
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Taylor RM, Scott B, Taylor S, Palmer M. An Acyl-Linked Dimer of Daptomycin Is Strongly Inhibited by the Bacterial Cell Wall. ACS Infect Dis 2017; 3:462-466. [PMID: 28350438 DOI: 10.1021/acsinfecdis.7b00019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The lipopeptide antibiotic daptomycin is active against Gram-positive pathogens. It permeabilizes bacterial cell membranes, which involves the formation of membrane-associated oligomers. We here studied a dimer of daptomycin whose two subunits were linked through a bivalent aliphatic acyl chain. Unexpectedly, the dimer had very low activity on vegetative Staphylococcus aureus and Bacillus subtilis cells. However, activity resembled that of monomeric daptomycin on liposomes and on B. subtilis L-forms. These findings underscore the importance of the bacterial cell wall in daptomycin resistance.
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Affiliation(s)
- Robert M. Taylor
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Bradley Scott
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Scott Taylor
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Michael Palmer
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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44
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Garcia-de-la-Maria C, Xiong YQ, Pericas JM, Armero Y, Moreno A, Mishra NN, Rybak MJ, Tran TT, Arias CA, Sullam PM, Bayer AS, Miro JM. Impact of High-Level Daptomycin Resistance in the Streptococcus mitis Group on Virulence and Survivability during Daptomycin Treatment in Experimental Infective Endocarditis. Antimicrob Agents Chemother 2017; 61:e02418-16. [PMID: 28264848 PMCID: PMC5404581 DOI: 10.1128/aac.02418-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 02/16/2017] [Indexed: 11/20/2022] Open
Abstract
Among the viridans group streptococci, the Streptococcus mitis group is the most common cause of infective endocarditis. These bacteria have a propensity to be β-lactam resistant, as well as to rapidly develop high-level and durable resistance to daptomycin (DAP). We compared a parental, daptomycin-susceptible (DAPs) S. mitis/S. oralis strain and its daptomycin-resistant (DAPr) variant in a model of experimental endocarditis in terms of (i) their relative fitness in multiple target organs in this model (vegetations, kidneys, spleen) when animals were challenged individually and in a coinfection strategy and (ii) their survivability during therapy with daptomycin-gentamicin (an in vitro combination synergistic against the parental strain). The DAPr variant was initially isolated from the cardiac vegetations of animals with experimental endocarditis caused by the parental DAPs strain following treatment with daptomycin. The parental strain and the DAPr variant were comparably virulent when animals were individually challenged. In contrast, in the coinfection model without daptomycin therapy, at both the 106- and 107-CFU/ml challenge inocula, the parental strain outcompeted the DAPr variant in all target organs, especially the kidneys and spleen. When the animals in the coinfection model of endocarditis were treated with DAP-gentamicin, the DAPs strain was completely eliminated, while the DAPr variant persisted in all target tissues. These data underscore that the acquisition of DAPr in S. mitis/S. oralis does come at an intrinsic fitness cost, although this resistance phenotype is completely protective against therapy with a potentially synergistic DAP regimen.
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Affiliation(s)
| | - Y Q Xiong
- LA Biomedical Research Institute, Torrance, California, USA
- Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - J M Pericas
- Hospital Clinic-IDIBAPS, University of Barcelona, Barcelona, Spain
| | - Y Armero
- Hospital Clinic-IDIBAPS, University of Barcelona, Barcelona, Spain
| | - A Moreno
- Hospital Clinic-IDIBAPS, University of Barcelona, Barcelona, Spain
| | - N N Mishra
- LA Biomedical Research Institute, Torrance, California, USA
- Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - M J Rybak
- Anti-Infective Research Laboratory, Wayne State University, Detroit, Michigan, USA
| | - T T Tran
- University of Texas School of Medicine, Houston, Texas, USA
| | - C A Arias
- University of Texas School of Medicine, Houston, Texas, USA
| | - P M Sullam
- Veterans Affairs Medical Center and the University of California, San Francisco, California, USA
| | - A S Bayer
- LA Biomedical Research Institute, Torrance, California, USA
- Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - J M Miro
- Hospital Clinic-IDIBAPS, University of Barcelona, Barcelona, Spain
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Wanner S, Schade J, Keinhörster D, Weller N, George SE, Kull L, Bauer J, Grau T, Winstel V, Stoy H, Kretschmer D, Kolata J, Wolz C, Bröker BM, Weidenmaier C. Wall teichoic acids mediate increased virulence in Staphylococcus aureus. Nat Microbiol 2017; 2:16257. [DOI: 10.1038/nmicrobiol.2016.257] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 11/28/2016] [Indexed: 12/15/2022]
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46
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The action mechanism of daptomycin. Bioorg Med Chem 2016; 24:6253-6268. [DOI: 10.1016/j.bmc.2016.05.052] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/20/2016] [Accepted: 05/26/2016] [Indexed: 11/15/2022]
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Miller WR, Bayer AS, Arias CA. Mechanism of Action and Resistance to Daptomycin in Staphylococcus aureus and Enterococci. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a026997. [PMID: 27580748 DOI: 10.1101/cshperspect.a026997] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lipopeptides are natural product antibiotics that consist of a peptide core with a lipid tail with a diverse array of target organisms and mechanisms of action. Daptomycin (DAP) is an example of these compounds with specific activity against Gram-positive organisms. DAP has become increasingly important to combat infections caused by Gram-positive bacteria because of the presence of multidrug resistance in these organisms, particularly in methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). However, emergence of resistance to DAP during therapy is a well-described phenomenon that threatens the clinical use of this antibiotic, limiting further the therapeutic options against both MRSA and VRE. This work will review the historical aspects of the development of DAP, as well as the current knowledge on its mechanism of action and pathways to resistance in a clinically relevant context.
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Affiliation(s)
- William R Miller
- University of Texas Medical School at Houston, Department of Internal Medicine, Division of Infectious Diseases, Houston, Texas 77030
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502.,David Geffen School of Medicine at UCLA, Los Angeles, California 90095
| | - Cesar A Arias
- University of Texas Medical School at Houston, Department of Internal Medicine, Division of Infectious Diseases, Houston, Texas 77030.,Department of Microbiology and Molecular Genetics, Houston, Texas 77030.,Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia.,International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia
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48
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Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains. Proc Natl Acad Sci U S A 2016; 113:E7077-E7086. [PMID: 27791134 DOI: 10.1073/pnas.1611173113] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Daptomycin is a highly efficient last-resort antibiotic that targets the bacterial cell membrane. Despite its clinical importance, the exact mechanism by which daptomycin kills bacteria is not fully understood. Different experiments have led to different models, including (i) blockage of cell wall synthesis, (ii) membrane pore formation, and (iii) the generation of altered membrane curvature leading to aberrant recruitment of proteins. To determine which model is correct, we carried out a comprehensive mode-of-action study using the model organism Bacillus subtilis and different assays, including proteomics, ionomics, and fluorescence light microscopy. We found that daptomycin causes a gradual decrease in membrane potential but does not form discrete membrane pores. Although we found no evidence for altered membrane curvature, we confirmed that daptomycin inhibits cell wall synthesis. Interestingly, using different fluorescent lipid probes, we showed that binding of daptomycin led to a drastic rearrangement of fluid lipid domains, affecting overall membrane fluidity. Importantly, these changes resulted in the rapid detachment of the membrane-associated lipid II synthase MurG and the phospholipid synthase PlsX. Both proteins preferentially colocalize with fluid membrane microdomains. Delocalization of these proteins presumably is a key reason why daptomycin blocks cell wall synthesis. Finally, clustering of fluid lipids by daptomycin likely causes hydrophobic mismatches between fluid and more rigid membrane areas. This mismatch can facilitate proton leakage and may explain the gradual membrane depolarization observed with daptomycin. Targeting of fluid lipid domains has not been described before for antibiotics and adds another dimension to our understanding of membrane-active antibiotics.
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Binding of Daptomycin to Anionic Lipid Vesicles Is Reduced in the Presence of Lysyl-Phosphatidylglycerol. Antimicrob Agents Chemother 2016; 60:5051-3. [PMID: 27216066 DOI: 10.1128/aac.00744-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/19/2016] [Indexed: 11/20/2022] Open
Abstract
The cytoplasmic membrane of Staphylococcus aureus contains ∼20 mol% of the net cationic lipid lysyl-phosphatidylglycerol (LPG). Elevated fractions of LPG are associated with increased resistance to cationic antibiotics, including the lipopeptide daptomycin (DAP). Although the surface charge of the bacterial cytoplasmic membrane is altered by LPG, surface binding of DAP was found to be only moderately affected in anionic vesicles containing 20 mol% LPG. These results suggest that charge repulsion cannot fully explain LPG-mediated resistance to cationic peptides.
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Antibiotic resistance profiles of coagulase-negative staphylococci in livestock environments. Vet Microbiol 2016; 200:79-87. [PMID: 27185355 DOI: 10.1016/j.vetmic.2016.04.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 04/18/2016] [Accepted: 04/22/2016] [Indexed: 11/22/2022]
Abstract
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) have globally emerged in animal husbandry. In addition to methicillin resistance, LA-MRSA may carry a variety of novel and uncommon antimicrobial resistance genes. Occurrence of the same resistance genes in coagulase-negative staphylococci (CoNS) and S. aureus suggests an ongoing genetic exchange between LA-MRSA and other staphylococci whose driving forces in the ecological niche of the farm environment are, however, still poorly understood. To assess the potential of CoNS as putative reservoirs for antibiotic resistance genes, we analysed the antimicrobial susceptibility of CoNS from dust and manure samples obtained in 41 pig farms in Germany, most of them (36 of 41) with a proven LA-MRSA/MSSA history. Among the 344 isolates analysed, 18 different CoNS species were identified and S. sciuri represented the most prevalent species (46%). High resistance rates were detected for tetracycline (71%), penicillin (65%) and oxacillin (64%) as well as fusidic acid (50%), which was mainly due to reduced susceptibility among S. sciuri isolates. S. sciuri exhibited pronounced multiresistance, and many isolates were characterised by the carriage of a number of uncommon (multi)resistance genes (e.g. cfr, apmA, fexA) and decreased susceptibility towards last resort antibiotics such as linezolid and daptomycin. The combined data suggest that S. sciuri harbours a significant resistance gene pool that requires further attention. We hypothesise that members of this species, due to their flexible lifestyle, might contribute to the spread of such genes in livestock environments.
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