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Hsu YC, Liu CH, Wu YC, Lai SJ, Lin CJ, Tseng TS. Combatting Antibiotic-Resistant Staphylococcus aureus: Discovery of TST1N-224, a Potent Inhibitor Targeting Response Regulator VraRC, through Pharmacophore-Based Screening and Molecular Characterizations. J Chem Inf Model 2024; 64:6132-6146. [PMID: 39078379 DOI: 10.1021/acs.jcim.4c01046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/31/2024]
Abstract
Staphylococcus aureus (S. aureus) is a major global health concern, causing various infections and presenting challenges due to antibiotic resistance. In particular, methicillin-resistant S. aureus, vancomycin-intermediate S. aureus (VISA), and vancomycin-resistant S. aureus pose significant obstacles in treating S. aureus infections. Therefore, the critical need for novel drugs to counter these resistant forms is pressing. Two-component systems (TCSs), integral to bacterial regulation, offer promising targets for disruption. In this study, a comprehensive approach, involving pharmacophore-based inhibitor screening, along with biochemical and biophysical analyses were conducted to identify, characterize, and validate potential inhibitors targeting the response regulator VraRC of S. aureus. The constructed pharmacophore model, Phar-VRPR-N3, demonstrated effectiveness in identifying a potent inhibitor, TST1N-224 (IC50 = 60.2 ± 4.0 μM), against the formation of the VraRC-DNA complex. Notably, TST1N-224 exhibited strong binding to VraRC (KD = 23.4 ± 1.2 μM) using a fast-on-fast-off binding mechanism. Additionally, NMR-based molecular modeling revealed that TST1N-224 predominantly interacts with the α9- and α10-helixes of the DNA-binding domain of VraR, where the interactive and functionally essential residues (N165, K180, S184, and R195) act as hotspots for structure-based inhibitor optimization. Furthermore, TST1N-224 evidently enhanced the susceptibility of VISA to both vancomycin and methicillin. Importantly, TST1N-224 distinguished by 1,2,5,6-tetrathiocane with the 3 and 8 positions modified with ethanesulfonates holds significant potential as a lead compound for the development of new antimicrobial agents.
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Affiliation(s)
- Ying-Chu Hsu
- Division of Neurology, Department of Internal Medicine, Ditmanson Medical Foundation ChiaYi Christian Hospital, Chiayi 600566, Taiwan
| | - Ching-Hui Liu
- Institute of Molecular Biology, National Chung Hsing University, Taichung 40202, Taiwan
| | - Yi-Chen Wu
- Institute of Molecular Biology, National Chung Hsing University, Taichung 40202, Taiwan
| | - Shu-Jung Lai
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 404333, Taiwan
- Research Center for Cancer Biology, China Medical University, Taichung 404333, Taiwan
| | - Chi-Jan Lin
- Institute of Molecular Biology, National Chung Hsing University, Taichung 40202, Taiwan
| | - Tien-Sheng Tseng
- Institute of Molecular Biology, National Chung Hsing University, Taichung 40202, Taiwan
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Deforet F, Carrière R, Dufour PL'A, Prat R, Desbiolles C, Cottin N, Reuzeau A, Dauwalder O, Dupieux-Chabert C, Tristan A, Cecchini T, Lemoine J, Vandenesch F. Proteomic assay for rapid characterisation of Staphylococcus aureus antimicrobial resistance mechanisms directly from blood cultures. Eur J Clin Microbiol Infect Dis 2024; 43:1329-1342. [PMID: 38750334 DOI: 10.1007/s10096-024-04811-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 03/11/2024] [Indexed: 07/20/2024]
Abstract
PURPOSE Staphylococcus aureus is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples. METHODS A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in S. aureus in the context of sepsis: PBP2a, PBP2c, APH(3')-III, ANT(4')-I, and AAC(6')-APH(2''), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124 S.aureus, accounting for the known genomic diversity of SCCmec types and the genetic background of the strains. RESULTS This method provided 99% agreement for PBP2a (n = 98/99 strains) detection. Agreement was 100% for PBP2c (n = 5/5), APH(3')-III (n = 16/16), and ANT(4')-I (n = 20/20), and 94% for AAC(6')-APH(2'') (n = 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4')-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the ant(4')-Ia gene. CONCLUSION The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of S. aureus resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.
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Affiliation(s)
- Francis Deforet
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Romain Carrière
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Pierre L 'Aour Dufour
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Roxane Prat
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Chloé Desbiolles
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Noémie Cottin
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Alicia Reuzeau
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Olivier Dauwalder
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Céline Dupieux-Chabert
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
| | - Anne Tristan
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Tiphaine Cecchini
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France
| | - Jérôme Lemoine
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - François Vandenesch
- Hospices Civils de Lyon, Institut des Agents Infectieux, Lyon, France.
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France.
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France.
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Ralhan K, Iyer KA, Diaz LL, Bird R, Maind A, Zhou QA. Navigating Antibacterial Frontiers: A Panoramic Exploration of Antibacterial Landscapes, Resistance Mechanisms, and Emerging Therapeutic Strategies. ACS Infect Dis 2024; 10:1483-1519. [PMID: 38691668 PMCID: PMC11091902 DOI: 10.1021/acsinfecdis.4c00115] [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: 02/10/2024] [Revised: 04/11/2024] [Accepted: 04/15/2024] [Indexed: 05/03/2024]
Abstract
The development of effective antibacterial solutions has become paramount in maintaining global health in this era of increasing bacterial threats and rampant antibiotic resistance. Traditional antibiotics have played a significant role in combating bacterial infections throughout history. However, the emergence of novel resistant strains necessitates constant innovation in antibacterial research. We have analyzed the data on antibacterials from the CAS Content Collection, the largest human-curated collection of published scientific knowledge, which has proven valuable for quantitative analysis of global scientific knowledge. Our analysis focuses on mining the CAS Content Collection data for recent publications (since 2012). This article aims to explore the intricate landscape of antibacterial research while reviewing the advancement from traditional antibiotics to novel and emerging antibacterial strategies. By delving into the resistance mechanisms, this paper highlights the need to find alternate strategies to address the growing concern.
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Affiliation(s)
| | | | - Leilani Lotti Diaz
- CAS,
A Division of the American Chemical Society, Columbus, Ohio 43210, United States
| | - Robert Bird
- CAS,
A Division of the American Chemical Society, Columbus, Ohio 43210, United States
| | - Ankush Maind
- ACS
International India Pvt. Ltd., Pune 411044, India
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Kowalski CH, Lawhorn S, Smith TJ, Corrigan RM, Barber MF. Adaptation to skin mycobiota promotes antibiotic tolerance in Staphylococcus aureus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.03.592489. [PMID: 38952794 PMCID: PMC11216364 DOI: 10.1101/2024.05.03.592489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
The microbiota can promote host health by inhibiting pathogen colonization, yet how host-resident fungi, or the mycobiota, contribute to this process remains unclear. The human skin mycobiota is uniquely stable compared to other body sites and dominated by yeasts of the genus Malassezia . We observe that colonization of human skin by Malassezia sympodialis significantly reduces subsequent colonization by the prominent bacterial pathogen Staphylococcus aureus . M. sympodialis secreted products possess potent bactericidal activity against S. aureus and are sufficient to impair S. aureus skin colonization. This bactericidal activity requires an acidic environment and is exacerbated by free fatty acids, demonstrating a unique synergy with host-derived epidermal defenses. Leveraging experimental evolution to pinpoint mechanisms of S. aureus adaptation in response to the skin mycobiota, we identified multiple mutations in the stringent response regulator Rel that promote survival against M. sympodialis . Similar Rel alleles have been reported in S. aureus clinical isolates, and natural Rel variants are sufficient for tolerance to M. sympodialis antagonism. Partial stringent response activation underlies tolerance to clinical antibiotics, with both laboratory-evolved and natural Rel variants conferring multidrug tolerance. These findings demonstrate the ability of the mycobiota to mediate pathogen colonization resistance, identify new mechanisms of bacterial adaptation in response to fungal antagonism, and reveal the potential for microbiota-driven evolution to shape pathogen antibiotic susceptibility. Highlights - M. sympodialis reduces colonization of human skin by S. aureus - Bactericidal activity of M. sympodialis is exacerbated by features of the skin niche - S. aureus Rel variants are sufficient for tolerance to Malassezia antagonism - Evolved tolerance to yeast antagonism coincides with S. aureus multidrug tolerance.
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Zeden MS. mSphere of Influence: Targeting bacterial signaling and metabolism to overcome antimicrobial resistance. mSphere 2024; 9:e0063223. [PMID: 38305167 PMCID: PMC10900877 DOI: 10.1128/msphere.00632-23] [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] [Indexed: 02/03/2024] Open
Abstract
Dr Merve Suzan Zeden works in the field of molecular bacteriology and antibiotic resistance. In this mSphere of Influence article, she reflects on how three papers, entitled "c-di-AMP modulates Listeria monocytogenes central metabolism to regulate growth, antibiotic resistance and osmoregulation," "Amino acid catabolism in Staphylococcus aureus and the function of carbon catabolite repression," and "Evolving MRSA: high-level β-lactam resistance in Staphylococcus aureus is associated with RNA polymerase alterations and fine tuning of gene expression," made an impact on her work on bacterial metabolism and antimicrobial resistance and how it shaped her research in understanding the link in between.
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Affiliation(s)
- Merve S Zeden
- School of Biological and Chemical Sciences, College of Science and Engineering, University of Galway, Galway, Ireland
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Zeden MS, Gallagher LA, Bueno E, Nolan AC, Ahn J, Shinde D, Razvi F, Sladek M, Burke Ó, O’Neill E, Fey PD, Cava F, Thomas VC, O’Gara JP. Metabolic reprogramming and altered cell envelope characteristics in a pentose phosphate pathway mutant increases MRSA resistance to β-lactam antibiotics. PLoS Pathog 2023; 19:e1011536. [PMID: 37486930 PMCID: PMC10399904 DOI: 10.1371/journal.ppat.1011536] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 08/03/2023] [Accepted: 07/04/2023] [Indexed: 07/26/2023] Open
Abstract
Central metabolic pathways control virulence and antibiotic resistance, and constitute potential targets for antibacterial drugs. In Staphylococcus aureus the role of the pentose phosphate pathway (PPP) remains largely unexplored. Mutation of the 6-phosphogluconolactonase gene pgl, which encodes the only non-essential enzyme in the oxidative phase of the PPP, significantly increased MRSA resistance to β-lactam antibiotics, particularly in chemically defined media with physiologically-relevant concentrations of glucose, and reduced oxacillin (OX)-induced lysis. Expression of the methicillin-resistance penicillin binding protein 2a and peptidoglycan architecture were unaffected. Carbon tracing and metabolomics revealed extensive metabolic reprogramming in the pgl mutant including increased flux to glycolysis, the TCA cycle, and several cell envelope precursors, which was consistent with increased β-lactam resistance. Morphologically, pgl mutant cells were smaller than wild-type with a thicker cell wall and ruffled surface when grown in OX. The pgl mutation reduced resistance to Congo Red, sulfamethoxazole and oxidative stress, and increased resistance to targocil, fosfomycin and vancomycin. Levels of lipoteichoic acids (LTAs) were significantly reduced in pgl, which may limit cell lysis, while the surface charge of pgl cells was significantly more positive. A vraG mutation in pgl reversed the increased OX resistance phenotype, and partially restored wild-type surface charge, but not LTA levels. Mutations in vraF or graRS from the VraFG/GraRS complex that regulates DltABCD-mediated d-alanylation of teichoic acids (which in turn controls β-lactam resistance and surface charge), also restored wild-type OX susceptibility. Collectively these data show that reduced levels of LTAs and OX-induced lysis combined with a VraFG/GraRS-dependent increase in cell surface positive charge are accompanied by significantly increased OX resistance in an MRSA pgl mutant.
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Affiliation(s)
- Merve S. Zeden
- Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Laura A. Gallagher
- Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Emilio Bueno
- Department of Molecular Biology, Umeå University, MIMS—Laboratory for Molecular Infection Medicine Sweden, Umeå, Sweden
| | - Aaron C. Nolan
- Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Jongsam Ahn
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Dhananjay Shinde
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Fareha Razvi
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Margaret Sladek
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Órla Burke
- Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Eoghan O’Neill
- Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Paul D. Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Felipe Cava
- Department of Molecular Biology, Umeå University, MIMS—Laboratory for Molecular Infection Medicine Sweden, Umeå, Sweden
| | - Vinai C. Thomas
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - James P. O’Gara
- Microbiology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
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Zeden MS, Gallagher LA, Bueno E, Nolan AC, Ahn J, Shinde D, Razvi F, Sladek M, Burke Ó, O'Neill E, Fey PD, Cava F, Thomas VC, O'Gara JP. Metabolic reprogramming and flux to cell envelope precursors in a pentose phosphate pathway mutant increases MRSA resistance to β-lactam antibiotics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.03.530734. [PMID: 36945400 PMCID: PMC10028837 DOI: 10.1101/2023.03.03.530734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Central metabolic pathways controls virulence and antibiotic resistance, and constitute potential targets for antibacterial drugs. In Staphylococcus aureus the role of the pentose phosphate pathway (PPP) remains largely unexplored. Mutation of the 6-phosphogluconolactonase gene pgl, which encodes the only non-essential enzyme in the oxidative phase of the PPP, significantly increased MRSA resistance to β-lactam antibiotics, particularly in chemically defined media with glucose, and reduced oxacillin (OX)-induced lysis. Expression of the methicillin-resistance penicillin binding protein 2a and peptidoglycan architecture were unaffected. Carbon tracing and metabolomics revealed extensive metabolic reprogramming in the pgl mutant including increased flux to glycolysis, the TCA cycle, and several cell envelope precursors, which was consistent with increased β-lactam resistance. Morphologically, pgl mutant cells were smaller than wild-type with a thicker cell wall and ruffled surface when grown in OX. Further evidence of the pleiotropic effect of the pgl mutation was reduced resistance to Congo Red, sulfamethoxazole and oxidative stress, and increased resistance to targocil, fosfomycin and vancomycin. Reduced binding of wheat germ agglutinin (WGA) to pgl was indicative of lower wall teichoic acid/lipoteichoic acid levels or altered teichoic acid structures. Mutations in the vraFG or graRS loci reversed the increased OX resistance phenotype and restored WGA binding to wild-type levels. VraFG/GraRS was previously implicated in susceptibility to cationic antimicrobial peptides and vancomycin, and these data reveal a broader role for this multienzyme membrane complex in the export of cell envelope precursors or modifying subunits required for resistance to diverse antimicrobial agents. Altogether our study highlights important roles for the PPP and VraFG/GraRS in β-lactam resistance, which will support efforts to identify new drug targets and reintroduce β-lactams in combination with adjuvants or other antibiotics for infections caused by MRSA and other β-lactam resistant pathogens. Author summary High-level resistance to penicillin-type (β-lactam) antibiotics significantly limits the therapeutic options for patients with MRSA infections necessitating the use of newer agents, for which reduced susceptibility has already been described. Here we report for the first time that the central metabolism pentose phosphate pathway controls MRSA resistance to penicillin-type antibiotics. We comprehensively demonstrated that mutation of the PPP gene pgl perturbed metabolism in MRSA leading to increased flux to cell envelope precursors to drive increased antibiotic resistance. Moreover, increased resistance was dependent on the VraRG/GraRS multienzyme membrane complex previously implicated in resistance to antimicrobial peptides and vancomycin. Our data thus provide new insights on MRSA mechanisms of β-lactam resistance, which will support efforts to expand the treatment options for infections caused by this and other antimicrobial resistant pathogens.
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Purine Nucleosides Interfere with c-di-AMP Levels and Act as Adjuvants To Re-Sensitize MRSA To β-Lactam Antibiotics. mBio 2023; 14:e0247822. [PMID: 36507833 PMCID: PMC9973305 DOI: 10.1128/mbio.02478-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The purine-derived signaling molecules c-di-AMP and (p)ppGpp control mecA/PBP2a-mediated β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) raise the possibility that purine availability can control antibiotic susceptibility. Consistent with this, exogenous guanosine and xanthosine, which are fluxed through the GTP branch of purine biosynthesis, were shown to significantly reduce MRSA β-lactam resistance. In contrast, adenosine (fluxed to ATP) significantly increased oxacillin resistance, whereas inosine (which can be fluxed to ATP and GTP via hypoxanthine) only marginally increased oxacillin susceptibility. Furthermore, mutations that interfere with de novo purine synthesis (pur operon), transport (NupG, PbuG, PbuX) and the salvage pathway (DeoD2, Hpt) increased β-lactam resistance in MRSA strain JE2. Increased resistance of a nupG mutant was not significantly reversed by guanosine, indicating that NupG is required for guanosine transport, which is required to reduce β-lactam resistance. Suppressor mutants resistant to oxacillin/guanosine combinations contained several purine salvage pathway mutations, including nupG and hpt. Guanosine significantly increased cell size and reduced levels of c-di-AMP, while inactivation of GdpP, the c-di-AMP phosphodiesterase negated the impact of guanosine on β-lactam susceptibility. PBP2a expression was unaffected in nupG or deoD2 mutants, suggesting that guanosine-induced β-lactam susceptibility may result from dysfunctional c-di-AMP-dependent osmoregulation. These data reveal the therapeutic potential of purine nucleosides, as β-lactam adjuvants that interfere with the normal activation of c-di-AMP are required for high-level β-lactam resistance in MRSA. IMPORTANCE The clinical burden of infections caused by antimicrobial resistant (AMR) pathogens is a leading threat to public health. Maintaining the effectiveness of existing antimicrobial drugs or finding ways to reintroduce drugs to which resistance is widespread is an important part of efforts to address the AMR crisis. Predominantly, the safest and most effective class of antibiotics are the β-lactams, which are no longer effective against methicillin-resistant Staphylococcus aureus (MRSA). Here, we report that the purine nucleosides guanosine and xanthosine have potent activity as adjuvants that can resensitize MRSA to oxacillin and other β-lactam antibiotics. Mechanistically, exposure of MRSA to these nucleosides significantly reduced the levels of the cyclic dinucleotide c-di-AMP, which is required for β-lactam resistance. Drugs derived from nucleotides are widely used in the treatment of cancer and viral infections highlighting the clinical potential of using purine nucleosides to restore or enhance the therapeutic effectiveness of β-lactams against MRSA and potentially other AMR pathogens.
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Synergistic Combinations of FDA-Approved Drugs with Ceftobiprole against Methicillin-Resistant Staphylococcus aureus. Microbiol Spectr 2023; 11:e0372622. [PMID: 36519895 PMCID: PMC9927495 DOI: 10.1128/spectrum.03726-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
New strategies are urgently needed to address the public health threat of antimicrobial resistance. Synergistic agent combinations provide one possible pathway toward addressing this need and are also of fundamental mechanistic interest. Effective methods for comprehensively identifying synergistic agent combinations are required for such efforts. In this study, an FDA-approved drug library was screened against methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43300) in the absence and presence of sub-MIC levels of ceftobiprole, a PBP2a-targeted anti-MRSA β-lactam. This screening identified numerous potential synergistic agent combinations, which were then confirmed and characterized for synergy using checkerboard analyses. The initial group of synergistic agents (sum of the minimum fractional inhibitory concentration ∑FICmin ≤0.5) were all β-lactamase-resistant β-lactams (cloxacillin, dicloxacillin, flucloxacillin, oxacillin, nafcillin, and cefotaxime). Cloxacillin-the agent with the greatest synergy with ceftobiprole-is also highly synergistic with ceftaroline, another PBP2a-targeted β-lactam. Further follow-up studies revealed a range of ceftobiprole synergies with other β-lactams, including with imipenem, meropenem, piperacillin, tazobactam, and cefoxitin. Interestingly, given that essentially all other ceftobiprole-β-lactam combinations showed synergy, ceftaroline and ceftobiprole showed no synergy. Modest to no synergy (0.5 < ∑FICmin ≤ 1.0) was observed for several non-β-lactam agents, including vancomycin, daptomycin, balofloxacin, and floxuridine. Mupirocin had antagonistic activity with ceftobiprole. Flucloxacillin appeared particularly promising, with both a low intrinsic MIC and good synergy with ceftobiprole. That so many β-lactam combinations with ceftobiprole show synergy suggests that β-lactam combinations can generally increase β-lactam effectiveness and may also be useful in reducing resistance emergence and spread in MRSA. IMPORTANCE Antimicrobial resistance represents a serious threat to public health. Antibacterial agent combinations provide a potential approach to combating this problem, and synergistic agent combinations-in which each agent enhances the antimicrobial activity of the other-are particularly valuable in this regard. Ceftobiprole is a late-generation β-lactam antibiotic developed for MRSA infections. Resistance has emerged to ceftobiprole, jeopardizing this agent's effectiveness. To identify synergistic agent combinations with ceftobiprole, an FDA-approved drug library was screened for potential synergistic combinations with ceftobiprole. This screening and follow-up studies identified numerous β-lactams with ceftobiprole synergy.
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Molecular Characterization of Clinical Rel Mutations and Consequences for Resistance Expression and Fitness in Staphylococcus aureus. Antimicrob Agents Chemother 2022; 66:e0093822. [PMID: 36346240 PMCID: PMC9764984 DOI: 10.1128/aac.00938-22] [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: 11/09/2022] Open
Abstract
The stringent response (SR) is a universal stress response that acts as a global regulator of bacterial physiology and virulence, and is a contributor to antibiotic tolerance and resistance. In most bacteria, the SR is controlled by a bifunctional enzyme, Rel, which both synthesizes and hydrolyzes the alarmone (p)ppGpp via two distinct catalytic domains. The balance between these antagonistic activities is fine-tuned to the needs of the cell and, in a "relaxed" state, the hydrolase activity of Rel dominates. We have previously shown that two single amino acid substitutions in Rel (that were identified in clinical isolates from persistent infections) confer elevated basal concentrations of (p)ppGpp and consequent multidrug tolerance in Staphylococcus aureus. Here, we explore the molecular details of how these mutations bring about this increase in cellular (p)ppGpp and investigate the wider cellular consequences in terms of resistance expression, resistance development, and bacterial fitness. Using enzyme assays, we show that both these mutations drastically reduce the hydrolase activity of Rel, thereby shifting the balance of Rel activity in favor of (p)ppGpp synthesis. We also demonstrate that these mutations induce high-level, homogeneous expression of β-lactam resistance and confer a significant fitness advantage in the presence of bactericidal antibiotics (but a fitness cost in the absence of antibiotic). In contrast, these mutations do not appear to accelerate the emergence of endogenous resistance mutations in vitro. Overall, our findings reveal the complex nature of Rel regulation and the multifaceted implications of clinical Rel mutations in terms of antibiotic efficacy and bacteria survival.
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In Mycobacterium abscessus, the stringent factor Rel regulates metabolism, but is not the only (p)ppGpp synthase. J Bacteriol 2021; 204:e0043421. [PMID: 34898264 DOI: 10.1128/jb.00434-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The stringent response is a broadly conserved stress response system that exhibits functional variability across bacterial clades. Here, we characterize the role of the stringent factor Rel in the non-tuberculous mycobacterial pathogen, Mycobacterium abscessus (Mab). We found that deletion of rel does not ablate (p)ppGpp synthesis, and that rel does not provide a survival advantage in several stress conditions, or in antibiotic treatment. Transcriptional data show that RelMab is involved in regulating expression of anabolism and growth genes in stationary phase. However, it does not activate transcription of stress response or antibiotic resistance genes, and actually represses transcription of many antibiotic resistance genes. This work shows that there is an unannotated (p)ppGpp synthetase in Mab. Importance In this study, we examined the functional roles of the stringent factor Rel in Mycobacterium abscessus (Mab). In most species, stringent factors synthesize the alarmone (p)ppGpp, which globally alters transcription to promote growth arrest and survival under stress and in antibiotic treatment. Our work shows that in Mab, an emerging pathogen which is resistant to many antibiotics, the stringent factor Rel is not solely responsible for synthesizing (p)ppGpp. We find that RelMab downregulates many metabolic genes under stress, but does not upregulate stress response genes and does not promote antibiotic tolerance. This study implies that there is another critical but unannotated (p)ppGpp synthetase in Mab, and suggests that RelMab inhibitors are unlikely to sensitize Mab infections to antibiotic treatment.
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Pulschen AA, Fernandes AZN, Cunha AF, Sastre DE, Matsuguma BE, Gueiros-Filho FJ. Many birds with one stone: targeting the (p)ppGpp signaling pathway of bacteria to improve antimicrobial therapy. Biophys Rev 2021; 13:1039-1051. [DOI: 10.1007/s12551-021-00895-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 10/25/2021] [Indexed: 12/19/2022] Open
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Accumulation of Succinyl Coenzyme A Perturbs the Methicillin-Resistant Staphylococcus aureus (MRSA) Succinylome and Is Associated with Increased Susceptibility to Beta-Lactam Antibiotics. mBio 2021; 12:e0053021. [PMID: 34182779 PMCID: PMC8437408 DOI: 10.1128/mbio.00530-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Penicillin binding protein 2a (PBP2a)-dependent resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) is regulated by the activity of the tricarboxylic acid (TCA) cycle via a poorly understood mechanism. We report that mutations in sucC and sucD, but not other TCA cycle enzymes, negatively impact β-lactam resistance without changing PBP2a expression. Increased intracellular levels of succinyl coenzyme A (succinyl-CoA) in the sucC mutant significantly perturbed lysine succinylation in the MRSA proteome. Suppressor mutations in sucA or sucB, responsible for succinyl-CoA biosynthesis, reversed sucC mutant phenotypes. The major autolysin (Atl) was the most succinylated protein in the proteome, and increased Atl succinylation in the sucC mutant was associated with loss of autolytic activity. Although PBP2a and PBP2 were also among the most succinylated proteins in the MRSA proteome, peptidoglycan architecture and cross-linking were unchanged in the sucC mutant. These data reveal that perturbation of the MRSA succinylome impacts two interconnected cell wall phenotypes, leading to repression of autolytic activity and increased susceptibility to β-lactam antibiotics.
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15
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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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16
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Nguyen PT, Nguyen MT, Bolhuis A. Inhibition of biofilm formation by alpha-mangostin loaded nanoparticles against Staphylococcus aureus. Saudi J Biol Sci 2021; 28:1615-1621. [PMID: 33732047 PMCID: PMC7938154 DOI: 10.1016/j.sjbs.2020.11.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 11/14/2020] [Indexed: 11/17/2022] Open
Abstract
This study aimed to investigate the antibiofilm activity of alpha-mangostin (AMG) loaded nanoparticles (nanoAMG) against Staphylococcus aureus, including the methicillin-resistant strain MRSA252. The results indicated that treatment with 24 μmol/L nanoAMG inhibited the formation of biofilm biomass by 53-62%, compared to 40-44% for free AMG (p < 0.05). At 48 μmol/L, biofilms in all nanoAMG treated samples were nearly fully disrupted for the two tested strains, MRSA252 and the methicillin-sensitive strain NCTC6571. That concentration resulted in killing of biofilm cells. A lower concentration of 12 µmol/L nanoAMG inhibited initial adherence of the two bacterial strains by > 50%. In contrast, activity of nanoAMG was limited on preformed mature biofilms, which at a concentration of 48 µmol/L were reduced only by 27% and 22% for NCTC6571 and MRSA252, respectively. The effects of AMG or nanoAMG on the expression of biofilm-related genes showed some noticeable differences between the two strains. For instance, the expression level of ebpS was downregulated in MRSA252 and upregulated in NCTC6571 when those strains were treated with either AMG or nanoAMG. In contrast, the expression of fnbB was down regulated in NCTC6571, while it was up-regulated in the MRSA252. The expression of other biofilm-related genes (icaC, clfB and fnbA) was down regulated in both strains. In conclusion, our results suggest that AMG coated nanoparticles had enhanced biological activity as compared to free AMG, indicating that nanoAMG could be a new and promising inhibitor of biofilm formation to tackle S. aureus, including strains that are resistant to multiple antibiotics.
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Affiliation(s)
- Phuong T.M. Nguyen
- Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam
- Corresponding authors at: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam.
| | - Minh T.H. Nguyen
- University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam
| | - Albert Bolhuis
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
- Corresponding authors at: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Viet Nam.
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17
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Mikkelsen K, Sirisarn W, Alharbi O, Alharbi M, Liu H, Nøhr-Meldgaard K, Mayer K, Vestergaard M, Gallagher LA, Derrick JP, McBain AJ, Biboy J, Vollmer W, O'Gara JP, Grunert T, Ingmer H, Xia G. The Novel Membrane-Associated Auxiliary Factors AuxA and AuxB Modulate β-lactam Resistance in MRSA by stabilizing Lipoteichoic Acids. Int J Antimicrob Agents 2021; 57:106283. [PMID: 33503451 DOI: 10.1016/j.ijantimicag.2021.106283] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/08/2020] [Accepted: 12/19/2020] [Indexed: 01/20/2023]
Abstract
A major determinant of β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) is the drug insensitive transpeptidase, PBP2a, encoded by mecA. Full expression of the resistance phenotype requires auxiliary factors. Two such factors, auxiliary factor A (auxA, SAUSA300_0980) and B (auxB, SAUSA300_1003), were identified in a screen against mutants with increased susceptibility to β-lactams in the MRSA strain, JE2. auxA and auxB encode transmembrane proteins, with AuxA predicted to be a transporter. Inactivation of auxA or auxB enhanced β-lactam susceptibility in community-, hospital- and livestock-associated MRSA strains without affecting PBP2a expression, peptidoglycan cross-linking or wall teichoic acid synthesis. Both mutants displayed increased susceptibility to inhibitors of lipoteichoic acid (LTA) synthesis and alanylation pathways and released LTA even in the absence of β-lactams. The β-lactam susceptibility of the aux mutants was suppressed by mutations inactivating gdpP, which was previously found to allow growth of mutants lacking the lipoteichoic synthase enzyme, LtaS. Using the Galleria mellonella infection model, enhanced survival of larvae inoculated with either auxA or auxB mutants was observed compared with the wild-type strain following treatment with amoxicillin. These results indicate that AuxA and AuxB are central for LTA stability and potential inhibitors can be tools to re-sensitize MRSA strains to β-lactams and combat MRSA infections.
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Affiliation(s)
- Kasper Mikkelsen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Denmark
| | - Wanchat Sirisarn
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Ohood Alharbi
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Mohanned Alharbi
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Huayong Liu
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | | | - Katharina Mayer
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
| | - Martin Vestergaard
- Department of Veterinary and Animal Sciences, University of Copenhagen, Denmark
| | - Laura A Gallagher
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Jeremy P Derrick
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom
| | - Andrew J McBain
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, NU Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4AX, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, NU Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4AX, United Kingdom
| | - James P O'Gara
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Tom Grunert
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
| | - Hanne Ingmer
- Department of Veterinary and Animal Sciences, University of Copenhagen, Denmark.
| | - Guoqing Xia
- Lydia Becker Institute of Immunology and Inflammation, Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, M13 9PT, United Kingdom.
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18
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Fritsch VN, Loi VV, Busche T, Tung QN, Lill R, Horvatek P, Wolz C, Kalinowski J, Antelmann H. The alarmone (p)ppGpp confers tolerance to oxidative stress during the stationary phase by maintenance of redox and iron homeostasis in Staphylococcus aureus. Free Radic Biol Med 2020; 161:351-364. [PMID: 33144262 PMCID: PMC7754856 DOI: 10.1016/j.freeradbiomed.2020.10.322] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 10/18/2020] [Accepted: 10/28/2020] [Indexed: 02/07/2023]
Abstract
Slow growing stationary phase bacteria are often tolerant to multiple stressors and antimicrobials. Here, we show that the pathogen Staphylococcus aureus develops a non-specific tolerance towards oxidative stress during the stationary phase, which is mediated by the nucleotide second messenger (p)ppGpp. The (p)ppGpp0 mutant was highly susceptible to HOCl stress during the stationary phase. Transcriptome analysis of the (p)ppGpp0 mutant revealed an increased expression of the PerR, SigB, QsrR, CtsR and HrcA regulons during the stationary phase, indicating an oxidative stress response. The (p)ppGpp0 mutant showed a slight oxidative shift in the bacillithiol (BSH) redox potential (EBSH) and an impaired H2O2 detoxification due to higher endogenous ROS levels. The increased ROS levels in the (p)ppGpp0 mutant were shown to be caused by higher respiratory chain activity and elevated total and free iron levels. Consistent with these results, N-acetyl cysteine and the iron-chelator dipyridyl improved the growth and survival of the (p)ppGpp0 mutant under oxidative stress. Elevated free iron levels caused 8 to 31-fold increased transcription of Fe-storage proteins ferritin (ftnA) and miniferritin (dps) in the (p)ppGpp0 mutant, while Fur-regulated uptake systems for iron, heme or siderophores (efeOBU, isdABCDEFG, sirABC and sstADBCD) were repressed. Finally, the susceptibility of the (p)ppGpp0 mutant towards the bactericidal action of the antibiotics ciprofloxacin and tetracycline was abrogated with N-acetyl cysteine and dipyridyl. Taken together, (p)ppGpp confers tolerance to ROS and antibiotics by down-regulation of respiratory chain activity and free iron levels, lowering ROS formation to ensure redox homeostasis in S. aureus.
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Affiliation(s)
- Verena Nadin Fritsch
- Freie Universität Berlin, Institute of Biology-Microbiology, D-14195, Berlin, Germany
| | - Vu Van Loi
- Freie Universität Berlin, Institute of Biology-Microbiology, D-14195, Berlin, Germany
| | - Tobias Busche
- Freie Universität Berlin, Institute of Biology-Microbiology, D-14195, Berlin, Germany; Center for Biotechnology, Bielefeld University, D-33594, Bielefeld, Germany
| | - Quach Ngoc Tung
- Freie Universität Berlin, Institute of Biology-Microbiology, D-14195, Berlin, Germany
| | - Roland Lill
- Institute of Cytobiology, Philipps-University of Marburg, D-35037, Marburg, Germany; Research Center for Synthetic Microbiology SynMikro, Hans-Meerwein-Str., D-35043, Marburg, Germany
| | - Petra Horvatek
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, D-72076, Tübingen, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, D-72076, Tübingen, Germany
| | - Jörn Kalinowski
- Center for Biotechnology, Bielefeld University, D-33594, Bielefeld, Germany
| | - Haike Antelmann
- Freie Universität Berlin, Institute of Biology-Microbiology, D-14195, Berlin, Germany.
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19
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Das B, Bhadra RK. (p)ppGpp Metabolism and Antimicrobial Resistance in Bacterial Pathogens. Front Microbiol 2020; 11:563944. [PMID: 33162948 PMCID: PMC7581866 DOI: 10.3389/fmicb.2020.563944] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/09/2020] [Indexed: 12/13/2022] Open
Abstract
Single cell microorganisms including pathogens relentlessly face myriads of physicochemical stresses in their living environment. In order to survive and multiply under such unfavorable conditions, microbes have evolved with complex genetic networks, which allow them to sense and respond against these stresses. Stringent response is one such adaptive mechanism where bacteria can survive under nutrient starvation and other related stresses. The effector molecules for the stringent response are guanosine-5'-triphosphate 3'-diphosphate (pppGpp) and guanosine-3', 5'-bis(diphosphate) (ppGpp), together called (p)ppGpp. These effector molecules are now emerging as master regulators for several physiological processes of bacteria including virulence, persistence, and antimicrobial resistance. (p)ppGpp may work independently or along with its cofactor DksA to modulate the activities of its prime target RNA polymerase and other metabolic enzymes, which are involved in different biosynthetic pathways. Enzymes involved in (p)ppGpp metabolisms are ubiquitously present in bacteria and categorized them into three classes, i.e., canonical (p)ppGpp synthetase (RelA), (p)ppGpp hydrolase/synthetase (SpoT/Rel/RSH), and small alarmone synthetases (SAS). While RelA gets activated in response to amino acid starvation, enzymes belonging to SpoT/Rel/RSH and SAS family can synthesize (p)ppGpp in response to glucose starvation and several other stress conditions. In this review, we will discuss about the current status of the following aspects: (i) diversity of (p)ppGpp biosynthetic enzymes among different bacterial species including enteropathogens, (ii) signals that modulate the activity of (p)ppGpp synthetase and hydrolase, (iii) effect of (p)ppGpp in the production of antibiotics, and (iv) role of (p)ppGpp in the emergence of antibiotic resistant pathogens. Emphasis has been given to the cholera pathogen Vibrio cholerae due to its sophisticated and complex (p)ppGpp metabolic pathways, rapid mutational rate, and acquisition of antimicrobial resistance determinants through horizontal gene transfer. Finally, we discuss the prospect of (p)ppGpp metabolic enzymes as potential targets for developing antibiotic adjuvants and tackling persistence of infections.
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Affiliation(s)
- Bhabatosh Das
- Infection and Immunology Division, Translational Health Science and Technology Institute (THSTI), Faridabad, India
| | - Rupak K Bhadra
- Infectious Diseases and Immunology Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB), Kolkata, India
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20
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Identification and characterization of mutations responsible for the β-lactam resistance in oxacillin-susceptible mecA-positive Staphylococcus aureus. Sci Rep 2020; 10:16907. [PMID: 33037239 PMCID: PMC7547103 DOI: 10.1038/s41598-020-73796-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 09/20/2020] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus strains that are susceptible to the β-lactam antibiotic oxacillin despite carrying mecA (OS-MRSA) cause serious clinical problems globally because of their ability to easily acquire β-lactam resistance. Understanding the genetic mechanism(s) of acquisition of the resistance is therefore crucial for infection control management. For this purpose, a whole-genome sequencing-based analysis was performed using 43 clinical OS-MRSA strains and 100 mutants with reduced susceptibility to oxacillin (MICs 1.0–256 µg/mL) generated from 26 representative OS-MRSA strains. Genome comparison between the mutants and their respective parent strains identified a total of 141 mutations in 46 genes and 8 intergenic regions. Among them, the mutations are frequently found in genes related to RNA polymerase (rpoBC), purine biosynthesis (guaA, prs, hprT), (p)ppGpp synthesis (relSau), glycolysis (pykA, fbaA, fruB), protein quality control (clpXP, ftsH), and tRNA synthase (lysS, gltX), whereas no mutations existed in mec and bla operons. Whole-genome transcriptional profile of the resistant mutants demonstrated that expression of genes associated with purine biosynthesis, protein quality control, and tRNA synthesis were significantly inhibited similar to the massive transcription downregulation seen in S. aureus during the stringent response, while the levels of mecA expression and PBP2a production were varied. We conclude that a combination effect of mecA upregulation and stringent-like response may play an important role in acquisition of β-lactam resistance in OS-MRSA.
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21
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The (p)ppGpp Synthetase RSH Mediates Stationary-Phase Onset and Antibiotic Stress Survival in Clostridioides difficile. J Bacteriol 2020; 202:JB.00377-20. [PMID: 32661079 DOI: 10.1128/jb.00377-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/09/2020] [Indexed: 12/31/2022] Open
Abstract
The human pathogen Clostridioides difficile is increasingly tolerant of multiple antibiotics and causes infections with a high rate of recurrence, creating an urgent need for new preventative and therapeutic strategies. The stringent response, a universal bacterial response to extracellular stress, governs antibiotic survival and pathogenesis in diverse organisms but has not previously been characterized in C. difficile Here, we report that the C. difficile (p)ppGpp synthetase RSH is incapable of utilizing GTP or GMP as a substrate but readily synthesizes ppGpp from GDP. The enzyme also utilizes many structurally diverse metal cofactors for reaction catalysis and remains functionally stable at a wide range of environmental pHs. Transcription of rsh is stimulated by stationary-phase onset and by exposure to the antibiotics clindamycin and metronidazole. Chemical inhibition of RSH by the ppGpp analog relacin increases antibiotic susceptibility in epidemic C. difficile R20291, indicating that RSH inhibitors may be a viable strategy for drug development against C. difficile infection. Finally, transcriptional suppression of rsh also increases bacterial antibiotic susceptibility, suggesting that RSH contributes to C. difficile antibiotic tolerance and survival.IMPORTANCE Clostridioides difficile infection (CDI) is an urgent public health threat with a high recurrence rate, in part because the causative bacterium has a high rate of antibiotic survival. The (p)ppGpp-mediated bacterial stringent response plays a role in antibiotic tolerance in diverse pathogens and is a potential target for development of new antimicrobials because the enzymes that metabolize (p)ppGpp have no mammalian homologs. We report that stationary-phase onset and antibiotics induce expression of the clostridial ppGpp synthetase RSH and that both chemical inhibition and translational suppression of RSH increase C. difficile antibiotic susceptibility. This demonstrates that development of RSH inhibitors to serve as adjuvants to antibiotic therapy is a potential approach for the development of new strategies to combat CDI.
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Lamret F, Colin M, Mongaret C, Gangloff SC, Reffuveille F. Antibiotic Tolerance of Staphylococcus aureus Biofilm in Periprosthetic Joint Infections and Antibiofilm Strategies. Antibiotics (Basel) 2020; 9:E547. [PMID: 32867208 PMCID: PMC7558573 DOI: 10.3390/antibiotics9090547] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/18/2020] [Accepted: 08/25/2020] [Indexed: 12/18/2022] Open
Abstract
The need for bone and joint prostheses is currently growing due to population aging, leading to an increase in prosthetic joint infection cases. Biofilms represent an adaptive and quite common bacterial response to several stress factors which confer an important protection to bacteria. Biofilm formation starts with bacterial adhesion on a surface, such as an orthopedic prosthesis, further reinforced by matrix synthesis. The biofilm formation and structure depend on the immediate environment of the bacteria. In the case of infection, the periprosthetic joint environment represents a particular interface between bacteria, host cells, and the implant, favoring biofilm initiation and maturation. Treating such an infection represents a huge challenge because of the biofilm-specific high tolerance to antibiotics and its ability to evade the immune system. It is crucial to understand these mechanisms in order to find new and adapted strategies to prevent and eradicate implant-associated infections. Therefore, adapted models mimicking the infectious site are of utmost importance to recreate a relevant environment in order to test potential antibiofilm molecules. In periprosthetic joint infections, Staphylococcus aureus is mainly involved because of its high adaptation to the human physiology. The current review deals with the mechanisms involved in the antibiotic resistance and tolerance of Staphylococcus aureus in the particular periprosthetic joint infection context, and exposes different strategies to manage these infections.
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Affiliation(s)
- Fabien Lamret
- EA 4691 Biomatériaux et Inflammation en Site Osseux (BIOS), Université de Reims Champagne-Ardenne, SFR Cap Santé (FED 4231), 51097 Reims, France; (F.L.); (M.C.); (C.M.); (S.C.G.)
| | - Marius Colin
- EA 4691 Biomatériaux et Inflammation en Site Osseux (BIOS), Université de Reims Champagne-Ardenne, SFR Cap Santé (FED 4231), 51097 Reims, France; (F.L.); (M.C.); (C.M.); (S.C.G.)
| | - Céline Mongaret
- EA 4691 Biomatériaux et Inflammation en Site Osseux (BIOS), Université de Reims Champagne-Ardenne, SFR Cap Santé (FED 4231), 51097 Reims, France; (F.L.); (M.C.); (C.M.); (S.C.G.)
- Service Pharmacie, CHU Reims, 51097 Reims, France
| | - Sophie C. Gangloff
- EA 4691 Biomatériaux et Inflammation en Site Osseux (BIOS), Université de Reims Champagne-Ardenne, SFR Cap Santé (FED 4231), 51097 Reims, France; (F.L.); (M.C.); (C.M.); (S.C.G.)
| | - Fany Reffuveille
- EA 4691 Biomatériaux et Inflammation en Site Osseux (BIOS), Université de Reims Champagne-Ardenne, SFR Cap Santé (FED 4231), 51097 Reims, France; (F.L.); (M.C.); (C.M.); (S.C.G.)
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23
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Fergestad ME, Stamsås GA, Morales Angeles D, Salehian Z, Wasteson Y, Kjos M. Penicillin-binding protein PBP2a provides variable levels of protection toward different β-lactams in Staphylococcus aureus RN4220. Microbiologyopen 2020; 9:e1057. [PMID: 32419377 PMCID: PMC7424258 DOI: 10.1002/mbo3.1057] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/21/2020] [Accepted: 04/25/2020] [Indexed: 12/31/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to most β-lactams due to the expression of an extra penicillin-binding protein, PBP2a, with low β-lactam affinity. It has long been known that heterologous expression of the PBP2a-encoding mecA gene in methicillin-sensitive S. aureus (MSSA) provides protection towards β-lactams, however, some reports suggest that the degree of protection can vary between different β-lactams. To test this more systematically, we introduced an IPTG-inducible mecA into the MSSA laboratory strain RN4220. We confirm, by growth assays as well as single-cell microfluidics time-lapse microscopy experiments, that PBP2a expression protects against β-lactams in S. aureus RN4220. By testing a panel of ten different β-lactams, we conclude that there is also a great variation in the level of protection conferred by PBP2a. Expression of PBP2a resulted in an only fourfold increase in minimum inhibitory concentration (MIC) for imipenem, while a 32-fold increase in MIC was observed for cefaclor and cephalexin. Interestingly, in our experimental setup, PBP2a confers the highest protection against cefaclor and cephalexin-two β-lactams that are known to have a high specific affinity toward the transpeptidase PBP3 of S. aureus. Notably, using a single-cell microfluidics setup we demonstrate a considerable phenotypic variation between cells upon β-lactam exposure and show that mecA-expressing S. aureus can survive β-lactam concentrations much higher than the minimal inhibitory concentrations. We discuss possible explanations and implications of these results including important aspects regarding treatment of infection.
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Affiliation(s)
- Marte Ekeland Fergestad
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.,Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Gro Anita Stamsås
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Danae Morales Angeles
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Zhian Salehian
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Yngvild Wasteson
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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24
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Fisher JF, Mobashery S. Constructing and deconstructing the bacterial cell wall. Protein Sci 2020; 29:629-646. [PMID: 31747090 PMCID: PMC7021008 DOI: 10.1002/pro.3737] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/11/2022]
Abstract
The history of modern medicine cannot be written apart from the history of the antibiotics. Antibiotics are cytotoxic secondary metabolites that are isolated from Nature. The antibacterial antibiotics disproportionately target bacterial protein structure that is distinct from eukaryotic protein structure, notably within the ribosome and within the pathways for bacterial cell-wall biosynthesis (for which there is not a eukaryotic counterpart). This review focuses on a pre-eminent class of antibiotics-the β-lactams, exemplified by the penicillins and cephalosporins-from the perspective of the evolving mechanisms for bacterial resistance. The mechanism of action of the β-lactams is bacterial cell-wall destruction. In the monoderm (single membrane, Gram-positive staining) pathogen Staphylococcus aureus the dominant resistance mechanism is expression of a β-lactam-unreactive transpeptidase enzyme that functions in cell-wall construction. In the diderm (dual membrane, Gram-negative staining) pathogen Pseudomonas aeruginosa a dominant resistance mechanism (among several) is expression of a hydrolytic enzyme that destroys the critical β-lactam ring of the antibiotic. The key sensing mechanism used by P. aeruginosa is monitoring the molecular difference between cell-wall construction and cell-wall deconstruction. In both bacteria, the resistance pathways are manifested only when the bacteria detect the presence of β-lactams. This review summarizes how the β-lactams are sensed and how the resistance mechanisms are manifested, with the expectation that preventing these processes will be critical to future chemotherapeutic control of multidrug resistant bacteria.
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Affiliation(s)
- Jed F. Fisher
- Department of Chemistry and BiochemistryUniversity of Notre DameSouth BendIndiana
| | - Shahriar Mobashery
- Department of Chemistry and BiochemistryUniversity of Notre DameSouth BendIndiana
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25
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Giulieri SG, Tong SYC, Williamson DA. Using genomics to understand meticillin- and vancomycin-resistant Staphylococcus aureus infections. Microb Genom 2020; 6:e000324. [PMID: 31913111 PMCID: PMC7067033 DOI: 10.1099/mgen.0.000324] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/12/2019] [Indexed: 12/15/2022] Open
Abstract
Resistance to meticillin and vancomycin in Staphylococcus aureus significantly complicates the management of severe infections like bacteraemia, endocarditis or osteomyelitis. Here, we review the molecular mechanisms and genomic epidemiology of resistance to these agents, with a focus on how genomics has provided insights into the emergence and evolution of major meticillin-resistant S. aureus clones. We also provide insights on the use of bacterial whole-genome sequencing to inform management of S. aureus infections and for control of transmission at the hospital and in the community.
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Affiliation(s)
- Stefano G. Giulieri
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Infectious Disease Department, Austin Health, Melbourne, Australia
| | - Steven Y. C. Tong
- Victorian Infectious Disease Service, Royal Melbourne Hospital, and Doherty Department University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Victoria, Australia
- Menzies School of Health Research, Darwin, Australia
| | - Deborah A. Williamson
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
- Microbiological Diagnostic Unit Public Health Laboratory, University of Melbourne at the Peter Doherty Institute of Infection and Immunity, Melbourne, Australia
- Microbiology, Royal Melbourne Hospital, Melbourne, Australia
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26
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Sarhan SR, Hashim HO, Al-Shuhaib MBS. The Gly152Val mutation possibly confers resistance to beta-lactam antibiotics in ovine Staphylococcus aureus isolates. Open Vet J 2019; 9:339-348. [PMID: 32042657 PMCID: PMC6971359 DOI: 10.4314/ovj.v9i4.12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/21/2019] [Indexed: 12/30/2022] Open
Abstract
Background: The mecA gene is a key factor that allows bacterial cells to resist several antibiotics. Aim: This study was conducted to detect the mecA gene polymorphism in ovine wounds and its possible association with the structure and function of penicillin binding protein A2 (PBP2A). Methods: One genetic locus of 1,967 bp that covered the majority of the coding regions of the mecA gene within methicillin-resistant Staphylococcus aureus (MRSA) DNA sequences was designed. Results: In addition to standard microbiological tests, PCR-sequencing reactions and phylogenetic analyses confirmed the identity of the targeted MRSA bacteria. Seven novel missense SNPs, including N57T, N115Y, D120N, D139N, G152V, E189K, and F211V, were observed in the mecA amplicons. Multiple state-of-the-art in silico tools were utilized to assess the consequences of each observed SNP in terms of its effect on the corresponding PBP2A protein structure and function. It was shown that some MRSA isolates exhibited a highly PBP2A-damaging SNP, G152V, which showed an entirely deleterious effect on the PBP2A. Furthermore, G152V induced an alteration in the PBP2A interaction with its receptor, which presumably reduced its affinity to bind with the beta-lactams. Conclusion: The present report indicated a possible role for the observed deleterious G152V SNP in the reduction of PBP2A binding with beta-lactams, which has led to a remarkable increase in MRSA’s resistance to antibiotics.
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Affiliation(s)
- Sarhan R Sarhan
- Department of Pharmacology and Physiology, College of Veterinary Medicine, Wasit University, Wasit, Iraq
| | - Hayder O Hashim
- Department of Clinical Laboratory Sciences, College of Pharmacy, University of Babylon, Iraq
| | - Mohammed Baqur S Al-Shuhaib
- Department of Animal Production, College of Agriculture, Al-Qasim Green University, Al-Qasim, Babil 51001, Iraq
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27
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de Melo DA, da S Soares B, da Motta CC, Dubenczuck FC, Barbieri NL, Logue CM, de O Coelho S, da S Coelho I, de Souza MMS. Accuracy of PCR universal primer for methicillin-resistant Staphylococcus and comparison of different phenotypic screening assays. Braz J Microbiol 2019; 51:403-407. [PMID: 31664699 DOI: 10.1007/s42770-019-00171-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/03/2019] [Indexed: 11/24/2022] Open
Abstract
Characterization of methicillin-resistant Staphylococcus (MRS) is a continuous challenge at diagnostic laboratories. The phenotypic methods present heterogeneous results and the occurrence of variants of mecA gene turned this goal even more challenging to achieve. The present study provided an accurate and highly discriminatory screening tool for MRS, improving its detection.
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Affiliation(s)
- Dayanne A de Melo
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bianca da S Soares
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cássia C da Motta
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Felipe C Dubenczuck
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nicolle L Barbieri
- Department of Population Health, University of Georgia, College of Veterinary Medicine, Athens, GA, USA
| | - Catherine M Logue
- Department of Population Health, University of Georgia, College of Veterinary Medicine, Athens, GA, USA
| | - Shana de O Coelho
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Irene da S Coelho
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Miliane M S de Souza
- Veterinary Microbiology and Immunology Department, Federal Rural University of Rio de Janeiro, Rio de Janeiro, Brazil.
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28
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Cabral DJ, Penumutchu S, Reinhart EM, Zhang C, Korry BJ, Wurster JI, Nilson R, Guang A, Sano WH, Rowan-Nash AD, Li H, Belenky P. Microbial Metabolism Modulates Antibiotic Susceptibility within the Murine Gut Microbiome. Cell Metab 2019; 30:800-823.e7. [PMID: 31523007 PMCID: PMC6948150 DOI: 10.1016/j.cmet.2019.08.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 06/24/2019] [Accepted: 08/20/2019] [Indexed: 12/22/2022]
Abstract
Although antibiotics disturb the structure of the gut microbiota, factors that modulate these perturbations are poorly understood. Bacterial metabolism is an important regulator of susceptibility in vitro and likely plays a large role within the host. We applied a metagenomic and metatranscriptomic approach to link antibiotic-induced taxonomic and transcriptional responses within the murine microbiome. We found that antibiotics significantly alter the expression of key metabolic pathways at the whole-community and single-species levels. Notably, Bacteroides thetaiotaomicron, which blooms in response to amoxicillin, upregulated polysaccharide utilization. In vitro, we found that the sensitivity of this bacterium to amoxicillin was elevated by glucose and reduced by polysaccharides. Accordingly, we observed that dietary composition affected the abundance and expansion of B. thetaiotaomicron, as well as the extent of microbiome disruption with amoxicillin. Our work indicates that the metabolic environment of the microbiome plays a role in the response of this community to antibiotics.
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Affiliation(s)
- Damien J Cabral
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Swathi Penumutchu
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Elizabeth M Reinhart
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Cheng Zhang
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55904, USA
| | - Benjamin J Korry
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Jenna I Wurster
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Rachael Nilson
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - August Guang
- Center for Computation & Visualization, Brown University, Brown University, Providence, RI 02906, USA; Center for Computational Biology of Human Disease, Brown University, Providence, RI 02906, USA
| | - William H Sano
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Aislinn D Rowan-Nash
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA
| | - Hu Li
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55904, USA
| | - Peter Belenky
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02906, USA.
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29
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Harrison EM, Ba X, Coll F, Blane B, Restif O, Carvell H, Köser CU, Jamrozy D, Reuter S, Lovering A, Gleadall N, Bellis KL, Uhlemann AC, Lowy FD, Massey RC, Grilo IR, Sobral R, Larsen J, Rhod Larsen A, Vingsbo Lundberg C, Parkhill J, Paterson GK, Holden MTG, Peacock SJ, Holmes MA. Genomic identification of cryptic susceptibility to penicillins and β-lactamase inhibitors in methicillin-resistant Staphylococcus aureus. Nat Microbiol 2019; 4:1680-1691. [PMID: 31235959 PMCID: PMC7611363 DOI: 10.1038/s41564-019-0471-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/26/2019] [Indexed: 01/04/2023]
Abstract
Antibiotic resistance in bacterial pathogens threatens the future of modern medicine. One such resistant pathogen is methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to nearly all β-lactam antibiotics, limiting treatment options. Here, we show that a significant proportion of MRSA isolates from different lineages, including the epidemic USA300 lineage, are susceptible to penicillins when used in combination with β-lactamase inhibitors such as clavulanic acid. Susceptibility is mediated by a combination of two different mutations in the mecA promoter region that lowers mecA-encoded penicillin-binding protein 2a (PBP2a) expression, and in the majority of isolates by either one of two substitutions in PBP2a (E246G or M122I) that increase the affinity of PBP2a for penicillin in the presence of clavulanic acid. Treatment of S. aureus infections in wax moth and mouse models shows that penicillin/β-lactamase inhibitor susceptibility can be exploited as an effective therapeutic choice for 'susceptible' MRSA infection. Finally, we show that isolates with the PBP2a E246G substitution have a growth advantage in the presence of penicillin but the absence of clavulanic acid, which suggests that penicillin/β-lactamase susceptibility is an example of collateral sensitivity (resistance to one antibiotic increases sensitivity to another). Our findings suggest that widely available and currently disregarded antibiotics could be effective in a significant proportion of MRSA infections.
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Affiliation(s)
- Ewan M Harrison
- Wellcome Sanger Institute, Hinxton, UK.
- Department of Medicine, University of Cambridge, Cambridge, UK.
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
| | - Xiaoliang Ba
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Francesc Coll
- London School of Hygiene and Tropical Medicine, London, UK
| | - Beth Blane
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Olivier Restif
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Henry Carvell
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Claudio U Köser
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | - Sandra Reuter
- Institute for Infection Prevention and Hospital Epidemiology, Medical Center - University of Freiburg, Freiburg, Germany
| | - Andrew Lovering
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | | | | | - Anne-Catrin Uhlemann
- Division of Infectious Diseases, Department of Medicine, Columbia University, New York, NY, USA
| | - Franklin D Lowy
- Division of Infectious Diseases, Department of Medicine, Columbia University, New York, NY, USA
| | - Ruth C Massey
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, UK
| | - Inês R Grilo
- UCIBIO@REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Rita Sobral
- UCIBIO@REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Jesper Larsen
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Anders Rhod Larsen
- Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | | | | | - Gavin K Paterson
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
- The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | | | - Sharon J Peacock
- Wellcome Sanger Institute, Hinxton, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
- London School of Hygiene and Tropical Medicine, London, UK
| | - Mark A Holmes
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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30
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Hobbs JK, Boraston AB. (p)ppGpp and the Stringent Response: An Emerging Threat to Antibiotic Therapy. ACS Infect Dis 2019; 5:1505-1517. [PMID: 31287287 DOI: 10.1021/acsinfecdis.9b00204] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In 1969, Cashel and Gallant first observed the presence of (p)ppGpp-the signaling molecule of the stringent response-in starved bacterial cells. Fifty years later, (p)ppGpp and the stringent response have emerged as essential master regulators of not only the bacterial response to stress but also almost all aspects of bacterial physiology, virulence, and immune evasion. More worryingly, a wealth of data now indicate that (p)ppGpp and stringent response activation pose a serious threat to the efficacy and clinical success of antimicrobial therapy. Here, we focus on the central role that (p)ppGpp and the stringent response play in the phenomenon of antibiotic tolerance, as well as the acquisition, development, and expression of antibiotic resistance. We review these consequences of stringent response activation in relation to the main proteins involved in (p)ppGpp production and control, in particular the complex interplay between monofunctional and bifunctional long RelA/SpoT homologues (RSHs) and small alarmone synthetases (SASs). We also review the growing evidence to suggest that there are multiple other indirect pathways of stringent response induction that can affect antibiotic efficacy. Finally, we summarize recent studies that indicate the in vivo and clinical impact of (p)ppGpp production on antibiotic treatment outcomes. We conclude by reviewing the progress to date in the search for novel therapeutics that target the stringent response.
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Affiliation(s)
- Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
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31
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Lian X, Wang X, Liu X, Xia J, Fang L, Sun J, Liao X, Liu Y. oqxAB-Positive IncHI2 Plasmid pHXY0908 Increase Salmonella enterica Serotype Typhimurium Strains Tolerance to Ciprofloxacin. Front Cell Infect Microbiol 2019; 9:242. [PMID: 31334135 PMCID: PMC6617520 DOI: 10.3389/fcimb.2019.00242] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 06/18/2019] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica serotype Typhimurium is a major global food-borne pathogen and causes life-threatening infections. Although the resistance mechanisms to fluoroquinolones in S. Typhimurium had been well-defined, tolerance to fluoroquinolones and the associated mechanism for this are obscure. In the current work, we investigated an oqxAB-positive plasmid pHXY0908 and analyzed its role in S. Typhimurium tolerance to ciprofloxacin using time-kill, transcriptome sequencing and real-time PCR. S. Typhimurium ATCC14028 could survive under lethal concentrations of ciprofloxacin after acquiring plasmid pHXY0908. Transcriptome sequence analysis showed the chromosomal genes were systematically regulated after acquiring this plasmid suggesting an interaction between chromosome and plasmid. Additionally, the chromosomal efflux pump genes acrB, acrA, tolC, and yceE were up-regulated after acquiring plasmid pHXY0908 suggesting that these efflux pumps may contribute to the survival of ATCC14028 exposed to the lethal concentrations of ciprofloxacin. In conclusion, this is the first known report demonstrating that an IncHI2 type plasmid harboring oqxAB could assist S. Typhimurium survival under lethal concentrations of ciprofloxacin.
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Affiliation(s)
- Xinlei Lian
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Xiran Wang
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Xiao Liu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Jing Xia
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Liangxing Fang
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Jian Sun
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Xiaoping Liao
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
| | - Yahong Liu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, China.,Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China
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Abstract
Dating back to the 1960s, initial studies on the staphylococcal cell wall were driven by the need to clarify the mode of action of the first antibiotics and the resistance mechanisms developed by the bacteria. During the following decades, the elucidation of the biosynthetic path and primary composition of staphylococcal cell walls was propelled by advances in microbial cell biology, specifically, the introduction of high-resolution analytical techniques and molecular genetic approaches. The field of staphylococcal cell wall gradually gained its own significance as the complexity of its chemical structure and involvement in numerous cellular processes became evident, namely its versatile role in host interactions, coordination of cell division and environmental stress signaling.This chapter includes an updated description of the anatomy of staphylococcal cell walls, paying particular attention to information from the last decade, under four headings: high-resolution analysis of the Staphylococcus aureus peptidoglycan; variations in peptidoglycan composition; genetic determinants and enzymes in cell wall synthesis; and complex functions of cell walls. The latest contributions to a more precise picture of the staphylococcal cell envelope were possible due to recently developed state-of-the-art microscopy and spectroscopy techniques and to a wide combination of -omics approaches, that are allowing to obtain a more integrative view of this highly dynamic structure.
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Affiliation(s)
- Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
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Identification of a Novel Gene Associated with High-Level β-Lactam Resistance in Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Strain Mu3 and Methicillin-Resistant S. aureus Strain N315. Antimicrob Agents Chemother 2019; 63:AAC.00712-18. [PMID: 30455230 DOI: 10.1128/aac.00712-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 10/25/2018] [Indexed: 12/16/2022] Open
Abstract
β-Lactam resistance levels vary among methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates, mediated by chromosomal mutations and exogenous resistance gene mecA However, MRSA resistance mechanisms are incompletely understood. A P440L mutation in the RNA polymerase β' subunit (RpoC) in slow-vancomycin-intermediate S. aureus (sVISA) strain V6-5 is associated with conversion of heterogeneous VISA (hVISA) to sVISA. In this study, we found a V6-5-derivative strain (L4) with significantly decreased MICs to oxacillin (OX) and vancomycin. Whole-genome sequencing revealed that L4 has nonsense mutations in two genes, relQ, encoding (p)ppGpp synthetase, an alarmone of the stringent response, and a gene of unknown function. relQ deletion in the hVISA strain Mu3 did not affect OX MIC. However, introducing nonsense mutation of the unknown gene into Mu3 decreased OX MIC, whereas wild-type gene recovered high-level resistance. Thus, mutation of this unknown gene (ehoM) decreased β-lactam resistance in Mu3 and L4. Presence of relQ in a multicopy plasmid restored high-level resistance in strain L4 but not in the ehoM mutant Mu3 strain, indicating a genetic interaction between ehoM and relQ depending on the L4 genetic background. While mupirocin (a stringent response inducer) can increase the β-lactam resistance of MRSA, mupirocin supplementation in an ehoM deletion mutant of N315 did not elevate resistance. ehoM expression in N315 was induced by mupirocin, and the relative amount of ehoM transcript in Mu3 was higher than in N315 induced by the stringent response. Our findings indicate that ehoM plays an essential role in high-level β-lactam resistance in MRSA via the stringent response.
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34
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High Prevalence of Multiple Drug Resistant and Biofilm Forming Staphylococcus aureus among HIV-Infected Patients with Suspected Pneumonia. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2018. [DOI: 10.22207/jpam.12.4.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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35
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Hua X, Yang Q, Zhang W, Dong Z, Yu S, Schwarz S, Liu S. Antibacterial Activity and Mechanism of Action of Aspidinol Against Multi-Drug-Resistant Methicillin-Resistant Staphylococcus aureus. Front Pharmacol 2018; 9:619. [PMID: 29950995 PMCID: PMC6008372 DOI: 10.3389/fphar.2018.00619] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/23/2018] [Indexed: 12/03/2022] Open
Abstract
This study aimed at investigating the antibacterial activity of aspidinol, an extract from Dryopteris fragrans (L.) Schott, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA isolates were treated with aspidinol to determine the differential expression of genes and associated pathways following the drug treatment. Aspidinol displayed significant anti-MRSA activity, both in vivo (minimum inhibitory concentration = 2 μg/mL) and in vitro, and achieved an antibacterial effect comparable to that of vancomycin. In the lethal septicemic mouse study, a dose of 50 mg/kg of either aspidinol or vancomycin provided significant protection from mortality. In the non-lethal septicemic mouse study, aspidinol and vancomycin produced a significant reduction in mean bacterial load in murine organs, including the spleen, lung, and liver. After treatment with aspidinol, we found through RNA-seq and RT-PCR experiments that the inhibition of the formation of ribosomes was the primary S. aureus cell-killing mechanism, and the inhibition of amino acid synthesis and the reduction of virulence factors might play a secondary role.
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Affiliation(s)
- Xin Hua
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Qin Yang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Wanjiang Zhang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhimin Dong
- Tianjin Animal Science and Veterinary Research Institute, Tianjin, China
| | - Shenye Yu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Stefan Schwarz
- Institute of Microbiology and Epizootics, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Siguo Liu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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36
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Genetic Determinants of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2018; 62:AAC.00206-18. [PMID: 29555636 DOI: 10.1128/aac.00206-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/11/2018] [Indexed: 12/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains carry either a mecA- or a mecC-mediated mechanism of resistance to beta-lactam antibiotics, and the phenotypic expression of resistance shows extensive strain-to-strain variation. In recent communications, we identified the genetic determinants associated with the stringent stress response that play a major role in the antibiotic resistant phenotype of the historically earliest "archaic" clone of MRSA and in the mecC-carrying MRSA strain LGA251. Here, we sought to test whether or not the same genetic determinants also contribute to the resistant phenotype of highly and homogeneously resistant (H*R) derivatives of a major contemporary MRSA clone, USA300. We found that the resistance phenotype was linked to six genes (fruB, gmk, hpt, purB, prsA, and relA), which were most frequently targeted among the analyzed 20 H*R strains (one mutation per clone in 19 of the 20 H*R strains). Besides the strong parallels with our previous findings (five of the six genes matched), all but one of the repeatedly targeted genes were found to be linked to guanine metabolism, pointing to the key role that this pathway plays in defining the level of antibiotic resistance independent of the clonal type of MRSA.
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Kim HY, Go J, Lee KM, Oh YT, Yoon SS. Guanosine tetra- and pentaphosphate increase antibiotic tolerance by reducing reactive oxygen species production in Vibrio cholerae. J Biol Chem 2018; 293:5679-5694. [PMID: 29475943 PMCID: PMC5900777 DOI: 10.1074/jbc.ra117.000383] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 02/16/2018] [Indexed: 02/06/2023] Open
Abstract
The pathogen Vibrio cholerae is the causative agent of cholera. Emergence of antibiotic-resistant V. cholerae strains is increasing, but the underlying mechanisms remain unclear. Herein, we report that the stringent response regulator and stress alarmone guanosine tetra- and pentaphosphate ((p)ppGpp) significantly contributes to antibiotic tolerance in V. cholerae We found that N16961, a pandemic V. cholerae strain, and its isogenic (p)ppGpp-overexpressing mutant ΔrelAΔspoT are both more antibiotic-resistant than (p)ppGpp0 (ΔrelAΔrelVΔspoT) and ΔdksA mutants, which cannot produce or utilize (p)ppGpp, respectively. We also found that additional disruption of the aconitase B-encoding and tricarboxylic acid (TCA) cycle gene acnB in the (p)ppGpp0 mutant increases its antibiotic tolerance. Moreover, expression of TCA cycle genes, including acnB, was increased in (p)ppGpp0, but not in the antibiotic-resistant ΔrelAΔspoT mutant, suggesting that (p)ppGpp suppresses TCA cycle activity, thereby entailing antibiotic resistance. Importantly, when grown anaerobically or incubated with an iron chelator, the (p)ppGpp0 mutant became antibiotic-tolerant, suggesting that reactive oxygen species (ROS) are involved in antibiotic-mediated bacterial killing. Consistent with that hypothesis, tetracycline treatment markedly increased ROS production in the antibiotic-susceptible mutants. Interestingly, expression of the Fe(III) ABC transporter substrate-binding protein FbpA was increased 10-fold in (p)ppGpp0, and fbpA gene deletion restored viability of tetracycline-exposed (p)ppGpp0 cells. Of note, FbpA expression was repressed in the (p)ppGpp-accumulating mutant, resulting in a reduction of intracellular free iron, required for the ROS-generating Fenton reaction. Our results indicate that (p)ppGpp-mediated suppression of central metabolism and iron uptake reduces antibiotic-induced oxidative stress in V. cholerae.
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Affiliation(s)
- Hwa Young Kim
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Junhyeok Go
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Kang-Mu Lee
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and
| | - Young Taek Oh
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Freshwater Bioresources Utilization Division, Nakdonggang National Institute of Biological Resources, SangJu 37242, Korea, To whom correspondence may be addressed:
Freshwater Bioresources Utilization Division, Nakdonggang National Institute of Biological Resources, SangJu-si 37242, Korea. Tel.:
82-54-530-0932; Fax:
82-54-530-0949; E-mail:
| | - Sang Sun Yoon
- From the Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, and ,the Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 03722, Korea and , To whom correspondence may be addressed:
Dept. of Microbiology and Immunology, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu Seoul 120-752, Korea. Tel.:
82-2-2228-1824; Fax:
82-2-392-7088; E-mail:
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Prevalence of Slow-Growth Vancomycin Nonsusceptibility in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2017; 61:AAC.00452-17. [PMID: 28827421 PMCID: PMC5655046 DOI: 10.1128/aac.00452-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 08/13/2017] [Indexed: 01/05/2023] Open
Abstract
We previously reported a novel phenotype of vancomycin-intermediate Staphylococcus aureus (VISA), i.e., “slow VISA,” whose colonies appear only after 72 h of incubation. Slow-VISA strains can be difficult to detect because prolonged incubation is required and the phenotype is unstable. To develop a method for detection of slow-VISA isolates, we studied 23 slow-VISA isolates derived from the heterogeneous VISA (hVISA) clinical strain Mu3. We identified single nucleotide polymorphisms (SNPs) in genes involved in various pathways which have been implicated in the stringent response, such as purine/pyrimidine synthesis, cell metabolism, and cell wall peptidoglycan synthesis. We found that mupirocin, which also induces the stringent response, caused stable expression of vancomycin resistance. On the basis of these results, we developed a method for detection of slow-VISA strains by use of 0.032 μg/ml mupirocin (Yuki Katayama, 7 March 2017, patent application PCT/JP2017/008975). Using this method, we detected 53 (15.6%) slow-VISA isolates among clinical methicillin-resistant S. aureus (MRSA) isolates. In contrast, the VISA phenotype was detected in fewer than 1% of isolates. Deep-sequencing analysis showed that slow-VISA clones are present in small numbers among hVISA isolates and proliferate in the presence of vancomycin. This slow-VISA subpopulation may account in part for the recurrence and persistence of MRSA infection.
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Antibiotic Resistance as a Stress Response: Recovery of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus "Auxiliary" ( fem) Mutants by Induction of the Stringent Stress Response. Antimicrob Agents Chemother 2017. [PMID: 28630179 DOI: 10.1128/aac.00313-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Studies with methicillin-resistant Staphylococcus aureus (MRSA) strain COL have shown that the optimal resistance phenotype requires not only mecA but also a large number of "auxiliary genes" identified by Tn551 mutagenesis. The majority of auxiliary mutants showed greatly increased levels of oxacillin resistance when grown in the presence of sub-MICs of mupirocin, suggesting that the mechanism of reduced resistance in the auxiliary mutants involved the interruption of a stringent stress response, causing reduced production of penicillin-binding protein 2A (PBP 2A).
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Schroeder M, Brooks BD, Brooks AE. The Complex Relationship between Virulence and Antibiotic Resistance. Genes (Basel) 2017; 8:E39. [PMID: 28106797 PMCID: PMC5295033 DOI: 10.3390/genes8010039] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/21/2016] [Accepted: 01/07/2017] [Indexed: 12/17/2022] Open
Abstract
Antibiotic resistance, prompted by the overuse of antimicrobial agents, may arise from a variety of mechanisms, particularly horizontal gene transfer of virulence and antibiotic resistance genes, which is often facilitated by biofilm formation. The importance of phenotypic changes seen in a biofilm, which lead to genotypic alterations, cannot be overstated. Irrespective of if the biofilm is single microbe or polymicrobial, bacteria, protected within a biofilm from the external environment, communicate through signal transduction pathways (e.g., quorum sensing or two-component systems), leading to global changes in gene expression, enhancing virulence, and expediting the acquisition of antibiotic resistance. Thus, one must examine a genetic change in virulence and resistance not only in the context of the biofilm but also as inextricably linked pathologies. Observationally, it is clear that increased virulence and the advent of antibiotic resistance often arise almost simultaneously; however, their genetic connection has been relatively ignored. Although the complexities of genetic regulation in a multispecies community may obscure a causative relationship, uncovering key genetic interactions between virulence and resistance in biofilm bacteria is essential to identifying new druggable targets, ultimately providing a drug discovery and development pathway to improve treatment options for chronic and recurring infection.
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Affiliation(s)
- Meredith Schroeder
- Department of Microbiological Sciences; North Dakota State University, Fargo, ND 58105, USA.
| | - Benjamin D Brooks
- Department of Electrical and Computer Engineering; North Dakota State University, Fargo, ND 58105, USA.
| | - Amanda E Brooks
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA.
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Okada BK, Seyedsayamdost MR. Antibiotic dialogues: induction of silent biosynthetic gene clusters by exogenous small molecules. FEMS Microbiol Rev 2016; 41:19-33. [PMID: 27576366 DOI: 10.1093/femsre/fuw035] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/03/2016] [Accepted: 07/29/2016] [Indexed: 12/21/2022] Open
Abstract
Natural products have traditionally served as a dominant source of therapeutic agents. They are produced by dedicated biosynthetic gene clusters that assemble complex, bioactive molecules from simple precursors. Recent genome sequencing efforts coupled with advances in bioinformatics indicate that the majority of biosynthetic gene clusters are not expressed under normal laboratory conditions. Termed 'silent' or 'cryptic', these gene clusters represent a treasure trove for discovery of novel small molecules, their regulatory circuits and their biosynthetic pathways. In this review, we assess the capacity of exogenous small molecules in activating silent secondary metabolite gene clusters. Several approaches that have been developed are presented, including coculture techniques, ribosome engineering, chromatin remodeling and high-throughput elicitor screens. The rationale, applications and mechanisms attendant to each are discussed. Some general conclusions can be drawn from our analysis: exogenous small molecules comprise a productive avenue for the discovery of cryptic metabolites. Specifically, growth-inhibitory molecules, in some cases clinically used antibiotics, serve as effective inducers of silent biosynthetic gene clusters, suggesting that old antibiotics may be used to find new ones. The involvement of natural antibiotics in modulating secondary metabolism at subinhibitory concentrations suggests that they represent part of the microbial vocabulary through which inter- and intraspecies interactions are mediated.
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Affiliation(s)
- Bethany K Okada
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Mohammad R Seyedsayamdost
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA .,Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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Chung M, Kim CK, Conceição T, Aires-De-Sousa M, De Lencastre H, Tomasz A. Heterogeneous oxacillin-resistant phenotypes and production of PBP2A by oxacillin-susceptible/mecA-positive MRSA strains from Africa. J Antimicrob Chemother 2016; 71:2804-9. [PMID: 27278899 DOI: 10.1093/jac/dkw209] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/04/2016] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVES Recent surveillance of MRSA colonizing patients and healthcare workers in two African countries (Angola and São Tomé and Príncipe) reported the frequent recovery of oxacillin-susceptible MRSA (OS-MRSA): Staphylococcus aureus strains that gave positive results with the mecA DNA probe, but had low oxacillin MIC values characteristic of susceptible S. aureus. This apparent dissociation of the drug-resistant phenotype from mecA-the primary genetic determinant of resistance-prompted us to perform a more detailed analysis on nine of the African OS-MRSA strains. METHODS Oxacillin MIC values were determined by Etest and population analysis profiles with and without induction of the stringent stress response by mupirocin. Biochemical profiling using SDS-PAGE followed by western blotting was used for the detection of PBP2A protein produced. RESULTS Cultures of the African MRSA strains (ST88-IVa and ST8-V) showed heterogeneous oxacillin resistance in which the majority of cells exhibited low oxacillin MICs (≤0.75 mg/L), but highly resistant subpopulations were also present with oxacillin MIC values up to several hundred mg/L and with frequencies of 10(-4) to 10(-6). The same strains after induction of the stringent stress response by mupirocin 'converted' the heterogeneous phenotypes into a more homogeneous and higher level resistance. After induction by oxacillin and mupirocin, each of the nine African OS-MRSA strains produced PBP2A-the protein product of mecA. CONCLUSIONS The resistant phenotype of OS-MRSA resembles the phenotypes of historically early MRSA clones. The nature of genetic determinants responsible for the heterogeneous phenotypes of OS-MRSA remains to be determined.
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Affiliation(s)
- Marilyn Chung
- Laboratory of Microbiology & Infectious Diseases, The Rockefeller University, New York, NY 10065, USA
| | - Choon Keun Kim
- Laboratory of Microbiology & Infectious Diseases, The Rockefeller University, New York, NY 10065, USA
| | - Teresa Conceição
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier (ITQB), Universidade Nova de Lisboa (UNL), Oeiras, Portugal
| | | | - Hermínia De Lencastre
- Laboratory of Microbiology & Infectious Diseases, The Rockefeller University, New York, NY 10065, USA Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier (ITQB), Universidade Nova de Lisboa (UNL), Oeiras, Portugal
| | - Alexander Tomasz
- Laboratory of Microbiology & Infectious Diseases, The Rockefeller University, New York, NY 10065, USA
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Complete Reconstitution of the Vancomycin-Intermediate Staphylococcus aureus Phenotype of Strain Mu50 in Vancomycin-Susceptible S. aureus. Antimicrob Agents Chemother 2016; 60:3730-42. [PMID: 27067329 PMCID: PMC4879404 DOI: 10.1128/aac.00420-16] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/01/2016] [Indexed: 12/23/2022] Open
Abstract
Complete reconstitution of the vancomycin-intermediate Staphylococcus aureus (VISA) phenotype of strain Mu50 was achieved by sequentially introducing mutations into six genes of vancomycin-susceptible S. aureus (VSSA) strain N315ΔIP. The six mutated genes were detected in VISA strain Mu50 but not in N315ΔIP. Introduction of the mutation Ser329Leu into vraS, encoding the sensor histidine kinase of the vraSR two-component regulatory (TCR) system, and another mutation, Glu146Lys, into msrR, belonging to the LytR-CpsA-Psr (LCP) family, increased the level of vancomycin resistance to that detected in heterogeneous vancomycin-intermediate S. aureus (hVISA) strain Mu3. Introduction of two more mutations, Asn197Ser into graR of the graSR TCR system and His481Tyr into rpoB, encoding the β subunit of RNA polymerase, converted the hVISA strain into a VISA strain with the same level of vancomycin resistance as Mu50. Surprisingly, however, the constructed quadruple mutant strain ΔIP4 did not have a thickened cell wall, a cardinal feature of the VISA phenotype. Subsequent study showed that cell wall thickening was an inducible phenotype in the mutant strain, whereas it was a constitutive one in Mu50. Finally, introduction of the Ala297Val mutation into fdh2, which encodes a putative formate dehydrogenase, or a 67-amino-acid sequence deletion into sle1 [sle1(Δ67aa)], encoding the hydrolase of N-acetylmuramyl-l-alanine amidase in the peptidoglycan, converted inducible cell wall thickening into constitutive cell wall thickening. sle1(Δ67aa) was found to cause a drastic decrease in autolysis activity. Thus, all six mutated genes required for acquisition of the VISA phenotype were directly or indirectly involved in the regulation of cell physiology. The VISA phenotype seemed to be achieved through multiple genetic events accompanying drastic changes in cell physiology.
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