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Niu H, Gu J, Zhang Y. Bacterial persisters: molecular mechanisms and therapeutic development. Signal Transduct Target Ther 2024; 9:174. [PMID: 39013893 PMCID: PMC11252167 DOI: 10.1038/s41392-024-01866-5] [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: 11/04/2023] [Revised: 05/06/2024] [Accepted: 05/13/2024] [Indexed: 07/18/2024] Open
Abstract
Persisters refer to genetically drug susceptible quiescent (non-growing or slow growing) bacteria that survive in stress environments such as antibiotic exposure, acidic and starvation conditions. These cells can regrow after stress removal and remain susceptible to the same stress. Persisters are underlying the problems of treating chronic and persistent infections and relapse infections after treatment, drug resistance development, and biofilm infections, and pose significant challenges for effective treatments. Understanding the characteristics and the exact mechanisms of persister formation, especially the key molecules that affect the formation and survival of the persisters is critical to more effective treatment of chronic and persistent infections. Currently, genes related to persister formation and survival are being discovered and confirmed, but the mechanisms by which bacteria form persisters are very complex, and there are still many unanswered questions. This article comprehensively summarizes the historical background of bacterial persisters, details their complex characteristics and their relationship with antibiotic tolerant and resistant bacteria, systematically elucidates the interplay between various bacterial biological processes and the formation of persister cells, as well as consolidates the diverse anti-persister compounds and treatments. We hope to provide theoretical background for in-depth research on mechanisms of persisters and suggest new ideas for choosing strategies for more effective treatment of persistent infections.
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Affiliation(s)
- Hongxia Niu
- School of Basic Medical Science and Key Laboratory of Blood-stasis-toxin Syndrome of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, China
| | - Jiaying Gu
- School of Basic Medical Science and Key Laboratory of Blood-stasis-toxin Syndrome of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, China
| | - Ying Zhang
- State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, 310003, Zhejiang, China.
- Jinan Microecological Biomedicine Shandong Laboratory, Jinan, 250022, Shandong, China.
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Xie S, Li Y, Cao W, Peng J, Huang K, Meng J, Li X. Dual-Responsive Nanogels with Cascaded Gentamicin Release and Lysosomal Escape to Combat Intracellular Small Colony Variants for Peritonitis and Sepsis Therapies. Adv Healthc Mater 2024; 13:e2303671. [PMID: 38416744 DOI: 10.1002/adhm.202303671] [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: 10/24/2023] [Revised: 02/22/2024] [Indexed: 03/01/2024]
Abstract
Intracellular bacteria are the major cause of serious infections including sepsis and peritonitis, but face great challenges in fighting against the stubborn intracellular small colony variants (SCVs). Herein, the authors have developed nanogels (NGs) to destroy both planktonic bacteria and SCVs and eliminate excessive inflammations for peritonitis and sepsis therapies. Free gentamicin (GEN) and hydroxyapatite nanoparticles (NPs) with GEN loading and mannose grafts (mHAG) are inoculated into ε-polylysine NGs to obtain NG@G1-mHAG2 through crosslinking with phenylboronic acid and tannic acid. The H2O2 consumption after reaction with phenylboronic esters and the elimination of free radicals by tannic acid alleviates the escalated inflammatory status to promote sepsis therapy. After mannose-mediated uptake into macrophages, the acid-triggered degradation of mHAG NPs generates Ca2+ to destabilize lysosomes and the efficient lysosomal escape leads to reversion of hypometabolic SCVs into normal phenotype and their sensitivity to GEN. In a peritonitis mouse model, NG@G1-mHAG2 treatment provides strong and persistent bactericidal effects against both extracellular bacteria and intracellular SCVs and extends survival of peritonitis mice without apparent hepatomegaly, splenomegaly, pulmonary edema, and inflammatory cell infiltration. Thus, this study demonstrates a concise and versatile strategy to eliminate SCVs and relieve inflammatory storms for peritonitis and sepsis therapies without infection recurrence.
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Affiliation(s)
- Shuang Xie
- School of Life Science and Engineering, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- Institute of Biomedical Engineering, College of Medicine, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Yu Li
- School of Life Science and Engineering, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- Institute of Biomedical Engineering, College of Medicine, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Wenxiong Cao
- Institute of Biomedical Engineering, College of Medicine, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Jiawen Peng
- Institute of Biomedical Engineering, College of Medicine, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Kun Huang
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Jie Meng
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
| | - Xiaohong Li
- School of Life Science and Engineering, Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- Institute of Biomedical Engineering, College of Medicine, Southwest Jiaotong University, Chengdu, 610031, P. R. China
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
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3
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Onyango LA, Liang J. Manuka honey as a non-antibiotic alternative against Staphylococcus spp. and their small colony variant (SCVs) phenotypes. Front Cell Infect Microbiol 2024; 14:1380289. [PMID: 38868298 PMCID: PMC11168119 DOI: 10.3389/fcimb.2024.1380289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 03/21/2024] [Indexed: 06/14/2024] Open
Abstract
The antibiotic resistance (ABR) crisis is an urgent global health priority. Staphylococci are among the problematic bacteria contributing to this emergency owing to their recalcitrance to many clinically important antibiotics. Staphylococcal pathogenesis is further complicated by the presence of small colony variants (SCVs), a bacterial subpopulation displaying atypical characteristics including retarded growth, prolific biofilm formation, heightened antibiotic tolerance, and enhanced intracellular persistence. These capabilities severely impede current chemotherapeutics, resulting in chronic infections, poor patient outcomes, and significant economic burden. Tackling ABR requires alternative measures beyond the conventional options that have dominated treatment regimens over the past 8 decades. Non-antibiotic therapies are gaining interest in this arena, including the use of honey, which despite having ancient therapeutic roots has now been reimagined as an alternative treatment beyond just traditional topical use, to include the treatment of an array of difficult-to-treat staphylococcal infections. This literature review focused on Manuka honey (MH) and its efficacy as an anti-staphylococcal treatment. We summarized the studies that have used this product and the technologies employed to study the antibacterial mechanisms that render MH a suitable agent for the management of problematic staphylococcal infections, including those involving staphylococcal SCVs. We also discussed the status of staphylococcal resistance development to MH and other factors that may impact its efficacy as an alternative therapy to help combat ABR.
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Affiliation(s)
- Laura A. Onyango
- Department of Biology, Trinity Western University, Langley, BC, Canada
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Jiang Z, Li J, Wang J, Pan Y, Liang S, Hu Y, Wang L. Multifunctional fucoidan-loaded Zn-MOF-encapsulated microneedles for MRSA-infected wound healing. J Nanobiotechnology 2024; 22:152. [PMID: 38575979 PMCID: PMC10996189 DOI: 10.1186/s12951-024-02398-4] [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: 10/11/2023] [Accepted: 03/18/2024] [Indexed: 04/06/2024] Open
Abstract
Infected wound healing remains a challenging task in clinical practice due to several factors: (I) drug-resistant infections caused by various pathogens, (II) persistent inflammation that hinders tissue regeneration and (III) the ability of pathogens to persist intracellularly and evade antibiotic treatment. Microneedle patches (MNs), recognized for their effecacious and painless subcutaneous drug delivery, could greatly enhance wound healing if integrated with antibacterial functionality and tissue regenerative potential. A multifunctional agent with subcellular targeting capability and contained novel antibacterial components, upon loading onto MNs, could yield excellent therapeutic effects on wound infections. In this study, we sythesised a zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) loaded with low molecular weight fucoidan (Fu) and further coating by hyaluronic acid (HA), obtained a multifunctional HAZ@Fu NPs, which could hinders Methicillin-resistant Staphylococcus aureus (MRSA) growth and promotes M2 polarization in macrophages. We mixed HAZ@Fu NPs with photocrosslinked gelatin methacryloyl (GelMA) and loaded it into the tips of the MNs (HAZ@Fu MNs), administered to mice model with MRSA-infected full-thickness cutaneous wounds. MNs are able to penetrate the skin barrier, delivering HAZ@Fu NPs into the dermal layer. Since cells within infected tissues extensively express the HA receptor CD44, we also confirmed the HA endows the nanoparticles with the ability to target MRSA in subcellular level. In vitro and in vivo murine studies have demonstrated that MNs are capable of delivering HAZ@Fu NPs deep into the dermal layers. And facilitated by the HA coating, HAZ@Fu NPs could target MRSA surviving at the subcellular level. The effective components, such as zinc ions, Fu, and hyaluronic acid could sustainably released, which contributes to antibacterial activity, mitigates inflammation, promotes epithelial regeneration and fosters neovascularization. Through the RNA sequencing of macrophages post co-culture with HAZ@Fu, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis reveals that the biological functionalities associated with wound healing could potentially be facilitated through the PI3K-Akt pathway. The results indicate that the synergistic application of HAZ@Fu NPs with biodegradable MNs may serve as a significant adjunct in the treatment of infected wounds. The intricate mechanisms driving its biological effects merit further investigation.
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Affiliation(s)
- Zichao Jiang
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jingyi Li
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jiahao Wang
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yixiao Pan
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Shuailong Liang
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yihe Hu
- Department of Orthopedics, First Affiliated Hospital, School of Medicine, Zhejiang, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.
| | - Long Wang
- Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, China.
- University Hunan Engineering Research Center of Biomedical Metal and Ceramic Implants, Xiangya Hospital, Central South University, Changsha, China.
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.
- Hunan Key Laboratory of Aging Biology, Xiangya Hospital, Central South University, Changsha, China.
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van den Biggelaar RHGA, Walburg KV, van den Eeden SJF, van Doorn CLR, Meiler E, de Ries AS, Meijer AH, Ottenhoff THM, Saris A. Identification of kinase modulators as host-directed therapeutics against intracellular methicillin-resistant Staphylococcus aureus. Front Cell Infect Microbiol 2024; 14:1367938. [PMID: 38590439 PMCID: PMC10999543 DOI: 10.3389/fcimb.2024.1367938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/11/2024] [Indexed: 04/10/2024] Open
Abstract
The increasing prevalence of antimicrobial-resistant Staphylococcus aureus strains, especially methicillin-resistant S. aureus (MRSA), poses a threat to successful antibiotic treatment. Unsuccessful attempts to develop a vaccine and rising resistance to last-resort antibiotics urge the need for alternative treatments. Host-directed therapy (HDT) targeting critical intracellular stages of S. aureus emerges as a promising alternative, potentially acting synergistically with antibiotics and reducing the risk of de novo drug resistance. We assessed 201 ATP-competitive kinase inhibitors from Published Kinase Inhibitor Sets (PKIS1 and PKIS2) against intracellular MRSA. Seventeen hit compounds were identified, of which the two most effective and well-tolerated hit compounds (i.e., GW633459A and GW296115X) were selected for further analysis. The compounds did not affect planktonic bacterial cultures, while they were active in a range of human cell lines of cervical, skin, lung, breast and monocyte origin, confirming their host-directed mechanisms. GW633459A, structurally related to lapatinib, exhibited an HDT effect on intracellular MRSA independently of its known human epidermal growth factor receptor (EGFR)/(HER) kinase family targets. GW296115X activated adenosine monophosphate-activated protein kinase (AMPK), thereby enhancing bacterial degradation via autophagy. Finally, GW296115X not only reduced MRSA growth in human cells but also improved the survival rates of MRSA-infected zebrafish embryos, highlighting its potential as HDT.
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Affiliation(s)
- Robin H. G. A. van den Biggelaar
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, Netherlands
| | - Kimberley V. Walburg
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Susan J. F. van den Eeden
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Cassandra L. R. van Doorn
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Eugenia Meiler
- Global Health Medicines R&D, GlaxoSmithKline, Tres Cantos, Spain
| | - Alex S. de Ries
- Institute of Biology Leiden, Leiden University, Leiden, Netherlands
| | | | - Tom H. M. Ottenhoff
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Anno Saris
- Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
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6
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Boggon C, Mairpady Shambat S, Zinkernagel AS, Secchi E, Isa L. Single-cell patterning and characterisation of antibiotic persistent bacteria using bio-sCAPA. LAB ON A CHIP 2023; 23:5018-5028. [PMID: 37909096 PMCID: PMC10661667 DOI: 10.1039/d3lc00611e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/13/2023] [Indexed: 11/02/2023]
Abstract
In microbiology, accessing single-cell information within large populations is pivotal. Here we introduce bio-sCAPA, a technique for patterning bacterial cells in defined geometric arrangements and monitoring their growth in various nutrient environments. We demonstrate bio-sCAPA with a study of subpopulations of antibiotic-tolerant bacteria, known as persister cells, which can survive exposure to high doses of antibiotics despite lacking any genetic resistance to the drug. Persister cells are associated with chronic and relapsing infections, yet are difficult to study due in part to a lack of scalable, single-cell characterisation methods. As >105 cells can be patterned on each template, and multiple templates can be patterned in parallel, bio-sCAPA allows for very rare population phenotypes to be monitored with single-cell precision across various environmental conditions. Using bio-sCAPA, we analysed the phenotypic characteristics of single Staphylococcus aureus cells tolerant to flucloxacillin and rifampicin killing. We find that antibiotic-tolerant S. aureus cells do not display significant heterogeneity in growth rate and are instead characterised by prolonged lag-time phenotypes alone.
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Affiliation(s)
- Cameron Boggon
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Switzerland.
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zürich, University of Zurich, Switzerland
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zürich, University of Zurich, Switzerland
| | - Eleonora Secchi
- Institute of Environmental Engineering, Department of Civil, Environmental, and Geomatic Engineering, ETH Zürich, Switzerland.
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Switzerland.
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7
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Choppa VSR, Liu G, Tompkins YH, Kim WK. Altered Osteogenic Differentiation in Mesenchymal Stem Cells Isolated from Compact Bone of Chicken Treated with Varying Doses of Lipopolysaccharides. Biomolecules 2023; 13:1626. [PMID: 38002308 PMCID: PMC10669906 DOI: 10.3390/biom13111626] [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: 09/25/2023] [Revised: 10/23/2023] [Accepted: 11/03/2023] [Indexed: 11/26/2023] Open
Abstract
Persistent inflammation biologically alters signaling molecules and ultimately affects osteogenic differentiation, including in modern-day broilers with unique physiology. Lipopolysaccharides (LPS) are Gram-negative bacterial components that activate cells via transmembrane receptor activation and other molecules. Previous studies have shown several pathways associated with osteogenic inductive ability, but the pathway has yet to be deciphered, and data related to its dose-dependent effect are limited. Primary mesenchymal stem cells (MSCs) were isolated from the bones of day-old broiler chickens, and the current study focused on the dose-dependent variation (3.125 micrograms/mL to 50 micrograms/mL) in osteogenic differentiation and the associated biomarkers in primary MSCs. The doses in this study were determined using a cell viability (MTT) assay. The study revealed that osteogenic differentiation varied with dose, and the cells exposed to higher doses of LPS were viable but lacked differentiating ability. However, this effect became transient with lower doses, and this phenotypic character was observed with differential staining methods like Alizarin Red, Von Kossa, and alkaline phosphatase. The data from this study revealed that LPS at varying doses had a varying effect on osteogenic differentiation via several pathways acting simultaneously during bone development.
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Affiliation(s)
| | | | | | - Woo Kyun Kim
- Department of Poultry Science, University of Georgia, Athens, GA 30605, USA; (V.S.R.C.); (G.L.); (Y.H.T.)
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8
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Niggli S, Schwyter L, Poveda L, Grossmann J, Kümmerli R. Rapid and strain-specific resistance evolution of Staphylococcus aureus against inhibitory molecules secreted by Pseudomonas aeruginosa. mBio 2023; 14:e0315322. [PMID: 37646506 PMCID: PMC10653847 DOI: 10.1128/mbio.03153-22] [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: 11/10/2022] [Accepted: 06/30/2023] [Indexed: 09/01/2023] Open
Abstract
IMPORTANCE Polymicrobial infections are common. In chronic infections, the different pathogens may repeatedly interact, which could spur evolutionary dynamics with pathogens adapting to one another. Here, we explore the potential of Staphylococcus aureus to adapt to its competitor Pseudomonas aeruginosa. These two pathogens frequently co-occur, and P. aeruginosa is seen as the dominant species being able to displace S. aureus. We studied three different S. aureus strains and found that all became quickly resistant to inhibitory compounds secreted by P. aeruginosa. Our experimental evolution revealed strains-specific adaptations with three main factors contributing to resistance evolution: (i) overproduction of staphyloxanthin, a molecule protecting from oxidative stress; (ii) the formation of small colony variants also protecting from oxidative stress; and (iii) alterations of membrane transporters possibly reducing toxin uptake. Our results show that species interactions can change over time potentially favoring species co-existence, which in turn could affect disease progression and treatment options.
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Affiliation(s)
- Selina Niggli
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Lukas Schwyter
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Lucy Poveda
- Functional Genomics Center Zurich, ETH Zurich and University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Swiss Institute of Bioinformatics (SIB) Quartier Sorge-Batiment Amphipole, Lausanne, Switzerland
| | - Jonas Grossmann
- Functional Genomics Center Zurich, ETH Zurich and University of Zurich, Winterthurerstrasse, Zurich, Switzerland
- Swiss Institute of Bioinformatics (SIB) Quartier Sorge-Batiment Amphipole, Lausanne, Switzerland
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
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9
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Worthan SB, McCarthy RDP, Behringer MG. Case Studies in the Assessment of Microbial Fitness: Seemingly Subtle Changes Can Have Major Effects on Phenotypic Outcomes. J Mol Evol 2023; 91:311-324. [PMID: 36752825 PMCID: PMC10276084 DOI: 10.1007/s00239-022-10087-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/21/2022] [Indexed: 02/09/2023]
Abstract
Following the completion of an adaptive evolution experiment, fitness evaluations are routinely conducted to assess the magnitude of adaptation. In doing so, proper consideration should be given when determining the appropriate methods as trade-offs may exist between accuracy and throughput. Here, we present three instances in which small changes in the framework or execution of fitness evaluations significantly impacted the outcomes. The first case illustrates that discrepancies in fitness conclusions can arise depending on the approach to evaluating fitness, the culture vessel used, and the sampling method. The second case reveals that variations in environmental conditions can occur associated with culture vessel material. Specifically, these subtle changes can greatly affect microbial physiology leading to changes in the culture pH and distorting fitness measurements. Finally, the last case reports that heterogeneity in CFU formation time can result in inaccurate fitness conclusions. Based on each case, considerations and recommendations are presented for future adaptive evolution experiments.
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Affiliation(s)
- Sarah B Worthan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN, USA
| | - Robert D P McCarthy
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Megan G Behringer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN, USA.
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
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10
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Riffaud CM, Rucks EA, Ouellette SP. Persistence of obligate intracellular pathogens: alternative strategies to overcome host-specific stresses. Front Cell Infect Microbiol 2023; 13:1185571. [PMID: 37284502 PMCID: PMC10239878 DOI: 10.3389/fcimb.2023.1185571] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/05/2023] [Indexed: 06/08/2023] Open
Abstract
In adapting to the intracellular niche, obligate intracellular bacteria usually undergo a reduction of genome size by eliminating genes not needed for intracellular survival. These losses can include, for example, genes involved in nutrient anabolic pathways or in stress response. Living inside a host cell offers a stable environment where intracellular bacteria can limit their exposure to extracellular effectors of the immune system and modulate or outright inhibit intracellular defense mechanisms. However, highlighting an area of vulnerability, these pathogens are dependent on the host cell for nutrients and are very sensitive to conditions that limit nutrient availability. Persistence is a common response shared by evolutionarily divergent bacteria to survive adverse conditions like nutrient deprivation. Development of persistence usually compromises successful antibiotic therapy of bacterial infections and is associated with chronic infections and long-term sequelae for the patients. During persistence, obligate intracellular pathogens are viable but not growing inside their host cell. They can survive for a long period of time such that, when the inducing stress is removed, reactivation of their growth cycles resumes. Given their reduced coding capacity, intracellular bacteria have adapted different response mechanisms. This review gives an overview of the strategies used by the obligate intracellular bacteria, where known, which, unlike model organisms such as E. coli, often lack toxin-antitoxin systems and the stringent response that have been linked to a persister phenotype and amino acid starvation states, respectively.
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11
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Personnic N, Doublet P, Jarraud S. Intracellular persister: A stealth agent recalcitrant to antibiotics. Front Cell Infect Microbiol 2023; 13:1141868. [PMID: 37065203 PMCID: PMC10102521 DOI: 10.3389/fcimb.2023.1141868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/06/2023] [Indexed: 04/03/2023] Open
Abstract
The bulk of bacteria transiently evading appropriate antibiotic regimes and recovered from non-resolutive infections are commonly refer to as persisters. In this mini-review, we discuss how antibiotic persisters stem from the interplay between the pathogen and the cellular defenses mechanisms and its underlying heterogeneity.
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Affiliation(s)
- Nicolas Personnic
- CIRI, Centre International de Recherche en Infectiologie, CNRS UMR 5308, INSERM U1111, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- Group Persistence and Single-Cell Dynamics of Respiratory Pathogens, Lyon, France
- *Correspondence: Nicolas Personnic,
| | - Patricia Doublet
- CIRI, Centre International de Recherche en Infectiologie, CNRS UMR 5308, INSERM U1111, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- Group Legionella Pathogenesis, Lyon, France
| | - Sophie Jarraud
- CIRI, Centre International de Recherche en Infectiologie, CNRS UMR 5308, INSERM U1111, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
- Group Legionella Pathogenesis, Lyon, France
- National Reference Centre for Legionella, Institute of Infectious Agents, Hospices Civils de Lyon, Lyon, France
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12
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Huemer M, Mairpady Shambat S, Hertegonne S, Bergada-Pijuan J, Chang CC, Pereira S, Gómez-Mejia A, Van Gestel L, Bär J, Vulin C, Pfammatter S, Stinear TP, Monk IR, Dworkin J, Zinkernagel AS. Serine-threonine phosphoregulation by PknB and Stp contributes to quiescence and antibiotic tolerance in Staphylococcus aureus. Sci Signal 2023; 16:eabj8194. [PMID: 36595572 DOI: 10.1126/scisignal.abj8194] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 12/06/2022] [Indexed: 01/05/2023]
Abstract
Staphylococcus aureus can cause infections that are often chronic and difficult to treat, even when the bacteria are not antibiotic resistant because most antibiotics act only on metabolically active cells. Subpopulations of persister cells are metabolically quiescent, a state associated with delayed growth, reduced protein synthesis, and increased tolerance to antibiotics. Serine-threonine kinases and phosphatases similar to those found in eukaryotes can fine-tune essential bacterial cellular processes, such as metabolism and stress signaling. We found that acid stress-mimicking conditions that S. aureus experiences in host tissues delayed growth, globally altered the serine and threonine phosphoproteome, and increased threonine phosphorylation of the activation loop of the serine-threonine protein kinase B (PknB). The deletion of stp, which encodes the only annotated functional serine-threonine phosphatase in S. aureus, increased the growth delay and phenotypic heterogeneity under different stress challenges, including growth in acidic conditions, the intracellular milieu of human cells, and abscesses in mice. This growth delay was associated with reduced protein translation and intracellular ATP concentrations and increased antibiotic tolerance. Using phosphopeptide enrichment and mass spectrometry-based proteomics, we identified targets of serine-threonine phosphorylation that may regulate bacterial growth and metabolism. Together, our findings highlight the importance of phosphoregulation in mediating bacterial quiescence and antibiotic tolerance and suggest that targeting PknB or Stp might offer a future therapeutic strategy to prevent persister formation during S. aureus infections.
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Affiliation(s)
- Markus Huemer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sanne Hertegonne
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Judith Bergada-Pijuan
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Chun-Chi Chang
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sandro Pereira
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Alejandro Gómez-Mejia
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Lies Van Gestel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Clément Vulin
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sibylle Pfammatter
- Functional Genomics Center Zurich, ETH/University of Zurich, Zurich, Switzerland
| | - Timothy P Stinear
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Ian R Monk
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Jonathan Dworkin
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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13
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Deciphering the induction of Listeria monocytogenes into sublethal injury using fluorescence microscopy and RT-qPCR. Int J Food Microbiol 2023; 385:109983. [DOI: 10.1016/j.ijfoodmicro.2022.109983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 10/16/2022] [Accepted: 10/17/2022] [Indexed: 11/22/2022]
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14
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Wang Z, Wang L, Bian H, Huang Z, Zhang X, Xiao Y. Outer Surface-Labeled Bacteria as Live Sensors Accurately Quantitating Interfacial pH: A Smart Technique for Antimicrobial Resistance. ACS NANO 2022; 16:18344-18354. [PMID: 36373972 DOI: 10.1021/acsnano.2c06226] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The techniques to quantitatively monitor environmental factors surrounding the bacterial outer surface rather than the host's subcellular regions (e.g., lysosomes) should be the key to evaluate bacterial immune escape behavior. We report wild Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) labeled with a fluorescent resonance energy transfer probe, 4SR-L-BDP, on their outer surfaces as smart live sensors to quantify interfacial pH. The dual emission of 4SR-L-BDP affords high sensitivity to pH change in a ratiometric way in the pH range of 4-8 with high precision. Notably, 4SR-L-BDP possesses an anchoring group to fix on the bacterial surface for sensing the microenvironment encountered. Super-resolution imaging clearly demonstrates the specific labeling of bacterial membranes. These live sensors are applied in two-channel ratiometric imaging to dynamically visualize and quantify their interfacial pH changes during infection of macrophages. It is found that the interfacial pH of MRSA is lower by 0.2 units compared to that of SA. Such small but critical difference in pH reflects MRSA's ability to adapt to microenvironmental pH inside macrophages. These labeled bacteria as live sensors are also proven to be practically applicable in mice models with immune deficiency and immune activation.
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Affiliation(s)
- Zehui Wang
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Lai Wang
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Hui Bian
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Zhenlong Huang
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Xinfu Zhang
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Yi Xiao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, Dalian 116024, China
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15
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Gamea GA, Elmehy DA, Salama AM, Soliman NA, Afifi OK, Elkaliny HH, Abo El gheit RE, El-Ebiary AA, Tahoon DM, Elkholy RA, Shoeib SM, Eleryan MA, Younis SS. Direct and indirect antiparasitic effects of chloroquine against the virulent RH strain of Toxoplasma gondii: An experimental study. Acta Trop 2022; 232:106508. [PMID: 35568067 DOI: 10.1016/j.actatropica.2022.106508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 11/01/2022]
Abstract
BACKGROUND Toxoplasmosis is a deleterious parasitic disease with harmful impact on both humans and animals. The present study was carried out to evaluate the antiparasitic effect of chloroquine (CQ), spiramycin (SP), and combination of both against the highly virulent RH HXGPRT (-) strain of Toxoplasma gondii (T. gondii) and to explore the mechanisms underlying such effect. METHODS We counted the tachyzoites in the peritoneal fluid and liver smears of mice and performed scanning and transmission electron microscopy and immunofluorescence staining of tachyzoites. Moreover, relative caspase 3 gene expression was measured by real time polymerase chain reaction of liver tissues and immunoassay of anti-apoptotic markers [B cell lymphoma-2 (Bcl-2) and X-chromosome linked inhibitor of apoptosis (XIAP)] and interferon gamma (IFN-γ) was done in liver tissues by ELISA. In addition, we estimated serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) and performed histopathological examination of liver sections for scoring of inflammation. RESULTS We found that both CQ and CQ/SP combination significantly reduced parasitic load in the peritoneal fluid and liver smears, induced apical disruption of tachyzoites, triggered host cell apoptosis through elevation of relative caspase 3 gene expression and suppression of both Bcl-2 and XIAP. Also, they upregulated IFN-γ level, reduced serum AST and ALT, and ameliorated liver inflammation. CONCLUSIONS Either of CQ and CQ/SP combination was more effective than SP alone against T. gondii with the CQ/SP combination being more efficient. Therefore, adding CQ to other anti-Toxoplasma therapeutic regimens may be considered in future research.
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16
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Zhou S, Rao Y, Li J, Huang Q, Rao X. Staphylococcus aureus small-colony variants: Formation, infection, and treatment. Microbiol Res 2022; 260:127040. [DOI: 10.1016/j.micres.2022.127040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/10/2022] [Accepted: 04/11/2022] [Indexed: 10/18/2022]
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17
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Kim SM, Zou G, Kim H, Kang M, Ahn S, Heo HY, Kim JS, Lim KM, Ausubel FM, Mylonakis E, Gao H, Kim W. Antimicrobial activity of the membrane-active compound nTZDpa is enhanced at low pH. Biomed Pharmacother 2022; 150:112977. [PMID: 35447554 DOI: 10.1016/j.biopha.2022.112977] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/03/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022] Open
Abstract
The opportunistic human pathogen Staphylococcus aureus can evade antibiotics by acquiring antibiotic resistance genes or by entering into a non-growing dormant state. Moreover, the particular circumstances of a specific infection site, such as acidity or anaerobicity, often weaken antibiotic potency. Decreased bacterial susceptibility combined with diminished antibiotic potency is responsible for high failure rates when treating S. aureus infections. Here, we report that the membrane-active antimicrobial agent nTZDpa does not only exhibit enhanced antibiotic activity against multidrug-resistant Gram-positive pathogens in acidic pH, but also retains antimicrobial potency under anaerobic conditions. This agent completely eradicated highly antibiotic-tolerant cells and biofilms formed by methicillin-resistant S. aureus at pH 5.5 at concentrations at which it was not potent at pH 7.4. Furthermore, nTZDpa was more potent at synergistically potentiating gentamicin killing against antibiotic-tolerant MRSA cells at low pH than at high pH. All-atom molecular dynamics simulations combined with membrane-permeabilization assays revealed that the neutral form of nTZDpa, which contains carboxylic acid, is more effective than the deprotonated form at penetrating the bacterial membrane and plays an essential role in membrane activity. An acidic pH increases the proportion of the neutrally charged nTZDpa, which results in antimicrobial enhancement. Our results provide key insights into rational design of pH-sensitive membrane-active antimicrobials and antibiotic adjuvants that are effective in an infection environment. These findings demonstrate that nTZDpa is a promising lead compound for developing new therapeutics against hard-to-cure infections caused by drug-resistant and -tolerant S. aureus.
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Affiliation(s)
- Soo Min Kim
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Guijin Zou
- Institute of High Performance Computing, A⁎STAR, Singapore 138632, Singapore
| | - Hyerim Kim
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Minjeong Kang
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Soyeon Ahn
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hee Young Heo
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jae-Seok Kim
- Department of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul 05355, Republic of Korea
| | - Kyung-Min Lim
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Frederick M Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Huajian Gao
- Institute of High Performance Computing, A⁎STAR, Singapore 138632, Singapore; School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639789, Singapore
| | - Wooseong Kim
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Republic of Korea.
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18
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Eichenseher F, Herpers BL, Badoux P, Leyva-Castillo JM, Geha RS, van der Zwart M, McKellar J, Janssen F, de Rooij B, Selvakumar L, Röhrig C, Frieling J, Offerhaus M, Loessner MJ, Schmelcher M. Linker-Improved Chimeric Endolysin Selectively Kills Staphylococcus aureus In Vitro, on Reconstituted Human Epidermis, and in a Murine Model of Skin Infection. Antimicrob Agents Chemother 2022; 66:e0227321. [PMID: 35416713 PMCID: PMC9112974 DOI: 10.1128/aac.02273-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/16/2022] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus causes a broad spectrum of diseases in humans and animals. It is frequently associated with inflammatory skin disorders such as atopic dermatitis, where it aggravates symptoms. Treatment of S. aureus-associated skin infections with antibiotics is discouraged due to their broad-range deleterious effect on healthy skin microbiota and their ability to promote the development of resistance. Thus, novel S. aureus-specific antibacterial agents are desirable. We constructed two chimeric cell wall-lytic enzymes, Staphefekt SA.100 and XZ.700, which are composed of functional domains from the bacteriophage endolysin Ply2638 and the bacteriocin lysostaphin. Both enzymes specifically killed S. aureus and were inactive against commensal skin bacteria such as Staphylococcus epidermidis, with XZ.700 proving more active than SA.100 in multiple in vitro activity assays. When surface-attached mixed staphylococcal cultures were exposed to XZ.700 in a simplified microbiome model, the enzyme selectively removed S. aureus and retained S. epidermidis. Furthermore, XZ.700 did not induce resistance in S. aureus during repeated rounds of exposure to sublethal concentrations. Finally, we demonstrated that XZ.700 formulated as a cream is effective at killing S. aureus on reconstituted human epidermis and that an XZ.700-containing gel significantly reduces bacterial numbers compared to an untreated control in a mouse model of S. aureus-induced skin infection.
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Affiliation(s)
- Fritz Eichenseher
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
- Micreos GmbH, Wädenswil, Switzerland
| | - Bjorn L. Herpers
- Regional Public Health Laboratory Kennemerland, Haarlem, The Netherlands
| | - Paul Badoux
- Regional Public Health Laboratory Kennemerland, Haarlem, The Netherlands
| | | | - Raif S. Geha
- Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | | | - Ferd Janssen
- Micreos Human Health B.V., Bilthoven, The Netherlands
| | - Bob de Rooij
- Micreos Human Health B.V., Bilthoven, The Netherlands
| | | | | | | | | | - Martin J. Loessner
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Mathias Schmelcher
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
- Micreos GmbH, Wädenswil, Switzerland
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19
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Abstract
Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.
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Affiliation(s)
- Gustaw M Szafraniec
- Department of Pathology and Veterinary Diagnostics, Institute of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Piotr Szeleszczuk
- Department of Pathology and Veterinary Diagnostics, Institute of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
| | - Beata Dolka
- Department of Pathology and Veterinary Diagnostics, Institute of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
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20
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Guo H, Tong Y, Cheng J, Abbas Z, Li Z, Wang J, Zhou Y, Si D, Zhang R. Biofilm and Small Colony Variants-An Update on Staphylococcus aureus Strategies toward Drug Resistance. Int J Mol Sci 2022; 23:ijms23031241. [PMID: 35163165 PMCID: PMC8835882 DOI: 10.3390/ijms23031241] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.
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21
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Bogut A, Magryś A. The road to success of coagulase-negative staphylococci: clinical significance of small colony variants and their pathogenic role in persistent infections. Eur J Clin Microbiol Infect Dis 2021; 40:2249-2270. [PMID: 34296355 PMCID: PMC8520507 DOI: 10.1007/s10096-021-04315-1] [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: 05/23/2021] [Accepted: 07/09/2021] [Indexed: 01/14/2023]
Abstract
Bacterial small colony variants represent an important aspect of bacterial variability. They are naturally occurring microbial subpopulations with distinctive phenotypic and pathogenic traits, reported for many clinically important bacteria. In clinical terms, SCVs tend to be associated with persistence in host cells and tissues and are less susceptible to antibiotics than their wild-type (WT) counterparts. The increased tendency of SCVs to reside intracellularly where they are protected against the host immune responses and antimicrobial drugs is one of the crucial aspects linking SCVs to recurrent or chronic infections, which are difficult to treat. An important aspect of the SCV ability to persist in the host is the quiescent metabolic state, reduced immune response and expression a changed pattern of virulence factors, including a reduced expression of exotoxins and an increased expression of adhesins facilitating host cell uptake. The purpose of this review is to describe in greater detail the currently available data regarding CoNS SCV and, in particular, their clinical significance and possible mechanisms by which SCVs contribute to the pathogenesis of the chronic infections. It should be emphasized that in spite of an increasing clinical significance of this group of staphylococci, the number of studies unraveling the mechanisms of CoNS SCVs formation and their impact on the course of the infectious process is still scarce, lagging behind the studies on S. aureus SCVs.
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Affiliation(s)
- Agnieszka Bogut
- Chair and Department of Medical Microbiology, Medical University of Lublin, ul. Chodźki 1, 20-093, Lublin, Poland
| | - Agnieszka Magryś
- Chair and Department of Medical Microbiology, Medical University of Lublin, ul. Chodźki 1, 20-093, Lublin, Poland.
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22
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Molecular reprogramming and phenotype switching in Staphylococcus aureus lead to high antibiotic persistence and affect therapy success. Proc Natl Acad Sci U S A 2021; 118:2014920118. [PMID: 33574060 DOI: 10.1073/pnas.2014920118] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Staphylococcus aureus causes invasive infections and easily acquires antibiotic resistance. Even antibiotic-susceptible S. aureus can survive antibiotic therapy and persist, requiring prolonged treatment and surgical interventions. These so-called persisters display an arrested-growth phenotype, tolerate high antibiotic concentrations, and are associated with chronic and recurrent infections. To characterize these persisters, we assessed S. aureus recovered directly from a patient suffering from a persistent infection. We show that host-mediated stress, including acidic pH, abscess environment, and antibiotic exposure promoted persister formation in vitro and in vivo. Multiomics analysis identified molecular changes in S. aureus in response to acid stress leading to an overall virulent population. However, further analysis of a persister-enriched population revealed major molecular reprogramming in persisters, including down-regulation of virulence and cell division and up-regulation of ribosomal proteins, nucleotide-, and amino acid-metabolic pathways, suggesting their requirement to fuel and maintain the persister phenotype and highlighting that persisters are not completely metabolically inactive. Additionally, decreased aconitase activity and ATP levels and accumulation of insoluble proteins involved in transcription, translation, and energy production correlated with persistence in S. aureus, underpinning the molecular mechanisms that drive the persister phenotype. Upon regrowth, these persisters regained their virulence potential and metabolically active phenotype, including reduction of insoluble proteins, exhibiting a reversible state, crucial for recurrent infections. We further show that a targeted antipersister combination therapy using retinoid derivatives and antibiotics significantly reduced lag-phase heterogeneity and persisters in a murine infection model. Our results provide molecular insights into persisters and help explain why persistent S. aureus infections are so difficult to treat.
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23
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Yokota M, Häffner N, Kassier M, Brunner M, Shambat SM, Brennecke F, Schniering J, Marques Maggio E, Distler O, Zinkernagel AS, Maurer B. Staphylococcus aureus impairs dermal fibroblast functions with deleterious effects on wound healing. FASEB J 2021; 35:e21695. [PMID: 34160101 DOI: 10.1096/fj.201902836r] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/16/2021] [Accepted: 05/10/2021] [Indexed: 12/28/2022]
Abstract
Chronic wounds are a major disease burden worldwide. The breach of the epithelial barrier facilitates transition of skin commensals to invasive facultative pathogens. Therefore, we investigated the potential effects of Staphylococcus aureus (SA) on dermal fibroblasts as key cells for tissue repair. In co-culture systems combining live or heat-killed SA with dermal fibroblasts derived from the BJ-5ta cell line, healthy individuals, and patients with systemic sclerosis, we assessed tissue repair including pro-inflammatory cytokines, matrix metalloproteases (MMPs), myofibroblast functions, and host defense responses. Only live SA induced the upregulation of IL-1β/-6/-8 and MMP1/3 as co-factors of tissue degradation. Additionally, the increased cell death reduced collagen production, proliferation, migration, and contractility, prerequisite mechanisms for wound closure. Intracellular SA triggered inflammatory and type I IFN responses via intracellular dsDNA sensor molecules and MyD88 and STING signaling pathways. In conclusion, live SA affected various key tissue repair functions of dermal fibroblasts from different sources to a similar extent. Thus, SA infection of dermal fibroblasts should be taken into account for future wound management strategies.
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Affiliation(s)
- Masaya Yokota
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland.,Department of Allergy and Clinical Immunology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Nicola Häffner
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Matthew Kassier
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
| | - Matthias Brunner
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Fabian Brennecke
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
| | - Janine Schniering
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
| | - Ewerton Marques Maggio
- Institute of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Oliver Distler
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
| | - Annelies Sophie Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Britta Maurer
- Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland.,Department of Rheumatology and Immunology, University Hospital Bern, University Bern, Bern, Switzerland
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24
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Shemyakin IG, Firstova VV, Fursova NK, Abaev IV, Filippovich SY, Ignatov SG, Dyatlov IA. Next-Generation Antibiotics, Bacteriophage Endolysins, and Nanomaterials for Combating Pathogens. BIOCHEMISTRY (MOSCOW) 2021; 85:1374-1388. [PMID: 33280580 DOI: 10.1134/s0006297920110085] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
This review presents various strategies to fight causative agents of infectious diseases. Species-specific programmable RNA-containing antibiotics open up new possibilities for creating next-generation of personalized drugs based on microbiome editing and can serve as a new tool for selective elimination of pathogenic bacterial species while keeping intact the rest of microbiota. Another promising approach in combating bacterial infections is genome editing using the CRISPR-Cas systems. Expanding knowledge on the molecular mechanisms of innate immunity has been actively used for developing new antimicrobials. However, obvious risks of using antibiotic adjuvants aimed at activation of the host immune system include development of the autoimmune response with subsequent organ damage. To avoid these risks, it is essential to elucidate action mechanisms of the specific ligands and signal molecules used as components of the hybrid antibiotics. Bacteriophage endolysins are also considered as effective antimicrobials against antibiotic-resistant bacteria, metabolically inactive persisters, and microbial biofilms. Despite significant advances in the design of implants with antibacterial properties, the problem of postoperative infections still remains. Different nanomodifications of the implant surface have been designed to reduce bacterial contamination. Here, we review bactericidal, fungicidal, and immunomodulating properties of compounds used for the implant surface nanomodifications, such as silver, boron nitride nanomaterials, nanofibers, and nanogalvanic materials.
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Affiliation(s)
- I G Shemyakin
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - V V Firstova
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia.
| | - N K Fursova
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - I V Abaev
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - S Yu Filippovich
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - S G Ignatov
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - I A Dyatlov
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
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25
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Vozza EG, Mulcahy ME, McLoughlin RM. Making the Most of the Host; Targeting the Autophagy Pathway Facilitates Staphylococcus aureus Intracellular Survival in Neutrophils. Front Immunol 2021; 12:667387. [PMID: 34220813 PMCID: PMC8242348 DOI: 10.3389/fimmu.2021.667387] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/28/2021] [Indexed: 12/21/2022] Open
Abstract
The success of Staphylococcus aureus as a human commensal and an opportunistic pathogen relies on its ability to adapt to several niches within the host. The innate immune response plays a key role in protecting the host against S. aureus infection; however, S. aureus adeptness at evading the innate immune system is indisputably evident. The “Trojan horse” theory has been postulated to describe a mechanism by which S. aureus takes advantage of phagocytes as a survival niche within the host to facilitate dissemination of S. aureus to secondary sites during systemic infection. Several studies have determined that S. aureus can parasitize both professional and non-professional phagocytes by manipulating the host autophagy pathway in order to create an intracellular survival niche. Neutrophils represent a critical cell type in S. aureus infection as demonstrated by the increased risk of infection among patients with congenital neutrophil disorders. However, S. aureus has been repeatedly shown to survive intracellularly within neutrophils with evidence now supporting a pathogenic role of host autophagy. By manipulating this pathway, S. aureus can also alter the apoptotic fate of the neutrophil and potentially skew other important signalling pathways for its own gain. Understanding these critical host-pathogen interactions could lead to the development of new host directed therapeutics for the treatment of S. aureus infection by removing its intracellular niche and restoring host bactericidal functions. This review discusses the current findings surrounding intracellular survival of S. aureus within neutrophils, the pathogenic role autophagy plays in this process and considers the therapeutic potential for targeting this immune evasion mechanism.
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Affiliation(s)
- Emilio G Vozza
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Michelle E Mulcahy
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Rachel M McLoughlin
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
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26
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Lysosomal alkalization to potentiate eradication of intra-osteoblastic Staphylococcus aureus in the bone and joint infection setting. Clin Microbiol Infect 2021; 28:135.e1-135.e7. [PMID: 33962064 DOI: 10.1016/j.cmi.2021.04.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 04/13/2021] [Accepted: 04/27/2021] [Indexed: 12/23/2022]
Abstract
OBJECTIVES Beyond intracellular penetration, acidic lysosomal pH might affect the intracellular activity of some antimicrobials. This study evaluated the ability of lysosomotropic alkalizing agents to potentiate the antimicrobial eradication of an intra-osteoblastic Staphylococcus aureus reservoir in the setting of bone and joint infection (BJI). METHODS MICs of 16 anti-staphylococcal molecules active against methicillin-sensitive S. aureus (MSSA) were evaluated at pH 5 and pH 7. Additionally, the lysosomal alkalizing potential (spectrofluorometry) and cytotoxicity (MTT assay) of hydroxychloroquine, amantadine and ammonium chloride were assessed. The results led to further investigation of clindamycin, cotrimoxazole, daptomycin and levofloxacin-alone or in combination with hydroxychloroquine-in an in vitro model of osteoblast infection. The impact of hydroxychloroquine on autophagy was finally investigated using Western blot detection of two autophagic flux indicators, the LC3 membrane protein and the SQSTM1 cargo protein. RESULTS Daptomycin, cotrimoxazole, clindamycin and levofloxacin alone significantly decreased the intracellular staphylococcal reservoir (5.12 log10 CFU/100 000 cells) by 0.14 (95%CI 0.01-0.34), 0.25 (95%CI 0.12-0.43), 0.16 (95%CI 0.004-0.39) and 1.18 (95%CI 1.04-1.38) log10 CFU/100 000 cells, respectively (p < 10-3). Adding hydroxychloroquine (20 mg/L) increased intralysosomal pH from 4.8 to 7, and concomitantly the inoculum of each antimicrobial was reduced by 0.50 (95%CI 0.30-0.84), 0.73 (95%CI 0.59-0.96), 0.59 (95%CI 0.46-0.78) and 1.8 (95%CI 1.66-2.1) log10 CFU/100 000 cells, respectively (p < 10-4). Cellular levels of LC3II and SQSTM1 showed that hydroxychloroquine has direct activity on the autophagic flux, fostering the eradication of intracellular S. aureus by antimicrobials. CONCLUSION At high concentrations, hydroxychloroquine used as an adjuvant to antimicrobials improves eradication of an S. aureus intra-osteoblastic reservoir in our in vitro cell infection model. These findings advocate further in vivo evaluation of alkalization efficacy and tolerance in S. aureus BJI.
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27
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Walsh L, Johnson CN, Hill C, Ross RP. Efficacy of Phage- and Bacteriocin-Based Therapies in Combatting Nosocomial MRSA Infections. Front Mol Biosci 2021; 8:654038. [PMID: 33996906 PMCID: PMC8116899 DOI: 10.3389/fmolb.2021.654038] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/07/2021] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus is a pathogen commonly found in nosocomial environments where infections can easily spread - especially given the reduced immune response of patients and large overlap between personnel in charge of their care. Although antibiotics are available to treat nosocomial infections, the increased occurrence of antibiotic resistance has rendered many treatments ineffective. Such is the case for methicillin resistant S. aureus (MRSA), which has continued to be a threat to public health since its emergence. For this reason, alternative treatment technologies utilizing antimicrobials such as bacteriocins, bacteriophages (phages) and phage endolysins are being developed. These antimicrobials provide an advantage over antibiotics in that many have narrow inhibition spectra, enabling treatments to be selected based on the target (pathogenic) bacterium while allowing for survival of commensal bacteria and thus avoiding collateral damage to the microbiome. Bacterial resistance to these treatments occurs less frequently than with antibiotics, particularly in circumstances where combinatory antimicrobial therapies are used. Phage therapy has been well established in Eastern Europe as an effective treatment against bacterial infections. While there are no Randomized Clinical Trials (RCTs) to our knowledge examining phage treatment of S. aureus infections that have completed all trial phases, numerous clinical trials are underway, and several commercial phage preparations are currently available to treat S. aureus infections. Bacteriocins have primarily been used in the food industry for bio-preservation applications. However, the idea of repurposing bacteriocins for human health is an attractive one considering their efficacy against many bacterial pathogens. There are concerns about the ability of bacteriocins to survive the gastrointestinal tract given their proteinaceous nature, however, this obstacle may be overcome by altering the administration route of the therapy through encapsulation, or by bioengineering protease-resistant variants. Obstacles such as enzymatic digestion are less of an issue for topical/local administration, for example, application to the surface of the skin. Bacteriocins have also shown impressive synergistic effects when used in conjunction with other antimicrobials, including antibiotics, which may allow antibiotic-based therapies to be used more sparingly with less resistance development. This review provides an updated account of known bacteriocins, phages and phage endolysins which have demonstrated an impressive ability to kill S. aureus strains. In particular, examples of antimicrobials with the ability to target MRSA strains and their subsequent use in a clinical setting are outlined.
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Affiliation(s)
- Lauren Walsh
- School of Microbiology, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Crystal N Johnson
- School of Microbiology, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland.,Teagasc Food Research Centre, Moorepark, Cork, Ireland
| | - Colin Hill
- School of Microbiology, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - R Paul Ross
- School of Microbiology, University College Cork, Cork, Ireland.,APC Microbiome Ireland, University College Cork, Cork, Ireland.,Teagasc Food Research Centre, Moorepark, Cork, Ireland
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28
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Huemer M, Mairpady Shambat S, Brugger SD, Zinkernagel AS. Antibiotic resistance and persistence-Implications for human health and treatment perspectives. EMBO Rep 2020; 21:e51034. [PMID: 33400359 PMCID: PMC7726816 DOI: 10.15252/embr.202051034] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/13/2020] [Accepted: 11/02/2020] [Indexed: 12/24/2022] Open
Abstract
Antimicrobial resistance (AMR) and persistence are associated with an elevated risk of treatment failure and relapsing infections. They are thus important drivers of increased morbidity and mortality rates resulting in growing healthcare costs. Antibiotic resistance is readily identifiable with standard microbiological assays, and the threat imposed by antibiotic resistance has been well recognized. Measures aiming to reduce resistance development and spreading of resistant bacteria are being enforced. However, the phenomenon of bacteria surviving antibiotic exposure despite being fully susceptible, so-called antibiotic persistence, is still largely underestimated. In contrast to antibiotic resistance, antibiotic persistence is difficult to measure and therefore often missed, potentially leading to treatment failures. In this review, we focus on bacterial mechanisms allowing evasion of antibiotic killing and discuss their implications on human health. We describe the relationship between antibiotic persistence and bacterial heterogeneity and discuss recent studies that link bacterial persistence and tolerance with the evolution of antibiotic resistance. Finally, we review persister detection methods, novel strategies aiming at eradicating bacterial persisters and the latest advances in the development of new antibiotics.
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Affiliation(s)
- Markus Huemer
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Silvio D Brugger
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital EpidemiologyUniversity Hospital ZurichUniversity of ZurichZurichSwitzerland
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29
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Huitema L, Phillips T, Alexeev V, Tomic-Canic M, Pastar I, Igoucheva O. Intracellular escape strategies of Staphylococcus aureus in persistent cutaneous infections. Exp Dermatol 2020; 30:1428-1439. [PMID: 33179358 DOI: 10.1111/exd.14235] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/19/2020] [Accepted: 11/04/2020] [Indexed: 12/14/2022]
Abstract
Pathogenic invasion of Staphylococcus aureus is a major concern in patients with chronic skin diseases like atopic dermatitis (AD), epidermolysis bullosa (EB), or chronic diabetic foot and venous leg ulcers, and can result in persistent and life-threatening chronic non-healing wounds. Staphylococcus aureus is generally recognized as extracellular pathogens. However, S. aureus can also invade, hide and persist in skin cells to contribute to wound chronicity. The intracellular life cycle of S. aureus is currently incompletely understood, although published studies indicate that its intracellular escape strategies play an important role in persistent cutaneous infections. This review provides current scientific knowledge about the intracellular life cycle of S. aureus in skin cells, which can be classified into professional and non-professional antigen-presenting cells, and its strategies to escape adaptive defense mechanisms. First, we discuss phenotypic switch of S. aureus, which affects intracellular routing and degradation. This review also evaluates potential intracellular escape mechanism of S. aureus to avoid intracellular degradation and antigen presentation, preventing an immune response. Furthermore, we discuss potential drug targets that can interfere with the intracellular life cycle of S. aureus. Taken together, this review aimed to increase scientific understanding about the intracellular life cycle of S. aureus into skin cells and its strategies to evade the host immune response, information that is crucial to reduce pathogenic invasion and life-threatening persistence of S. aureus in chronic cutaneous infections.
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Affiliation(s)
- Leonie Huitema
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Taylor Phillips
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Vitali Alexeev
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Marjana Tomic-Canic
- Wound Healing and Regenerative Medicine Research Program, Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Irena Pastar
- Wound Healing and Regenerative Medicine Research Program, Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Olga Igoucheva
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
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30
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Abstract
Many bacterial pathogens can permanently colonize their host and establish either chronic or recurrent infections that the immune system and antimicrobial therapies fail to eradicate. Antibiotic persisters (persister cells) are believed to be among the factors that make these infections challenging. Persisters are subpopulations of bacteria which survive treatment with bactericidal antibiotics in otherwise antibiotic-sensitive cultures and were extensively studied in a hope to discover the mechanisms that cause treatment failures in chronically infected patients; however, most of these studies were conducted in the test tube. Research into antibiotic persistence has uncovered large intrapopulation heterogeneity of bacterial growth and regrowth but has not identified essential, dedicated molecular mechanisms of antibiotic persistence. Diverse factors and stresses that inhibit bacterial growth reduce killing of the bulk population and may also increase the persister subpopulation, implying that an array of mechanisms are present. Hopefully, further studies under conditions that simulate the key aspects of persistent infections will lead to identifying target mechanisms for effective therapeutic solutions.
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31
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De Maesschalck V, Gutiérrez D, Paeshuyse J, Lavigne R, Briers Y. Advanced engineering of third-generation lysins and formulation strategies for clinical applications. Crit Rev Microbiol 2020; 46:548-564. [PMID: 32886565 DOI: 10.1080/1040841x.2020.1809346] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
One of the possible solutions for the current antibiotic resistance crisis may be found in (often bacteriophage-derived) peptidoglycan hydrolases. The first clinical trials of these natural enzymes, coined here as first-generation lysins, are currently ongoing. Moving beyond natural endolysins with protein engineering established the second generation of lysins. In second-generation lysins, the focus lies on improving antibacterial and biochemical properties such as antimicrobial activity and stability, as well as expanding their activities towards Gram-negative pathogens. However, solutions to particular key challenges regarding clinical applications are only beginning to emerge in the third generation of lysins, in which protein and biochemical engineering efforts focus on improving properties relevant under clinical conditions. In addition, increasingly advanced formulation strategies are developed to increase the bioavailability, antibacterial activity, and half-life, and to reduce pro-inflammatory responses. This review focuses on third-generation and advanced formulation strategies that are developed to treat infections, ranging from topical to systemic applications. Together, these efforts may fully unlock the potential of lysin therapy and will propel it as a true antibiotic alternative or supplement.
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Affiliation(s)
- Vincent De Maesschalck
- Department of Biosystems, KU Leuven, Leuven, Belgium.,Department of Biotechnology, Ghent University, Gent, Belgium
| | - Diana Gutiérrez
- Department of Biotechnology, Ghent University, Gent, Belgium
| | - Jan Paeshuyse
- Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Rob Lavigne
- Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Yves Briers
- Department of Biotechnology, Ghent University, Gent, Belgium
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32
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Häffner N, Bär J, Dengler Haunreiter V, Mairpady Shambat S, Seidl K, Crosby HA, Horswill AR, Zinkernagel AS. Intracellular Environment and agr System Affect Colony Size Heterogeneity of Staphylococcus aureus. Front Microbiol 2020; 11:1415. [PMID: 32695082 PMCID: PMC7339952 DOI: 10.3389/fmicb.2020.01415] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/02/2020] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus causes chronic and relapsing infections, which may be difficult to treat. So-called small colony variants (SCVs) have been associated with chronic infections and their occurrence has been shown to increase under antibiotic pressure, low pH and intracellular localization. In clinics, S. aureus isolated from invasive infections often show a dysfunction in the accessory gene regulator (agr), a major virulence regulatory system in S. aureus. To assess whether intracellular environment and agr function influence SCV formation, an infection model was established using lung epithelial cells and skin fibroblasts. This allowed analyzing intracellular survival and localization of a panel of S. aureus wild type strains and their isogenic agr knock out mutants as well as a natural dysfunctional agr strain by confocal laser scanning microscopy (CLSM). Furthermore, bacterial colonies were quantified after 1, 3, and 5 days of intracellular survival by time-lapse analysis to determine kinetics of colony appearance and SCV formation. Here, we show that S. aureus strains with an agr knock out predominantly resided in a neutral environment, whereas wild type strains and an agr complemented strain resided in an acidic environment. S. aureus agr mutants derived from an intracellular environment showed a higher percentage of SCVs as compared to their corresponding wild type strains. Neutralizing acidic phagolysosomes with chloroquine resulted in a significant reduction of SCVs in S. aureus wild type strain 6850, but not in its agr mutant indicating a pH dependent formation of SCVs in the wild type strain. The in-depth understanding of the interplay between intracellular persistence, agr function and pH should help to identify new therapeutic options facilitating the treatment of chronic S. aureus infections in the future.
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Affiliation(s)
- Nicola Häffner
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Vanina Dengler Haunreiter
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Kati Seidl
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Heidi A Crosby
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Veterans Affairs Eastern Colorado Health Care System, Denver, CO, United States
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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33
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Montanari E, Mancini P, Galli F, Varani M, Santino I, Coviello T, Mosca L, Matricardi P, Rancan F, Di Meo C. Biodistribution and intracellular localization of hyaluronan and its nanogels. A strategy to target intracellular S. aureus in persistent skin infections. J Control Release 2020; 326:1-12. [PMID: 32553788 DOI: 10.1016/j.jconrel.2020.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023]
Abstract
Intracellular pathogens are a critical challenge for antimicrobial therapies. Staphylococcus aureus (S. aureus) causes approximately 85% of all skin and soft tissue infections in humans worldwide and more than 30% of patients develop chronic or recurrent infections within three months, even after appropriate antibacterial therapies. S. aureus is also one of the most common bacteria found in chronic wounds. Recent evidences suggest that S. aureus is able to persist within phagolysosomes of skin cells (i.e. keratinocytes, phagocytic cells), being protected from both the immune system and a number of antimicrobials. To overcome these limits, nano-formulations that enable targeted therapies against intracellular S. aureus might be developed. Herein, the biodistribution and intracellular localisation of hyaluronan (HA) and HA-based nanoparticles (nanogels, NHs) are investigated, both after intravenous (i.v.) injections (in mice) and topical administrations (in ex vivo human skin). Results indicate HA and NHs accumulate especially in skin and liver of mice after i.v. injection. After topical application on human skin explants, no penetration of both HA and NHs was detected in skin with intact stratum corneum. By contrast, in barrier-disrupted human skin (with partial removal and loosening of stratum corneum), HA and NHs penetrate to the viable epidermis and are taken up by keratinocytes. In mechanically produced wounds (skin without epidermis) they accumulate in wound tissue and are taken up by dermis cells, e.g. fibroblasts and phagocytic cells. Interestingly, in all cases, the cellular uptake is CD44-mediated. In vitro studies confirmed that after CD44-mediated uptake, both HA and NHs accumulate in lysosomes of dermal fibroblasts and macrophages, as previously reported for keratinocytes. Finally, the colocalisation between intracellular S. aureus and HA or NHs is demonstrated, in macrophages. Altogether, for the first time, these results strongly suggest that HA and HA-based NHs can provide a targeted therapy to intracellular S. aureus, in persistent skin or wound infections.
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Affiliation(s)
- E Montanari
- Departments of Drug Chemistry and Technologies, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - P Mancini
- Department of Experimental Medicine, Sapienza University of Rome, V.le Regina Elena 324, Rome 00161, Italy
| | - F Galli
- Department of Medical-Surgical Sciences and Translational Medicine, Sapienza University of Rome, Sant'Andrea Hospital, Via di Grottarossa 1035, 00189 Rome, Italy
| | - M Varani
- Department of Medical-Surgical Sciences and Translational Medicine, Sapienza University of Rome, Sant'Andrea Hospital, Via di Grottarossa 1035, 00189 Rome, Italy
| | - I Santino
- Department of Molecular and Clinical Medicine, Sapienza University of Rome, Sant'Andrea Hospital, Via di Grottarossa 1035, 00189 Rome, Italy
| | - T Coviello
- Departments of Drug Chemistry and Technologies, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - L Mosca
- Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - P Matricardi
- Departments of Drug Chemistry and Technologies, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy.
| | - F Rancan
- Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - C Di Meo
- Departments of Drug Chemistry and Technologies, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
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Stoneham SM, Cantillon DM, Waddell SJ, Llewelyn MJ. Spontaneously Occurring Small-Colony Variants of Staphylococcus aureus Show Enhanced Clearance by THP-1 Macrophages. Front Microbiol 2020; 11:1300. [PMID: 32595630 PMCID: PMC7303551 DOI: 10.3389/fmicb.2020.01300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/20/2020] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a common cause of chronic and relapsing infection, especially when the ability of the immune system to sterilize a focus of infection is compromised (e.g., because of a foreign body or in the cystic fibrosis lung). Chronic infections are associated with slow-growing colony phenotypes of S. aureus on solid media termed small-colony variants (SCVs). Stable SCVs show characteristic mutations in the electron transport chain that convey resistance to antibiotics, particularly aminoglycosides. This can be used to identify SCVs from within mixed-colony phenotype populations of S. aureus. More recently, populations of SCVs that rapidly revert to a “wild-type” (WT) colony phenotype, in the absence of selection pressure, have also been described. In laboratory studies, SCVs accumulate through prolonged infection of non-professional phagocytes and may represent an adaptation to the intracellular environment. However, data from phagocytic cells are lacking. In this study, we mapped SCV and WT colony populations in axenic growth of multiple well-characterized methicillin-sensitive and methicillin-resistant S. aureus strains. We identified SCVs populations on solid media both in the presence and absence of gentamicin. We generated stable SCVs from Newman strain S. aureus, and infected human macrophages with WT S. aureus (Newman, 8325-4) and their SCV counterparts (SCV3, I10) to examine intracellular formation and survival of SCVs. We show that SCVs arise spontaneously during axenic growth, and that the ratio of SCV:WT morphology differs between strains. Exposure to the intracellular environment of human macrophages did not increase formation of SCVs over 5 days and macrophages were able to clear stable SCV bacteria more effectively than their WT counterparts.
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Affiliation(s)
- Simon M Stoneham
- Department of Microbiology and Infection, Royal Sussex County Hospital, Brighton, United Kingdom.,Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Daire M Cantillon
- Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Simon J Waddell
- Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Martin J Llewelyn
- Department of Microbiology and Infection, Royal Sussex County Hospital, Brighton, United Kingdom.,Department of Global Health and Infection, Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
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35
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Kuehl R, Morata L, Meylan S, Mensa J, Soriano A. When antibiotics fail: a clinical and microbiological perspective on antibiotic tolerance and persistence of Staphylococcus aureus. J Antimicrob Chemother 2020; 75:1071-1086. [PMID: 32016348 DOI: 10.1093/jac/dkz559] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen causing a vast array of infections with significant mortality. Its versatile physiology enables it to adapt to various environments. Specific physiological changes are thought to underlie the frequent failure of antimicrobial therapy despite susceptibility in standard microbiological assays. Bacteria capable of surviving high antibiotic concentrations despite having a genetically susceptible background are described as 'antibiotic tolerant'. In this review, we put current knowledge on environmental triggers and molecular mechanisms of increased antibiotic survival of S. aureus into its clinical context. We discuss animal and clinical evidence of its significance and outline strategies to overcome infections with antibiotic-tolerant S. aureus.
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Affiliation(s)
- Richard Kuehl
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland
| | - Laura Morata
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
| | - Sylvain Meylan
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland
- Division de Maladies Infectieuses, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Josep Mensa
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
| | - Alex Soriano
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
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36
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Röhrig C, Huemer M, Lorgé D, Luterbacher S, Phothaworn P, Schefer C, Sobieraj AM, Zinsli LV, Mairpady Shambat S, Leimer N, Keller AP, Eichenseher F, Shen Y, Korbsrisate S, Zinkernagel AS, Loessner MJ, Schmelcher M. Targeting Hidden Pathogens: Cell-Penetrating Enzybiotics Eradicate Intracellular Drug-Resistant Staphylococcus aureus. mBio 2020; 11:e00209-20. [PMID: 32291298 PMCID: PMC7157818 DOI: 10.1128/mbio.00209-20] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/17/2020] [Indexed: 01/21/2023] Open
Abstract
Staphylococcus aureus is a major concern in human health care, mostly due to the increasing prevalence of antibiotic resistance. Intracellular localization of S. aureus plays a key role in recurrent infections by protecting the pathogens from antibiotics and immune responses. Peptidoglycan hydrolases (PGHs) are highly specific bactericidal enzymes active against both drug-sensitive and -resistant bacteria. However, PGHs able to effectively target intracellular S. aureus are not yet available. To overcome this limitation, we first screened 322 recombineered PGHs for staphylolytic activity under conditions found inside eukaryotic intracellular compartments. The most active constructs were modified by fusion to different cell-penetrating peptides (CPPs), resulting in increased uptake and enhanced intracellular killing (reduction by up to 4.5 log units) of various S. aureus strains (including methicillin-resistant S. aureus [MRSA]) in different tissue culture infection models. The combined application of synergistic PGH-CPP constructs further enhanced their intracellular efficacy. Finally, synergistically active PGH-CPP cocktails reduced the total S. aureus by more than 2.2 log units in a murine abscess model after peripheral injection. Significantly more intracellular bacteria were killed by the PGH-CPPs than by the PGHs alone. Collectively, our findings show that CPP-fused PGHs are effective novel protein therapeutics against both intracellular and drug-resistant S. aureusIMPORTANCE The increasing prevalence of antibiotic-resistant bacteria is one of the most urgent problems of our time. Staphylococcus aureus is an important human pathogen that has acquired several mechanisms to evade antibiotic treatment. In addition, S. aureus is able to invade and persist within human cells, hiding from the immune response and antibiotic therapies. For these reasons, novel antibacterial strategies against these pathogens are needed. Here, we developed lytic enzymes which are able to effectively target drug-resistant and intracellular S. aureus Fusion of these so-called enzybiotics to cell-penetrating peptides enhanced their uptake and intracellular bactericidal activity in cell culture and in an abscess mouse model. Our results suggest that cell-penetrating enzybiotics are a promising new class of therapeutics against staphylococcal infections.
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Affiliation(s)
- Christian Röhrig
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Markus Huemer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Dominique Lorgé
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Samuel Luterbacher
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Preeda Phothaworn
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | | | - Anna M Sobieraj
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Léa V Zinsli
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Nadja Leimer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Anja P Keller
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Fritz Eichenseher
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Yang Shen
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Sunee Korbsrisate
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Martin J Loessner
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Mathias Schmelcher
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
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Wen Q, Gu F, Sui Z, Su Z, Yu T. The Process of Osteoblastic Infection by Staphylococcus Aureus. Int J Med Sci 2020; 17:1327-1332. [PMID: 32624688 PMCID: PMC7330672 DOI: 10.7150/ijms.45960] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/18/2020] [Indexed: 12/22/2022] Open
Abstract
Bone infection is difficult to cure, and relapse frequently occurs, which is a major treatment problem. One of the main reasons for the refractory and recurrent nature of bone infection is that bacteria, such as Staphylococcus aureus (S. aureus), can be internalized into osteoblasts after infecting bone tissue, thereby avoiding attack by the immune system and antibiotics. Understanding how bacteria (such as S. aureus) are internalized into osteoblasts is key to effective treatment. S. aureus is the most common pathogenic bacterium that causes bone infection. This paper reviews the literature, analyzes the specific process of osteoblastic S. aureus infection, and summarizes specific treatment strategies to improve bone infection treatment.
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Affiliation(s)
- Qiangqiang Wen
- Department of Orthopedics, First Hospital of Jilin University, Changchun 130021, Jilin, China
| | - Feng Gu
- Department of Orthopedics, First Hospital of Jilin University, Changchun 130021, Jilin, China
| | - Zhenjiang Sui
- Department of Orthopedics, First Hospital of Jilin University, Changchun 130021, Jilin, China
| | - Zilong Su
- Department of Orthopedics, First Hospital of Jilin University, Changchun 130021, Jilin, China
| | - Tiecheng Yu
- Department of Orthopedics, First Hospital of Jilin University, Changchun 130021, Jilin, China
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Tan J, Wang J, Yang C, Zhu C, Guo G, Tang J, Shen H. Antimicrobial characteristics of Berberine against prosthetic joint infection-related Staphylococcus aureus of different multi-locus sequence types. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 19:218. [PMID: 31419978 PMCID: PMC6697971 DOI: 10.1186/s12906-019-2558-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 06/11/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Staphylococcal aureus (S. aureus) has become the leading causative pathogen of Prosthetic Joint Infection (PJI), which is the most devastating complication after arthroplasty surgeries. Due to the biofilm formation ability and emergence of multiple-drugs resistance strains of S. aureus, it has become an urgency to find new anti-staphylococcal agents to establish effective prophylaxis and treatment strategy for PJI. Extracted from a traditional Chinese herb, berberine is proved active in inhibiting S. aureus, while whether it exerts the same effect on PJI-related S. aureus remains unknown. This study aims to investigate the antimicrobial activity of berbrine against clinical derived PJI-related S. aureus and whether its inhibiting efficacy is associated with subtypes of S. aureus. METHODS Eighteen PJI-associated S. aureus were collected and their Multi-locus Sequence Types (MLST) and susceptibility to berberine both in planktonic and biofilm form were investigated. Additionally, one S. aureus strain (ST1792) was selected from the group and its transcriptomic profiling in berberine incubation was performed. The statistical analyses were conducted using Student's t-test with SPSS 24.0(SPSS, IBM, USA). The data were expressed as the means ± standard deviation. Values of p < 0.05 were considered statistically significant. RESULTS It was found out that the Minimum Inhibitory Concentration values of PJI-related S. aureus varied in a broad range (from 64 to 512 μg/ml) among different MLST subtypes and the bacteria were able to regain growth after 24 h in berberine of MIC value or higher concentrations. In addition, sub-inhibitory concentrations of berberine surprisingly enhanced biofilm formation in some S. aureus strains. CONCLUSION Traditional medicine is utilised by a large number of individuals, which provides abundant resources for modern medical science. In our study, berberine was found bactericidal against PJI related S. aureus, however, its antibacterial property was impacted by the MLST subtypes of the bacteria, both in planktonic and biofilm growth forms.
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Hingston PA, Truelstrup Hansen L, Pombert JF, Wang S. Characterization of Listeria monocytogenes enhanced cold-tolerance variants isolated during prolonged cold storage. Int J Food Microbiol 2019; 306:108262. [PMID: 31362162 DOI: 10.1016/j.ijfoodmicro.2019.108262] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 05/04/2019] [Accepted: 07/07/2019] [Indexed: 11/25/2022]
Abstract
In this study, we show that growth and prolonged storage of Listeria monocytogenes at 4 °C can promote the selection of variants with enhanced cold and heat tolerance. Enhanced cold-tolerance (ECT) variants (n = 12) were successfully isolated from a strain with impaired cold growth abilities following 84 days of storage at 4 °C in brain heart infusion broth (BHIB). Whole genome sequencing, membrane fatty acid analysis, and stress tolerance profiling were performed on the parent strain and two ECT variants: one displaying regular-sized colonies and the other displaying small colonies when grown at 37 °C on BHI agar. Under cold stress conditions, the parent strain exhibited an impaired ability to produce branched-chain fatty acids which are known to be important for cold adaptation in L.monocytogenes. The ECT variants were able to overcome this limitation, a finding which is hypothesized to be associated with the identification of two independent single-nucleotide polymorphisms in genes encoding subunits of acetyl-coA carboxylase, an enzyme critical for fatty acid biosynthesis. While the ECT phenotype was not found to be associated with improved salt (BHIB + 6% NaCl, 25 °C), acid (BHIB pH 5, 25 °C) or desiccation (33% RH, 20 °C) tolerance, the small-colony variant exhibited significantly (p < 0.05) enhanced heat tolerance at 52 °C in buffered peptone water compared to the parent strain and the other variant. The results from this study demonstrate that the continuous use of refrigeration along the food-supply chain has the potential to select for L.monocytogenes variants with enhanced cold and heat tolerance, highlighting the impact that microbial intervention strategies can have on the evolution of bacterial strains and likewise, food safety.
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Affiliation(s)
- Patricia A Hingston
- Food, Nutrition and Health, The University of British Columbia, Vancouver, British Columbia, Canada
| | | | | | - Siyun Wang
- Food, Nutrition and Health, The University of British Columbia, Vancouver, British Columbia, Canada.
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Abstract
The origin of novel genes and beneficial functions is of fundamental interest in evolutionary biology. New genes can originate from different mechanisms, including horizontal gene transfer, duplication-divergence, and de novo from noncoding DNA sequences. Comparative genomics has generated strong evidence for de novo emergence of genes in various organisms, but experimental demonstration of this process has been limited to localized randomization in preexisting structural scaffolds. This bypasses the basic requirement of de novo gene emergence, i.e., lack of an ancestral gene. We constructed highly diverse plasmid libraries encoding randomly generated open reading frames and expressed them in Escherichia coli to identify short peptides that could confer a beneficial and selectable phenotype in vivo (in a living cell). Selections on antibiotic-containing agar plates resulted in the identification of three peptides that increased aminoglycoside resistance up to 48-fold. Combining genetic and functional analyses, we show that the peptides are highly hydrophobic, and by inserting into the membrane, they reduce membrane potential, decrease aminoglycoside uptake, and thereby confer high-level resistance. This study demonstrates that randomized DNA sequences can encode peptides that confer selective benefits and illustrates how expression of random sequences could spark the origination of new genes. In addition, our results also show that this question can be addressed experimentally by expression of highly diverse sequence libraries and subsequent selection for specific functions, such as resistance to toxic compounds, the ability to rescue auxotrophic/temperature-sensitive mutants, and growth on normally nonused carbon sources, allowing the exploration of many different phenotypes.IMPORTANCE De novo gene origination from nonfunctional DNA sequences was long assumed to be implausible. However, recent studies have shown that large fractions of genomic noncoding DNA are transcribed and translated, potentially generating new genes. Experimental validation of this process so far has been limited to comparative genomics, in vitro selections, or partial randomizations. Here, we describe selection of novel peptides in vivo using fully random synthetic expression libraries. The peptides confer aminoglycoside resistance by inserting into the bacterial membrane and thereby partly reducing membrane potential and decreasing drug uptake. Our results show that beneficial peptides can be selected from random sequence pools in vivo and support the idea that expression of noncoding sequences could spark the origination of new genes.
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Perez K, Patel R. Staphylococcusepidermidis Small-Colony Variants Are Induced by Low pH and Their Frequency Reduced by Lysosomal Alkalinization. J Infect Dis 2019; 215:488-490. [PMID: 27974434 DOI: 10.1093/infdis/jiw503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 10/13/2016] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Robin Patel
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, and.,Division of Infectious Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota
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42
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Leimer N, Zinkernagel AS. Reply to Perez and Patel. J Infect Dis 2019; 215:490-491. [PMID: 27974435 DOI: 10.1093/infdis/jiw504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 10/13/2016] [Indexed: 11/12/2022] Open
Affiliation(s)
- Nadja Leimer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Switzerland
| | - Annelies S Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Switzerland
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Paul P, Sahu BR, Suar M. Plausible role of bacterial toxin-antitoxin system in persister cell formation and elimination. Mol Oral Microbiol 2019; 34:97-107. [PMID: 30891951 DOI: 10.1111/omi.12258] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/22/2019] [Accepted: 03/16/2019] [Indexed: 12/11/2022]
Abstract
Although, a large proportion of pathogenic bacteria gets eliminated from hosts after antibiotic treatment, a fraction of population confronts against such effects and undergoes growth arrest to form persisters. Persistence in bacteria is a dormant physiological state where cells escape the effects of antimicrobials as well as other host immune defences without any genetic mutations. The state of dormancy is achieved through various complex phenomena and it is known that a gene pair named as toxin-antitoxin (TA) acts as a key player of persister cell formation where the toxin is activated either stochastically or after an environmental insult, thereby silencing the physiological processes. However, the controversial role of TA modules in persister cell formation has also been documented with reasonable clarity. Persisters may revert back from state of quiescence and regrow when conditions become favourable for their propagation. Therefore, the elimination of dormant bacteria is crucial, and currently, research interest is highly focussed on developing several antipersister strategies that may kill persister bacteria by targeting different molecules. It is worth examining these targets to develop appropriate therapeutic interventions against bacterial infections and it is believed that earmarking TA system can be a novel approach for resuscitation of persisters. In this review, we discussed the role of TA modules in mediating persistence with highlighting on the debatable issues regarding contribution of these modules in dormant bacteria formation. Furthermore, we discussed if these modules in bacteria can be targeted for successful elimination of dormant persister cells.
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Affiliation(s)
- Prajita Paul
- School of Biotechnology, KIIT (Deemed to be University), Bhubaneswar, India
| | - Bikash R Sahu
- School of Biotechnology, KIIT (Deemed to be University), Bhubaneswar, India
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT (Deemed to be University), Bhubaneswar, India
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44
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Magryś A, Deryło K, Bogut A, Olender A, Tchórzewski M. Intraphagolysosomal conditions predispose to Staphylococcus epidermidis small colony variants persistence in macrophages. PLoS One 2018; 13:e0207312. [PMID: 30412620 PMCID: PMC6226201 DOI: 10.1371/journal.pone.0207312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 10/29/2018] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus epidermidis small colony variants can survive inside macrophages and their survival has been proposed as a pivotal process in the pathogenesis of biomaterial associated infections. In the present study the intracellular location of clinical isolates of SCV and parental wild type strains inside macrophages was determined. Furthermore, the effect of IFN-γ and rapamycin on the level of SCV/WT as well as lysosomes colocalisation and iNOS induction in THP-activated macrophages in response to WT and SCV strains of Staphylococcus epidermidis were examined. It was demonstrated that SCV strain of S. epidermidis can survive and persist inside macrophages and its intracellular survival is supported by the induction of phagosomal acidification. The ability to reduce the high proportion of LysoTracker positive SCV containing phagosomes was exclusively found when IFN-γ was used. The findings suggest that IFN-γ mediates SCV killing via two distinct mechanisms, phagosome alkalisation and an increased iNOS synthesis, so the cytokine may control S. epidermidis WT and SCV infection in macrophages. Staphylococcus epidermidis SCV is a less potent stimulus of iNOS than the WT strain and the feature may help SCV to persist in hostile environment of macrophages. Rapamycin treatment did not influence the iNOS synthesis but reduced the percentage of both bacterial strains within acidic organelles. However, the percentage of SCV within LysoTracker positive organelles, even though reduced comparing to non-primed cells, was higher than in the WT strain indicating that Staphylococcus epidermidis possesses unique metabolic features allowing SCV to survive within macrophages.
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Affiliation(s)
- Agnieszka Magryś
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
- * E-mail:
| | - Kamil Deryło
- Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland
| | - Agnieszka Bogut
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
| | - Alina Olender
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
| | - Marek Tchórzewski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland
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Abuaita BH, Schultz TL, O'Riordan MX. Mitochondria-Derived Vesicles Deliver Antimicrobial Reactive Oxygen Species to Control Phagosome-Localized Staphylococcus aureus. Cell Host Microbe 2018; 24:625-636.e5. [PMID: 30449314 DOI: 10.1016/j.chom.2018.10.005] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/10/2018] [Accepted: 10/05/2018] [Indexed: 12/20/2022]
Abstract
Pathogenic bacteria taken up into the macrophage phagosome are the target of many anti-microbial mechanisms. Although mitochondria-derived antimicrobial effectors like reactive oxygen species (mROS) aid in bacterial killing, it is unclear how these effectors reach bacteria within the phagosomal lumen. We show here that endoplasmic reticulum stress triggered upon methicillin-resistant Staphylococcus aureus (MRSA) infection induces mROS that are delivered to bacteria-containing phagosomes via mitochondria-derived vesicles (MDVs). The endoplasmic reticulum stress sensor IRE1α induces mROS, specifically hydrogen peroxide (mH2O2), upon MRSA infection. MRSA infection also stimulates the generation of MDVs, which require the mitochondrial stress response factor Parkin, and contributes to mH2O2 accumulation in bacteria-containing phagosomes. Accumulation of phagosomal H2O2 requires Toll-like receptor signaling and the mitochondrial enzyme superoxide dismutase-2 (Sod2), which is delivered to phagosomes by MDVs. Sod2 depletion compromises mH2O2 production and bacterial killing. Thus, mitochondrial redox capacity enhances macrophage antimicrobial function by delivering mitochondria-derived effector molecules into bacteria-containing phagosomes.
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Affiliation(s)
- Basel H Abuaita
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Tracey L Schultz
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Mary X O'Riordan
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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46
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Vulin C, Leimer N, Huemer M, Ackermann M, Zinkernagel AS. Prolonged bacterial lag time results in small colony variants that represent a sub-population of persisters. Nat Commun 2018; 9:4074. [PMID: 30287875 PMCID: PMC6172231 DOI: 10.1038/s41467-018-06527-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022] Open
Abstract
Persisters are a subpopulation of bacteria that are not killed by antibiotics even though they lack genetic resistance. Here we provide evidence that persisters can manifest as small colony variants (SCVs) in clinical infections. We analyze growth kinetics of Staphylococcus aureus sampled from in vivo conditions and in vitro stress conditions that mimic growth in host compartments. We report that SCVs arise as a result of a long lag time, and that this phenotype emerges de novo during the growth phase in various stress conditions including abscesses and acidic media. We further observe that long lag time correlates with antibiotic usage. These observations suggest that treatment strategies should be carefully tailored to address bacterial persisters in clinics. Persisters are bacterial subpopulations that are not killed by antibiotics even though they lack genetic resistance. Here, the authors show that persisters can manifest as small colony variants in clinical infections, and arise as a result of a long lag time in stress conditions including antibiotic exposure.
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Affiliation(s)
- Clément Vulin
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, 8092, Switzerland.,Department of Environmental Microbiology, Eawag, Dubendorf, 8600, Switzerland
| | - Nadja Leimer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland.,Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Markus Huemer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, 8092, Switzerland. .,Department of Environmental Microbiology, Eawag, Dubendorf, 8600, Switzerland.
| | - Annelies S Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland.
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Darisipudi MN, Nordengrün M, Bröker BM, Péton V. Messing with the Sentinels-The Interaction of Staphylococcus aureus with Dendritic Cells. Microorganisms 2018; 6:microorganisms6030087. [PMID: 30111706 PMCID: PMC6163568 DOI: 10.3390/microorganisms6030087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/12/2018] [Accepted: 08/14/2018] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is a dangerous pathogen as well as a frequent colonizer, threatening human health worldwide. Protection against S. aureus infection is challenging, as the bacteria have sophisticated strategies to escape the host immune response. To maintain equilibrium with S. aureus, both innate and adaptive immune effector mechanisms are required. Dendritic cells (DCs) are critical players at the interface between the two arms of the immune system, indispensable for inducing specific T cell responses. In this review, we highlight the importance of DCs in mounting innate as well as adaptive immune responses against S. aureus with emphasis on their role in S. aureus-induced respiratory diseases. We also review what is known about mechanisms that S. aureus has adopted to evade DCs or manipulate these cells to its advantage.
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Affiliation(s)
- Murthy N Darisipudi
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Maria Nordengrün
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Barbara M Bröker
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
| | - Vincent Péton
- Department of Immunology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße DZ7, D-17475 Greifswald, Germany.
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48
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Sakatos A, Babunovic GH, Chase MR, Dills A, Leszyk J, Rosebrock T, Bryson B, Fortune SM. Posttranslational modification of a histone-like protein regulates phenotypic resistance to isoniazid in mycobacteria. SCIENCE ADVANCES 2018; 4:eaao1478. [PMID: 29732401 PMCID: PMC5931751 DOI: 10.1126/sciadv.aao1478] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 03/20/2018] [Indexed: 05/08/2023]
Abstract
There is increasing evidence that phenotypically drug-resistant bacteria may be important determinants of antibiotic treatment failure. Using high-throughput imaging, we defined distinct subpopulations of mycobacterial cells that exhibit heritable but semi-stable drug resistance. These subpopulations have distinct transcriptional signatures and growth characteristics at both bulk and single-cell levels, which are also heritable and semi-stable. We find that the mycobacterial histone-like protein HupB is required for the formation of these subpopulations. Using proteomic approaches, we further demonstrate that HupB is posttranslationally modified by lysine acetylation and lysine methylation. Mutation of a single posttranslational modification site specifically abolishes the formation of one of the drug-resistant subpopulations of cells, providing the first evidence in prokaryotes that posttranslational modification of a bacterial nucleoid-associated protein may epigenetically regulate cell state.
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Affiliation(s)
- Alexandra Sakatos
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Gregory H. Babunovic
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Michael R. Chase
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Alexander Dills
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - John Leszyk
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 02129, USA
| | - Tracy Rosebrock
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Stonehill College, North Easton, MA 02357, USA
| | - Bryan Bryson
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Sarah M. Fortune
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- The Ragon Institute of Massachusetts General Hospital, Harvard, and Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Corresponding author.
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49
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Abstract
An implicit aim in cellular infection biology is to understand the mechanisms how viruses, microbes, eukaryotic parasites, and fungi usurp the functions of host cells and cause disease. Mechanistic insight is a deep understanding of the biophysical and biochemical processes that give rise to an observable phenomenon. It is typically subject to falsification, that is, it is accessible to experimentation and empirical data acquisition. This is different from logic and mathematics, which are not empirical, but built on systems of inherently consistent axioms. Here, we argue that modeling and computer simulation, combined with mechanistic insights, yields unprecedented deep understanding of phenomena in biology and especially in virus infections by providing a way of showing sufficiency of a hypothetical mechanism. This ideally complements the necessity statements accessible to empirical falsification by additional positive evidence. We discuss how computational implementations of mathematical models can assist and enhance the quantitative measurements of infection dynamics of enveloped and non-enveloped viruses and thereby help generating causal insights into virus infection biology.
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50
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The Electron Transport Chain Sensitizes Staphylococcus aureus and Enterococcus faecalis to the Oxidative Burst. Infect Immun 2017; 85:IAI.00659-17. [PMID: 28993457 DOI: 10.1128/iai.00659-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 09/28/2017] [Indexed: 12/16/2022] Open
Abstract
Small-colony variants (SCVs) of Staphylococcus aureus typically lack a functional electron transport chain and cannot produce virulence factors such as leukocidins, hemolysins, or the antioxidant staphyloxanthin. Despite this, SCVs are associated with persistent infections of the bloodstream, bones, and prosthetic devices. The survival of SCVs in the host has been ascribed to intracellular residency, biofilm formation, and resistance to antibiotics. However, the ability of SCVs to resist host defenses is largely uncharacterized. To address this, we measured the survival of wild-type and SCV S. aureus in whole human blood, which contains high numbers of neutrophils, the key defense against staphylococcal infection. Despite the loss of leukocidin production and staphyloxanthin biosynthesis, SCVs defective for heme or menaquinone biosynthesis were significantly more resistant to the oxidative burst than wild-type bacteria in human blood or the presence of purified neutrophils. Supplementation of the culture medium of the heme-auxotrophic SCV with heme, but not iron, restored growth, hemolysin and staphyloxanthin production, and sensitivity to the oxidative burst. Since Enterococcus faecalis is a natural heme auxotroph and cause of bloodstream infection, we explored whether restoration of the electron transport chain in this organism also affected survival in blood. Incubation of E. faecalis with heme increased growth and restored catalase activity but resulted in decreased survival in human blood via increased sensitivity to the oxidative burst. Therefore, the lack of functional electron transport chains in SCV S. aureus and wild-type E. faecalis results in reduced growth rate but provides resistance to a key immune defense mechanism.
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