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Chen KW, Broz P. Gasdermins as evolutionarily conserved executors of inflammation and cell death. Nat Cell Biol 2024; 26:1394-1406. [PMID: 39187689 DOI: 10.1038/s41556-024-01474-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 07/04/2024] [Indexed: 08/28/2024]
Abstract
The gasdermins are a family of pore-forming proteins that have recently emerged as executors of pyroptosis, a lytic form of cell death that is induced by the innate immune system to eradicate infected or malignant cells. Mammalian gasdermins comprise a cytotoxic N-terminal domain, a flexible linker and a C-terminal repressor domain. Proteolytic cleavage in the linker releases the cytotoxic domain, thereby allowing it to form β-barrel membrane pores. Formation of gasdermin pores in the plasma membrane eventually leads to a loss of the electrochemical gradient, cell death and membrane rupture. Here we review recent work that has expanded our understanding of gasdermin biology and function in mammals by revealing their activation mechanism, their regulation and their roles in autoimmunity, host defence and cancer. We further highlight fungal and bacterial gasdermin pore formation pointing to a conserved mechanism of cell death induction.
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Affiliation(s)
- Kaiwen W Chen
- Immunology Translational Research Programme, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Immunology Programme, Life Sciences Institute, National University of Singapore, Singapore, Singapore.
| | - Petr Broz
- Department of Immunobiology, University of Lausanne, Lausanne, Switzerland.
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2
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Wadhwani N, Bhola N, Yelne P. Necrotizing Fasciitis Co-existing With Oral Squamous Cell Carcinoma: A Case Report of a Diagnostic Dilemma. Cureus 2024; 16:e62947. [PMID: 39050346 PMCID: PMC11265955 DOI: 10.7759/cureus.62947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Accepted: 06/23/2024] [Indexed: 07/27/2024] Open
Abstract
Necrotizing fasciitis is an uncommon yet highly dangerous bacterial infection characterized by rapid spread along the fascial planes and subcutaneous tissue, leading to extensive tissue necrosis and often resulting in death. The swift progression of necrosis can induce systemic sepsis, toxic shock syndrome, and multi-organ failure. While necrotizing fasciitis of the neck is rare, it typically originates from dental or pharyngeal sources. Successful treatment hinges on early diagnosis, appropriate antibiotic therapy, and surgical intervention for tissue debridement. This article presents the case of a 40-year-old individual with necrotizing fasciitis of the neck. We herein review the clinical features, pathogenesis, and treatment approach for the case. Rapid recovery necessitated comprehensive medical treatment targeting the underlying cause with aggressive supportive measures. Surgical intervention involved thorough debridement to remove necrotic tissue, irrigation with antiseptic solutions, and early application of topical antimicrobials.
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Affiliation(s)
- Nikhar Wadhwani
- Oral and Maxillofacial Surgery, Sharad Pawar Dental College and Hospital, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Nitin Bhola
- Oral and Maxillofacial Surgery, Sharad Pawar Dental College and Hospital, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Pallavi Yelne
- Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
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3
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Nagayama J, Sato T, Takanori I, Kouji K, Mitsunobu N. Necrotising fasciitis with extensive necrosis caused by Lactobacillus: a case report. BMC Infect Dis 2024; 24:425. [PMID: 38649870 PMCID: PMC11034093 DOI: 10.1186/s12879-024-09291-3] [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: 12/28/2023] [Accepted: 04/04/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Necrotising fasciitis (NF) is a life-threatening soft-tissue infection that rapidly destroys the epidermis, subcutaneous tissue, and fascia. Despite their low virulence, Lactobacillus spp. can cause NF, and because of its rare incidence, there is limited information about its molecular and clinicopathological characteristics. We report a rare case of NF in a patient with type 2 diabetes mellitus diagnosed on admission and severe obesity due to infection with two types of Lactobacillus spp. that manifested in extensive necrosis. CASE PRESENTATION A 48-year-old woman was referred to our hospital with a complaint of difficulty walking due to severe bilateral thigh pain. She presented with mild erythema, swelling, and severe skin pain extending from the pubic region to the groin. The patient was morbidly obese, had renal dysfunction, and had diabetes mellitus diagnosed on admission.; her LRINEC (Laboratory Risk Indicator for Necrotising Fasciitis) score was 9, indicating a high risk of NF. An exploratory surgical incision was made, and NF was diagnosed based on fascial necrosis. Emergent surgical debridement was performed, and cultures of the tissue culture and aspirated fluid/pus revealed two types of Lactobacillus spp.: Lactobacillus salivarius and L. iners. The patient was admitted to the intensive care unit (ICU), where antibiotics were administered and respiratory and circulatory management was performed. Diabetic ketoacidosis was detected, which was treated by controlling the blood glucose level stringently via intravenous insulin infusion. The patient underwent a second debridement on day 11 and a skin suture and skin grafting on day 36. The patient progressed well, was transferred from the ICU to the general ward on day 41, and was discharged unassisted on day 73. CONCLUSIONS Lactobacillus spp. are rarely pathogenic to healthy individuals and can scarcely trigger NF. However, these bacteria can cause rare infections such as NF in immunocompromised individuals, such as those with diabetes and obesity, and an early diagnosis of NF is imperative; surgical intervention may be required for the prevention of extensive necrosis. The LRINEC score may be useful for the early diagnosis of NF, even for less pathogenic bacteria such as Lactobacillus.
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Affiliation(s)
- Jun Nagayama
- Advanced Medical Emergency Department and Critical Care Center, Japanese Red Cross Maebashi Hospital, 389-1, Asakura-machi, 371-0811, Maebashi, Gunma, Japan.
| | - Takeo Sato
- Center for Community Clinical Education, Jichi Medical University, 3311-1 Yakushiji, 329-0498, Shimotsuke-shi, Tochigi-ken, Japan
| | - Ishida Takanori
- Advanced Medical Emergency Department and Critical Care Center, Japanese Red Cross Maebashi Hospital, 389-1, Asakura-machi, 371-0811, Maebashi, Gunma, Japan
| | - Koga Kouji
- Advanced Medical Emergency Department and Critical Care Center, Japanese Red Cross Maebashi Hospital, 389-1, Asakura-machi, 371-0811, Maebashi, Gunma, Japan
| | - Nakamura Mitsunobu
- Advanced Medical Emergency Department and Critical Care Center, Japanese Red Cross Maebashi Hospital, 389-1, Asakura-machi, 371-0811, Maebashi, Gunma, Japan
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4
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Okai N, Otsuka Y, Masaki S, Kudo M, Watanabe T. Necrotizing Fasciitis of the Serratus Anterior in a Patient Treated With Infliximab and Prednisolone for Ulcerative Colitis and Rheumatoid Arthritis. Cureus 2024; 16:e59346. [PMID: 38817521 PMCID: PMC11137776 DOI: 10.7759/cureus.59346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2024] [Indexed: 06/01/2024] Open
Abstract
Necrotizing fasciitis (NF) is a rapidly progressive bacterial infection with high mortality. Invasive group A Streptococcus (GAS) infection is the leading cause of NF. Our understanding regarding clinicopathological features and pathogenesis of invasive GAS infection is expanding as the incidence of NF in healthy individuals increases. However, clinicopathological features of NF in the presence of autoimmune diseases have been poorly defined. We experienced NF in a patient treated with infliximab and prednisolone for ulcerative colitis and rheumatoid arthritis. Herein, we present time kinetics findings of clinical symptoms and laboratory data of GAS-associated NF in the presence of immunosuppressant-treated immune disorders.
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Affiliation(s)
- Natsuki Okai
- Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, JPN
| | - Yasuo Otsuka
- Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, JPN
| | - Sho Masaki
- Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, JPN
| | - Masatoshi Kudo
- Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, JPN
| | - Tomohiro Watanabe
- Gastroenterology and Hepatology, Kindai University Faculty of Medicine, Osaka-Sayama, JPN
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5
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Mercadante S, Ficari A, Romani L, De Luca M, Tripiciano C, Chiurchiù S, Calo Carducci FI, Cursi L, Di Giuseppe M, Krzysztofiak A, Bernardi S, Lancella L. The Thousand Faces of Invasive Group A Streptococcal Infections: Update on Epidemiology, Symptoms, and Therapy. CHILDREN (BASEL, SWITZERLAND) 2024; 11:383. [PMID: 38671600 PMCID: PMC11048970 DOI: 10.3390/children11040383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/15/2024] [Accepted: 03/20/2024] [Indexed: 04/28/2024]
Abstract
Invasive infections caused by Streptococcus pyogfenes (iGAS), commonly known as Group A Streptococcus, represent a significant public health concern due to their potential for rapid progression and life-threatening complications. Epidemiologically, invasive GAS infections exhibit a diverse global distribution, affecting individuals of all ages with varying predisposing factors. The pathogenesis of invasive GAS involves an array of virulence factors that contribute to tissue invasion, immune evasion, and systemic dissemination. In pediatrics, in the last few years, an increase in iGAS infections has been reported worldwide becoming a challenging disease to diagnose and treat promptly. This review highlights the current knowledge on pathogenesis, clinical presentations, and therapeutic approaches for iGAS in children.
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Affiliation(s)
- Stefania Mercadante
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Andrea Ficari
- Residency School of Pediatrics, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Lorenza Romani
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Maia De Luca
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Costanza Tripiciano
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Sara Chiurchiù
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Francesca Ippolita Calo Carducci
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Laura Cursi
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Martina Di Giuseppe
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Andrzej Krzysztofiak
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Stefania Bernardi
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
| | - Laura Lancella
- Infectious Disease Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; (S.M.); (L.R.); (C.T.); (S.C.); (S.B.); (L.L.)
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6
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Kant S, Sun Y, Pancholi V. StkP- and PhpP-Mediated Posttranslational Modifications Modulate the S. pneumoniae Metabolism, Polysaccharide Capsule, and Virulence. Infect Immun 2023; 91:e0029622. [PMID: 36877045 PMCID: PMC10112228 DOI: 10.1128/iai.00296-22] [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: 07/15/2022] [Accepted: 02/09/2023] [Indexed: 03/07/2023] Open
Abstract
Pneumococcal Ser/Thr kinase (StkP) and its cognate phosphatase (PhpP) play a crucial role in bacterial cytokinesis. However, their individual and reciprocal metabolic and virulence regulation-related functions have yet to be adequately investigated in encapsulated pneumococci. Here, we demonstrate that the encapsulated pneumococcal strain D39-derived D39ΔPhpP and D39ΔStkP mutants displayed differential cell division defects and growth patterns when grown in chemically defined media supplemented with glucose or nonglucose sugars as the sole carbon source. Microscopic and biochemical analyses supported by RNA-seq-based global transcriptomic analyses of these mutants revealed significantly down- and upregulated polysaccharide capsule formation and cps2 genes in D39ΔPhpP and D39ΔStkP mutants, respectively. While StkP and PhpP individually regulated several unique genes, they also participated in sharing the regulation of the same set of differentially regulated genes. Cps2 genes were reciprocally regulated in part by the StkP/PhpP-mediated reversible phosphorylation but independent of the MapZ-regulated cell division process. StkP-mediated dose-dependent phosphorylation of CcpA proportionately inhibited CcpA-binding to Pcps2A, supporting increased cps2 gene expression and capsule formation in D39ΔStkP. While the attenuation of the D39ΔPhpP mutant in two mouse infection models corroborated with several downregulated capsules-, virulence-, and phosphotransferase systems (PTS)-related genes, the D39ΔStkP mutant with increased amounts of polysaccharide capsules displayed significantly decreased virulence in mice compared to the D39 wild-type, but more virulence compared to D39ΔPhpP. NanoString technology-based inflammation-related gene expression and Meso Scale Discovery-based multiplex chemokine analysis of human lung cells cocultured with these mutants confirmed their distinct virulence phenotypes. StkP and PhpP may, therefore, serve as critical therapeutic targets.
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Affiliation(s)
- Sashi Kant
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Youcheng Sun
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Vijay Pancholi
- Department of Pathology, Ohio State University College of Medicine, Columbus, Ohio, USA
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Abstract
Necrotizing fasciitis is a severe infectious disease that results in significant mortality. Streptococcus pyogenes (group A Streptococcus, GAS) is one of the most common bacterial pathogens of monomicrobial necrotizing fasciitis. The early diagnosis of necrotizing fasciitis is crucial; however, the typical cutaneous manifestations are not always presented in patients with GAS necrotizing fasciitis, which would lead to miss- or delayed diagnosis. GAS with spontaneous inactivating mutations in the CovR/CovS two-component regulatory system is significantly associated with destructive diseases such as necrotizing fasciitis and toxic shock syndrome; however, no specific marker has been used to identify these invasive clinical isolates. This study evaluated the sensitivity and specificity of using CovR/CovS-controlled phenotypes to identify CovR/CovS-inactivated isolates. Results showed that the increase of hyaluronic acid capsule production and streptolysin O expression were not consistently presented in CovS-inactivated clinical isolates. The repression of SpeB is the phenotype with 100% sensitivity of identifying in CovS-inactivated isolates among 61 clinical isolates. Nonetheless, this phenotype failed to distinguish RopB-inactivated isolates from CovS-inactivated isolates and cannot be utilized to identify CovR-inactivated mutant and RocA (Regulator of Cov)-inactivated isolates. In this study, we identified and verified that PepO, the endopeptidase which regulates SpeB expression through degrading SpeB-inducing quorum-sensing peptide, was a bacterial marker to identify isolates with defects in the CovR/CovS pathway. These results also inform the potential strategy of developing rapid detection methods to identify invasive GAS variants during infection. IMPORTANCE Necrotizing fasciitis is rapidly progressive and life-threatening; if the initial diagnosis is delayed, deep soft tissue infection can progress to massive tissue destruction and toxic shock syndrome. Group A Streptococcus (GAS) with inactivated mutations in the CovR/CovS two-component regulatory system are related to necrotizing fasciitis and toxic shock syndrome; however, no bacterial marker is available to identify these invasive clinical isolates. Inactivation of CovR/CovS resulted in the increased expression of endopeptidase PepO. Our study showed that the upregulation of PepO mediates a decrease in SpeB-inducing peptide (SIP) in the covR mutant, indicating that CovR/CovS modulates SIP-dependent quorum-sensing activity through PepO. Importantly, the sensitivity and specificity of utilizing PepO to identify clinical isolates with defects in the CovR/CovS pathway, including its upstream RocA regulator, were 100%. Our results suggest that identification of invasive GAS by PepO may be a strategy for preventing severe manifestation or poor prognosis after GAS infection.
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8
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Lee MS, Bensinger SJ. Reprogramming cholesterol metabolism in macrophages and its role in host defense against cholesterol-dependent cytolysins. Cell Mol Immunol 2022; 19:327-336. [PMID: 35017717 PMCID: PMC8891295 DOI: 10.1038/s41423-021-00827-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/07/2021] [Indexed: 12/14/2022] Open
Abstract
Cholesterol is a critical lipid for all mammalian cells, ensuring proper membrane integrity, fluidity, and biochemical function. Accumulating evidence indicates that macrophages rapidly and profoundly reprogram their cholesterol metabolism in response to activation signals to support host defense processes. However, our understanding of the molecular details underlying how and why cholesterol homeostasis is specifically reshaped during immune responses remains less well understood. This review discusses our current knowledge of cellular cholesterol homeostatic machinery and introduces emerging concepts regarding how plasma membrane cholesterol is partitioned into distinct pools. We then discuss how proinflammatory signals can markedly reshape the cholesterol metabolism of macrophages, with a focus on the differences between MyD88-dependent pattern recognition receptors and the interferon signaling pathway. We also discuss recent work investigating the capacity of these proinflammatory signals to selectively reshape plasma membrane cholesterol homeostasis. We examine how these changes in plasma membrane cholesterol metabolism influence sensitivity to a set of microbial pore-forming toxins known as cholesterol-dependent cytolysins that specifically target cholesterol for their effector functions. We also discuss whether lipid metabolic reprogramming can be leveraged for therapy to mitigate tissue damage mediated by cholesterol-dependent cytolysins in necrotizing fasciitis and other related infections. We expect that advancing our understanding of the crosstalk between metabolism and innate immunity will help explain how inflammation underlies metabolic diseases and highlight pathways that could be targeted to normalize metabolic homeostasis in disease states.
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Affiliation(s)
- Min-Sub Lee
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA.
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA.
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9
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Johnson AF, LaRock CN. Antibiotic Treatment, Mechanisms for Failure, and Adjunctive Therapies for Infections by Group A Streptococcus. Front Microbiol 2021; 12:760255. [PMID: 34803985 PMCID: PMC8601407 DOI: 10.3389/fmicb.2021.760255] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Group A Streptococcus (GAS; Streptococcus pyogenes) is a nearly ubiquitous human pathogen responsible for a significant global disease burden. No vaccine exists, so antibiotics are essential for effective treatment. Despite a lower incidence of antimicrobial resistance than many pathogens, GAS is still a top 10 cause of death due to infections worldwide. The morbidity and mortality are primarily a consequence of the immune sequelae and invasive infections that are difficult to treat with antibiotics. GAS has remained susceptible to penicillin and other β-lactams, despite their widespread use for 80 years. However, the failure of treatment for invasive infections with penicillin has been consistently reported since the introduction of antibiotics, and strains with reduced susceptibility to β-lactams have emerged. Furthermore, isolates responsible for outbreaks of severe infections are increasingly resistant to other antibiotics of choice, such as clindamycin and macrolides. This review focuses on the challenges in the treatment of GAS infection, the mechanisms that contribute to antibiotic failure, and adjunctive therapeutics. Further understanding of these processes will be necessary for improving the treatment of high-risk GAS infections and surveillance for non-susceptible or resistant isolates. These insights will also help guide treatments against other leading pathogens for which conventional antibiotic strategies are increasingly failing.
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Affiliation(s)
- Anders F Johnson
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA, United States
| | - Christopher N LaRock
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA, United States.,Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States.,Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States.,Emory Antibiotic Resistance Center, Atlanta, GA, United States
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10
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Anand A, Sharma A, Ravins M, Biswas D, Ambalavanan P, Lim KXZ, Tan RYM, Johri AK, Tirosh B, Hanski E. Unfolded protein response inhibitors cure group A streptococcal necrotizing fasciitis by modulating host asparagine. Sci Transl Med 2021; 13:13/605/eabd7465. [PMID: 34349034 DOI: 10.1126/scitranslmed.abd7465] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/24/2021] [Accepted: 06/25/2021] [Indexed: 11/02/2022]
Abstract
Group A streptococcus (GAS) is among the top 10 causes of mortality from an infectious disease, producing mild to invasive life-threatening manifestations. Necrotizing fasciitis (NF) is characterized by a rapid GAS spread into fascial planes followed by extensive tissue destruction. Despite prompt treatments of antibiotic administration and tissue debridement, mortality from NF is still high. Moreover, there is no effective vaccine against GAS, and early diagnosis of NF is problematic because its clinical presentations are not specific. Thus, there is a genuine need for effective treatments against GAS NF. Previously, we reported that GAS induces endoplasmic reticulum (ER) stress to gain asparagine from the host. Here, we demonstrate that GAS-mediated asparagine induction and release occur through the PERK-eIF2α-ATF4 branch of the unfolded protein response. Inhibitors of PERK or integrated stress response (ISR) blocked the formation and release of asparagine by infected mammalian cells, and exogenously added asparagine overcame this inhibition. Moreover, in a murine model of NF, we show that the inhibitors minimized mortality when mice were challenged with a lethal dose of GAS and reduced bacterial counts and lesion size when mice were challenged with a sublethal dose. Immunohistopathology studies demonstrated that PERK/ISR inhibitors protected mice by enabling neutrophil infiltration into GAS-infected fascia and reducing the pro-inflammatory response that causes tissue damage. Inhibitor treatment was also effective in mice when started at 12 hours after infection. We conclude that host metabolic alteration induced by PERK or ISR inhibitors is a promising therapeutic strategy to treat highly invasive GAS infections.
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Affiliation(s)
- Aparna Anand
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Abhinay Sharma
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Miriam Ravins
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Debabrata Biswas
- Singapore-HUJ Alliance for Research and Enterprise, MMID Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 117576, Singapore.,Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Poornima Ambalavanan
- Singapore-HUJ Alliance for Research and Enterprise, MMID Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 117576, Singapore.,Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Kimberly Xuan Zhen Lim
- Singapore-HUJ Alliance for Research and Enterprise, MMID Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 117576, Singapore.,Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Rachel Ying Min Tan
- Singapore-HUJ Alliance for Research and Enterprise, MMID Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 117576, Singapore.,Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
| | - Atul Kumar Johri
- School of Life Sciences, Jawaharlal Nehru University, New Mehrauli Road, New Delhi 110067, India
| | - Boaz Tirosh
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
| | - Emanuel Hanski
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research, Israel-Canada (IMRIC), Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel. .,Singapore-HUJ Alliance for Research and Enterprise, MMID Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 117576, Singapore.,Department of Microbiology and Immunology, National University of Singapore, Singapore 138602, Singapore
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11
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Kim HJ, Ryu JH, Park HY, Kim SI, Chang DG. Rapidly progressive gas-forming infection involving the spine as a life-threatening fatal condition : a case report. BMC Musculoskelet Disord 2021; 22:696. [PMID: 34399703 PMCID: PMC8365979 DOI: 10.1186/s12891-021-04589-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/05/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Gas forming infection of the spine is a consequence of vertebral osteomyelitis, necrotizing fasciitis, or a gas-forming epidural abscess, which is very rare and fatal conditions. This is the rare case of necrotizing fasciitis that rapidly progressed from the lumbar area to upper thoracic area. CASE PRESENTATION A 58-year-old male complained of lower back pain with fever and chills. The patient had a history of uncontrolled diabetes mellitus without diabetic medication over the previous 3 months, and he had received several local injections around the lumbar area. Laboratory data revealed white blood cell count of 19,710 /mm3, erythrocyte sedimentation of 40 mm/h, and C-reactive protein of 30.7 mg/L. Radiological findings revealed a small amount of air bubbles in the paraspinal area and lumbar epidural spaces. The patient refused emergency surgery and was discharged from the hospital. The patient re-visited the emergency department two days after discharge complaining of more severe back pain with persistent fever, and his vital signs had deteriorated, with low blood pressure and tachycardia. K. pneumoniae was isolated in cultures from ultrasound-guided aspirates and peripheral blood. The follow-up radiographs revealed aggressive dissemination of innumerable air bubbles from the lumbar area to the T5 level. The patient underwent emergent decompressive laminectomy and debridement of infected paravertebral fascia and musculature. Despite intensive care for deteriorated vital signs and his back wound, the patient died on postoperative day 3 due to multi-organ failure. CONCLUSIONS Necrotizing fasciitis involving the spine is a very rare disease with life-threatening conditions, rapid progression, and a high mortality rate. Therefore, prompt surgical treatment with a high index of suspicion is imperative to prevent potentially fatal conditions in similar extremely rare cases.
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Affiliation(s)
- Hong Jin Kim
- Spine Center and Department of Orthopedic Surgery, College of Medicine, Inje University Sanggye Paik Hospital, Inje University, 1342, Dongil-Ro, Nowon-Gu, 01757, Seoul, Republic of Korea
| | - Ji-Hyun Ryu
- Department of Orthopaedic Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyung-Youl Park
- Department of Orthopaedic Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sang-Il Kim
- Department of Orthopaedic Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Dong-Gune Chang
- Spine Center and Department of Orthopedic Surgery, College of Medicine, Inje University Sanggye Paik Hospital, Inje University, 1342, Dongil-Ro, Nowon-Gu, 01757, Seoul, Republic of Korea.
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12
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Damisa J, Ahmed S, Harrison S. Necrotising fasciitis: a narrative review of the literature. Br J Hosp Med (Lond) 2021; 82:1-9. [PMID: 33914635 DOI: 10.12968/hmed.2020.0577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Necrotising fasciitis is a severe, life-threatening and rapidly progressive soft tissue infection that often requires aggressive surgical management, with an estimated incidence of about 0.24-0.40 per 100 000 in the UK. Necrotising fasciitis can be classified based on its microbiology or the anatomy or body region affected. Initial signs of necrotising fasciitis can be minimal and non-specific but a patient often presents with pain out of proportion to clinical signs on examination, as well as erythema and oedema, in addition to systemic symptoms associated with sepsis. Diagnosis is often based on high clinical suspicion with biochemical and clinical imaging used as adjuncts. To aid with early diagnosis of necrotising fasciitis, a scoring system known as the Laboratory Risk Indicator for necrotising fasciitis was developed which has a positive predictive value of 92%. Once diagnosed, appropriate resuscitation and antibiotics, along with prompt and aggressive surgical debridement, is the mainstay of treatment.
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Affiliation(s)
- Josiah Damisa
- Department of General Surgery, Darlington Memorial Hospital, Darlington, UK
| | - Sohail Ahmed
- Department of General Surgery, Darlington Memorial Hospital, Darlington, UK
| | - Sanjay Harrison
- Department of General Surgery, Darlington Memorial Hospital, Darlington, UK
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13
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Hedetoft M, Bennett MH, Hyldegaard O. Adjunctive hyperbaric oxygen treatment for necrotising soft-tissue infections: A systematic review and meta-analysis. Diving Hyperb Med 2021; 51:34-43. [PMID: 33761539 DOI: 10.28920/dhm51.1.34-43] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Surgical intervention, broad-spectrum antibiotics and intensive care support are the standard of care in the treatment of necrotising soft-tissue infections (NSTI). Hyperbaric oxygen treatment (HBOT) may be a useful adjunctive treatment and has been used for almost 60 years, but its efficacy remains unknown and has not been systematically appraised. The aim was to systematically review and synthesise the highest level of clinical evidence available to support or refute the use of HBOT in the treatment of NSTI. METHODS The review was prospectively registered (PROSPERO; CRD42020148706). MEDLINE, EMBASE, CENTRAL and CINAHL were searched for eligible studies that reported outcomes in both HBOT treated and non-HBOT treated individuals with NSTI. In-hospital mortality was the primary outcome. Odds ratio (ORs) were pooled using random-effects models. RESULTS The search identified 486 papers of which 31 were included in the qualitative synthesis and 21 in the meta-analyses. Meta-analysis on 48,744 patients with NSTI (1,237 (2.5%) HBOT versus 47,507 (97.5%) non-HBOT) showed in-hospital mortality was 4,770 of 48,744 patients overall (9.8%) and the pooled OR was 0.44 (95% CI 0.33-0.58) in favour of HBOT. For major amputation the pooled OR was 0.60 (95% CI 0.28-1.28) in favour of HBOT. The dose of oxygen in these studies was incompletely reported. CONCLUSIONS Meta-analysis of the non-random comparative data indicates patients with NSTI treated with HBOT have reduced odds of dying during the sentinel event and may be less likely to require a major amputation. The most effective dose of oxygen remains unclear.
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Affiliation(s)
- Morten Hedetoft
- Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, Denmark.,Department of Anaesthesia and Hyperbaric Medicine, Prince of Wales Hospital, Sydney, Australia.,Corresponding author: Dr Morten Hedetoft, Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Blegdamsvej 8, 2100 Copenhagen, Denmark,
| | - Michael H Bennett
- Department of Anaesthesia and Hyperbaric Medicine, Prince of Wales Hospital, Sydney, Australia
| | - Ole Hyldegaard
- Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, University of Copenhagen, Denmark
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14
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Siemens N, Snäll J, Svensson M, Norrby-Teglund A. Pathogenic Mechanisms of Streptococcal Necrotizing Soft Tissue Infections. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1294:127-150. [PMID: 33079367 DOI: 10.1007/978-3-030-57616-5_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Necrotizing skin and soft tissue infections (NSTIs) are severe life-threatening and rapidly progressing infections. Beta-hemolytic streptococci, particularly S. pyogenes (group A streptococci (GAS)) but also S. dysgalactiae subsp. equisimilis (SDSE, most group G and C streptococcus), are the main causative agents of monomicrobial NSTIs and certain types, such as emm1 and emm3, are over-represented in NSTI cases. An arsenal of bacterial virulence factors contribute to disease pathogenesis, which is a complex and multifactorial process. In this chapter, we summarize data that have provided mechanistic and immuno-pathologic insight into host-pathogens interactions that contribute to tissue pathology in streptococcal NSTIs. The role of streptococcal surface associated and secreted factors contributing to the hyper-inflammatory state and immune evasion, bacterial load in the tissue and persistence strategies, including intracellular survival and biofilm formation, as well as strategies to mimic NSTIs in vitro are discussed.
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Affiliation(s)
- Nikolai Siemens
- Department of Molecular Genetics and Infection Biology, University of Greifswald, Greifswald, Germany.
| | - Johanna Snäll
- Department of Medicine, Center for Infectious Medicine, Karolinska Institutet, Huddinge, Sweden
| | - Mattias Svensson
- Department of Medicine, Center for Infectious Medicine, Karolinska Institutet, Huddinge, Sweden
| | - Anna Norrby-Teglund
- Department of Medicine, Center for Infectious Medicine, Karolinska Institutet, Huddinge, Sweden
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15
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Bernard PE, Duarte A, Bogdanov M, Musser JM, Olsen RJ. Single Amino Acid Replacements in RocA Disrupt Protein-Protein Interactions To Alter the Molecular Pathogenesis of Group A Streptococcus. Infect Immun 2020; 88:e00386-20. [PMID: 32817331 PMCID: PMC7573446 DOI: 10.1128/iai.00386-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/12/2020] [Indexed: 12/31/2022] Open
Abstract
Group A Streptococcus (GAS) is a human-specific pathogen and major cause of disease worldwide. The molecular pathogenesis of GAS, like many pathogens, is dependent on the coordinated expression of genes encoding different virulence factors. The control of virulence regulator/sensor (CovRS) two-component system is a major virulence regulator of GAS that has been extensively studied. More recent investigations have also involved regulator of Cov (RocA), a regulatory accessory protein to CovRS. RocA interacts, in some manner, with CovRS; however, the precise molecular mechanism is unknown. Here, we demonstrate that RocA is a membrane protein containing seven transmembrane helices with an extracytoplasmically located N terminus and cytoplasmically located C terminus. For the first time, we demonstrate that RocA directly interacts with itself (RocA) and CovS, but not CovR, in intact cells. Single amino acid replacements along the entire length of RocA disrupt RocA-RocA and RocA-CovS interactions to significantly alter the GAS virulence phenotype as defined by secreted virulence factor activity in vitro and tissue destruction and mortality in vivo In summary, we show that single amino acid replacements in a regulatory accessory protein can affect protein-protein interactions to significantly alter the virulence of a major human pathogen.
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Affiliation(s)
- Paul E Bernard
- Center for Molecular and Translational Human Infectious Disease Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, USA
- Texas A&M Health Science Center College of Medicine, Bryan, Texas, USA
| | - Amey Duarte
- Center for Molecular and Translational Human Infectious Disease Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, USA
| | - Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, Texas, USA
| | - James M Musser
- Center for Molecular and Translational Human Infectious Disease Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York, USA
| | - Randall J Olsen
- Center for Molecular and Translational Human Infectious Disease Research, Department of Pathology and Genomic Medicine, Houston Methodist Research Institute and Houston Methodist Hospital, Houston, Texas, USA
- Texas A&M Health Science Center College of Medicine, Bryan, Texas, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York, USA
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16
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Siggins MK, Lynskey NN, Lamb LE, Johnson LA, Huse KK, Pearson M, Banerji S, Turner CE, Woollard K, Jackson DG, Sriskandan S. Extracellular bacterial lymphatic metastasis drives Streptococcus pyogenes systemic infection. Nat Commun 2020; 11:4697. [PMID: 32943639 PMCID: PMC7498588 DOI: 10.1038/s41467-020-18454-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 08/24/2020] [Indexed: 12/15/2022] Open
Abstract
Unassisted metastasis through the lymphatic system is a mechanism of dissemination thus far ascribed only to cancer cells. Here, we report that Streptococcus pyogenes also hijack lymphatic vessels to escape a local infection site, transiting through sequential lymph nodes and efferent lymphatic vessels to enter the bloodstream. Contrasting with previously reported mechanisms of intracellular pathogen carriage by phagocytes, we show S. pyogenes remain extracellular during transit, first in afferent and then efferent lymphatics that carry the bacteria through successive draining lymph nodes. We identify streptococcal virulence mechanisms important for bacterial lymphatic dissemination and show that metastatic streptococci within infected lymph nodes resist and subvert clearance by phagocytes, enabling replication that can seed intense bloodstream infection. The findings establish the lymphatic system as both a survival niche and conduit to the bloodstream for S. pyogenes, explaining the phenomenon of occult bacteraemia. This work provides new perspectives in streptococcal pathogenesis with implications for immunity. Pathogenic agents can spread from an initial to a secondary site via the lymphatics. Here, using a mouse model of infection, the authors show that S. pyogenes readily transit through sequential lymph nodes within efferent lymphatics to reach the bloodstream and drive systemic infection, while remaining extracellular.
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Affiliation(s)
- Matthew K Siggins
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK. .,MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2DD, UK. .,NLHI, Imperial College London, London, W2 1PG, UK.
| | - Nicola N Lynskey
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK.,MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2DD, UK.,The Roslin Institute, University of Edinburgh, Edinburgh, EH25 9RG, UK
| | - Lucy E Lamb
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK
| | - Louise A Johnson
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Kristin K Huse
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK.,MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2DD, UK
| | - Max Pearson
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK.,MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2DD, UK
| | - Suneale Banerji
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Claire E Turner
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK.,The Florey Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Kevin Woollard
- Centre for Inflammatory Disease, Department of Immunology & Inflammation, Imperial College London, London, W12 0NN, UK
| | - David G Jackson
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Shiranee Sriskandan
- Department of Infectious Disease, Imperial College London, London, W12 0NN, UK. .,MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2DD, UK.
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17
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Qu D, Qiao DF, Klintschar M, Qu Z, Yue X. High-throughput 16S rDNA sequencing assisting in the detection of bacterial pathogen candidates: a fatal case of necrotizing fasciitis in a child. Int J Legal Med 2020; 135:399-407. [PMID: 32895762 DOI: 10.1007/s00414-020-02421-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/02/2020] [Indexed: 12/19/2022]
Abstract
Postmortem detection of pathogens in infectious deaths is quite important for diagnosing the cause of death and public health. However, it is difficult to detect possible bacterial pathogens in forensic practice using conventional methods like bacterial culture, especially in cases with putrefaction and antibiotic treatment. We report a fatal case caused by necrotizing fasciitis due to bacterial infection. An 8-year-old girl was found dead during sleep 4 days after a minor trauma to her left knee. The gross autopsy suggested that bacterial soft tissue infection might be the cause of death, and the microscopic examination confirmed the diagnosis. The slight putrefaction found at gross autopsy might interfere through postmortem bacterial translocation and reproduction with bacterial culture. High-throughput 16S rDNA sequencing was employed to identify possible pathogens. Bacterial DNA sequencing results suggested Streptococcus pyogenes and Staphylococcus, typical pathogens of necrotizing fasciitis in the tissue. 16S rDNA sequencing might thus be a useful tool for accurate detection of pathogens in forensic practice.
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Affiliation(s)
- Dong Qu
- Department of Forensic Pathology, School of Forensic Medicine, Southern Medical University, Guangzhou, 510515, China.,Institute of Legal Medicine, Hannover Medical School, 30625, Hannover, Germany
| | - Dong-Fang Qiao
- Department of Forensic Pathology, School of Forensic Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Michael Klintschar
- Institute of Legal Medicine, Hannover Medical School, 30625, Hannover, Germany
| | - Zhi Qu
- Institute for Epidemiology, Social Medicine and Health Systems Research, Hannover Medical School, 30625, Hannover, Germany
| | - Xia Yue
- Department of Forensic Pathology, School of Forensic Medicine, Southern Medical University, Guangzhou, 510515, China.
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18
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T4 Pili Promote Colonization and Immune Evasion Phenotypes of Nonencapsulated M4 Streptococcus pyogenes. mBio 2020; 11:mBio.01580-20. [PMID: 32694142 PMCID: PMC7374061 DOI: 10.1128/mbio.01580-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Streptococcus pyogenes (group A Streptococcus [GAS]) is an important human pathogen causing a broad spectrum of diseases and associated with significant global morbidity and mortality. Almost all GAS isolates express a surface hyaluronic acid capsule, a virulence determinant that facilitates host colonization and impedes phagocyte killing. However, recent epidemiologic surveillance has reported a sustained increase in both mucosal and invasive infections caused by nonencapsulated GAS, which questions the indispensable role of hyaluronic acid capsule in GAS pathogenesis. In this study, we found that pilus of M4 GAS not only significantly promotes biofilm formation, adherence, and cytotoxicity to human upper respiratory tract epithelial cells and keratinocytes, but also promotes survival in human whole blood and increased virulence in murine models of invasive infection. T4 antigen, the pilus backbone protein of M4 GAS, binds haptoglobin, an abundant human acute-phase protein upregulated upon infection and inflammation, on the bacterial surface. Haptoglobin sequestration reduces the susceptibility of nonencapsulated M4 GAS to antimicrobial peptides released from activated neutrophils and platelets. Our results reveal a previously unappreciated virulence-promoting role of M4 GAS pili, in part mediated by co-opting the biology of haptoglobin to mitigate host antimicrobial defenses.IMPORTANCE Group A Streptococcus (GAS) is a strict human pathogen causing more than 700 million infections globally each year. The majority of the disease-causing GAS are encapsulated, which greatly guarantees survival and dissemination in the host. Emergence of the capsule-negative GAS, such as M4 GAS, in recent epidemiologic surveillance alarms the necessity to elucidate the virulence determinants of these pathogens. Here, we found that M4 pili play an important role in promoting M4 GAS adherence and cytotoxicity to human pharyngeal epithelial cells and keratinocytes. The same molecule also significantly enhanced M4 GAS survival and replication in human whole blood and experimental murine infection. T4 antigen, which composes the backbone of M4 pili, was able to sequester the very abundant serum protein haptoglobin to further confer M4 GAS resistance to antibacterial substances released by neutrophils and platelets.
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19
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Mirzaei R, Mohammadzadeh R, Alikhani MY, Shokri Moghadam M, Karampoor S, Kazemi S, Barfipoursalar A, Yousefimashouf R. The biofilm‐associated bacterial infections unrelated to indwelling devices. IUBMB Life 2020; 72:1271-1285. [DOI: 10.1002/iub.2266] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/23/2020] [Accepted: 02/24/2020] [Indexed: 12/15/2022]
Affiliation(s)
- Rasoul Mirzaei
- Department of Microbiology, School of MedicineHamadan University of Medical Sciences Hamadan Iran
| | - Rokhsareh Mohammadzadeh
- Department of Microbiology, School of MedicineIran University of Medical Sciences Tehran Iran
| | - Mohammad Yousef Alikhani
- Department of Microbiology, School of MedicineHamadan University of Medical Sciences Hamadan Iran
| | | | - Sajad Karampoor
- Department of Virology, School of MedicineIran University of Medical Sciences Tehran Iran
| | - Sima Kazemi
- Department of Microbiology, School of MedicineHamadan University of Medical Sciences Hamadan Iran
| | | | - Rasoul Yousefimashouf
- Department of Microbiology, School of MedicineHamadan University of Medical Sciences Hamadan Iran
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20
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Würtz NS, Mikkelsen LH, Jørgensen JS, Hansen MS, Madsen MB, Hyldegaard O, Heegaard S. Periocular necrotizing soft tissue infection in Greater Copenhagen. Acta Ophthalmol 2020; 98:207-212. [PMID: 31359628 DOI: 10.1111/aos.14205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/07/2019] [Indexed: 12/01/2022]
Abstract
PURPOSE Necrotizing soft tissue infection, also known as necrotizing fasciitis (NF), is a fast-spreading life-threatening infection that most commonly affects the lower limbs, groin, or abdomen. Periocular necrotizing fasciitis (PNF) is rare. Limited data exist on PNF immune cell subset; hence, this study aims to determine the representation of immune cell subsets in patients diagnosed with PNF using immunohistochemical stainings. METHODS All patients diagnosed with PNF at Copenhagen University Hospital from 2008 to 2018 were included. Their electronic medical records and pathology reports were assessed, and available tissue specimens were reviewed and stained with monoclonal antibodies for CD1a+ Langerhans' cells, CD3+ T lymphocytes, CD15+ granulocytes, CD44+ lymphohematopoietic cells, CD68+ histiocytes, CD79α+ B lymphocytes, and FXIIIa+ dendritic macrophages and Langerhans' cells. The number of positive cells was counted, and an average score was calculated. The location of immune cells and bacteria was assessed. RESULTS The specimens were characterized by acute inflammation and necrosis of the fascia, while striated muscle involvement was less frequent. Haemolytic group A streptococci and Staphylococcus aureus were identified and mainly located in the deep dermis and subcutis in close relation to the fascia. Only few areas harboured both bacteria and inflammatory cells. Granulocytes, histiocytes and CD44+ lymphohematopoietic cells were demonstrated to be abundant in all patients, while B and T lymphocytes, dendritic macrophages and Langerhans' cells were less frequent. CONCLUSION The immune cell subsets found in this study of PNF were consistent with those identified in the literature on NF in other anatomical locations. This study concludes that immune cells are abundant and exhibit a typical pattern in PNF.
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Affiliation(s)
- Natacha Storm Würtz
- Department of Pathology Eye Pathology Section Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
| | - Lauge Hjorth Mikkelsen
- Department of Pathology Eye Pathology Section Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
- Department of Ophthalmology Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
| | | | - Michael Stormly Hansen
- Department of Ophthalmology Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
| | - Martin Bruun Madsen
- Department of Intensive Care Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
| | - Ole Hyldegaard
- Hyperbaric Unit Department of Anesthesia Center for Head and Orthopedics Rigshospitalet Copenhagen Denmark
- Institute of Clinical Medicine University of Copenhagen Copenhagen Denmark
| | - Steffen Heegaard
- Department of Pathology Eye Pathology Section Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
- Department of Ophthalmology Copenhagen University Hospital Rigshospitalet Copenhagen Denmark
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21
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Abstract
The development of a vaccine for group A streptococcus (GAS) is of paramount importance given that GAS infections cause more than 500,000 deaths annually across the world. This prospective passive surveillance laboratory study evaluated the potential coverage of the M protein-based vaccine currently under development. While a number of GAS strains isolated from this sub-Sahara African study were included in the current vaccine formulation, we nevertheless report that potential vaccine coverage for GAS infection in our setting was approximately 60%, with four of the most prevalent strains not included. This research emphasizes the need to reformulate the vaccine to improve coverage in areas where the burden of disease is high. Group A streptococcus (GAS) is responsible for a wide range of noninvasive group A streptococcal (non-iGAS) and invasive group A streptococcal (iGAS) infections. Information about the emm type variants of the M protein causing GAS disease is important to assess potential vaccine coverage of a 30-valent vaccine under development, particularly with respect to how they compare and contrast with non-iGAS isolates, especially in regions with a high burden of GAS. We conducted a prospective passive surveillance study of samples from patients attending public health facilities in Cape Town, South Africa. We documented demographic data and clinical presentation. emm typing was conducted using CDC protocols. GAS was commonly isolated from pus swabs, blood, deep tissue, and aspirates. Clinical presentations included wound infections (20%), bacteremia (15%), abscesses (9%), and septic arthritis (8%). Forty-six different emm types were identified, including M76 (16%), M81 (10%), M80 (6%), M43 (6%), and M183 (6%), and the emm types were almost evenly distributed between non-iGAS and iGAS isolates. There was a statistically significant association with M80 in patients presenting with noninvasive abscesses. Compared to the 30-valent vaccine under development, the levels of potential vaccine coverage for non-iGAS and iGAS infection were 60% and 58%, respectively, notably lower than the coverage in developed countries; five of the most prevalent emm types, M76, M81, M80, M43, and M183, were not included. The emm types from GAS isolated from patients with invasive disease did not differ significantly from those from noninvasive disease cases. There is low coverage of the multivalent M protein vaccine in our setting, emphasizing the need to reformulate the vaccine to improve coverage in areas where the burden of disease is high. IMPORTANCE The development of a vaccine for group A streptococcus (GAS) is of paramount importance given that GAS infections cause more than 500,000 deaths annually across the world. This prospective passive surveillance laboratory study evaluated the potential coverage of the M protein-based vaccine currently under development. While a number of GAS strains isolated from this sub-Sahara African study were included in the current vaccine formulation, we nevertheless report that potential vaccine coverage for GAS infection in our setting was approximately 60%, with four of the most prevalent strains not included. This research emphasizes the need to reformulate the vaccine to improve coverage in areas where the burden of disease is high.
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22
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Streptococcus pyogenes Transcriptome Changes in the Inflammatory Environment of Necrotizing Fasciitis. Appl Environ Microbiol 2019; 85:AEM.01428-19. [PMID: 31471300 PMCID: PMC6803311 DOI: 10.1128/aem.01428-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 08/23/2019] [Indexed: 12/31/2022] Open
Abstract
Necrotizing fasciitis, a life-threatening subcutaneous soft-tissue infection, is principally caused by S. pyogenes. The inflammatory environment at the site of infection causes global gene expression changes for survival of the bacterium and pathogenesis. However, no known study regarding transcriptomic profiling of S. pyogenes in cases of necrotizing fasciitis has been presented. We identified 483 bacterial genes whose expression was consistently altered during infection. Our results showed that S. pyogenes infection induces drastic upregulation of the expression of virulence-associated genes and shifts metabolic pathway usage. In particular, high-level expression of toxins, such as cytolysins, proteases, and nucleases, was observed at infection sites. In addition, genes identified as consistently enriched included those related to metabolism of arginine and histidine as well as carbohydrate uptake and utilization. Conversely, genes associated with the oxidative stress response and cell division were consistently downregulated during infection. The present findings provide useful information for establishing novel treatment strategies. Streptococcus pyogenes is a major cause of necrotizing fasciitis, a life-threatening subcutaneous soft-tissue infection. At the host infection site, the local environment and interactions between the host and bacteria have effects on bacterial gene expression profiles, while the gene expression pattern of S. pyogenes related to this disease remains unknown. In this study, we used a mouse model of necrotizing fasciitis and performed RNA-sequencing (RNA-seq) analysis of S. pyogenes M1T1 strain 5448 by isolating total RNA from infected hind limbs obtained at 24, 48, and 96 h postinfection. RNA-seq analysis results identified 483 bacterial genes whose expression was consistently altered in the infected hindlimbs compared to their expression under in vitro conditions. Genes showing consistent enrichment during infection included 306 encoding molecules involved in virulence, carbohydrate utilization, amino acid metabolism, trace-metal transport, and the vacuolar ATPase transport system. Surprisingly, drastic upregulation of 3 genes, encoding streptolysin S precursor (sagA), cysteine protease (speB), and secreted DNase (spd), was noted in the present mouse model (log2 fold change, >6.0, >9.4, and >7.1, respectively). Conversely, the number of consistently downregulated genes was 177, including those associated with the oxidative stress response and cell division. These results suggest that in necrotizing fasciitis, S. pyogenes shows an altered metabolism, decreased cell proliferation, and upregulation of expression of major toxins. Our findings are considered to provide critical information for developing novel treatment strategies and vaccines for necrotizing fasciitis. IMPORTANCE Necrotizing fasciitis, a life-threatening subcutaneous soft-tissue infection, is principally caused by S. pyogenes. The inflammatory environment at the site of infection causes global gene expression changes for survival of the bacterium and pathogenesis. However, no known study regarding transcriptomic profiling of S. pyogenes in cases of necrotizing fasciitis has been presented. We identified 483 bacterial genes whose expression was consistently altered during infection. Our results showed that S. pyogenes infection induces drastic upregulation of the expression of virulence-associated genes and shifts metabolic pathway usage. In particular, high-level expression of toxins, such as cytolysins, proteases, and nucleases, was observed at infection sites. In addition, genes identified as consistently enriched included those related to metabolism of arginine and histidine as well as carbohydrate uptake and utilization. Conversely, genes associated with the oxidative stress response and cell division were consistently downregulated during infection. The present findings provide useful information for establishing novel treatment strategies.
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23
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Li Y, Liu L, Huang Z, Yang L, Ye Y, Li R. A case of streptococcus necrotizing fasciitis secondary to acute tonsillitis and review of literatures. HONG KONG J EMERG ME 2019. [DOI: 10.1177/1024907918767190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Necrotizing fasciitis, officially named by Wilson in 1952, was a rare potentially life-threatening necrotizing soft tissue infections disease. The main lesions showed subcutaneous fat and fascia layer in progressive necrosis, generally not involving muscles. It was characterized by acute onset, rapid progress, and dangerous condition, often accompanied by systemic toxin shock, which was a relatively rare clinical acute critical disease with high mortality rate. Necrotizing fasciitis is a rare but clinical critical disease. The overall incidence of necrotizing fasciitis is approximately 0.04 cases per 1000 persons in the United States, the 30-day mortality is 27%, and necrotizing fasciitis–related mortality in Asian region is about 28%. Streptococcus pyogenes (group A streptococcus) are human-specific pathogens that can cause upper respiratory tract infection such as tonsillitis, associated with post-infection diseases such as rheumatic fever, and also can induce severe invasive diseases such as necrotizing fasciitis and streptococcus toxin shock syndrome. This article reports a case of streptococcus necrotizing fasciitis secondary to suppurative tonsillitis, which was seldom reported before and our successful management with delayed debridement. This study was anonymous and was approved by the local Research Ethics Committee. Informed consent was obtained from the patient.
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Affiliation(s)
- Yongsheng Li
- Department of Intensive Care Unit, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Lu Liu
- Department of Pharmacy, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Zhonghui Huang
- Department of Intensive Care Unit, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Le Yang
- Department of Intensive Care Unit, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Yan Ye
- Department of Intensive Care Unit, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Renjie Li
- Department of Intensive Care Unit, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
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24
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Dhawan G, Kapoor R, Dhamija A, Singh R, Monga B, Calabrese EJ. Necrotizing Fasciitis: Low-Dose Radiotherapy as a Potential Adjunct Treatment. Dose Response 2019; 17:1559325819871757. [PMID: 31496924 PMCID: PMC6716184 DOI: 10.1177/1559325819871757] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/11/2019] [Accepted: 07/18/2019] [Indexed: 12/27/2022] Open
Abstract
Necrotizing fasciitis (NF) is a rapidly spreading bacterial infection causing extensive tissue necrosis and destruction. Despite appropriate therapy, the disease results in significant morbidity/mortality and substantial treatment costs. Several studies published in the early 1900s demonstrated the effective use of low-dose X-ray radiotherapy (RT) for the treatment of many diverse inflammatory conditions and diseases (eg, gas gangrene, sinus infections, arthritis, tendonitis, and serious inflammatory lung conditions). The mechanism by which therapeutic RT doses produce positive patient outcomes is related at least in part to its capacity to induce tissue-based anti-inflammatory responses. This action is due to the polarization of macrophages to an anti-inflammatory or M2 phenotype via optimized low-dose RT. Low-dose RT has the potential to significantly reduce debilitating surgeries and aggressive treatments required for NF, providing a 3-prong benefit in terms of patient mortality, length of hospitalization stays, and cost of health care (both short term and long term). Low cost and easy availability of low-dose RT makes it a potentially useful option for patients of every age-group. In addition, low-dose RT may be a particularly useful option in countries treating many patients who are unable to afford surgeries, antibiotics, and hyperbaric oxygen.
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Affiliation(s)
- Gaurav Dhawan
- Human Research Protection Office, University of Massachusetts, Amherst, MA, USA
| | - Rachna Kapoor
- Saint Francis Hospital and Medical Center, Hartford, CT, USA
| | | | | | - Bharat Monga
- Division of Hospital Medicine, Mount Sinai St Luke's Hospital, New York, NY, USA
| | - Edward J Calabrese
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, USA
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25
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Thänert R, Itzek A, Hoßmann J, Hamisch D, Madsen MB, Hyldegaard O, Skrede S, Bruun T, Norrby-Teglund A, Medina E, Pieper DH. Molecular profiling of tissue biopsies reveals unique signatures associated with streptococcal necrotizing soft tissue infections. Nat Commun 2019; 10:3846. [PMID: 31451691 PMCID: PMC6710258 DOI: 10.1038/s41467-019-11722-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 07/25/2019] [Indexed: 12/21/2022] Open
Abstract
Necrotizing soft tissue infections (NSTIs) are devastating infections caused by either a single pathogen, predominantly Streptococcus pyogenes, or by multiple bacterial species. A better understanding of the pathogenic mechanisms underlying these different NSTI types could facilitate faster diagnostic and more effective therapeutic strategies. Here, we integrate microbial community profiling with host and pathogen(s) transcriptional analysis in patient biopsies to dissect the pathophysiology of streptococcal and polymicrobial NSTIs. We observe that the pathogenicity of polymicrobial communities is mediated by synergistic interactions between community members, fueling a cycle of bacterial colonization and inflammatory tissue destruction. In S. pyogenes NSTIs, expression of specialized virulence factors underlies infection pathophysiology. Furthermore, we identify a strong interferon-related response specific to S. pyogenes NSTIs that could be exploited as a potential diagnostic biomarker. Our study provides insights into the pathophysiology of mono- and polymicrobial NSTIs and highlights the potential of host-derived signatures for microbial diagnosis of NSTIs.
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Affiliation(s)
- Robert Thänert
- Microbial Interactions and Processes Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Andreas Itzek
- Microbial Interactions and Processes Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Jörn Hoßmann
- Microbial Interactions and Processes Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Domenica Hamisch
- Microbial Interactions and Processes Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Martin Bruun Madsen
- Department of Intensive Care, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Ole Hyldegaard
- Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Steinar Skrede
- Department of Medicine, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Trond Bruun
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Anna Norrby-Teglund
- Center for Infectious Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden
| | | | - Eva Medina
- Infection Immunity Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Dietmar H Pieper
- Microbial Interactions and Processes Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany.
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26
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Smith C, Scott J. Necrotising fasciitis complicating hand, foot and mouth disease. BMJ Case Rep 2019; 12:12/8/e228581. [PMID: 31434667 DOI: 10.1136/bcr-2018-228581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
A literature search confirmed no previous cases of necrotising fasciitis (NF) complicating hand,foot and mouth disease (HFMD). This report explores the case of a previously well 55-week-old Caucasian boy who attended accident and emergency with an acutely swollen right hand and atypical viral rash affecting the hands and face. He was admitted under plastic surgery and treated with intravenous antibiotics and fluid resuscitation for sepsis secondary to cellulitis. Following dermatological review of the rash, a clinical diagnosis of atypical HFMD was made. He deteriorated over the first 12 hours with progression of cellulitis despite intervention. Emergency exploration and debridement were performed for suspected NF. NF was subsequently confirmed by laboratory testing. He required 5 days in paediatric intensive care but made a full recovery. Recent reports highlight an increase in atypical cases of HFMD. Clinicians should be aware of the potential for superadded necrotising infection in cases of atypical HFMD.
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Affiliation(s)
- Clara Smith
- Plastic Surgery, NHS Greater Glasgow and Clyde, Glasgow, UK
| | - John Scott
- Canniesburn Plastic Surgery Unit, NHS Greater Glasgow and Clyde, Glasgow, UK
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27
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Phobalysin: Fisheye View of Membrane Perforation, Repair, Chemotaxis and Adhesion. Toxins (Basel) 2019; 11:toxins11070412. [PMID: 31315179 PMCID: PMC6669599 DOI: 10.3390/toxins11070412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/04/2019] [Accepted: 07/11/2019] [Indexed: 11/30/2022] Open
Abstract
Phobalysin P (PhlyP, for photobacterial lysin encoded on a plasmid) is a recently described small β-pore forming toxin of Photobacterium damselae subsp. damselae (Pdd). This organism, belonging to the family of Vibrionaceae, is an emerging pathogen of fish and various marine animals, which occasionally causes life-threatening soft tissue infections and septicemia in humans. By using genetically modified Pdd strains, PhlyP was found to be an important virulence factor. More recently, in vitro studies with purified PhlyP elucidated some basic consequences of pore formation. Being the first bacterial small β-pore forming toxin shown to trigger calcium-influx dependent membrane repair, PhlyP has advanced to a revealing model toxin to study this important cellular function. Further, results from co-culture experiments employing various Pdd strains and epithelial cells together with data on other bacterial toxins indicate that limited membrane damage may generally enhance the association of bacteria with target cells. Thereby, remodeling of plasma membrane and cytoskeleton during membrane repair could be involved. In addition, a chemotaxis-dependent attack-and track mechanism influenced by environmental factors like salinity may contribute to PhlyP-dependent association of Pdd with cells. Obviously, a synoptic approach is required to capture the regulatory links governing the interaction of Pdd with target cells. The characterization of Pdd’s secretome may hold additional clues because it may lead to the identification of proteases activating PhlyP’s pro-form. Current findings on PhlyP support the notion that pore forming toxins are not just killer proteins but serve bacteria to fulfill more subtle functions, like accessing their host.
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28
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Do H, Makthal N, VanderWal AR, Saavedra MO, Olsen RJ, Musser JM, Kumaraswami M. Environmental pH and peptide signaling control virulence of Streptococcus pyogenes via a quorum-sensing pathway. Nat Commun 2019; 10:2586. [PMID: 31197146 PMCID: PMC6565748 DOI: 10.1038/s41467-019-10556-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 05/14/2019] [Indexed: 12/20/2022] Open
Abstract
Bacteria control gene expression in concert with their population density by a process called quorum sensing, which is modulated by bacterial chemical signals and environmental factors. In the human pathogen Streptococcus pyogenes, production of secreted virulence factor SpeB is controlled by a quorum-sensing pathway and environmental pH. The quorum-sensing pathway consists of a secreted leaderless peptide signal (SIP), and its cognate receptor RopB. Here, we report that the SIP quorum-sensing pathway has a pH-sensing mechanism operative through a pH-sensitive histidine switch located at the base of the SIP-binding pocket of RopB. Environmental acidification induces protonation of His144 and reorganization of hydrogen bonding networks in RopB, which facilitates SIP recognition. The convergence of two disparate signals in the SIP signaling pathway results in induction of SpeB production and increased bacterial virulence. Our findings provide a model for investigating analogous crosstalk in other microorganisms.
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Affiliation(s)
- Hackwon Do
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Nishanth Makthal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Arica R VanderWal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Matthew Ojeda Saavedra
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
| | - Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY, 10021, USA
| | - James M Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY, 10021, USA
| | - Muthiah Kumaraswami
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, 77030, USA.
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, 77030, USA.
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29
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Neilly DW, Smith M, Woo A, Bateman V, Stevenson I. Necrotising fasciitis in the North East of Scotland: a 10-year retrospective review. Ann R Coll Surg Engl 2019; 101:363-372. [PMID: 30855976 PMCID: PMC6513372 DOI: 10.1308/rcsann.2019.0013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2018] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Necrotising fasciitis is a life-threatening rapidly progressing bacterial infection of the skin requiring prompt diagnosis and treatment. Optimum care warrants a combination of surgical debridement, antibiotics and intensive care support. All cases of necrotising fasciitis in 10 years in the North East of Scotland were reviewed to investigate and improve patient care. METHODS Cases between August 2006 and February 2016 were reviewed using case notes and electronic hospital records. Data including mode of admission, clinical observations, investigations, operative interventions, microbiological and clinical outcomes was collected and reviewed. Analysis required multidisciplinary input including microbiology, infectious disease, trauma and orthopaedics, plastic surgery and intensive care teams. RESULTS A total of 36 cases were identified. The mean laboratory risk indicator for necrotising fasciitis (LRINEC) score was 7 and 86% of patients fulfilled the criteria for necrotising fasciitis. Patients were commonly haemodynamically stable upon admission but deteriorated rapidly; 36% of patients had a temperature of over 37.5 degrees C on initial observations; 29/36 patients were discharged, 6 patients died acutely (acute mortality rate of 17%); 18/31 of cases were polymicrobial with Streptococcus pyogenes, the common organism. Six amputations or disarticulations were performed from a total of 82 operations in this group, with radical debridement the usual primary operation. The mean time to theatre was 3.54 hours. Highly elevated admission respiratory rate (50 breaths/minute) was associated with increased mortality. CONCLUSIONS Necrotising fasciitis presents subtly and carries significant morbidity and mortality. A high index of suspicion allows early diagnosis and intervention. We believe that a pan-specialty approach is the cornerstone for good outcomes.
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Affiliation(s)
- DW Neilly
- Department of Trauma and Orthopaedics, Aberdeen Royal Infirmary, Aberdeen, UK
| | - M Smith
- Department of Trauma and Orthopaedics, Aberdeen Royal Infirmary, Aberdeen, UK
| | - A Woo
- Department of Trauma and Orthopaedics, Aberdeen Royal Infirmary, Aberdeen, UK
| | - V Bateman
- Department of Microbiology, Aberdeen Royal Infirmary, Aberdeen, UK
| | - I Stevenson
- Department of Trauma and Orthopaedics, Aberdeen Royal Infirmary, Aberdeen, UK
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30
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Abstract
Necrotizing soft-tissue infections are caused by a variety of bacterial pathogens that may affect patients at any age or health status. This orthopaedic emergency initially presents with nonspecific signs such as erythema and edema. As the disease progresses, classic signs such as bullae, cutaneous anesthesia, ecchymosis, tense edema, and gas can be seen. A high level of suspicion is needed to properly identify and treat in a timely manner. Pain out of proportion to presentation and rapid progression even with appropriate antibiotic treatment should heighten suspicion of a necrotizing soft-tissue infection. The mainstay of management is extensive débridement and decompression of all necrotic tissue and broad-spectrum antibiotics. Débridements are repeated to ensure that disease progression has been halted. Early surgical débridements should take precedent over transfer because of the high rate of limb loss and mortality as a result of surgical delay.
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31
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Integrated analysis of population genomics, transcriptomics and virulence provides novel insights into Streptococcus pyogenes pathogenesis. Nat Genet 2019; 51:548-559. [PMID: 30778225 DOI: 10.1038/s41588-018-0343-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 12/21/2018] [Indexed: 12/22/2022]
Abstract
Streptococcus pyogenes causes 700 million human infections annually worldwide, yet, despite a century of intensive effort, there is no licensed vaccine against this bacterium. Although a number of large-scale genomic studies of bacterial pathogens have been published, the relationships among the genome, transcriptome, and virulence in large bacterial populations remain poorly understood. We sequenced the genomes of 2,101 emm28 S. pyogenes invasive strains, from which we selected 492 phylogenetically diverse strains for transcriptome analysis and 50 strains for virulence assessment. Data integration provided a novel understanding of the virulence mechanisms of this model organism. Genome-wide association study, expression quantitative trait loci analysis, machine learning, and isogenic mutant strains identified and confirmed a one-nucleotide indel in an intergenic region that significantly alters global transcript profiles and ultimately virulence. The integrative strategy that we used is generally applicable to any microbe and may lead to new therapeutics for many human pathogens.
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32
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Chiang-Ni C, Shi YA, Lai CH, Chiu CH. Cytotoxicity and Survival Fitness of Invasive covS Mutant of Group A Streptococcus in Phagocytic Cells. Front Microbiol 2018; 9:2592. [PMID: 30425702 PMCID: PMC6218877 DOI: 10.3389/fmicb.2018.02592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 10/11/2018] [Indexed: 11/27/2022] Open
Abstract
Group A streptococci (GAS) with spontaneous mutations in the CovR/CovS regulatory system are more invasive and related to severe manifestations. GAS can replicate inside phagocytic cells; therefore, phagocytic cells could serve as the niche to select invasive covS mutants. Nonetheless, the encapsulated covS mutant is resistant to phagocytosis. The fate of intracellular covS mutant in phagocytic cells and whether the intracellular covS mutant contributes to invasive infections are unclear. In this study, capsule-deficient (cap-) strains were utilized to study how intracellular bacteria interacted with phagocytic cells. Results from the competitive infection model showed that the cap-covS mutant had better survival fitness than the cap- wild-type strain in the PMA-activated U937 cells. In addition, the cap-covS mutant caused more cell damages than the cap- wild-type strain and encapsulated covS mutant. Furthermore, treatments with infected cells with clindamycin to inhibit the intracellular bacteria growth was more effective to reduce bacterial toxicity than utilized penicillin to kill the extracellular bacteria. These results not only suggest that the covS mutant could be selected from the intracellular niche of phagocytic cells but also indicating that inactivating or killing intracellular GAS may be critical to prevent invasive infection.
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Affiliation(s)
- Chuan Chiang-Ni
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yong-An Shi
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Ho Lai
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Cheng-Hsun Chiu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Pediatrics, Chang Gung Children's Hospital, Taoyuan, Taiwan
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33
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RocA Has Serotype-Specific Gene Regulatory and Pathogenesis Activities in Serotype M28 Group A Streptococcus. Infect Immun 2018; 86:IAI.00467-18. [PMID: 30126898 DOI: 10.1128/iai.00467-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/13/2018] [Indexed: 12/21/2022] Open
Abstract
Serotype M28 group A streptococcus (GAS) is a common cause of infections such as pharyngitis ("strep throat") and necrotizing fasciitis ("flesh-eating" disease). Relatively little is known about the molecular mechanisms underpinning M28 GAS pathogenesis. Whole-genome sequencing studies of M28 GAS strains recovered from patients with invasive infections found an unexpectedly high number of missense (amino acid-changing) and nonsense (protein-truncating) polymorphisms in rocA (regulator of Cov), leading us to hypothesize that altered RocA activity contributes to M28 GAS molecular pathogenesis. To test this hypothesis, an isogenic rocA deletion mutant strain was created. Transcriptome sequencing (RNA-seq) analysis revealed that RocA inactivation significantly alters the level of transcripts for 427 and 323 genes at mid-exponential and early stationary growth phases, respectively, including genes for 41 transcription regulators and 21 virulence factors. In contrast, RocA transcriptomes from other GAS M protein serotypes are much smaller and include fewer transcription regulators. The rocA mutant strain had significantly increased secreted activity of multiple virulence factors and grew to significantly higher colony counts under acid stress in vitro RocA inactivation also significantly increased GAS virulence in a mouse model of necrotizing myositis. Our results demonstrate that RocA is an important regulator of transcription regulators and virulence factors in M28 GAS and raise the possibility that naturally occurring polymorphisms in rocA in some fashion contribute to human invasive infections caused by M28 GAS strains.
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34
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Lamb LE, Siggins MK, Scudamore C, Macdonald W, Turner CE, Lynskey NN, Tan LKK, Sriskandan S. Impact of contusion injury on intramuscular emm1 group a streptococcus infection and lymphatic spread. Virulence 2018; 9:1074-1084. [PMID: 30052105 PMCID: PMC6068544 DOI: 10.1080/21505594.2018.1482180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Invasive group A Streptococcus (iGAS) is frequently associated with emm1 isolates, with an attendant mortality of around 20%. Cases occasionally arise in previously healthy individuals with a history of upper respiratory tract infection, soft tissue contusion, and no obvious portal of entry. Using a new murine model of contusion, we determined the impact of contusion on iGAS bacterial burden and phenotype. Calibrated mild blunt contusion did not provide a focus for initiation or seeding of GAS that was detectable following systemic GAS bacteremia, but instead enhanced GAS migration to the local draining lymph node following GAS inoculation at the same time and site of contusion. Increased migration to lymph node was associated with emergence of mucoid bacteria, although was not specific to mucoid bacteria. In one study, mucoid colonies demonstrated a significant increase in capsular hyaluronan that was not linked to a covRS or rocA mutation, but to a deletion in the promoter of the capsule synthesis locus, hasABC, resulting in a strain with increased fitness for lymph node migration. In summary, in the mild contusion model used, we could not detect seeding of muscle by GAS. Contusion promoted bacterial transit to the local lymph node. The consequences of contusion-associated bacterial lymphatic migration may vary depending on the pathogen and virulence traits selected.
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Affiliation(s)
- L E Lamb
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK.,b Royal Centre for Defence Medicine , University of Birmingham , Birmingham , UK
| | - M K Siggins
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK
| | - C Scudamore
- c Harwell Science and Innovation Campus , MRC Harwell , Oxfordshire , UK
| | - W Macdonald
- d Department of Bio-engineering , Royal School of Mines, Imperial College London , London , UK
| | - C E Turner
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK
| | - N N Lynskey
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK
| | - L K K Tan
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK
| | - S Sriskandan
- a Section of Infectious Diseases and Immunity, Department of Medicine , Imperial College London , London , UK
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35
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Teles AR, Montgomery S, Thomas KC. Necrotizing Fasciitis Involving Spine: Unusual Medical Emergency for Spine Surgeon. World Neurosurg 2018; 121:124-126. [PMID: 30321674 DOI: 10.1016/j.wneu.2018.10.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/01/2018] [Accepted: 10/03/2018] [Indexed: 01/22/2023]
Abstract
BACKGROUND Necrotizing fasciitis (NF) is a surgical diagnosis characterized by a rapidly progressive soft tissue infection, widespread tissue necrosis, and associated systemic illness. Friability of the superficial fascia, dishwater-gray exudate, and absence of pus are surgical characteristics of this diagnosis. Due to rapid progression of the infection, early recognition and aggressive surgical debridement are crucial to reduce mortality. Despite being commonly seen by general, plastic, and orthopedic surgeons, NF is an extremely rare spine surgery emergency. Our objective is to report on a case of NF involving the spine and highlight this unusual surgical emergency for the spine surgeon. CASE DESCRIPTION We present a rare case of a 61-year-old woman who presented to the emergency department in septic shock. She had a 1-week history of increasing back pain before presenting to us. Computed tomography revealed extensive soft tissue emphysema with involvement of the L3 vertebral body and spina canal. She underwent emergency surgical debridement. Despite maximal medical and surgical therapies, the patient died secondary to multisystem organ failure within 36 hours of initial presentation. CONCLUSIONS To the best of our knowledge, the literature presents only 1 previous case reported involving the spine. Necrotizing fasciitis is an unusual surgical spine surgery emergency. Spine surgeons should be aware of this diagnosis in order to provide timely aggressive surgical debridement.
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Affiliation(s)
- Alisson R Teles
- McGill Scoliosis & Spine Group, McGill University, Montreal, Quebec.
| | - Spencer Montgomery
- Department of Surgery, Section of Orthopedic Surgery, University of Calgary, Alberta, Canada
| | - Kenneth C Thomas
- Department of Surgery, Section of Orthopedic Surgery, University of Calgary, Alberta, Canada
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36
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Vajjala A, Biswas D, Tay WH, Hanski E, Kline KA. Streptolysin-induced endoplasmic reticulum stress promotes group A Streptococcal host-associated biofilm formation and necrotising fasciitis. Cell Microbiol 2018; 21:e12956. [PMID: 30239106 DOI: 10.1111/cmi.12956] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 09/10/2018] [Accepted: 09/12/2018] [Indexed: 12/24/2022]
Abstract
Group A Streptococcus (GAS) is a human pathogen that causes infections ranging from mild to fulminant and life-threatening. Biofilms have been implicated in acute GAS soft-tissue infections such as necrotising fasciitis (NF). However, most in vitro models used to study GAS biofilms have been designed to mimic chronic infections and insufficiently recapitulate in vivo conditions along with the host-pathogen interactions that might influence biofilm formation. Here, we establish and characterise an in vitro model of GAS biofilm development on mammalian cells that simulates microcolony formation observed in a mouse model of human NF. We show that on mammalian cells, GAS forms dense aggregates that display hallmark biofilm characteristics including a 3D architecture and enhanced tolerance to antibiotics. In contrast to abiotic-grown biofilms, host-associated biofilms require the expression of secreted GAS streptolysins O and S (SLO, SLS) that induce endoplasmic reticulum (ER) stress in the host. In an in vivo mouse model, the streptolysin null mutant is attenuated in both microcolony formation and bacterial spread, but pretreatment of soft-tissue with an ER stressor restores the ability of the mutant to form wild-type-like microcolonies that disseminate throughout the soft tissue. Taken together, we have identified a new role of streptolysin-driven ER stress in GAS biofilm formation and NF disease progression.
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Affiliation(s)
- Anuradha Vajjala
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore
| | - Debabrata Biswas
- Cellular and Molecular Mechanisms of Inflammation, Campus for Research Excellence and Technological Enterprise (CREATE), Department of Microbiology and Immunology, National University of Singapore (NUS)-The Hebrew University of Jerusalem (HUJ), Singapore
| | - Wei Hong Tay
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore.,Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate School, Nanyang Technological University, Singapore
| | - Emanuel Hanski
- Cellular and Molecular Mechanisms of Inflammation, Campus for Research Excellence and Technological Enterprise (CREATE), Department of Microbiology and Immunology, National University of Singapore (NUS)-The Hebrew University of Jerusalem (HUJ), Singapore.,Department of Microbiology and Molecular Genetics, Faculty of Medicine, The Institute for Medical Research, Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore
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37
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Healthcare Resource Utilization Associated with Burns and Necrotizing Fasciitis: A Single-Center Comparative Analysis. J Burn Care Res 2018; 38:e886-e891. [PMID: 28296669 DOI: 10.1097/bcr.0000000000000513] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Necrotizing fasciitis (NF) patients are increasingly managed in burn units. Although treated similarly to burns, the healthcare resource utilization (HRU) in NF appears to be greater. Accurate knowledge of the HRU is important to better allocate resources and to compare outcomes between units. The goal of this study is to provide better understanding of the HRU for NF compared with burns. A retrospective chart review of patients ≥18 years admitted to two regional tertiary referral centers with either NF or burns requiring surgery. The authors examined age, sex, %TBSA, geographic region, anatomical location, length of stay (LOS) in hospital, LOS in intensive care unit, number of operative procedures, number of packed red blood cells transfused, amputation, death, and use of free tissue transfer or skin graft. There were 210 NF and 209 burn patients. The NF cohort had a smaller TBSA (3.3 vs 10.0%), longer LOS (20 vs 14 days), and consequently a longer LOS/%TBSA (6.0 vs 1.5 days). This difference persisted after adjusting for age. More of the NF cohort (44.8%) spent ≥1 day in the intensive care unit. The NF cohort also had more procedures (median 2 vs 1), required blood (46.2 vs 16.7%), died in hospital (13.3 vs 4.3%), had an amputation (12.4 vs 4.8%), or required free tissue transfer (7.6 vs 2.9%). This study shows that NF requires substantially more HRU compared with burns. This information is important in recognizing the impact of these patients on burn units and planning for allocation of appropriate resources.
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Dextromethorphan Attenuates NADPH Oxidase-Regulated Glycogen Synthase Kinase 3β and NF-κB Activation and Reduces Nitric Oxide Production in Group A Streptococcal Infection. Antimicrob Agents Chemother 2018; 62:AAC.02045-17. [PMID: 29581121 DOI: 10.1128/aac.02045-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 03/12/2018] [Indexed: 12/16/2022] Open
Abstract
Group A Streptococcus (GAS) is an important human pathogen that causes a wide spectrum of diseases, including necrotizing fasciitis and streptococcal toxic shock syndrome. Dextromethorphan (DM), an antitussive drug, has been demonstrated to efficiently reduce inflammatory responses, thereby contributing to an increased survival rate of GAS-infected mice. However, the anti-inflammatory mechanisms underlying DM treatment in GAS infection remain unclear. DM is known to exert neuroprotective effects through an NADPH oxidase-dependent regulated process. In the present study, membrane translocation of NADPH oxidase subunit p47phox and subsequent reactive oxygen species (ROS) generation induced by GAS infection were significantly inhibited via DM treatment in RAW264.7 murine macrophage cells. Further determination of proinflammatory mediators revealed that DM effectively suppressed inducible nitric oxide synthase (iNOS) expression and NO, tumor necrosis factor alpha, and interleukin-6 generation in GAS-infected RAW264.7 cells as well as in air-pouch-infiltrating cells from GAS/DM-treated mice. GAS infection caused AKT dephosphorylation, glycogen synthase kinase-3β (GSK-3β) activation, and subsequent NF-κB nuclear translocation, which were also markedly inhibited by treatment with DM and an NADPH oxidase inhibitor, diphenylene iodonium. These results suggest that DM attenuates GAS infection-induced overactive inflammation by inhibiting NADPH oxidase-mediated ROS production that leads to downregulation of the GSK-3β/NF-κB/NO signaling pathway.
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Blocking Neuronal Signaling to Immune Cells Treats Streptococcal Invasive Infection. Cell 2018; 173:1083-1097.e22. [PMID: 29754819 DOI: 10.1016/j.cell.2018.04.006] [Citation(s) in RCA: 267] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 02/08/2018] [Accepted: 04/03/2018] [Indexed: 11/21/2022]
Abstract
The nervous system, the immune system, and microbial pathogens interact closely at barrier tissues. Here, we find that a bacterial pathogen, Streptococcus pyogenes, hijacks pain and neuronal regulation of the immune response to promote bacterial survival. Necrotizing fasciitis is a life-threatening soft tissue infection in which "pain is out of proportion" to early physical manifestations. We find that S. pyogenes, the leading cause of necrotizing fasciitis, secretes streptolysin S (SLS) to directly activate nociceptor neurons and produce pain during infection. Nociceptors, in turn, release the neuropeptide calcitonin gene-related peptide (CGRP) into infected tissues, which inhibits the recruitment of neutrophils and opsonophagocytic killing of S. pyogenes. Botulinum neurotoxin A and CGRP antagonism block neuron-mediated suppression of host defense, thereby preventing and treating S. pyogenes necrotizing infection. We conclude that targeting the peripheral nervous system and blocking neuro-immune communication is a promising strategy to treat highly invasive bacterial infections. VIDEO ABSTRACT.
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Teatero S, McGeer A, Tyrrell GJ, Hoang L, Smadi H, Domingo MC, Levett PN, Finkelstein M, Dewar K, Plevneshi A, Athey TBT, Gubbay JB, Mulvey MR, Martin I, Demczuk W, Fittipaldi N. Canada-Wide Epidemic of emm74 Group A Streptococcus Invasive Disease. Open Forum Infect Dis 2018; 5:ofy085. [PMID: 29780850 DOI: 10.1093/ofid/ofy085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/17/2018] [Indexed: 11/14/2022] Open
Abstract
Background The number of invasive group A Streptococcus (iGAS) infections due to hitherto extremely rare type emm74 strains has increased in several Canadian provinces since late 2015. We hypothesized that the cases recorded in the different provinces are linked and caused by strains of an emm74 clone that recently emerged and expanded explosively. Methods We analyzed both active and passive surveillance data for iGAS infections and used whole-genome sequencing to investigate the phylogenetic relationships of the emm74 strains responsible for these invasive infections country-wide. Results Genome analysis showed that highly clonal emm74 strains, genetically different from emm74 organisms previously circulating in Canada, were responsible for a country-wide epidemic of >160 invasive disease cases. The emerging clone belonged to multilocus sequence typing ST120. The analysis also revealed dissemination patterns of emm74 subclonal lineages across Canadian provinces. Clinical data analysis indicated that the emm74 epidemic disproportionally affected middle-aged or older male individuals. Homelessness, alcohol abuse, and intravenous drug usage were significantly associated with invasive emm74 infections. Conclusions In a period of 20 months, an emm74 GAS clone emerged and rapidly spread across several Canadian provinces located more than 4500 km apart, causing invasive infections primarily among disadvantaged persons.
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Affiliation(s)
- Sarah Teatero
- Public Health Ontario Laboratory, Toronto, ON, Canada
| | - Allison McGeer
- Sinai Health System, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Gregory J Tyrrell
- Alberta Provincial Laboratory for Public Health, and Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada
| | - Linda Hoang
- British Columbia Centre for Disease Control Public Health Laboratory, Vancouver, BC, Canada
| | - Hanan Smadi
- New Brunswick Department of Health, Communicable Disease and Control, Fredericton, NB, Canada
| | - Marc-Christian Domingo
- Laboratoire de Santé Publique du Québec, Institut National de Santé Publique du Québec, Ste-Anne de Bellevue, QC, Canada
| | - Paul N Levett
- Saskatchewan Disease Control Laboratory, Regina, SK, Canada
| | | | - Ken Dewar
- Genome Québec Innovation Centre, and McGill University, Montreal, QC, Canada
| | | | | | - Jonathan B Gubbay
- Public Health Ontario Laboratory, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Michael R Mulvey
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Irene Martin
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Walter Demczuk
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Nahuel Fittipaldi
- Public Health Ontario Laboratory, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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Babbar A, Bruun T, Hyldegaard O, Nekludov M, Arnell P, Pieper DH, Itzek A. Pivotal Role of Preexisting Pathogen-Specific Antibodies in the Development of Necrotizing Soft-Tissue Infections. J Infect Dis 2018; 218:44-52. [DOI: 10.1093/infdis/jiy110] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Anshu Babbar
- Microbial Interactions and Processes, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Trond Bruun
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Ole Hyldegaard
- Hyperbaric Unit, Department of Anesthesia, Center for Head and Orthopedics, Rigshospitalet, Copenhagen
| | - Michael Nekludov
- Section of Anesthesiology and Intensive Care, Department of Physiology and Pharmacology, Stockholm
| | - Per Arnell
- Department of Anesthesia and Intensive Care, Sahlgrenska University Hospital/Ostra, Gothenburg, Sweden
| | - Dietmar H Pieper
- Microbial Interactions and Processes, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Andreas Itzek
- Microbial Interactions and Processes, Helmholtz Center for Infection Research, Braunschweig, Germany
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Identification and Characterization of Serotype-Specific Variation in Group A Streptococcus Pilus Expression. Infect Immun 2018; 86:IAI.00792-17. [PMID: 29158432 DOI: 10.1128/iai.00792-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 11/13/2017] [Indexed: 12/22/2022] Open
Abstract
Isolates of a given bacterial pathogen often display phenotypic variation, and this can negatively impact public health, for example, by reducing the efficacy of preventative measures. Here, we identify that the human pathogen group A Streptococcus (GAS; Streptococcus pyogenes) expresses pili on its cell surface in a serotype-specific manner. Specifically, we show that serotype M3 GAS isolates, which are nonrandomly associated with causing particularly severe and lethal invasive infections, produce negligible amounts of pili relative to serotype M1 and M49 isolates. Performance of an interserotype transcriptome comparison (serotype M1 versus serotype M3) was instrumental in this discovery. We also identified that the transcriptional regulator Nra positively regulates pilus expression in M3 GAS isolates and that the low level of pilus expression of these isolates correlates with a low level of nra transcription. Finally, we discovered that the phenotypic consequences of low levels of pilus expression by M3 GAS isolates are a reduced ability to adhere to host cells and an increased ability to survive and proliferate in human blood. We propose that an enhanced ability to survive in human blood, in part due to reduced pilus expression, is a contributing factor in the association of serotype M3 isolates with highly invasive infections. In conclusion, our data show that GAS isolates express pili in a serotype-dependent manner and may inform vaccine development, given that pilus proteins are being discussed as possible GAS vaccine antigens.
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Requirement and Synergistic Contribution of Platelet-Activating Factor Acetylhydrolase Sse and Streptolysin S to Inhibition of Neutrophil Recruitment and Systemic Infection by Hypervirulent emm3 Group A Streptococcus in Subcutaneous Infection of Mice. Infect Immun 2017; 85:IAI.00530-17. [PMID: 28947648 DOI: 10.1128/iai.00530-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/18/2017] [Indexed: 01/18/2023] Open
Abstract
Hypervirulent group A streptococcus (GAS) can inhibit neutrophil recruitment and cause systemic infection in a mouse model of skin infection. The purpose of this study was to determine whether platelet-activating factor acetylhydrolase Sse and streptolysin S (SLS) have synergistic contributions to inhibition of neutrophil recruitment and systemic infection in subcutaneous infection of mice by MGAS315, a hypervirulent genotype emm3 GAS strain. Deletion of sse and sagA in MGAS315 synergistically reduced the skin lesion size and GAS burden in the liver and spleen. However, the mutants were persistent at skin sites and had similar growth factors in nonimmune blood. Thus, the low numbers of Δsse ΔsagA mutants in the liver and spleen were likely due to their reduction in the systemic dissemination. Few intact and necrotic neutrophils were detected at MGAS315 infection sites. In contrast, many neutrophils and necrotic cells were present at the edge of Δsse mutant infection sites on day 1 and at the edge of and inside Δsse mutant infection sites on day 2. ΔsagA mutant infection sites had massive numbers of and few intact neutrophils at the edge and center of the infection sites, respectively, on day 1 and were full of intact neutrophils or necrotic cells on day 2. Δsse ΔsagA mutant infection sites had massive numbers of intact neutrophils throughout the whole infection site. These sse and sagA deletion-caused changes in the histological pattern at skin infection sites could be complemented. Thus, the sse and sagA deletions synergistically enhance neutrophil recruitment. These findings indicate that both Sse and SLS are required but that neither is sufficient for inhibition of neutrophil recruitment and systemic infection by hypervirulent GAS.
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44
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Whole-Genome Sequencing of a Human Clinical Isolate of emm28 Streptococcus pyogenes Causing Necrotizing Fasciitis Acquired Contemporaneously with Hurricane Harvey. GENOME ANNOUNCEMENTS 2017; 5:5/45/e01269-17. [PMID: 29122881 PMCID: PMC5679814 DOI: 10.1128/genomea.01269-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We discovered an emm28 Streptococcus pyogenes isolate causing necrotizing fasciitis in a patient exposed to the floodwaters of Hurricane Harvey in the Houston, TX, metropolitan area in August 2017. The Oxford Nanopore MinION instrument provided sufficient genome sequence data within 1 h of beginning sequencing to close the genome.
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45
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Do H, Makthal N, VanderWal AR, Rettel M, Savitski MM, Peschek N, Papenfort K, Olsen RJ, Musser JM, Kumaraswami M. Leaderless secreted peptide signaling molecule alters global gene expression and increases virulence of a human bacterial pathogen. Proc Natl Acad Sci U S A 2017; 114:E8498-E8507. [PMID: 28923955 PMCID: PMC5635878 DOI: 10.1073/pnas.1705972114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Successful pathogens use complex signaling mechanisms to monitor their environment and reprogram global gene expression during specific stages of infection. Group A Streptococcus (GAS) is a major human pathogen that causes significant disease burden worldwide. A secreted cysteine protease known as streptococcal pyrogenic exotoxin B (SpeB) is a key virulence factor that is produced abundantly during infection and is critical for GAS pathogenesis. Although identified nearly a century ago, the molecular basis for growth phase control of speB gene expression remains unknown. We have discovered that GAS uses a previously unknown peptide-mediated intercellular signaling system to control SpeB production, alter global gene expression, and enhance virulence. GAS produces an eight-amino acid leaderless peptide [SpeB-inducing peptide (SIP)] during high cell density and uses the secreted peptide for cell-to-cell signaling to induce population-wide speB expression. The SIP signaling pathway includes peptide secretion, reimportation into the cytosol, and interaction with the intracellular global gene regulator Regulator of Protease B (RopB), resulting in SIP-dependent modulation of DNA binding and regulatory activity of RopB. Notably, SIP signaling causes differential expression of ∼14% of GAS core genes. Several genes that encode toxins and other virulence genes that enhance pathogen dissemination and infection are significantly up-regulated. Using three mouse infection models, we show that the SIP signaling pathway is active during infection and contributes significantly to GAS pathogenesis at multiple host anatomic sites. Together, our results delineate the molecular mechanisms involved in a previously undescribed virulence regulatory pathway of an important human pathogen and suggest new therapeutic strategies.
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Affiliation(s)
- Hackwon Do
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Nishanth Makthal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Arica R VanderWal
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
| | - Mandy Rettel
- Genome Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Mikhail M Savitski
- Genome Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nikolai Peschek
- Munich Center for Integrated Protein Science, Department of Microbiology, Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Kai Papenfort
- Munich Center for Integrated Protein Science, Department of Microbiology, Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10021
| | - James M Musser
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
- Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY 10021
| | - Muthiah Kumaraswami
- Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX 77030;
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030
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Case Series Description and Genomic Characterization of Invasive Group A Streptococcal Infections in Pediatric Patients. Pediatr Infect Dis J 2017; 36:618-620. [PMID: 28030528 DOI: 10.1097/inf.0000000000001519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
We report an unusual cluster of invasive group A Streptococcus infections in 6 pediatric patients and demonstrate that the strains were derived from diverse genetic backgrounds, confirming the occurrence of a community cluster rather than a clonal outbreak. Whole genome sequencing provided a rapid and comprehensive view of group A Streptococcus genotypes and helped guide our institutional response and public health maneuvers.
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47
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Charbonneau ARL, Forman OP, Cain AK, Newland G, Robinson C, Boursnell M, Parkhill J, Leigh JA, Maskell DJ, Waller AS. Defining the ABC of gene essentiality in streptococci. BMC Genomics 2017; 18:426. [PMID: 28569133 PMCID: PMC5452409 DOI: 10.1186/s12864-017-3794-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 05/14/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Utilising next generation sequencing to interrogate saturated bacterial mutant libraries provides unprecedented information for the assignment of genome-wide gene essentiality. Exposure of saturated mutant libraries to specific conditions and subsequent sequencing can be exploited to uncover gene essentiality relevant to the condition. Here we present a barcoded transposon directed insertion-site sequencing (TraDIS) system to define an essential gene list for Streptococcus equi subsp. equi, the causative agent of strangles in horses, for the first time. The gene essentiality data for this group C Streptococcus was compared to that of group A and B streptococci. RESULTS Six barcoded variants of pGh9:ISS1 were designed and used to generate mutant libraries containing between 33,000-66,000 unique mutants. TraDIS was performed on DNA extracted from each library and data were analysed separately and as a combined master pool. Gene essentiality determined that 19.5% of the S. equi genome was essential. Gene essentialities were compared to those of group A and group B streptococci, identifying concordances of 90.2% and 89.4%, respectively and an overall concordance of 83.7% between the three species. CONCLUSIONS The use of barcoded pGh9:ISS1 to generate mutant libraries provides a highly useful tool for the assignment of gene function in S. equi and other streptococci. The shared essential gene set of group A, B and C streptococci provides further evidence of the close genetic relationships between these important pathogenic bacteria. Therefore, the ABC of gene essentiality reported here provides a solid foundation towards reporting the functional genome of streptococci.
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Affiliation(s)
- Amelia R L Charbonneau
- Animal Health Trust, Lanwades Park, Newmarket, Suffolk, UK. .,Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
| | | | - Amy K Cain
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK.,Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, Australia
| | - Graham Newland
- Animal Health Trust, Lanwades Park, Newmarket, Suffolk, UK
| | - Carl Robinson
- Animal Health Trust, Lanwades Park, Newmarket, Suffolk, UK
| | - Mike Boursnell
- Animal Health Trust, Lanwades Park, Newmarket, Suffolk, UK
| | - Julian Parkhill
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK
| | - James A Leigh
- The School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, Nottingham, UK
| | - Duncan J Maskell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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Iron Efflux by PmtA Is Critical for Oxidative Stress Resistance and Contributes Significantly to Group A Streptococcus Virulence. Infect Immun 2017; 85:IAI.00091-17. [PMID: 28348051 DOI: 10.1128/iai.00091-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/20/2017] [Indexed: 12/20/2022] Open
Abstract
Group A Streptococcus (GAS) is a human-only pathogen that causes a spectrum of disease conditions. Given its survival in inflamed lesions, the ability to sense and overcome oxidative stress is critical for GAS pathogenesis. PerR senses oxidative stress and coordinates the regulation of genes involved in GAS antioxidant defenses. In this study, we investigated the role of PerR-controlled metal transporter A (PmtA) in GAS pathogenesis. Previously, PmtA was implicated in GAS antioxidant defenses and suggested to protect against zinc toxicity. Here, we report that PmtA is a P1B4-type ATPase that functions as an Fe(II) exporter and aids GAS defenses against iron intoxication and oxidative stress. The expression of pmtA is specifically induced by excess iron, and this induction requires PerR. Furthermore, a pmtA mutant exhibited increased sensitivity to iron toxicity and oxidative stress due to an elevated intracellular accumulation of iron. RNA-sequencing analysis revealed that GAS undergoes significant alterations in gene expression to adapt to iron toxicity. Finally, using two mouse models of invasive infection, we demonstrated that iron efflux by PmtA is critical for bacterial survival during infection and GAS virulence. Together, these data demonstrate that PmtA is a key component of GAS antioxidant defenses and contributes significantly to GAS virulence.
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49
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Sarkar P, Sumby P. Regulatory gene mutation: a driving force behind group a Streptococcus strain- and serotype-specific variation. Mol Microbiol 2016; 103:576-589. [PMID: 27868255 DOI: 10.1111/mmi.13584] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2016] [Indexed: 01/13/2023]
Abstract
Data from multiple bacterial pathogens are consistent with regulator-encoding genes having higher mutation frequencies than the genome average. Such mutations drive both strain- and type- (e.g., serotype, haplotype) specific phenotypic heterogeneity, and may challenge public health due to the potential of variants to circumvent established treatment and/or preventative regimes. Here, using the human bacterial pathogen the group A Streptococcus (GAS; S. pyogenes) as a model organism, we review the types and regulatory-, phenotypic-, and disease-specific consequences of naturally occurring regulatory gene mutations. Strain-specific regulator mutations that will be discussed include examples that transform isolates into hyper-invasive forms by enhancing expression of immunomodulatory virulence factors, and examples that promote asymptomatic carriage of the organism. The discussion of serotype-specific regulator mutations focuses on serotype M3 GAS isolates, and how the identified rewiring of regulatory networks in this serotype may be contributing to a decades old epidemiological association of M3 isolates with particularly severe invasive infections. We conclude that mutation plays an outsized role in GAS pathogenesis and has clinical relevance. Given the phenotypic variability associated with regulatory gene mutations, the rapid examination of these genes in infecting isolates may inform with respect to potential patient complications and treatment options.
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Affiliation(s)
- Poulomee Sarkar
- Department of Microbiology & Immunology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
| | - Paul Sumby
- Department of Microbiology & Immunology, University of Nevada, Reno School of Medicine, Reno, Nevada, USA
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50
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Multimerization of the Virulence-Enhancing Group A Streptococcus Transcription Factor RivR Is Required for Regulatory Activity. J Bacteriol 2016; 199:JB.00452-16. [PMID: 27795318 DOI: 10.1128/jb.00452-16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/17/2016] [Indexed: 12/27/2022] Open
Abstract
Group A Streptococcus (GAS) (Streptococcus pyogenes) causes more than 700 million human infections each year. The significant morbidity and mortality rates associated with GAS infections are in part a consequence of the ability of this pathogen to coordinately regulate virulence factor expression during infection. RofA-like protein IV (RivR) is a member of the Mga-like family of transcriptional regulators, and previously we reported that RivR negatively regulates transcription of the hasA and grab virulence factor-encoding genes. Here, we determined that RivR inhibits the ability of GAS to survive and to replicate in human blood. To begin to assess the biochemical basis of RivR activity, we investigated its ability to form multimers, which is a characteristic of Mga-like proteins. We found that RivR forms both dimers and a higher-molecular-mass multimer, which we hypothesize is a tetramer. As cysteine residues are known to contribute to the ability of proteins to dimerize, we created a library of expression plasmids in which each of the four cysteines in RivR was converted to serine. While the C68S RivR protein was essentially unaffected in its ability to dimerize, the C32S and C377S proteins were attenuated, while the C470S protein completely lacked the ability to dimerize. Consistent with dimerization being required for regulatory activity, the C470S RivR protein was unable to repress hasA and grab gene expression in a rivR mutant. Thus, multimer formation is a prerequisite for RivR activity, which supports recent data obtained for other Mga-like family members, suggesting a common regulatory mechanism. IMPORTANCE The modulation of gene transcription is key to the ability of bacterial pathogens to infect hosts to cause disease. Here, we discovered that the group A Streptococcus transcription factor RivR negatively regulates the ability of this pathogen to survive in human blood, and we also began biochemical characterization of this protein. We determined that, in order for RivR to function, it must self-associate, forming both dimers (consisting of two RivR proteins) and higher-order complexes (consisting of more than two RivR proteins). This functional requirement for RivR is shared by other regulators in the same family of proteins, suggesting a common regulatory mechanism. Insight into how these transcription factors function may facilitate the development of novel therapeutic agents targeting their activity.
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