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Chen Y, Li L, Wang C, Zhang Y, Zhou Y. Necrotizing Pneumonia in Children: Early Recognition and Management. J Clin Med 2023; 12:jcm12062256. [PMID: 36983257 PMCID: PMC10051935 DOI: 10.3390/jcm12062256] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 03/17/2023] Open
Abstract
Necrotizing pneumonia (NP) is an uncommon complicated pneumonia with an increasing incidence. Early recognition and timely management can bring excellent outcomes. The diagnosis of NP depends on chest computed tomography, which has radiation damage and may miss the optimal treatment time. The present review aimed to elaborate on the reported predictors for NP. The possible pathogenesis of Streptococcus pneumoniae, Staphylococcus aureus, Mycoplasma pneumoniae and coinfection, clinical manifestations and management were also discussed. Although there is still a long way for these predictors to be used in clinical, it is necessary to investigate early predictors for NP in children.
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Affiliation(s)
- Yuanyuan Chen
- Department of Pulmonology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China
- National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Lanxin Li
- Department of Pulmonology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China
- National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Chenlu Wang
- Department of Pulmonology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China
- National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Yuanyuan Zhang
- Department of Pulmonology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China
- National Clinical Research Center for Child Health, Hangzhou 310052, China
- Correspondence: (Y.Z.); (Y.Z.)
| | - Yunlian Zhou
- Department of Pulmonology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China
- National Clinical Research Center for Child Health, Hangzhou 310052, China
- Correspondence: (Y.Z.); (Y.Z.)
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2
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Nie Z, Shi L, Song K, Xu X, Ding P, Lu B, Wu G, Ma X. LukS-PV inhibits the proliferation of hepatocellular carcinoma cells by maintaining FOXO3 stability via the PI3K/AKT signaling pathway. Cell Signal 2022; 95:110357. [PMID: 35589047 DOI: 10.1016/j.cellsig.2022.110357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 05/12/2022] [Accepted: 05/12/2022] [Indexed: 12/24/2022]
Abstract
Hepatocellular carcinoma(HCC) is one of the common malignant tumors. LukS-PV is the S component of Panton-Valetine leukocidin(PVL) secreted by Staphylococcus aureus. Forkhead box O3 (FOXO3) is a member of the FOXO subfamily of transcription factors that acts as a tumor suppressor. In this study, we investigated the role of LukS-PV on the proliferation of HCC and explored possible mechanisms. We treated HCC cells with various concentrations of LukS-PV and evaluated the effect of LukS-PV on cell viability using the cell counting kit-8 and colony formation assays. Real-time PCR and western blot assays were used to analyze mRNA and protein expression levels, respectively. Immunofluorescence staining was performed to examine the intracellular localization of FOXO3. The expression of FOXO3 and its downstream target genes were analyzed by immunohistochemical staining. The protein synthesis inhibitor cycloheximide and the proteosome inhibitor MG132 were used to explore the potential mechanisms by which LukS-PV regulated FOXO3. We demonstrated that LukS-PV inhibited the proliferation of HCC cells in a concentration dependent manner. LukS-PV upregulated FOXO3 expression both in vitro and in vivo. Moreover, LukS-PV facilitated the entry of FOXO3 into the nucleus and, subsequently, regulated the transcription of downstream target genes. In addition, we discovered that LukS-PV decreased the expression of phosphorylated FOXO3 through the PI3K/AKT signaling pathway and maintained FOXO3 protein stability via the ubiquitin-proteasome pathway. Taken together, our data indicated that LukS-PV exert anticancer activities through FOXO3. LukS-PV may be a promising candidate for HCC treatment.
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Affiliation(s)
- Zhengchao Nie
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Lan Shi
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Kaidi Song
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Xuexue Xu
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Pengsheng Ding
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Bing Lu
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Gang Wu
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Xiaoling Ma
- The First Affifiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China.
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3
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Staphylococcus aureus isolates from Eurasian Beavers (Castor fiber) carry a novel phage-borne bicomponent leukocidin related to the Panton-Valentine leukocidin. Sci Rep 2021; 11:24394. [PMID: 34937862 PMCID: PMC8695587 DOI: 10.1038/s41598-021-03823-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/08/2021] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus can be a harmless coloniser, but it can also cause severe infections in humans, livestock and wildlife. Regarding the latter, only few studies have been performed and knowledge on virulence factors is insufficient. The aim of the present study was to study S. aureus isolates from deceased wild beavers (Castor fiber). Seventeen isolates from eleven beavers, found in Germany and Austria, were investigated. Antimicrobial and biocide susceptibility tests were performed. Isolates were characterised using S. aureus-specific DNA microarrays, spa typing and whole-genome sequencing. From two isolates, prophages were induced by mitomycin C and studied by transmission electron microscopy. Four isolates belonged to clonal complex (CC) 8, CC12, and CC398. Twelve isolates belonged to CC1956 and one isolate was CC49. The CC49 and CC1956 isolates carried distinct lukF/S genes related to the Panton-Valentine leukocidin (PVL) from human isolates of S. aureus. These genes were located on related, but not identical, Siphovirus prophages. The beavers, from which those isolates originated, suffered from abscesses, purulent organ lesions and necrotising pneumonia, i.e., clinical manifestations resembling symptoms of severe PVL-associated disease in humans. It might thus be assumed that the “Beaver Leukocidin (BVL, lukF/S-BV)”-positive strains are beaver-specific pathogens, and further studies on their clinical role as well as on a possible transmissibility to other species, including humans, are warranted.
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Breiner-Goldstein E, Eyal Z, Matzov D, Halfon Y, Cimicata G, Baum M, Rokney A, Ezernitchi A, Lowell A, Schmidt J, Rozenberg H, Zimmerman E, Bashan A, Valinsky L, Anzai Y, Sherman D, Yonath A. Ribosome-binding and anti-microbial studies of the mycinamicins, 16-membered macrolide antibiotics from Micromonospora griseorubida. Nucleic Acids Res 2021; 49:9560-9573. [PMID: 34417608 PMCID: PMC8450085 DOI: 10.1093/nar/gkab684] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 02/02/2023] Open
Abstract
Macrolides have been effective clinical antibiotics for over 70 years. They inhibit protein biosynthesis in bacterial pathogens by narrowing the nascent protein exit tunnel in the ribosome. The macrolide class of natural products consist of a macrolactone ring linked to one or more sugar molecules. Most of the macrolides used currently are semi-synthetic erythromycin derivatives, composed of a 14- or 15-membered macrolactone ring. Rapidly emerging resistance in bacterial pathogens is among the most urgent global health challenges, which render many antibiotics ineffective, including next-generation macrolides. To address this threat and advance a longer-term plan for developing new antibiotics, we demonstrate how 16-membered macrolides overcome erythromycin resistance in clinically isolated Staphylococcus aureus strains. By determining the structures of complexes of the large ribosomal subunit of Deinococcus radiodurans (D50S) with these 16-membered selected macrolides, and performing anti-microbial studies, we identified resistance mechanisms they may overcome. This new information provides important insights toward the rational design of therapeutics that are effective against drug resistant human pathogens.
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Affiliation(s)
- Elinor Breiner-Goldstein
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Zohar Eyal
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Donna Matzov
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Yehuda Halfon
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Giuseppe Cimicata
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Moti Baum
- Government Central Laboratories, Ministry of Health, Jerusalem 91342, Israel
| | - Assaf Rokney
- Government Central Laboratories, Ministry of Health, Jerusalem 91342, Israel
| | - Analia V Ezernitchi
- Government Central Laboratories, Ministry of Health, Jerusalem 91342, Israel
| | - Andrew N Lowell
- Life Sciences Institute and Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109-2216, USA
| | - Jennifer J Schmidt
- Life Sciences Institute and Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109-2216, USA
| | - Haim Rozenberg
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Ella Zimmerman
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Anat Bashan
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
| | - Lea Valinsky
- Government Central Laboratories, Ministry of Health, Jerusalem 91342, Israel
| | - Yojiro Anzai
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-0072, Japan
| | - David H Sherman
- Life Sciences Institute and Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology, University of Michigan, Ann Arbor, MI 48109-2216, USA
| | - Ada Yonath
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 760001, Israel
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5
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Silva-Santana G, Aguiar-Alves F, Lenzi-Almeida KC, Lopes VGS, Silva LE, Hirata Júnior R, Viana VG, Simpson-Lourêdo L, Escaleira ACN, Gerth JC, Almosny NRP, Souza AM, Mattos-Guaraldi AL. Pathological profiles of systemic infections by Panton-Valentine leukocidin-positive, methicillin-resistant Staphylococcus aureus strains in a murine model. J Appl Microbiol 2020; 128:1820-1842. [PMID: 31999872 DOI: 10.1111/jam.14598] [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: 12/03/2019] [Accepted: 01/26/2020] [Indexed: 12/13/2022]
Abstract
AIMS Staphylococcus aureus is one of the most common pathogens in hospital environment and community. Panton-Valentine leukocidin (PVL) production is clinically associated with skin abscesses, soft tissues infections, bacteraemia and sepsis. This study aimed to investigate the effects of the presence of genes lukF/S-PV coding for PVL, in histological and haematological features during systemic infection, using a Swiss mice experimental model. METHODS AND RESULTS Experiments were performed using 25 mice distributed into five experimental groups, intravenously inoculated with 50 µl suspensions at density 1·0 × 107 CFU per ml of strains: methicillin-susceptible (MSSA) and pvl-negative strains isolated from nasal colonization; MSSA pvl-positive strains isolated from nasal colonization; methicillin-resistant (MRSA) and pvl-positive strains isolated from peripheral blood of a patient with severe pulmonary infection; and a MRSA pvl-positive strains isolated from a peripheral blood culture of a patient with bacteraemia. Haematological analysis was performed at 24, 48, 72 and 96 h post-infection. Morphoanatomy and histopathological analyses were performed at 96 h post-infection. For all S. aureus strains tested, the capability of intravenous dissemination and survival into mice tissues was demonstrated. Inflammatory processes at different levels were related to the presence of pvl genes, and included alterations in the format, size and colour of the organs. Staphylococcus aureus pvl-positive strains were detected in greater numbers in the organs of the infected animals. CONCLUSIONS The pvl-positive strains isolated from blood cultures were capable to induce the greatest modifications in both haematological and histopathological profiles, and seemed to aggravate the systemic infections. SIGNIFICANCE AND IMPACT OF THE STUDY These findings are valuable in characterizing infections caused by S. aureus in humans and murine.
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Affiliation(s)
- G Silva-Santana
- Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brasil.,Health Sciences Center, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil
| | - F Aguiar-Alves
- Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brasil
| | - K C Lenzi-Almeida
- Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brasil.,Environmental Science and Conservation Department, College of Medicine, Federal University of Rio de Janeiro, Macaé, Brazil
| | - V G S Lopes
- Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brasil
| | - L E Silva
- Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brasil.,Department of Statistics, Institute of Mathematics and Statistics, Fluminense Federal University, Niterói, Brazil
| | - R Hirata Júnior
- Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil.,Microbiology, Immunology and Parasitology Department, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - V G Viana
- Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil.,Microbiology, Immunology and Parasitology Department, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - L Simpson-Lourêdo
- Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil.,Microbiology, Immunology and Parasitology Department, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - A C N Escaleira
- Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil.,Microbiology, Immunology and Parasitology Department, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - J C Gerth
- Pathology and Veterinary Clinic Departament, College of Veterinary Medicine, Fluminense Federal University, Niterói, Brazil
| | - N R P Almosny
- Pathology and Veterinary Clinic Departament, College of Veterinary Medicine, Fluminense Federal University, Niterói, Brazil
| | - A M Souza
- Pathology and Veterinary Clinic Departament, College of Veterinary Medicine, Fluminense Federal University, Niterói, Brazil
| | - A L Mattos-Guaraldi
- Health Sciences Center, Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Laboratory of Diphtheria and Corynebacteria of Clinical Relevance, The Collaborating Centre for Reference and Research on Diphtheria/National Health Foundation/Ministry of Health, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brasil.,Microbiology, Immunology and Parasitology Department, College of Medical Sciences, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
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6
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Molecular characterisation of methicillin-resistant Staphylococcus pseudintermedius from dogs and the description of their SCCmec elements. Vet Microbiol 2019; 233:196-203. [PMID: 31053353 DOI: 10.1016/j.vetmic.2019.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/05/2019] [Accepted: 04/05/2019] [Indexed: 11/20/2022]
Abstract
In recent years an increasing number of methicillin-resistant S. pseudintermedius (MRSP) has been observed in both, healthy and clinically infected dogs. The aim of the study was the characterisation of MRSP isolates from clinical routine diagnostics of a German laboratory in order to assess the abundancy of resistance genes and SCCmec elements. 97 isolates from 96 dogs were analysed using microarrays detecting resistance genes and SCCmec-associated markers. All isolates harboured mecA and blaZ. Other abundant resistance markers (in >80% of isolates) included aacA-aphD, aphA3 and sat as well as erm(B). Tetracycline resistance genes (tet(K), tet(M)) and cat also were common (in >20%). The vast majority (n = 59) of isolates carried SCCmec III elements. SCCmec IV and V elements were identified in 21 and 15 isolates, respectively. Irregular or pseudo-SCCmec elements were found in 2 isolates. The high degree of uniformity of hybridisation patterns of tested strains suggest that the majority of MRSP infections was caused by one single strain and comparison to previously published reports and sequences suggest that this was the ST71-SCCmec III strain that also predominates elsewhere in Western Europe.
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Gill AAS, Singh S, Thapliyal N, Karpoormath R. Nanomaterial-based optical and electrochemical techniques for detection of methicillin-resistant Staphylococcus aureus: a review. Mikrochim Acta 2019; 186:114. [PMID: 30648216 DOI: 10.1007/s00604-018-3186-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 12/14/2018] [Indexed: 12/15/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a number of life-threatening complications in humans. Mutations in the genetic sequence of S. aureus due to the presence of certain genes results in resistance against β-lactamases. Thus, there is an urgent need for developing highly sensitive techniques for the early detection of MRSA to counter the rise in resistant strains. This review (142 refs.) extensively covers literature reports on nanomaterial-based optical and electrochemical sensors from the year 1983 to date, with particularly emphasis on recent advances in electrochemical sensing (such as voltammetry and impedimetric) and optical sensing (such as colorimetry and fluorometry) techniques. Among the electrochemical methods, various nanomaterials were employed for the modification of electrodes. Whereas, in optical assays, formats such as enzyme linked immunosorbent assay, lateral flow assays or in optical fiber systems are common. In addition, novel sensing platforms are reported by applying advanced nanomaterials which include gold nanoparticles, nanotitania, graphene, graphene-oxide, cadmium telluride and related quantum dots, nanocomposites, upconversion nanoparticles and bacteriophages. Finally, closing remarks and an outlook conclude the review. Graphical abstract Schematic of the diversity of nanomaterial-based methods for detection of methicillin-resistant Staphylococcus aureus (MRSA). AuNPs: gold nanoparticles; QDs: quantum dots; PVL: Panton-Valentine leukocidin; mecA gene: mec-gene complex encoding methicillin resistance.
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Affiliation(s)
- Atal A S Gill
- Department of Pharmaceutical Chemistry, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - Sima Singh
- Department of Pharmaceutical Chemistry, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
| | - Neeta Thapliyal
- Department of Applied Science, Women Institute of Technology, Sudhowala, Dehradun, Uttarakhand, 248007, India
| | - Rajshekhar Karpoormath
- Department of Pharmaceutical Chemistry, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa.
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Buchan KD, Foster SJ, Renshaw SA. Staphylococcus aureus: setting its sights on the human innate immune system. MICROBIOLOGY-SGM 2019; 165:367-385. [PMID: 30625113 DOI: 10.1099/mic.0.000759] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Staphylococcus aureus has colonized humans for at least 10 000 years, and today inhabits roughly a third of the population. In addition, S. aureus is a major pathogen that is responsible for a significant disease burden, ranging in severity from mild skin and soft-tissue infections to life-threatening endocarditis and necrotizing pneumonia, with treatment often hampered by resistance to commonly available antibiotics. Underpinning its versatility as a pathogen is its ability to evade the innate immune system. S. aureus specifically targets innate immunity to establish and sustain infection, utilizing a large repertoire of virulence factors to do so. Using these factors, S. aureus can resist phagosomal killing, impair complement activity, disrupt cytokine signalling and target phagocytes directly using proteolytic enzymes and cytolytic toxins. Although most of these virulence factors are well characterized, their importance during infection is less clear, as many display species-specific activity against humans or against animal hosts, including cows, horses and chickens. Several staphylococcal virulence factors display species specificity for components of the human innate immune system, with as few as two amino acid changes reducing binding affinity by as much as 100-fold. This represents a major issue for studying their roles during infection, which cannot be examined without the use of humanized infection models. This review summarizes the major factors S. aureus uses to impair the innate immune system, and provides an in-depth look into the host specificity of S. aureus and how this problem is being approached.
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Affiliation(s)
- Kyle D Buchan
- 1The Bateson Centre and Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Simon J Foster
- 2Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Stephen A Renshaw
- 1The Bateson Centre and Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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O'Callaghan RJ. The Pathogenesis of Staphylococcus aureus Eye Infections. Pathogens 2018; 7:pathogens7010009. [PMID: 29320451 PMCID: PMC5874735 DOI: 10.3390/pathogens7010009] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 01/02/2018] [Accepted: 01/04/2018] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus is a major pathogen of the eye able to infect the tear duct, eyelid, conjunctiva, cornea, anterior and posterior chambers, and the vitreous chamber. Of these infections, those involving the cornea (keratitis) or the inner chambers of the eye (endophthalmitis) are the most threatening because of their potential to cause a loss in visual acuity or even blindness. Each of these ocular sites is protected by the constitutive expression of a variety of antimicrobial factors and these defenses are augmented by a protective host response to the organism. Such infections often involve a predisposing factor that weakens the defenses, such as the use of contact lenses prior to the development of bacterial keratitis or, for endophthalmitis, the trauma caused by cataract surgery or intravitreal injection. The structural carbohydrates of the bacterial surface induce an inflammatory response able to reduce the bacterial load, but contribute to the tissue damage. A variety of bacterial secreted proteins including alpha-toxin, beta-toxin, gamma-toxin, Panton-Valentine leukocidin and other two-component leukocidins mediate tissue damage and contribute to the induction of the inflammatory response. Quantitative animal models of keratitis and endophthalmitis have provided insights into the S. aureus virulence and host factors active in limiting such infections.
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Affiliation(s)
- Richard J O'Callaghan
- Department of Microbiology and Immunology, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216, USA.
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10
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Ravensbergen SJ, Berends M, Stienstra Y, Ott A. High prevalence of MRSA and ESBL among asylum seekers in the Netherlands. PLoS One 2017; 12:e0176481. [PMID: 28441421 PMCID: PMC5404783 DOI: 10.1371/journal.pone.0176481] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 04/11/2017] [Indexed: 11/19/2022] Open
Abstract
Migration is one of the risk factors for the spread of multidrug-resistant organisms (MDRO). The increasing influx of migrants challenges local health care systems. To provide evidence for both hospital hygiene measure and empirical antibiotic therapy, we analysed all cultures performed in asylum seekers between January 1st 2014 and December 31st 2015 for methicillin resistant Staphylococcus aureus (MRSA) and for multidrug-resistant Enterobacteriaceae (MDRE). We compared these with cultures from the Dutch patient population with risk factors for carriage of MDRO. A total of 7181 patients were screened for MRSA. 7357 S. aureus were isolated in clinical cultures. Of 898 screened asylum seekers, almost 10% were MRSA positive. Of 118 asylum seekers with S. aureus in clinical cultures almost 19% were MRSA positive. The general patient population had a 1.3% rate of MRSA in S. aureus isolates. A higher rate of Panton-Valentine leukocidin (PVL) positive strains (RR: 2.4; 95% CI: 1.6-3.4) was found in asylum seekers compared to the general patient population. In 33475 patients one or more Enterobacteriaceae were obtained. More than 21% of the asylum seekers were carrier of MDRE, most of them producing extended spectrum beta-lactamases (20.3%). 5.1% of the general patient population was MDRE carrier. It can be concluded that asylum seekers present with higher rate of MDRO compared to the general patient population. These results justify continued screening of asylum seekers to anticipate multidrug-resistant organisms during hospital care of patients.
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Affiliation(s)
- Sofanne J. Ravensbergen
- Department of Internal Medicine/Infectious Diseases, University of Groningen, University Medical Centre Groningen, Groningen, the Netherlands
- * E-mail:
| | - Matthijs Berends
- Department of Medical Microbiology, Certe, Groningen, the Netherlands
| | - Ymkje Stienstra
- Department of Internal Medicine/Infectious Diseases, University of Groningen, University Medical Centre Groningen, Groningen, the Netherlands
| | - Alewijn Ott
- Department of Medical Microbiology, Certe, Groningen, the Netherlands
- Department of Medical Microbiology, University of Groningen, University Medical Centre Groningen, Groningen, the Netherlands
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11
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Lakhundi S, Siddiqui R, Khan NA. Pathogenesis of microbial keratitis. Microb Pathog 2017; 104:97-109. [DOI: 10.1016/j.micpath.2016.12.013] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 11/30/2016] [Accepted: 12/05/2016] [Indexed: 01/03/2023]
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12
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Wang X, Ouyang L, Luo L, Liu J, Song C, Li C, Yan H, Wang P. Methicillin-resistant staphylococcus aureus isolates in a hospital of shanghai. Oncotarget 2017; 8:6079-6084. [PMID: 28030828 PMCID: PMC5351614 DOI: 10.18632/oncotarget.14036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/13/2016] [Indexed: 11/25/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains are now common both in the health care setting and in the community. Active surveillance is critical for MRSA control and prevention. Specimens of patients (200 patients with 1119 specimens) as well as medical staff and hospital setting (1000 specimens) were randomly sampled in a level 2 hospital in Shanghai from September 2011 to August 2012. Isolation, cultivation and identification of S. aureus were performed. Totally, 67 S. aureus strains were isolated. 32 S. aureus strains were isolated from patient samples; 13 (13/32, 40.6%) of the 32 S. aureus isolates were MRSA; sputum sample and patients in the department of general internal medicine were the most frequent specimen and patient group for S. aureus strains isolation. Remaining 35 S. aureus strains were isolated from the medical staff and hospital setting; 20 (20/35, 57.1%) of the 35 S. aureus isolates were MRSA; specimens sampled from doctors and nurses' hands and nose and hospital facilities were the most frequent samples to isolate S. aureus. Resistant and virulent genes detection showed that, all 33 MRSA strains were mecA positive which accounts for 49.3% of the 67 S. aureus strains; 38 isolates were Panton-Valentine leukocidin (PVL) gene positive which accounts for 56.7% of the 67 S. aureus strains; and 17 (17/67, 25.4%) isolates are mecA and PVL genes dual positive. Multidrug-resistant strains of MRSA and PVL positive S. aureus are common in patients, medical staff and hospital setting, the potential health threat is worthy of our attention.
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Affiliation(s)
- Xiaoguang Wang
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Lin Ouyang
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Lingfei Luo
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Jiqian Liu
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Chiping Song
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Cuizhen Li
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Hongjing Yan
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
| | - Ping Wang
- The Center for Disease Control and Prevention of Minghang District, Minghang District, Shanghai 201101, P.R. China
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13
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Valle DL, Paclibare PAP, Cabrera EC, Rivera WL. Molecular and phenotypic characterization of methicillin-resistant Staphylococcus aureus isolates from a tertiary hospital in the Philippines. Trop Med Health 2016; 44:3. [PMID: 27398062 PMCID: PMC4934148 DOI: 10.1186/s41182-016-0003-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/15/2016] [Indexed: 11/10/2022] Open
Abstract
Background Methicillin-resistant Staphylococcus aureus (MRSA) poses a major threat to public health worldwide. There are relatively few studies addressing the molecular epidemiology of MRSA in the Philippines. Methods This study characterized MRSA isolates in terms of their antimicrobial susceptibility profile, the SCCmec type, and the presence of lukF-lukS genes for Panton-Valentine leukocidin (PVL) and determined the relatedness of the isolates by random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR). Results A total of 236 S. aureus were isolated from clinical specimens of the Makati Medical Center in Makati City, Philippines, between January 2013 and June 2013, and 108 or 45.76 % were found to be MRSA. Results showed that the MRSA strains were resistant to trimethoprim-sulfamethoxazole (20.37 %), azithromycin (10.19 %), gentamicin (5.56 %), and linezolid (4.63 %), while all were susceptible to vancomycin, nitrofurantoin, levofloxacin, minocycline, rifampin, and tetracycline. One isolate was found positive for inducible clindamycin resistance. All of the 108 MRSA strains were confirmed to carry the mecA and SCCmec genes, while the PVL genes were detected in 41 (38 %) of the isolates. Ninety-six isolates (89 %) carried SCCmec type IV, while the remaining isolates carried SCCmec type I (11 isolates) or type III (one isolate). Conclusion This study is the first to present a comprehensive MRSA surveillance data with molecular characterization in a tertiary hospital in the Philippines.
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Affiliation(s)
- Demetrio L Valle
- Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101 Philippines ; Department of Pathology and Laboratories, Makati Medical Center, Makati City, 1229 Philippines
| | - Phyllis Anne P Paclibare
- Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101 Philippines ; Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101 Philippines
| | - Esperanza C Cabrera
- Biology Department, De La Salle University, Taft Ave., Manila City, 1004 Philippines
| | - Windell L Rivera
- Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101 Philippines ; Natural Sciences Research Institute, University of the Philippines, Diliman, Quezon City, 1101 Philippines
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Tseng CW, Biancotti JC, Berg BL, Gate D, Kolar SL, Müller S, Rodriguez MD, Rezai-Zadeh K, Fan X, Beenhouwer DO, Town T, Liu GY. Increased Susceptibility of Humanized NSG Mice to Panton-Valentine Leukocidin and Staphylococcus aureus Skin Infection. PLoS Pathog 2015; 11:e1005292. [PMID: 26618545 PMCID: PMC4664407 DOI: 10.1371/journal.ppat.1005292] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 10/30/2015] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus aureus is a leading cause of skin and soft-tissue infections worldwide. Mice are the most commonly used animals for modeling human staphylococcal infections. However a supra-physiologic S. aureus inoculum is required to establish gross murine skin pathology. Moreover, many staphylococcal factors, including Panton-Valentine leukocidin (PVL) elaborated by community-associated methicillin-resistant S. aureus (CA-MRSA), exhibit selective human tropism and cannot be adequately studied in mice. To overcome these deficiencies, we investigated S. aureus infection in non-obese diabetic (NOD)/severe combined immune deficiency (SCID)/IL2rγnull (NSG) mice engrafted with human CD34+ umbilical cord blood cells. These “humanized” NSG mice require one to two log lower inoculum to induce consistent skin lesions compared with control mice, and exhibit larger cutaneous lesions upon infection with PVL+ versus isogenic PVL-S. aureus. Neutrophils appear important for PVL pathology as adoptive transfer of human neutrophils alone to NSG mice was sufficient to induce dermonecrosis following challenge with PVL+S. aureus but not PVL-S. aureus. PMX53, a human C5aR inhibitor, blocked PVL-induced cellular cytotoxicity in vitro and reduced the size difference of lesions induced by the PVL+ and PVL-S. aureus, but PMX53 also reduced recruitment of neutrophils and exacerbated the infection. Overall, our findings establish humanized mice as an important translational tool for the study of S. aureus infection and provide strong evidence that PVL is a human virulence factor. S. aureus infection has emerged in the past decade as a major burden to public health and is responsible for a surge in preclinical research. Mice are the most commonly studied animals for modeling of human S. aureus infection. However, it is increasingly evident that available murine models poorly mimic human S. aureus disease. Routinely, a supra-physiologic inoculum is required to establish soft-tissue pathology. Additionally, many S. aureus factors exhibit unique human tropism and cannot be adequately investigated in rodents. Here we investigated S. aureus infection in NSG mice engrafted with human umbilical CD34+ cells. We showed that a one to two log lower infectious inoculum of S. aureus establishes consistent skin lesions in humanized NSG mice. This inoculum is comparable to published inocula required to induce infection in humans. In addition, we showed that Panton-Valentine Leucocidin, a human tropic factor secreted by S. aureus, contributes to the development of dermonecrosis in the humanized mice, and its interaction with human neutrophils and human C5a receptor appears to be important for immunopathology. Overall our study suggests that humanized mice are an improved tool for modeling of human S. aureus infection.
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Affiliation(s)
- Ching Wen Tseng
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail: (GYL); (CWT)
| | - Juan Carlos Biancotti
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Bethany L. Berg
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - David Gate
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Stacey L. Kolar
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Sabrina Müller
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Maria D. Rodriguez
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Kavon Rezai-Zadeh
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Xuemo Fan
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - David O. Beenhouwer
- Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
| | - Terrence Town
- Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - George Y. Liu
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, United States of America
- * E-mail: (GYL); (CWT)
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15
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The bicomponent pore-forming leucocidins of Staphylococcus aureus. Microbiol Mol Biol Rev 2015; 78:199-230. [PMID: 24847020 DOI: 10.1128/mmbr.00055-13] [Citation(s) in RCA: 192] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability to produce water-soluble proteins with the capacity to oligomerize and form pores within cellular lipid bilayers is a trait conserved among nearly all forms of life, including humans, single-celled eukaryotes, and numerous bacterial species. In bacteria, some of the most notable pore-forming molecules are protein toxins that interact with mammalian cell membranes to promote lysis, deliver effectors, and modulate cellular homeostasis. Of the bacterial species capable of producing pore-forming toxic molecules, the Gram-positive pathogen Staphylococcus aureus is one of the most notorious. S. aureus can produce seven different pore-forming protein toxins, all of which are believed to play a unique role in promoting the ability of the organism to cause disease in humans and other mammals. The most diverse of these pore-forming toxins, in terms of both functional activity and global representation within S. aureus clinical isolates, are the bicomponent leucocidins. From the first description of their activity on host immune cells over 100 years ago to the detailed investigations of their biochemical function today, the leucocidins remain at the forefront of S. aureus pathogenesis research initiatives. Study of their mode of action is of immediate interest in the realm of therapeutic agent design as well as for studies of bacterial pathogenesis. This review provides an updated perspective on our understanding of the S. aureus leucocidins and their function, specificity, and potential as therapeutic targets.
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16
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Sheikh HQ, Aqil A, Kirby A, Hossain FS. Panton-Valentine leukocidin osteomyelitis in children: a growing threat. Br J Hosp Med (Lond) 2015; 76:18-24. [PMID: 25585179 DOI: 10.12968/hmed.2015.76.1.18] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Panton-Valentine leukocidin-producing Staphylococcus aureus osteomyelitis is associated with multiple complications including multiple abscesses, deep vein thrombosis and fulminant sepsis. This article reviews the literature concerning this emerging threat which is currently under-recognized.
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Affiliation(s)
- Hassaan Q Sheikh
- Specialty Registrar in the Department of Trauma and Orthopaedics
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17
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Bhan U, Podsiad AB, Kovach MA, Ballinger MN, Keshamouni V, Standiford TJ. Linezolid has unique immunomodulatory effects in post-influenza community acquired MRSA pneumonia. PLoS One 2015; 10:e0114574. [PMID: 25635685 PMCID: PMC4312022 DOI: 10.1371/journal.pone.0114574] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 11/11/2014] [Indexed: 12/17/2022] Open
Abstract
Introduction Post influenza pneumonia is a leading cause of mortality and morbidity, with mortality rates approaching 60% when bacterial infections are secondary to multi-drug resistant (MDR) pathogens. Staphylococcus aureus, in particular community acquired MRSA (cMRSA), has emerged as a leading cause of post influenza pneumonia. Hypothesis Linezolid (LZD) prevents acute lung injury in murine model of post influenza bacterial pneumonia Methods Mice were infected with HINI strain of influenza and then challenged with cMRSA at day 7, treated with antibiotics (LZD or Vanco) or vehicle 6 hours post bacterial challenge and lungs and bronchoalveolar lavage fluid (BAL) harvested at 24 hours for bacterial clearance, inflammatory cell influx, cytokine/chemokine analysis and assessment of lung injury. Results Mice treated with LZD or Vanco had lower bacterial burden in the lung and no systemic dissemination, as compared to the control (no antibiotic) group at 24 hours post bacterial challenge. As compared to animals receiving Vanco, LZD group had significantly lower numbers of neutrophils in the BAL (9×103 vs. 2.3×104, p < 0.01), which was associated with reduced levels of chemotactic chemokines and inflammatory cytokines KC, MIP-2, IFN-γ, TNF-α and IL-1β in the BAL. Interestingly, LZD treatment also protected mice from lung injury, as assessed by albumin concentration in the BAL post treatment with H1N1 and cMRSA when compared to vanco treatment. Moreover, treatment with LZD was associated with significantly lower levels of PVL toxin in lungs. Conclusion Linezolid has unique immunomodulatory effects on host inflammatory response and lung injury in a murine model of post-viral cMRSA pneumonia.
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Affiliation(s)
- Urvashi Bhan
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
- * E-mail:
| | - Amy B. Podsiad
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Melissa A. Kovach
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Megan N. Ballinger
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Ohio State University, Columbus, Ohio, United States of America
| | - Venkateshwar Keshamouni
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Theodore J. Standiford
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
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18
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Padmaja RJ, Halami PM. Immunogenicity of Staphylococcus aureus LukM/F'-PV recombinant subunits: validation of diagnostic potential and evaluation of protective efficacy in vitro. Vet Microbiol 2014; 170:358-67. [PMID: 24674742 DOI: 10.1016/j.vetmic.2014.02.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 02/19/2014] [Accepted: 02/24/2014] [Indexed: 11/30/2022]
Abstract
Leukotoxin M/F'-Panton Valentine (LukM/F'-PV), a beta pore-forming toxin secreted by Staphylococcus aureus, is a major virulence factor involved in the pathogenesis of bovine mastitis. The present study was aimed to determine immunogenicity of two recombinant subunits of LukM/F'-PV, rLukM (MW 38 kDa) and rLukF (MW 39 kDa), develop and validate an indirect enzyme linked immunosorbent assay (ELISA) using polyclonal antibodies raised in rabbits, and evaluate applicability of the assay to diagnose clinical and subclinical bovine mastitis. Additionally, in vitro assays were conducted to determine abilities of antibodies to neutralize cytotoxicity of the native leukotoxin. A total of 87 bovine milk samples (healthy, subclinical and clinical mastitis) were evaluated for the presence of toxin determinants. Receiver-operator characteristic curve for the experimental ELISA values statistically interpreted a cut-off score of >0.109 OD405, with an assay specificity of 100% and sensitivity in the range of 80-87.5%. In addition, area under curve of 0.93-0.98 revealed the test was accurate in categorizing samples from infected and non-infected bovine. The rLukF IgG-ELISA was more sensitive than rLukM IgG-ELISA. Furthermore, it was evident from MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium) dye reduction, indirect immunofluorescence and lactate dehydrogenase assays that anti-rLukM/rLukF antibodies, with high neutralizing titers, inhibited in vitro leukotoxic activity and protected bovine neutrophil membrane integrity from cytotoxicity of native leukotoxin. The findings demonstrated that antibodies produced from recombinant subunits contribute to specific and sensitive immunodiagnosis and may also have the potential to provide passive therapeutic benefit in the management of bovine mastitis.
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Affiliation(s)
- R J Padmaja
- Department of Food Microbiology, CSIR-Central Food Technological Research Institute, Mysore 570 020, India
| | - P M Halami
- Department of Food Microbiology, CSIR-Central Food Technological Research Institute, Mysore 570 020, India.
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19
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Qu T, Feng Y, Jiang Y, Zhu P, Wei Z, Chen Y, Otto M, Yu Y. Whole genome analysis of a community-associated methicillin-resistant Staphylococcus aureus ST59 isolate from a case of human sepsis and severe pneumonia in China. PLoS One 2014; 9:e89235. [PMID: 24586619 PMCID: PMC3930696 DOI: 10.1371/journal.pone.0089235] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 01/16/2014] [Indexed: 12/12/2022] Open
Abstract
We report a case of necrotizing pneumonia in a young patient caused by community acquired-methicillin resistant Staphylococcus aureus (CA-MRSA) in a teaching hospital in the People's Republic of China. The patient had a typical clinical presentation and was successfully treated with antibiotics and intravenous immunoglobulin. A CA-MRSA strain, named SA268, was isolated from the blood of the patient. The isolate was susceptible to most antimicrobial agents, except cephalosporins, penicillins, and β-lactamase inhibitor combinations. Multi-locus sequence typing (MLST) assigned SA268 to ST59, a clone widely spread in eastern Asia. The strain was positive for Panton Valentine Leukocidin (PVL)-encoding genes and SCCmec type V. We sequenced the complete genome of the SA268 isolate. The genome of SA268 was almost identical to that of the Taiwanese ST59 CA-MRSA strains M013 and SA957. However, we observed several differences in gene composition, which included differences in the SCCmec element and several lipoprotein genes that were present in the Taiwanese strains but absent from SA268.
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Affiliation(s)
- Tingting Qu
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ye Feng
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yan Jiang
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Peiqiong Zhu
- Department of Clinical Medicine, Zhejiang Medical College, Hangzhou, Zhejiang, China
| | - Zeqing Wei
- State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yan Chen
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (YY); (MO)
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail: (YY); (MO)
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Chronisch rezidivierende Infektionen der Haut und Weichgewebe durch Staphylococcus aureus. Hautarzt 2014; 65:15-25. [DOI: 10.1007/s00105-013-2636-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Cheung GYC, Joo HS, Chatterjee SS, Otto M. Phenol-soluble modulins--critical determinants of staphylococcal virulence. FEMS Microbiol Rev 2014; 38:698-719. [PMID: 24372362 DOI: 10.1111/1574-6976.12057] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 12/05/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022] Open
Abstract
Phenol-soluble modulins (PSMs) are a recently discovered family of amphipathic, alpha-helical peptides that have multiple roles in staphylococcal pathogenesis and contribute to a large extent to the pathogenic success of virulent staphylococci, such as Staphylococcus aureus. PSMs may cause lysis of many human cell types including leukocytes and erythrocytes, stimulate inflammatory responses, and contribute to biofilm development. PSMs appear to have an original role in the commensal lifestyle of staphylococci, where they facilitate growth and spreading on epithelial surfaces. Aggressive, cytolytic PSMs seem to have evolved from that original role and are mainly expressed in highly virulent S. aureus. Here, we will review the biochemistry, genetics, and role of PSMs in the commensal and pathogenic lifestyles of staphylococci, discuss how diversification of PSMs defines the aggressiveness of staphylococcal species, and evaluate potential avenues to target PSMs for drug development against staphylococcal infections.
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Affiliation(s)
- Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD, USA
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22
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Löffler B, Niemann S, Ehrhardt C, Horn D, Lanckohr C, Lina G, Ludwig S, Peters G. Pathogenesis of Staphylococcus aureus necrotizing pneumonia: the role of PVL and an influenza coinfection. Expert Rev Anti Infect Ther 2013; 11:1041-51. [PMID: 24073746 DOI: 10.1586/14787210.2013.827891] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Only recently necrotizing pneumonia was defined as a specific disease entity that is caused by a Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus strain and is frequently preceded by an influenza infection. Necrotizing pneumonia is characterized by a sudden onset and rapid worsening of symptoms, leukopenia, airway hemorrhages, severe respiratory failure and a high mortality rate. Despite clear epidemiological data, the function of PVL in necrotizing pneumonia has been controversially discussed due to conflicting results from different disease models. Furthermore, there are many proposed mechanisms how a viral infection could facilitate and interact with a bacterial superinfection. In this review, we summarize current data from 43 clinical cases and results from various infection models on necrotizing pneumonia. We discuss the contribution of S. aureus PVL and a preceding influenza infection and present a concept of the pathogenesis of necrotizing pneumonia.
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Affiliation(s)
- Bettina Löffler
- Institute of Medical Microbiology, University Hospital of Münster, Domagkstraße 10, D-48149 Münster, Germany
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Diep BA, Afasizheva A, Le HN, Kajikawa O, Matute-Bello G, Tkaczyk C, Sellman B, Badiou C, Lina G, Chambers HF. Effects of linezolid on suppressing in vivo production of staphylococcal toxins and improving survival outcomes in a rabbit model of methicillin-resistant Staphylococcus aureus necrotizing pneumonia. J Infect Dis 2013; 208:75-82. [PMID: 23532096 DOI: 10.1093/infdis/jit129] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Linezolid is recommended for treatment of pneumonia and other invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA). The premise underlying this recommendation is that linezolid inhibits in vivo production of potent staphylococcal exotoxins, including Panton-Valentine leukocidin (PVL) and α-hemolysin (Hla), although supporting evidence is lacking. METHODS A rabbit model of necrotizing pneumonia using MRSA clone USA300 was used to compare therapeutic effects of linezolid (50 mg/kg 3 times/day) and vancomycin (30 mg/kg 2 times/day) administered 1.5, 4, and 9 hours after infection on host survival outcomes and in vivo bacterial toxin production. RESULTS Mortality rates were 100% for untreated rabbits and 83%-100% for vancomycin-treated rabbits. In contrast, mortality rates were 25%, 50%, and 100% for rabbits treated with linezolid 1.5, 4, and 9 hours after infection, respectively. Compared with untreated and vancomycin-treated rabbits, improved survival of rabbits treated 1.5 hours after infection with linezolid was associated with a significant decrease in bacterial counts, suppressed bacterial production of PVL and Hla, and reduced production of the neutrophil-chemoattractant interleukin 8 in the lungs. CONCLUSIONS Across the study interval, only early treatment with linezolid resulted in significant suppression of exotoxin synthesis and improved survival outcomes in a rabbit model of MRSA necrotizing pneumonia.
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Affiliation(s)
- Binh An Diep
- Division of Infectious Diseases, Department of Medicine, University of California-San Francisco, 1001 Potrero Ave, San Francisco, CA 94110, USA.
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Abstract
While infections with methicillin-resistant Staphylococcus aureus (MRSA) were traditionally restricted to the hospital setting, novel MRSA strains emerged over the last two decades that have the capacity to infect otherwise healthy people outside of the hospital setting. These community-associated (CA-)MRSA strains combine methicillin resistance with enhanced virulence and fitness. Interestingly, CA-MRSA strains emerged globally and from different backgrounds, indicating that the "trade-off" between maintaining sufficient levels of methicillin resistance and obtaining enhanced virulence at a low fitness cost was achieved on several occasions in convergent evolution. However, frequently this process comprised similar changes. First and foremost, all CA-MRSA strains typically carry a novel type of methicillin resistance locus that appears to cause less of a fitness burden. Additionally, acquisition of specific toxin genes, most notably that encoding Panton-Valentine leukocidin (PVL), and adaptation of gene expression of genome-encoded toxins, such as alpha-toxin and phenol-soluble modulins (PSMs), further contributed to the evolution of CA-MRSA. Finally, the exceptional epidemiological success of the USA300 CA-MRSA clone in particular may have been due to yet another gene acquisition, namely that of the speG gene, which is located on the arginine catabolic mobile element (ACME) and involved in detoxifying harmful host-derived polyamines.
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Affiliation(s)
- Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD, USA.
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Infectious keratitis: secreted bacterial proteins that mediate corneal damage. J Ophthalmol 2013; 2013:369094. [PMID: 23365719 PMCID: PMC3556867 DOI: 10.1155/2013/369094] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 12/12/2012] [Indexed: 12/17/2022] Open
Abstract
Ocular bacterial infections are universally treated with antibiotics, which can eliminate the organism but cannot reverse the damage caused by bacterial products already present. The three very common causes of bacterial keratitis—Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae—all produce proteins that directly or indirectly cause damage to the cornea that can result in reduced vision despite antibiotic treatment. Most, but not all, of these proteins are secreted toxins and enzymes that mediate host cell death, degradation of stromal collagen, cleavage of host cell surface molecules, or induction of a damaging inflammatory response. Studies of these bacterial pathogens have determined the proteins of interest that could be targets for future therapeutic options for decreasing corneal damage.
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Niemann S, Ehrhardt C, Medina E, Warnking K, Tuchscherr L, Heitmann V, Ludwig S, Peters G, Löffler B. Combined action of influenza virus and Staphylococcus aureus panton-valentine leukocidin provokes severe lung epithelium damage. J Infect Dis 2012; 206:1138-48. [PMID: 22837490 PMCID: PMC3433859 DOI: 10.1093/infdis/jis468] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus necrotizing pneumonia is a life-threatening disease that is frequently preceded by influenza infection. The S. aureus toxin Panton–Valentine leukocidin (PVL) is most likely causative for necrotizing diseases, but the precise pathogenic mechanisms of PVL and a possible contribution of influenza virus remain to be elucidated. In this study, we present a model that explains how influenza virus and PVL act together to cause necrotizing pneumonia: an influenza infection activates the lung epithelium to produce chemoattractants for neutrophils. Upon superinfection with PVL-expressing S. aureus, the recruited neutrophils are rapidly killed by PVL, resulting in uncontrolled release of neutrophil proteases that damage the airway epithelium. The host counteracts this pathogen strategy by generating PVL-neutralizing antibodies and by neutralizing the released proteases via protease inhibitors present in the serum. These findings explain why necrotizing infections mainly develop in serum-free spaces (eg, pulmonary alveoli) and open options for new therapeutic approaches.
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Affiliation(s)
- Silke Niemann
- Institute of Medical Microbiology, University Hospital of Münster, Germany
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Malachowa N, Kobayashi SD, DeLeo FR. Community-associated methicillin-resistant Staphylococcus aureus and athletes. PHYSICIAN SPORTSMED 2012; 40:13-21. [PMID: 22759601 DOI: 10.3810/psm.2012.05.1960] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The remarkable ability of Staphylococcus aureus to develop antibiotic resistance in conjunction with the emergence of highly virulent and/or transmissible strains has established the pathogen as a leading cause of human bacterial infections worldwide. Historically, methicillin-resistant S aureus (MRSA) was found almost exclusively in hospitals and/or health care-related facilities. However, in the late 1990s, community-associated MRSA strains emerged in the United States and rapidly became the leading cause of community-associated bacterial infections. An enhanced understanding of the pathogenesis and epidemiology of this bacterium is fundamental for the prevention and/or treatment of community-associated MRSA infections. This review highlights salient features of S aureus biology that contribute to the exceptional ability of this pathogen to cause human disease, as well as discusses, in brief, the established approaches for treatment and prevention of infection.
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Affiliation(s)
- Natalia Malachowa
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institute of Health, Hamilton, MT 59840, USA.
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Rosenstein R, Götz F. What Distinguishes Highly Pathogenic Staphylococci from Medium- and Non-pathogenic? Curr Top Microbiol Immunol 2012; 358:33-89. [DOI: 10.1007/82_2012_286] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Tong SYC, Chen LF, Fowler VG. Colonization, pathogenicity, host susceptibility, and therapeutics for Staphylococcus aureus: what is the clinical relevance? Semin Immunopathol 2011; 34:185-200. [PMID: 22160374 DOI: 10.1007/s00281-011-0300-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 10/28/2011] [Indexed: 12/20/2022]
Abstract
Staphylococcus aureus is a human commensal that can also cause a broad spectrum of clinical disease. Factors associated with clinical disease are myriad and dynamic and include pathogen virulence, antimicrobial resistance, and host susceptibility. Additionally, infection control measures aimed at the environmental niches of S. aureus and therapeutic advances continue to impact upon the incidence and outcomes of staphylococcal infections. This review article focuses on the clinical relevance of advances in our understanding of staphylococcal colonization, virulence, host susceptibility, and therapeutics. Over the past decade key developments have arisen. First, rates of nosocomial methicillin-resistant S. aureus (MRSA) infections have significantly declined in many countries. Second, we have made great strides in our understanding of the molecular pathogenesis of S. aureus in general and community-associated MRSA in particular. Third, host risk factors for invasive staphylococcal infections, such as advancing age, increasing numbers of invasive medical interventions, and a growing proportion of patients with healthcare contact, remain dynamic. Finally, several new antimicrobial agents active against MRSA have become available for clinical use. Humans and S. aureus co-exist, and the dynamic interface between host, pathogen, and our attempts to influence these interactions will continue to rapidly change. Although progress has been made in the past decade, we are likely to face further surprises such as the recent waves of community-associated MRSA.
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Affiliation(s)
- Steven Y C Tong
- Division of Infectious Diseases and International Health, Duke University Medical Center, Box 102359, Durham, NC 27705, USA.
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Targeting the host–pathogen interface for treatment of Staphylococcus aureus infection. Semin Immunopathol 2011; 34:299-315. [DOI: 10.1007/s00281-011-0297-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 10/17/2011] [Indexed: 12/15/2022]
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Rigby KM, DeLeo FR. Neutrophils in innate host defense against Staphylococcus aureus infections. Semin Immunopathol 2011; 34:237-59. [PMID: 22080185 PMCID: PMC3271231 DOI: 10.1007/s00281-011-0295-3] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 10/14/2011] [Indexed: 12/29/2022]
Abstract
Staphylococcus aureus has been an important human pathogen throughout history and is currently a leading cause of bacterial infections worldwide. S. aureus has the unique ability to cause a continuum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Moreover, the emergence of highly virulent, drug-resistant strains such as methicillin-resistant S. aureus in both healthcare and community settings is a major therapeutic concern. Neutrophils are the most prominent cellular component of the innate immune system and provide an essential primary defense against bacterial pathogens such as S. aureus. Neutrophils are rapidly recruited to sites of infection where they bind and ingest invading S. aureus, and this process triggers potent oxidative and non-oxidative antimicrobial killing mechanisms that serve to limit pathogen survival and dissemination. S. aureus has evolved numerous mechanisms to evade host defense strategies employed by neutrophils, including the ability to modulate normal neutrophil turnover, a process critical to the resolution of acute inflammation. Here we provide an overview of the role of neutrophils in host defense against bacterial pathogens and discuss strategies employed by S. aureus to circumvent neutrophil function.
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Affiliation(s)
- Kevin M Rigby
- Laboratory of Human Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840, USA
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Kobayashi SD, Malachowa N, Whitney AR, Braughton KR, Gardner DJ, Long D, Bubeck Wardenburg J, Schneewind O, Otto M, Deleo FR. Comparative analysis of USA300 virulence determinants in a rabbit model of skin and soft tissue infection. J Infect Dis 2011; 204:937-41. [PMID: 21849291 DOI: 10.1093/infdis/jir441] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are frequently associated with strains harboring genes encoding Panton-Valentine leukocidin (PVL). The role of PVL in the success of the epidemic CA-MRSA strain USA300 remains unknown. Here we developed a skin and soft tissue infection model in rabbits to test the hypothesis that PVL contributes to USA300 pathogenesis and compare it with well-established virulence determinants: alpha-hemolysin (Hla), phenol-soluble modulin-alpha peptides (PSMα), and accessory gene regulator (Agr). The data indicate that Hla, PSMα, and Agr contribute to the pathogenesis of USA300 skin infections in rabbits, whereas a role for PVL could not be detected.
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Affiliation(s)
- Scott D Kobayashi
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, and Bethesda, Maryland, USA
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Sensing of pathogenic bacteria based on their interaction with supported bilayer membranes studied by impedance spectroscopy and surface plasmon resonance. Biosens Bioelectron 2011; 28:227-31. [DOI: 10.1016/j.bios.2011.07.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 07/11/2011] [Accepted: 07/11/2011] [Indexed: 02/06/2023]
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Otto M. Basis of Virulence in Community-Associated Methicillin-ResistantStaphylococcus aureus. Annu Rev Microbiol 2010; 64:143-62. [DOI: 10.1146/annurev.micro.112408.134309] [Citation(s) in RCA: 350] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael Otto
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
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Malachowa N, DeLeo FR. Mobile genetic elements of Staphylococcus aureus. Cell Mol Life Sci 2010; 67:3057-71. [PMID: 20668911 PMCID: PMC2929429 DOI: 10.1007/s00018-010-0389-4] [Citation(s) in RCA: 328] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 04/06/2010] [Accepted: 04/26/2010] [Indexed: 01/30/2023]
Abstract
Bacteria such as Staphylococcus aureus are successful as commensal organisms or pathogens in part because they adapt rapidly to selective pressures imparted by the human host. Mobile genetic elements (MGEs) play a central role in this adaptation process and are a means to transfer genetic information (DNA) among and within bacterial species. Importantly, MGEs encode putative virulence factors and molecules that confer resistance to antibiotics, including the gene that confers resistance to beta-lactam antibiotics in methicillin-resistant S. aureus (MRSA). Inasmuch as MRSA infections are a significant problem worldwide and continue to emerge in epidemic waves, there has been significant effort to improve diagnostic assays and to develop new antimicrobial agents for treatment of disease. Our understanding of S. aureus MGEs and the molecules they encode has played an important role toward these ends and has provided detailed insight into the evolution of antimicrobial resistance mechanisms and virulence.
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Affiliation(s)
- Natalia Malachowa
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840 USA
| | - Frank R. DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840 USA
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Ventura CL, Malachowa N, Hammer CH, Nardone GA, Robinson MA, Kobayashi SD, DeLeo FR. Identification of a novel Staphylococcus aureus two-component leukotoxin using cell surface proteomics. PLoS One 2010; 5:e11634. [PMID: 20661294 PMCID: PMC2905442 DOI: 10.1371/journal.pone.0011634] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 06/23/2010] [Indexed: 01/13/2023] Open
Abstract
Staphylococcus aureus is a prominent human pathogen and leading
cause of bacterial infection in hospitals and the community.
Community-associated methicillin-resistant S. aureus (CA-MRSA)
strains such as USA300 are highly virulent and, unlike hospital strains, often
cause disease in otherwise healthy individuals. The enhanced virulence of
CA-MRSA is based in part on increased ability to produce high levels of secreted
molecules that facilitate evasion of the innate immune response. Although
progress has been made, the factors that contribute to CA-MRSA virulence are
incompletely defined. We analyzed the cell surface proteome (surfome) of USA300
strain LAC to better understand extracellular factors that contribute to the
enhanced virulence phenotype. A total of 113 identified proteins were associated
with the surface of USA300 during the late-exponential phase of growth
in vitro. Protein A was the most abundant surface molecule
of USA300, as indicated by combined Mascot score following analysis of peptides
by tandem mass spectrometry. Unexpectedly, we identified a previously
uncharacterized two-component leukotoxin–herein named LukS-H and
LukF-G (LukGH)-as two of the most abundant surface-associated proteins of
USA300. Rabbit antibody specific for LukG indicated it was also freely secreted
by USA300 into culture media. We used wild-type and isogenic
lukGH deletion strains of USA300 in combination with human
PMN pore formation and lysis assays to identify this molecule as a leukotoxin.
Moreover, LukGH synergized with PVL to enhance lysis of human PMNs in
vitro, and contributed to lysis of PMNs after phagocytosis. We
conclude LukGH is a novel two-component leukotoxin with cytolytic activity
toward neutrophils, and thus potentially contributes to S.
aureus virulence.
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Affiliation(s)
- Christy L. Ventura
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Natalia Malachowa
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Carl H. Hammer
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Glenn A. Nardone
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Mary Ann Robinson
- Research Technologies Branch, National Institute of Allergy and
Infectious Diseases, National Institutes of Health, Rockville, Maryland, United
States of America
| | - Scott D. Kobayashi
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
| | - Frank R. DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories,
National Institute of Allergy and Infectious Diseases, National Institutes of
Health, Hamilton, Montana, United States of America
- * E-mail:
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Abstract
IMPORTANCE OF THE FIELD Staphylococcus aureus is a leading human pathogen in the hospital and the community. Many S. aureus strains are resistant to antibiotics, making treatment of S. aureus infections often very complicated. In contrast to many other bacterial pathogens, a working vaccine has never been found for S. aureus despite considerable efforts in academia and pharmaceutical companies. AREAS COVERED IN THIS REVIEW The latest strategies aimed at finding a working vaccine against S. aureus, including active and passive immunization efforts in pre-clinical and clinical stages, and the molecular reasons for why it may be difficult to develop a vaccine are discussed. WHAT THE READER WILL GAIN In addition to receiving an overview of current efforts in S. aureus vaccine research, the reader will understand that vaccine development for S. aureus may be difficult owing to the facts that S. aureus is a commensal microorganism and produces toxins that lyse white blood cells, thereby undermining a vaccine's role as a facilitator of opsonophagocytosis. TAKE HOME MESSAGE As a result of failed clinical trials with monovalent traditional vaccines, recent developments include a shift towards the potential use of polyvalent formulas and therapeutic antibodies and more systematic selection of optimal antigens.
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Affiliation(s)
- Michael Otto
- National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Laboratory of Human Bacterial Pathogenesis, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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Molecular characteristics of community-associated methicillin-resistant Staphylococcus aureus strains for clinical medicine. Arch Microbiol 2010; 192:603-17. [PMID: 20544179 DOI: 10.1007/s00203-010-0594-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 03/29/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022]
Abstract
Infections caused by methicillin-resistant S. aureus strains are mainly associated with a hospital setting. However, nowadays, the MRSA infections of non-hospitalized patients are observed more frequently. In order to distinguish them from hospital-associated methicillin-resistant S. aureus (HA-MRSA) strains, given them the name of community-associated methicillin-resistant S. aureus (CA-MRSA). CA-MRSA strains most commonly cause skin infections, but may lead to more severe diseases, and consequently the patient's death. The molecular markers of CA-MRSA strains are the presence of accessory gene regulator (agr) of group I or III, staphylococcal cassette chromosome mec (SCCmec) type IV, V or VII and genes encoding for Panton-Valentine leukocidin (PVL). In addition, CA-MRSA strains show resistance to beta-lactam antibiotics. Studies on the genetic elements of CA-MRSA strains have a key role in the unambiguous identification of strains, monitoring of infections, improving the treatment, work on new antimicrobial agents and understanding the evolution of these pathogens.
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Abstract
Meticillin-resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide, and causes substantial morbidity and mortality. Health-care-associated MRSA infections arise in individuals with predisposing risk factors, such as surgery or presence of an indwelling medical device. By contrast, many community-associated MRSA (CA-MRSA) infections arise in otherwise healthy individuals who do not have such risk factors. Additionally, CA-MRSA infections are epidemic in some countries. These features suggest that CA-MRSA strains are more virulent and transmissible than are traditional hospital-associated MRSA strains. The restricted treatment options for CA-MRSA infections compound the effect of enhanced virulence and transmission. Although progress has been made towards understanding emergence of CA-MRSA, virulence, and treatment of infections, our knowledge remains incomplete. Here we review the most up-to-date knowledge and provide a perspective for the future prophylaxis or new treatments for CA-MRSA infections.
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Affiliation(s)
- Frank R DeLeo
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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Otto M. Looking toward basic science for potential drug discovery targets against community-associated MRSA. Med Res Rev 2010; 30:1-22. [PMID: 19399829 DOI: 10.1002/med.20160] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The difficulties to find a conventional vaccine against Staphylococcus aureus and the increasing resistance of S. aureus to many antibiotics demand the exploration of novel therapeutic options, such as by targeting virulence determinants and using specific antibodies in an antitoxin-like approach. Community-associated methicillin-resistant S. aureus (CA-MRSA) strains have recently emerged predominantly in the US, causing epidemic outbreaks of mostly skin and soft tissue infections, but also more dramatic and sometimes fatal diseases. MRSA is now the most frequent cause of death by a single infectious agent in the US. The fact that, at least in the US, CA-MRSA infections are almost entirely due to one sequence type, USA300, gives researchers a novel, unique chance to focus on one clone in their efforts to analyze pathogenesis in a clinically important S. aureus. While the molecular underpinnings of the exceptional virulence and transmissibility of USA300 are not yet well understood, recent findings indicate that increased expression of widespread virulence determinants and acquisition of mobile genetic elements have to be considered. Delineating the relative importance of virulence determinants in USA300 and other important clinical strains is a key endeavor needed to develop a potential antitoxin for CA-MRSA disease.
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Affiliation(s)
- Michael Otto
- Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bldg. 33 1W10, Bethesda, Maryland 20892, USA.
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Antri K, Rouzic N, Boubekri I, Dauwalder O, Beloufa A, Ziane H, Djennane F, Neggazi M, Benhabyles B, Bes M, Tazir M, Étienne J, Ramdani-Bouguessa N. Forte prévalence des infections communautaires et nosocomiales à Staphylococus aureus résistant à la méticilline et portant le gène de la leucocidine de Panton-Valentine dans l’Algérois. ACTA ACUST UNITED AC 2010; 58:e15-20. [DOI: 10.1016/j.patbio.2009.07.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 07/12/2009] [Indexed: 12/16/2022]
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Abstract
PURPOSE OF REVIEW To consider the relevance to severe human lung infections of recently discovered virulence mechanisms of Staphylococcus aureus and Francisella tularensis. RECENT FINDINGS S. aureus has long been considered an opportunistic pathogen. However, due to the emergence of community-acquired methicillin-resistant S. aureus (CA-MRSA) strains that can readily infect and kill normal hosts, S. aureus must now be considered a potentially virulent pathogen. The evolution of S. aureus from an organism associated with asymptomatic nasopharyngeal colonization to one associated with community-acquired lethal infections may reflect horizontal acquisition of bacterial genes that enable efficient spread, aggressive host invasion, and effective immune evasion. Alleviating the burden of staphylococcal disease will require better understanding of host susceptibility and of staphylococcal virulence and antibiotic resistance. In contrast to the rapidly evolving staphylococcal virulence strategy, recent genomic analysis of F. tularensis has revealed a small set of bacterial genes associated with the marked virulence of its North American subspecies. This suggests that a relatively stable strategy of immune evasion underlies this pathogen's ability to establish serious life-threatening lung infections from a very small inoculum. SUMMARY Understanding bacterial pathogenesis will require additional research into both host susceptibility factors and bacterial virulence mechanisms, including horizontal gene transfer. Refinements in the molecular detection of bacteria in the clinical setting, as well as whole genome analysis of both pathogens and patients, are expected to aid in the understanding of bacterial-induced lung injury.
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Polymorphonuclear leukocytes mediate Staphylococcus aureus Panton-Valentine leukocidin-induced lung inflammation and injury. Proc Natl Acad Sci U S A 2010; 107:5587-92. [PMID: 20231457 DOI: 10.1073/pnas.0912403107] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is epidemic in the United States, even rivaling HIV/AIDS in its public health impact. The pandemic clone USA300, like other CA-MRSA strains, expresses Panton-Valentine leukocidin (PVL), a pore-forming toxin that targets polymorphonuclear leukocytes (PMNs). PVL is thought to play a key role in the pathogenesis of necrotizing pneumonia, but data from rodent infection models are inconclusive. Rodent PMNs are less susceptible than human PMNs to PVL-induced cytolysis, whereas rabbit PMNs, like those of humans, are highly susceptible to PVL-induced cytolysis. This difference in target cell susceptibility could affect results of experimental models. Therefore, we developed a rabbit model of necrotizing pneumonia to compare the virulence of a USA300 wild-type strain with that of isogenic PVL-deletion mutant and -complemented strains. PVL enhanced the capacity of USA300 to cause severe lung necrosis, pulmonary edema, alveolar hemorrhage, hemoptysis, and death, hallmark clinical features of fatal human necrotizing pneumonia. Purified PVL instilled directly into the lung caused lung inflammation and injury by recruiting and lysing PMNs, which damage the lung by releasing cytotoxic granule contents. These findings provide insights into the mechanism of PVL-induced lung injury and inflammation and demonstrate the utility of the rabbit for studying PVL-mediated pathogenesis.
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Lee MH, Arrecubieta C, Martin FJ, Prince A, Borczuk AC, Lowy FD. A postinfluenza model of Staphylococcus aureus pneumonia. J Infect Dis 2010; 201:508-15. [PMID: 20078212 DOI: 10.1086/650204] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Postinfluenza Staphylococcus aureus pneumonias are increasingly recognized as a major form of life-threatening infections. METHODS A mouse model of postinfluenza S. aureus pneumonia was developed. Mice were intranasally infected with bacteria alone or bacteria plus virus. Infection was assessed by mouse survival, lung histopathology, bacterial density in the lungs, and cellular response to infection. RESULTS Mice infected with both influenza virus and S. aureus showed higher mortality, greater lung parenchymal damage, and greater bacterial density at metastatic tissue sites than mice infected with only S. aureus. At 4 h, more polymorphonuclear leukocytes and fewer CD11c(+) cells were found in lung samples from mice infected with virus and bacteria than in those from mice infected with bacteria. alpha-Hemolysin and protein A were maximally expressed 4 h after infection, and Panton-Valentine leukocidin was maximally expressed 72 h after infection, with higher levels of alpha-hemolysin expression in mice infected with bacteria alone. Interferon gamma expression was higher in tissue collected from mice infected with virus plus bacteria than in those from bacteria-infected mice. CONCLUSIONS The results from this model demonstrate diverse effects caused by antecedent influenza virus infection, which have a profound influence on the morbidity and mortality associated with S. aureus pneumonia.
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Affiliation(s)
- Mei-Ho Lee
- Division of Infectious Diseases, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Graves SF, Kobayashi SD, Braughton KR, Diep BA, Chambers HF, Otto M, Deleo FR. Relative contribution of Panton-Valentine leukocidin to PMN plasma membrane permeability and lysis caused by USA300 and USA400 culture supernatants. Microbes Infect 2010; 12:446-56. [PMID: 20172045 DOI: 10.1016/j.micinf.2010.02.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/10/2010] [Accepted: 02/15/2010] [Indexed: 01/15/2023]
Abstract
Panton-Valentine leukocidin (PVL) is a cytolytic toxin associated with severe community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. However, the relative contribution of PVL to host cell lysis during CA-MRSA infection remains unknown. Here we investigated the relative contribution of PVL to human polymorphonuclear leukocyte (PMN) plasma membrane permeability and lysis in vitro by using culture supernatants from wild-type and isogenic lukS/F-PV negative (Deltapvl) USA300 and USA400 strains. Using S. aureus culture conditions that favor selective high production of PVL (CCY medium), there was on average more PMN plasma membrane permeability and cell lysis caused by supernatants derived from wild-type strains compared with those from Deltapvl strains. Unexpectedly, plasma membrane permeability did not necessarily correlate with ultimate cell lysis. Moreover, the level of pore formation caused by culture supernatants varied dramatically (e.g., range was 0.32-99.09% for wild-type USA300 supernatants at 30 min) and was not attributable to differences in PMN susceptibility to PVL among human blood donors. We conclude that PMN pore formation assays utilizing S. aureus culture supernatants have limited ability to estimate the relative contribution of PVL to pathogenesis (or cytolysis in vitro or in vivo), especially when assayed using culture media that promote selective high production of PVL.
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Affiliation(s)
- Shawna F Graves
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840, USA
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Olsen RJ, Kobayashi SD, Ayeras AA, Ashraf M, Graves SF, Ragasa W, Humbird T, Greaver JL, Cantu C, Swain JL, Jenkins L, Blasdel T, Cagle PT, Gardner DJ, DeLeo FR, Musser JM. Lack of a major role of Staphylococcus aureus Panton-Valentine leukocidin in lower respiratory tract infection in nonhuman primates. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:1346-54. [PMID: 20093487 DOI: 10.2353/ajpath.2010.090960] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Panton-Valentine leukocidin (PVL) is a two-component cytolytic toxin epidemiologically linked to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections, including serious invasive infections caused by the epidemic clone referred to as strain USA300. Although PVL has long been known to be a S. aureus virulence molecule in vitro, the relative contribution of this leukotoxin to invasive CA-MRSA infections such as pneumonia remains controversial. We developed a nonhuman primate model of CA-MRSA pneumonia and used it to test the hypothesis that PVL contributes to lower respiratory tract infections caused by S. aureus strain USA300. The lower respiratory tract disease observed in this monkey model mimicked the clinical and pathological features of early mild to moderate S. aureus pneumonia in humans, including fine-structure histopathology. In this experiment using a large sample of monkeys and multiple time points of examination, no involvement of PVL in virulence could be detected. Compared with the wild-type parental USA300 strain, the isogenic PVL deletion-mutant strain caused equivalent lower respiratory tract pathology. We conclude that PVL does not contribute to lower respiratory tract infection in this nonhuman primate model of human CA-MRSA pneumonia.
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Affiliation(s)
- Randall J Olsen
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, the Methodist Hospital, and University of Houston, B490, 6565 Fannin Street, Houston, TX 77030, USA
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Staphylococcus aureus panton-valentine leukocidin is a very potent cytotoxic factor for human neutrophils. PLoS Pathog 2010; 6:e1000715. [PMID: 20072612 PMCID: PMC2798753 DOI: 10.1371/journal.ppat.1000715] [Citation(s) in RCA: 311] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 12/03/2009] [Indexed: 02/02/2023] Open
Abstract
The role of the pore-forming Staphylococcus aureus toxin Panton-Valentine leukocidin (PVL) in severe necrotizing diseases is debated due to conflicting data from epidemiological studies of community-associated methicillin-resistant S. aureus (CA-MRSA) infections and various murine disease-models. In this study, we used neutrophils isolated from different species to evaluate the cytotoxic effect of PVL in comparison to other staphylococcal cytolytic components. Furthermore, to study the impact of PVL we expressed it heterologously in a non-virulent staphylococcal species and examined pvl-positive and pvl-negative clinical isolates as well as the strain USA300 and its pvl-negative mutant. We demonstrate that PVL induces rapid activation and cell death in human and rabbit neutrophils, but not in murine or simian cells. By contrast, the phenol-soluble modulins (PSMs), a newly identified group of cytolytic staphylococcal components, lack species-specificity. In general, after phagocytosis of bacteria different pvl-positive and pvl-negative staphylococcal strains, expressing a variety of other virulence factors (such as surface proteins), induced cell death in neutrophils, which is most likely associated with the physiological clearing function of these cells. However, the release of PVL by staphylococcal strains caused rapid and premature cell death, which is different from the physiological (and programmed) cell death of neutrophils following phagocytosis and degradation of virulent bacteria. Taken together, our results question the value of infection-models in mice and non-human primates to elucidate the impact of PVL. Our data clearly demonstrate that PVL acts differentially on neutrophils of various species and suggests that PVL has an important cytotoxic role in human neutrophils, which has major implications for the pathogenesis of CA-MRSA infections. Staphylococcus aureus can cause serious diseases, including necrotizing pneumonia, which often affects young immunocompetent patients and has a high lethality rate. Several clinical studies demonstrated a clear association between this form of pneumonia and S. aureus strains carrying the gene for the pore-forming toxin Panton-Valentine leukocidin (PVL). However, laboratory work, which mainly used murine disease models, has created very contrasting results and often fails to show a pathogenic role for PVL. In this study, we demonstrate that the expression of PVL by staphylococcal strains confers strong and rapid cytotoxic activity against neutrophils. However, this action was basically restricted to human cells and could not be reproduced in murine or Java monkeys’ cells. These results indicate that infection-models in mice and in non-human primates fail to replicate the pathogenic activity of PVL seen in human cells. Our data with human neutrophils clearly show that PVL has a major cytotoxic effect, as the release of PVL by staphylococcal strains caused rapid and premature cell death, which is different from the physiological (and programmed) cell death of neutrophils following phagocytosis and degradation of virulent bacteria. These results have important implications especially for infections with CA-MRSA strains, which often carry the gene for PVL and have spread widely in the community.
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Community-associated methicillin-resistant Staphylococcus aureus immune evasion and virulence. J Mol Med (Berl) 2010; 88:109-14. [PMID: 20049412 DOI: 10.1007/s00109-009-0573-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 11/17/2009] [Accepted: 12/02/2009] [Indexed: 12/31/2022]
Abstract
Staphylococcus aureus is a significant cause of human infections globally. Methicillin-resistant S. aureus (MRSA) emerged in the early 1960s and is now endemic in most healthcare facilities. Although healthcare-associated MRSA infections remain a major problem in most industrialized countries, those caused by community-associated MRSA (CA-MRSA) are now the most abundant cause of bacterial infections in the community in some parts of the world, such as the United States. The basis for the emergence and subsequent success of CA-MRSA is incompletely defined. However, the ability of the pathogen to cause disease in otherwise healthy individuals is likely attributed, in part, to its ability to circumvent killing by the innate immune system, which includes survival after phagocytosis by neutrophils. In this review, we discuss the role of neutrophils in host defense against S. aureus and highlight progress made toward understanding mechanisms of CA-MRSA virulence and pathogenesis.
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49
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DeLeo FR, Chambers HF. Reemergence of antibiotic-resistant Staphylococcus aureus in the genomics era. J Clin Invest 2009; 119:2464-74. [PMID: 19729844 DOI: 10.1172/jci38226] [Citation(s) in RCA: 337] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is the leading cause of bacterial infections in developed countries and produces a wide spectrum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Although S. aureus infections were historically treatable with common antibiotics, emergence of drug-resistant organisms is now a major concern. Methicillin-resistant S. aureus (MRSA) was endemic in hospitals by the late 1960s, but it appeared rapidly and unexpectedly in communities in the 1990s and is now prevalent worldwide. This Review focuses on progress made toward understanding the success of community-associated MRSA as a human pathogen, with an emphasis on genome-wide approaches and virulence determinants.
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Affiliation(s)
- Frank R DeLeo
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, Montana 59840, USA.
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Staphylococcus aureus Panton-Valentine leukocidin contributes to inflammation and muscle tissue injury. PLoS One 2009; 4:e6387. [PMID: 19633710 PMCID: PMC2711303 DOI: 10.1371/journal.pone.0006387] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 06/26/2009] [Indexed: 11/20/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) threatens public health worldwide, and epidemiologic data suggest that the Panton-Valentine Leukocidin (PVL) expressed by most CA-MRSA strains could contribute to severe human infections, particularly in young and immunocompetent hosts. PVL is proposed to induce cytolysis or apoptosis of phagocytes. However, recent comparisons of isogenic CA-MRSA strains with or without PVL have revealed no differences in human PMN cytolytic activity. Furthermore, many of the mouse studies performed to date have failed to demonstrate a virulence role for PVL, thereby provoking the question: does PVL have a mechanistic role in human infection? In this report, we evaluated the contribution of PVL to severe skin and soft tissue infection. We generated PVL mutants in CA-MRSA strains isolated from patients with necrotizing fasciitis and used these tools to evaluate the pathogenic role of PVL in vivo. In a model of necrotizing soft tissue infection, we found PVL caused significant damage of muscle but not the skin. Muscle injury was linked to induction of pro-inflammatory chemokines KC, MIP-2, and RANTES, and recruitment of neutrophils. Tissue damage was most prominent in young mice and in those strains of mice that more effectively cleared S. aureus, and was not significant in older mice and mouse strains that had a more limited immune response to the pathogen. PVL mediated injury could be blocked by pretreatment with anti-PVL antibodies. Our data provide new insights into CA-MRSA pathogenesis, epidemiology and therapeutics. PVL could contribute to the increased incidence of myositis in CA-MRSA infection, and the toxin could mediate tissue injury by mechanisms other than direct killing of phagocytes.
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