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Beadell B, Nehra S, Gusenov E, Huse H, Wong-Beringer A. Machine Learning with Alpha Toxin Phenotype to Predict Clinical Outcome in Patients with Staphylococcus aureus Bloodstream Infection. Toxins (Basel) 2023; 15:417. [PMID: 37505686 PMCID: PMC10467129 DOI: 10.3390/toxins15070417] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/17/2023] [Accepted: 06/25/2023] [Indexed: 07/29/2023] Open
Abstract
Staphylococcus aureus bloodstream (SAB) infection remains a leading cause of sepsis-related mortality. Yet, current treatment does not account for variable virulence traits that mediate host dysregulated immune response, such as SA α-toxin (Hla)-mediated thrombocytopenia. Here, we applied machine learning (ML) to bacterial growth images combined with platelet count data to predict patient outcomes. We profiled Hla phenotypes of SA isolates collected from patients with bacteremia by taking smartphone images of beta-hemolytic growth on sheep blood agar (SBA). Electronic medical records were reviewed to extract relevant laboratory and clinical data. A convolutional neural network was applied to process the plate image data for input along with day 1 patient platelet count to generate ML-based models that predict thrombocytopenia on day 4 and mortality. A total of 229 patients infected with SA strains exhibiting varying zone sizes of beta-hemolysis on SBA were included. A total of 539 images of bacterial growth on SBA were generated as inputs for model development. One-third of patients developed thrombocytopenia at onset, with an overall mortality rate of 18.8%. The models developed from the ML algorithm showed strong performance (AUC 0.92) for predicting thrombocytopenia on day 4 of infection and modest performance (AUC 0.711) for mortality. Our findings support further development and validation of a proof-of-concept ML application in digital microbiology, with a measure of bacterial virulence factor production that carries prognostic significance and can help guide treatment selection.
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Affiliation(s)
- Brent Beadell
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (B.B.); (E.G.)
| | - Surya Nehra
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA;
| | - Elizabeth Gusenov
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (B.B.); (E.G.)
| | - Holly Huse
- Department of Microbiology, Harbor-UCLA Medical Center, Torrance, CA 90502, USA;
| | - Annie Wong-Beringer
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (B.B.); (E.G.)
- Department of Pharmacy, Huntington Hospital, Pasadena, CA 91105, USA
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2
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Braï MA, Hannachi N, El Gueddari N, Baudoin JP, Dahmani A, Lepidi H, Habib G, Camoin-Jau L. The Role of Platelets in Infective Endocarditis. Int J Mol Sci 2023; 24:ijms24087540. [PMID: 37108707 PMCID: PMC10143005 DOI: 10.3390/ijms24087540] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/02/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
Over the last decade, the incidence of infective endocarditis (IE) has increased, with a change in the frequency of causative bacteria. Early evidence has substantially demonstrated the crucial role of bacterial interaction with human platelets, with no clear mechanistic characterization in the pathogenesis of IE. The pathogenesis of endocarditis is so complex and atypical that it is still unclear how and why certain bacterial species will induce the formation of vegetation. In this review, we will analyze the key role of platelets in the physiopathology of endocarditis and in the formation of vegetation, depending on the bacterial species. We provide a comprehensive outline of the involvement of platelets in the host immune response, investigate the latest developments in platelet therapy, and discuss prospective research avenues for solving the mechanistic enigma of bacteria-platelet interaction for preventive and curative medicine.
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Affiliation(s)
- Mustapha Abdeljalil Braï
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- IHU Méditerranée Infection, Boulevard Jean Moulin, 13385 Marseille, France
| | - Nadji Hannachi
- Laboratoire de Biopharmacie et Pharmacotechnie, Faculté de Médecine, Université Ferhat Abbas Sétif I, Sétif 19000, Algeria
| | - Nabila El Gueddari
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Service de Chirurgie Cardiaque, Hôpital de la Timone, APHM, Boulevard Jean-Moulin, 13385 Marseille, France
| | - Jean-Pierre Baudoin
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- IHU Méditerranée Infection, Boulevard Jean Moulin, 13385 Marseille, France
| | - Abderrhamane Dahmani
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- IHU Méditerranée Infection, Boulevard Jean Moulin, 13385 Marseille, France
| | - Hubert Lepidi
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Service d'Anatomo-Pathologie, Hôpital de la Timone, APHM, Boulevard Jean-Moulin, 13385 Marseille, France
| | - Gilbert Habib
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Service de Cardiologie, Hôpital de la Timone, APHM, Boulevard Jean-Moulin, 13385 Marseille, France
| | - Laurence Camoin-Jau
- IRD, APHM, MEPHI, IHU Méditerranée Infection, Aix Marseille University, 19-21 Boulevard Jean Moulin, 13005 Marseille, France
- Laboratoire d'Hématologie, Hôpital de la Timone, APHM, Boulevard Jean-Moulin, 13385 Marseille, France
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3
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Activation of Human Platelets by Staphylococcus aureus Secreted Protease Staphopain A. Pathogens 2022; 11:pathogens11111237. [DOI: 10.3390/pathogens11111237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/19/2022] [Accepted: 10/24/2022] [Indexed: 11/17/2022] Open
Abstract
Infection by Staphylococcus aureus is the leading cause of infective endocarditis (IE). Activation of platelets by this pathogen results in their aggregation and thrombus formation which are considered to be important steps in the development and pathogenesis of IE. Here, we show that a secreted cysteine protease, staphopain A, activates human platelets and induces their aggregation. The culture supernatant of a scpA mutant deficient in staphopain A production was reduced in its ability to trigger platelet aggregation. The platelet agonist activity of purified staphopain A was inhibited by staphostatin A, a specific inhibitor, thus implicating its protease activity in the agonism. In whole blood, using concentrations of staphopain A that were otherwise insufficient to induce platelet aggregation, increased binding to collagen and thrombus formation was observed. Using antagonists specific to protease-activated receptors 1 and 4, we demonstrate their role in mediating staphopain A induced platelet activation.
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4
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Impact of Clopidogrel on Clinical Outcomes in Patients with Staphylococcus aureus Bacteremia: a National Retrospective Cohort Study. Antimicrob Agents Chemother 2022; 66:e0211721. [PMID: 35416712 PMCID: PMC9211425 DOI: 10.1128/aac.02117-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Activated platelets have known antimicrobial activity against Staphylococcus aureus. Accelerated clearance of platelets induced by S. aureus can result in thrombocytopenia and increased mortality in patients. Recent studies suggest that P2Y12 inhibition protects platelets from accelerated clearance. We therefore evaluated the effect of P2Y12 inhibition on clinical outcomes in patients with S. aureus bacteremia across a large national cohort. Our retrospective cohort (2010 to 2018) included patients admitted to Veterans Affairs (VA) hospitals with blood cultures positive for S. aureus and treated with standard-of-care antibiotics. Employing propensity score-matched Cox proportional hazards regression models, we compared clinical outcomes in patients treated with clopidogrel for at least the 30 days prior to admission and continuing for at least 5 days after admission to patients without any P2Y12 inhibitor use in the year preceding admission. Mortality was significantly lower among clopidogrel users than P2Y12 inhibitor nonusers (n = 147 propensity score-matched pairs): the inpatient mortality hazard ratio (HR) was 0.11 (95% confidence interval [CI], 0.01 to 0.86), and 30-day mortality HR was 0.43 (95% CI, 0.19 to 0.98). There were no differences in 30-day readmission, 30-day S. aureus reinfection, microbiological clearance, or thrombocytopenia. Clopidogrel use at the time of infection reduced in-hospital mortality by 89% and 30-day mortality by 57% among a cohort of patients with S. aureus bacteremia. These results support the need to further study the use of P2Y12 inhibitors as adjunctive therapy in S. aureus bloodstream infections.
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Gilbertie J, Ulloa ER, Daiker JC, Nguyen K, Smelter D, Rose W, Geriak M, Schnabel LV, Nizet V, Sakoulas G. Potent Activity of Ertapenem Plus Cefazolin Within Staphylococcal Biofilms: A Contributing Factor in the Treatment of Methicillin-Susceptible Staphylococcus aureus Endocarditis. Open Forum Infect Dis 2022; 9:ofac159. [PMID: 35493130 PMCID: PMC9045957 DOI: 10.1093/ofid/ofac159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/22/2022] [Indexed: 11/21/2022] Open
Abstract
Background Besides antistaphylococcal beta-lactams and source control, there are limited validated antimicrobial salvage options in patients with prolonged methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, including infective endocarditis (IE). Methods MSSA IE cases treated with ertapenem (ETP) plus cefazolin (CZ) were compared with matched IE cases treated with standard beta-lactam monotherapy. The bactericidal activity of ETP plus CZ was also compared with nafcillin (NAF), CZ, and ETP alone using an in vitro MSSA biofilm model. Results The median duration of bacteremia experienced by patients (n = 12) while on CZ or NAF was 4 days (range 1-16 days) compared with 1 day (range 1-3 days) for patients (n = 5) treated with ETP + CZ (P = .01, Mann-Whitney U test). Cefazolin and NAF alone or in combination did not achieve biofilm eradication at clinically relevant concentrations. However, the addition of ETP to CZ led to bactericidal eradication within biofilms at standard dosing. Conclusions Ertapenem reduces CZ concentrations required to eradicate MSSA biofilms to those achievable in vivo by standard dosing, translating into shorter bacteremia duration in patients with MSSA endocarditis. Larger studies are needed to investigate ETP plus CZ therapy in the treatment of biofilm-related MSSA infections such as endocarditis.
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Affiliation(s)
- Jessica Gilbertie
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Erlinda R Ulloa
- Department of Pediatrics, University of California Irvine School of Medicine, Irvine, California, USA.,Division of Infectious Disease, Children's Hospital of Orange County, Orange, California, USA
| | - Jennifer C Daiker
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Khanh Nguyen
- Sharp Memorial Hospital, San Diego, California, USA
| | - Dan Smelter
- Department and School of Pharmacy, University of Wisconsin Health, Madison, Wisconsin, USA
| | - Warren Rose
- Department and School of Pharmacy, University of Wisconsin Health, Madison, Wisconsin, USA
| | | | - Lauren V Schnabel
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Victor Nizet
- Collaborative to Halt Antibiotic-Resistant Microbes (CHARM), Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California, USA.,Skaggs School of Pharmacy, University of California San Diego, La Jolla, California, USA
| | - George Sakoulas
- Sharp Memorial Hospital, San Diego, California, USA.,Collaborative to Halt Antibiotic-Resistant Microbes (CHARM), Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, California, USA
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6
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Ogura K, Furuya H, Takahashi N, Shibata K, Endo M, Watanabe S, Cui L, Miyoshi-Akiyama T, Okamoto S, Ogai K, Sugama J. Interspecies Regulation Between Staphylococcus caprae and Staphylococcus aureus Colonized on Healed Skin After Injury. Front Microbiol 2022; 13:818398. [PMID: 35300478 PMCID: PMC8921658 DOI: 10.3389/fmicb.2022.818398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/20/2022] [Indexed: 12/04/2022] Open
Abstract
Staphylococcus spp. colonize commensally on the human skin. Some commensal coagulase-negative staphylococci and Staphylococcus aureus are also involved in nosocomial infections. Bacteria were collected from skin healed from pressure injury (PI). After the collection time points, some patients suffered from recurrent PI (RPI). This study analyzed the characteristics of Staphylococcus spp. on healed skin before recurrence between healed skin that suffered from RPI within 6 weeks (RPI group) and healed skin that did not suffer within the duration (non-RPI group) by Staphylococcus spp.-specific sequencing. Of the seven patients in the RPI group, two were dominated by S. aureus and four by Staphylococcus caprae, coagulase-negative human commensal staphylococci in the RPI group. Using mouse models, both S. caprae and S. aureus, but not Staphylococcus epidermidis, colonized on skin healed from injury at significantly higher rates than normal skin. Although subcutaneous injection of S. caprae did not induce lesion formation, the bacterium exhibited high hemolytic activity on human red blood cells. Lesion formation by subcutaneous injection of S. aureus was significantly suppressed in the presence of S. caprae. The hemolytic activity of rabbit blood cells of S. aureus was suppressed by S. caprae, whereas the hemolytic activity of S. caprae was dramatically suppressed by S. aureus. Data indicated that each of the two Staphylococcus spp. suppresses the pathogenicity of the other and that the imbalance between the two is associated with RPI.
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Affiliation(s)
- Kohei Ogura
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Hiroka Furuya
- Department of Clinical Laboratory Science, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Natsuki Takahashi
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Kana Shibata
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Maho Endo
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Shinya Watanabe
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Longzhu Cui
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Tohru Miyoshi-Akiyama
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Shinjuku, Japan
| | - Shigefumi Okamoto
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan.,Department of Clinical Laboratory Science, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Kazuhiro Ogai
- AI Hospital/Macro Signal Dynamics Research and Development Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Junko Sugama
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan.,Research Center for Implementation Nursing Science Initiative, School of Health Sciences, Fujita Health University, Toyoake, Japan
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7
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Lerche CJ, Schwartz F, Pries-Heje MM, Fosbøl EL, Iversen K, Jensen PØ, Høiby N, Hyldegaard O, Bundgaard H, Moser C. Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis. Front Cell Infect Microbiol 2022; 12:805964. [PMID: 35186793 PMCID: PMC8851036 DOI: 10.3389/fcimb.2022.805964] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/06/2022] [Indexed: 12/22/2022] Open
Abstract
Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.
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Affiliation(s)
- Christian Johann Lerche
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Virus and Microbiology Special Diagnostics, Statens Serum Institut, Copenhagen, Denmark
- *Correspondence: Christian Johann Lerche,
| | - Franziska Schwartz
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Mia Marie Pries-Heje
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Emil Loldrup Fosbøl
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Kasper Iversen
- Department of Cardiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
- Department of Emergency Medicine, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ole Hyldegaard
- Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Henning Bundgaard
- Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Claus Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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8
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Leeten K, Jacques N, Lancellotti P, Oury C. Aspirin or Ticagrelor in Staphylococcus aureus Infective Endocarditis: Where Do We Stand? Front Cell Dev Biol 2021; 9:716302. [PMID: 34692677 PMCID: PMC8529053 DOI: 10.3389/fcell.2021.716302] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/21/2021] [Indexed: 12/04/2022] Open
Abstract
Infective endocarditis is a challenging disease with a high mortality and morbidity rate. Antibiotic prophylaxis is currently recommended in high-risk infective endocarditis patients. However, the use of antibiotics faces the challenge of a low efficacy and contributes further to the emerging infection rate by antibiotic-resistant strains, emphasizing the need for new therapeutic strategies. Platelets are essential in the initial phase of infective endocarditis, acting as first-line immune responders. During the first phase of disease, bacteria can interact with platelets and counteract platelet antimicrobial activities. Mechanistic in vitro and animal studies on the effect of aspirin on bacteria-platelet interactions and the prevention of vegetation development showed promising results. However, data from clinical studies on the outcome of infective endocarditis patients who were receiving medically indicated aspirin therapy remain controversial. Therefore, the benefit of antiplatelet agents in infective endocarditis prevention has been questioned. Besides aspirin, it has been discovered that the platelet P2Y12 receptor antagonist ticagrelor has antibacterial properties in addition to its potent antiplatelet activity. Furthermore, a recent study in mice and a case report remarkably indicated the ability of this drug to eradicate Staphylococcus aureus bacteremia. This review will focus on current knowledge on antibacterial activity of ticagrelor, compared to aspirin, pointing out main unanswered questions. The goal is to provide food for thought as to whether a prior ticagrelor therapy might be beneficial for the prevention of infective endocarditis.
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Affiliation(s)
- Kirsten Leeten
- Laboratory of Cardiology, Department of Cardiology, GIGA Institute, University of Liège Hospital, Liège, Belgium
| | - Nicolas Jacques
- Laboratory of Cardiology, Department of Cardiology, GIGA Institute, University of Liège Hospital, Liège, Belgium
| | - Patrizio Lancellotti
- Laboratory of Cardiology, Department of Cardiology, GIGA Institute, University of Liège Hospital, Liège, Belgium.,Gruppo Villa Maria Care and Research, Maria Cecilia Hospital, Cotignola, and Anthea Hospital, Bari, Italy
| | - Cécile Oury
- Laboratory of Cardiology, Department of Cardiology, GIGA Institute, University of Liège Hospital, Liège, Belgium
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9
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Liu F, Guan Z, Liu Y, Li J, Liu C, Gao Y, Ma Y, Feng J, Shen B, Yang G. Identification of a Human Anti-Alpha-Toxin Monoclonal Antibody Against Staphylococcus aureus Infection. Front Microbiol 2021; 12:692279. [PMID: 34335518 PMCID: PMC8319846 DOI: 10.3389/fmicb.2021.692279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is a major pathogenic bacterium that causes a variety of clinical infections. The emergence of multi-drug resistant mechanisms requires novel strategies to mitigate S. aureus infection. Alpha-hemolysin (Hla) is a key virulence factor that is believed to play a significant role in the pathogenesis of S. aureus infections. In this study, we screened a naïve human Fab library for identification of monoclonal antibodies targeting Hla by phage display technology. We found that the monoclonal antibody YG1 blocked the Hla-mediated lysis of rabbit red blood cells and inhibited Hla binding to A549 cells in a concentration-dependent manner. YG1 also provided protection against acute peritoneal infection, bacteremia, and pneumonia in murine models. We further characterized its epitope using different Hla variants and found that the amino acids N209 and F210 of Hla were functionally and structurally important for YG1 binding. Overall, these results indicated that targeting Hla with YG1 could serve as a promising protective strategy against S. aureus infection.
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Affiliation(s)
- Fangjie Liu
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Zhangchun Guan
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Yu Liu
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Jingjing Li
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Chenghua Liu
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Yaping Gao
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Yuanfang Ma
- Laboratory of Cellular and Molecular Immunology, Institute of Immunology, Henan University, Kaifeng, China
| | - Jiannan Feng
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Beifen Shen
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
| | - Guang Yang
- Beijing Institute of Pharmacology and Toxicology, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing, China
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10
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Volk CF, Burgdorf S, Edwardson G, Nizet V, Sakoulas G, Rose WE. Interleukin (IL)-1β and IL-10 Host Responses in Patients With Staphylococcus aureus Bacteremia Determined by Antimicrobial Therapy. Clin Infect Dis 2021; 70:2634-2640. [PMID: 31365924 DOI: 10.1093/cid/ciz686] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/18/2019] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Patient interleukin (IL)-1β and IL-10 responses early in Staphylococcus aureus bacteremia (SaB) are associated with bacteremia duration and mortality. We hypothesized that these responses vary depending on antimicrobial therapy, with particular interest in whether the superiority of β-lactams links to key cytokine pathways. METHODS Three medical centers included 59 patients with SaB (47 methicillin-resistant S. aureus [MRSA], 12 methicillin-sensitive S. aureus [MSSA]) from 2015-2017. In the first 48 hours, patients were treated with either a β-lactam (n = 24), including oxacillin, cefazolin, or ceftaroline, or a glyco-/lipopeptide (n = 35), that is, vancomycin or daptomycin. Patient sera from days 1, 3, and 7 were assayed for IL-1β and IL-10 by enzyme-linked immunosorbent assay and compared using the Mann-Whitney U test. RESULTS On presentation, IL-10 was elevated in mortality (P = .008) and persistent bacteremia (P = .034), while no difference occurred in IL-1β. Regarding treatment groups, IL-1β and IL-10 were similar prior to receiving antibiotic. Patients treated with β-lactam had higher IL-1β on days 3 (median +5.6 pg/mL; P = .007) and 7 (+10.9 pg/mL; P = .016). Ex vivo, addition of the IL-1 receptor antagonist anakinra to whole blood reduced staphylococcal killing, supporting an IL-1β functional significance in SaB clearance. β-lactam-treated patients had sharper declines in IL-10 than vancomycin or daptomycin -treated patients over 7 days. CONCLUSIONS These data underscore the importance of β-lactams for SaB, including consideration that the adjunctive role of β-lactams for MRSA in select patients helps elicit favorable host cytokine responses.
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Affiliation(s)
- Cecilia F Volk
- School of Pharmacy, University of Wisconsin-Madison, La Jolla
| | - Sarah Burgdorf
- Department of Pediatrics, University of California-San Diego School of Medicine, La Jolla
| | | | - Victor Nizet
- Department of Pediatrics, University of California-San Diego School of Medicine, La Jolla
| | - George Sakoulas
- Department of Pediatrics, University of California-San Diego School of Medicine, La Jolla
| | - Warren E Rose
- School of Pharmacy, University of Wisconsin-Madison, La Jolla
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11
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Reed JM, Gardner SG, Mishra NN, Bayer AS, Somerville GA. Metabolic interventions for the prevention and treatment of daptomycin non-susceptibility in Staphylococcus aureus. J Antimicrob Chemother 2020; 74:2274-2283. [PMID: 31074482 DOI: 10.1093/jac/dkz194] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/03/2019] [Accepted: 04/07/2019] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND A major developing problem in the treatment of Staphylococcus aureus infections is the emergence of resistance during treatment with daptomycin. Previous metabolomic analyses of isogenic S. aureus strains prior to and after evolution into a daptomycin non-susceptible (DapNS) state provided important metabolic information about this transition (e.g. perturbations of the tricarboxylic acid cycle). OBJECTIVES To assess the significance of these metabolic changes, in vitro susceptibility to daptomycin was determined in daptomycin-susceptible (DapS) and DapNSS. aureus strains cultivated with metabolic inhibitors targeting these changes. METHODS Only inhibitors that are approved for use in humans were chosen (i.e. fosfomycin, valproate, trimetazidine and 6-mercaptopurine) to assess the importance of metabolic pathways for daptomycin non-susceptibility. The ability of these inhibitors to forestall the emergence of DapNS strains was also assessed. RESULTS The combination of daptomycin and fosfomycin synergistically killed both DapS and DapNS strains in vitro and enhanced the in vivo outcome against a DapNS strain in experimental endocarditis. Interestingly, fosfomycin acts on the peptidoglycan biosynthetic enzyme UDP-N-acetylglucosamine enolpyruvyl transferase (MurA); however, it also had a significant effect on the enzymatic activity of enolase, an essential enzyme in S. aureus. While fosfomycin acted synergistically with daptomycin, it failed to prevent the in vitro evolution of daptomycin non-susceptibility. In contrast, trimetazidine, an anti-angina drug that stimulates glucose oxidation, abolished the ability of DapSS. aureus strains to transition to a DapNS state. CONCLUSIONS These data reveal that metabolic adaptations associated with DapNS strains can be targeted to prevent the emergence of and/or reverse pre-existing resistance to daptomycin.
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Affiliation(s)
- Joseph M Reed
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
| | - Stewart G Gardner
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
| | - Nagendra N Mishra
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.,Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Arnold S Bayer
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA.,Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Greg A Somerville
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0905, USA
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12
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Martin DR, Witten JC, Tan CD, Rodriguez ER, Blackstone EH, Pettersson GB, Seifert DE, Willard BB, Apte SS. Proteomics identifies a convergent innate response to infective endocarditis and extensive proteolysis in vegetation components. JCI Insight 2020; 5:135317. [PMID: 32544089 DOI: 10.1172/jci.insight.135317] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 06/10/2020] [Indexed: 02/06/2023] Open
Abstract
Infective endocarditis is a life-threatening infection of heart valves and adjacent structures characterized by vegetations on valves and other endocardial surfaces, with tissue destruction and risk of embolization. We used high-resolution mass spectrometry to define the proteome of staphylococcal and non-staphylococcal vegetations and Terminal Amine Isotopic Labeling of Substrates (TAILS) to define their proteolytic landscapes. These approaches identified over 2000 human proteins in staphylococcal and non-staphylococcal vegetations. Individual vegetation proteomes demonstrated comparable profiles of quantitatively major constituents that overlapped with serum, platelet, and neutrophil proteomes. Staphylococcal vegetation proteomes resembled one another more than the proteomes of non-staphylococcal vegetations. TAILS demonstrated extensive proteolysis within vegetations, with numerous previously undescribed cleavages. Several proteases and pathogen-specific proteins, including virulence factors, were identified in most vegetations. Proteolytic peptides in fibronectin and complement C3 were identified as potential infective endocarditis biomarkers. Overlap of staphylococcal and non-staphylococcal vegetation proteomes suggests a convergent thrombotic and immune response to endocardial infection by diverse pathogens. However, the differences between staphylococcal and non-staphylococcal vegetations and internal variance within the non-staphylococcal group indicate that additional pathogen- or patient-specific effects exist. Pervasive proteolysis of vegetation components may arise from vegetation-intrinsic proteases and destabilize vegetations, contributing to embolism.
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Affiliation(s)
- Daniel R Martin
- Department of Biomedical Engineering, Lerner Research Institute
| | - James C Witten
- Department of Thoracic and Cardiovascular Surgery, Miller Family Heart and Vascular Institute
| | - Carmela D Tan
- Department of Pathology, Robert J. Tomsich Pathology & Laboratory Medicine Institute, and
| | - E Rene Rodriguez
- Department of Pathology, Robert J. Tomsich Pathology & Laboratory Medicine Institute, and
| | - Eugene H Blackstone
- Department of Thoracic and Cardiovascular Surgery, Miller Family Heart and Vascular Institute
| | - Gosta B Pettersson
- Department of Thoracic and Cardiovascular Surgery, Miller Family Heart and Vascular Institute
| | | | - Belinda B Willard
- Proteomics and Metabolomics Core, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Suneel S Apte
- Department of Biomedical Engineering, Lerner Research Institute
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13
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Page MJ, Pretorius E. A Champion of Host Defense: A Generic Large-Scale Cause for Platelet Dysfunction and Depletion in Infection. Semin Thromb Hemost 2020; 46:302-319. [PMID: 32279287 PMCID: PMC7339151 DOI: 10.1055/s-0040-1708827] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Thrombocytopenia is commonly associated with sepsis and infections, which in turn are characterized by a profound immune reaction to the invading pathogen. Platelets are one of the cellular entities that exert considerable immune, antibacterial, and antiviral actions, and are therefore active participants in the host response. Platelets are sensitive to surrounding inflammatory stimuli and contribute to the immune response by multiple mechanisms, including endowing the endothelium with a proinflammatory phenotype, enhancing and amplifying leukocyte recruitment and inflammation, promoting the effector functions of immune cells, and ensuring an optimal adaptive immune response. During infection, pathogens and their products influence the platelet response and can even be toxic. However, platelets are able to sense and engage bacteria and viruses to assist in their removal and destruction. Platelets greatly contribute to host defense by multiple mechanisms, including forming immune complexes and aggregates, shedding their granular content, and internalizing pathogens and subsequently being marked for removal. These processes, and the nature of platelet function in general, cause the platelet to be irreversibly consumed in the execution of its duty. An exaggerated systemic inflammatory response to infection can drive platelet dysfunction, where platelets are inappropriately activated and face immunological destruction. While thrombocytopenia may arise by condition-specific mechanisms that cause an imbalance between platelet production and removal, this review evaluates a generic large-scale mechanism for platelet depletion as a repercussion of its involvement at the nexus of responses to infection.
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Affiliation(s)
- Martin J Page
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Etheresia Pretorius
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
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14
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Effect of antiplatelet agents on platelet antistaphylococcal capacity: An in vitro study. Int J Antimicrob Agents 2020; 55:105890. [DOI: 10.1016/j.ijantimicag.2020.105890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/14/2019] [Accepted: 12/28/2019] [Indexed: 01/26/2023]
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15
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Sakoulas G, Geriak M, Nizet V. Is a Reported Penicillin Allergy Sufficient Grounds to Forgo the Multidimensional Antimicrobial Benefits of β-Lactam Antibiotics? Clin Infect Dis 2020; 68:157-164. [PMID: 29986019 DOI: 10.1093/cid/ciy557] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 07/07/2018] [Indexed: 12/18/2022] Open
Abstract
The majority of patients with reported penicillin allergy are not allergic when tested or challenged. Penicillin allergy testing has been shown to significantly reduce annual healthcare expenditures. Data have emerged showing β-lactams have multidimensional antibacterial effects in vivo, far beyond what is appreciated in standard bacteriological susceptibility testing media. These include enhancing bacterial killing by the innate immune system. Supporting the clinical relevance of these secondary underappreciated effects are recent clinical and pharmacoeconomic analyses that show worse outcomes in patients with reported penicillin allergies who receive non-β-lactam antibiotics when compared to their non-penicillin-allergic counterparts. This is particularly relevant in the treatment of Staphylococcus aureus bacteremia. This article reviews the tremendous advantages offered by β-lactam therapy and makes a strong case that the debunking of false penicillin allergies through a detailed allergy history and penicillin allergy testing should be a vital component of antimicrobial stewardship practices.
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Affiliation(s)
- George Sakoulas
- Sharp Memorial Hospital, San Diego, La Jolla.,School of Medicine, University of California, San Diego, La Jolla
| | | | - Victor Nizet
- School of Medicine, University of California, San Diego, La Jolla.,Skaggs School of Pharmacy, University of California, San Diego, La Jolla
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16
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Horino T, Hori S. Metastatic infection during Staphylococcus aureus bacteremia. J Infect Chemother 2019; 26:162-169. [PMID: 31676266 DOI: 10.1016/j.jiac.2019.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/25/2019] [Accepted: 10/03/2019] [Indexed: 12/17/2022]
Abstract
Staphylococcus aureus causes various infections, including skin and soft tissue infections and pneumonia via both, community-associated and nosocomial infection. These infectious diseases can lead to bacteremia, and may subsequently result in metastatic infections in several cases. Metastatic infections are critical complications in patients with S. aureus bacteremia, since the optimal duration of the antimicrobial treatment differs in patients with and without metastatic infection. Notably, two weeks of antimicrobial treatment is recommended in case of uncomplicated S. aureus bacteremia, whereas in patients with S. aureus bacteremia-associated endocarditis or vertebral osteomyelitis, six weeks of antimicrobial administration is vital. In addition, misdiagnosis or insufficient treatment in metastatic infection is associated with poor prognosis, functional disability, and relapse. Although echocardiography is recommended to examine endocarditis in the patients with S. aureus bacteremia, it remains unclear which patients should undergo additional examinations, such as CT and MRI, to detect the presence of other metastatic infections. Clinical studies have revealed that permanent foreign body and persistent bacteremia are predictive factors for metastatic infections, and experimental studies have demonstrated that the virulence factors of S. aureus, such as fnbA and clfA, are associated with endocarditis; however, these factors are not proven to increase the risk of metastatic infections. In this review, we assessed the incidence, predictive factors, diagnosis, and treatment for metastatic infections during S. aureus bacteremia.
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Affiliation(s)
- Tetsuya Horino
- Department of Infectious Diseases and Infection Control, Jikei University School of Medicine, Japan.
| | - Seiji Hori
- Department of Infectious Diseases and Infection Control, Jikei University School of Medicine, Japan
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17
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Hannachi N, Habib G, Camoin-Jau L. Aspirin Effect on Staphylococcus aureus-Platelet Interactions During Infectious Endocarditis. Front Med (Lausanne) 2019; 6:217. [PMID: 31681776 PMCID: PMC6803506 DOI: 10.3389/fmed.2019.00217] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 09/23/2019] [Indexed: 12/29/2022] Open
Abstract
Infectious endocarditis (IE) is a rare disease associated with high mortality and morbidity rate. The platelet-bacterial interaction presents the cornerstone of the development of endocardial vegetation. The epidemiology of IE has undergone profound changes between the last and the new decade, with Staphylococcus aureus becoming the main incriminated species. Despite improvements in antibiotic and surgical therapies, embolic disorders remain highly associated with IE that can be fatal. Antiplatelet drugs have been widely proposed to overcome embolic events associated with IE. This proposal has been supported by numerous in vitro, experimental, and clinical studies. However, other studies have yielded conflicting results. In this review, we focus on the effect of aspirin on the genesis of S. aureus endocarditic vegetation, as well as on the management of embolic and hemorrhagic events related to it, starting by its influence on the platelet-bacteria interaction.
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Affiliation(s)
- Nadji Hannachi
- Aix Marseille Univ, IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France
| | - Gilbert Habib
- Aix Marseille Univ, IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France
- Département de Cardiologie, Hôpital de la Timone, AP-HM, Marseille, France
| | - Laurence Camoin-Jau
- Aix Marseille Univ, IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France
- Laboratoire d'Hématologie, Hôpital de la Timone, APHM, Marseille, France
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18
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Gudeta DD, Lei MG, Lee CY. Contribution of hla Regulation by SaeR to Staphylococcus aureus USA300 Pathogenesis. Infect Immun 2019; 87:e00231-19. [PMID: 31209148 PMCID: PMC6704604 DOI: 10.1128/iai.00231-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/11/2019] [Indexed: 02/08/2023] Open
Abstract
The SaeRS two-component system in Staphylococcus aureus is critical for regulation of many virulence genes, including hla, which encodes alpha-toxin. However, the impact of regulation of alpha-toxin by Sae on S. aureus pathogenesis has not been directly addressed. Here, we mutated the SaeR-binding sequences in the hla regulatory region and determined the contribution of this mutation to hla expression and pathogenesis in strain USA300 JE2. Western blot analyses revealed drastic reduction of alpha-toxin levels in the culture supernatants of SaeR-binding mutant in contrast to the marked alpha-toxin production in the wild type. The SaeR-binding mutation had no significant effect on alpha-toxin regulation by Agr, MgrA, and CcpA. In animal studies, we found that the SaeR-binding mutation did not contribute to USA300 JE2 pathogenesis using a rat infective endocarditis model. However, in a rat skin and soft tissue infection model, the abscesses on rats infected with the mutant were significantly smaller than the abscesses on those infected with the wild type but similar to the abscesses on those infected with a saeR mutant. These studies indicated that there is a direct effect of hla regulation by SaeR on pathogenesis but that the effect depends on the animal model used.
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Affiliation(s)
- Dereje D Gudeta
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Mei G Lei
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Chia Y Lee
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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19
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Sharma-Kuinkel BK, Tkaczyk C, Bonnell J, Yu L, Tovchigrechko A, Tabor DE, Park LP, Ruffin F, Esser MT, Sellman BR, Fowler VG, Ruzin A. Associations of pathogen-specific and host-specific characteristics with disease outcome in patients with Staphylococcus aureus bacteremic pneumonia. Clin Transl Immunology 2019; 8:e01070. [PMID: 31360464 PMCID: PMC6640002 DOI: 10.1002/cti2.1070] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/24/2019] [Accepted: 06/30/2019] [Indexed: 11/08/2022] Open
Abstract
Objective To understand the relationships of Staphylococcus aureus (SA) bacteremic pneumonia (SABP) outcome with patient‐specific and SA‐specific variables. Methods We analysed SA bloodstream isolates and matching sera in SABP patients by sequencing SA isolates (n = 50) and measuring in vitro AT production, haemolytic activity and expression of ClfA and ClfB. Controls were sera from gram‐negative bacteremia patients with or without pneumonia and uninfected subjects. Levels of IgGs, IgMs and neutralizing antibodies (NAbs) against SA antigens were quantified and analysed by one‐way ANOVA. Associations of patient outcomes with patient variables, antibody levels and isolate characteristics were evaluated by univariate and multivariate logistic regression analyses. Results SABP patients had higher levels of IgGs against eight virulence factors and anti‐alpha toxin (AT) NAbs than uninfected controls. Levels of IgG against AT and IgMs against ClfA, FnbpA and SdrC were higher in clinically cured SABP patients than in clinical failures. Anti‐LukAB NAb levels were elevated in all cohorts. Increased odds of cure correlated with higher haemolytic activity of SA strains, longer time between surgery and bacteremia (> 30 days), longer duration of antibiotic therapy, lower acute physiology and total APACHE II scores, lack of persistent fever for > 72 h and higher levels of antibodies against AT (IgG), ClfA (IgM), FnbpA (IgM) and SdrC (IgM). Discussion Limitations included the cross‐sectional observational nature of the study, small sample size and inability to measure antibody levels against all SA virulence factors. Conclusion Our results suggest that SABP patients may benefit from immunotherapy targeting multiple SA antigens.
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Affiliation(s)
- Batu K Sharma-Kuinkel
- Division of Infectious Diseases, Department of Medicine, Duke University Durham NC USA
| | | | | | - Li Yu
- Statistical Sciences, AstraZeneca Gaithersburg MD USA
| | | | | | - Lawrence P Park
- Division of Infectious Diseases, Department of Medicine, Duke University Durham NC USA
| | - Felicia Ruffin
- Division of Infectious Diseases, Department of Medicine, Duke University Durham NC USA
| | - Mark T Esser
- Microbial Sciences, AstraZeneca Gaithersburg MD USA
| | | | - Vance G Fowler
- Division of Infectious Diseases, Department of Medicine, Duke University Durham NC USA
| | - Alexey Ruzin
- Microbial Sciences, AstraZeneca Gaithersburg MD USA
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20
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Brothers KM, Callaghan JD, Stella NA, Bachinsky JM, AlHigaylan M, Lehner KL, Franks JM, Lathrop KL, Collins E, Schmitt DM, Horzempa J, Shanks RMQ. Blowing epithelial cell bubbles with GumB: ShlA-family pore-forming toxins induce blebbing and rapid cellular death in corneal epithelial cells. PLoS Pathog 2019; 15:e1007825. [PMID: 31220184 PMCID: PMC6586354 DOI: 10.1371/journal.ppat.1007825] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 05/07/2019] [Indexed: 12/18/2022] Open
Abstract
Medical devices, such as contact lenses, bring bacteria in direct contact with human cells. Consequences of these host-pathogen interactions include the alteration of mammalian cell surface architecture and induction of cellular death that renders tissues more susceptible to infection. Gram-negative bacteria known to induce cellular blebbing by mammalian cells, Pseudomonas and Vibrio species, do so through a type III secretion system-dependent mechanism. This study demonstrates that a subset of bacteria from the Enterobacteriaceae bacterial family induce cellular death and membrane blebs in a variety of cell types via a type V secretion-system dependent mechanism. Here, we report that ShlA-family cytolysins from Proteus mirabilis and Serratia marcescens were required to induce membrane blebbling and cell death. Blebbing and cellular death were blocked by an antioxidant and RIP-1 and MLKL inhibitors, implicating necroptosis in the observed phenotypes. Additional genetic studies determined that an IgaA family stress-response protein, GumB, was necessary to induce blebs. Data supported a model where GumB and shlBA are in a regulatory circuit through the Rcs stress response phosphorelay system required for bleb formation and pathogenesis in an invertebrate model of infection and proliferation in a phagocytic cell line. This study introduces GumB as a regulator of S. marcescens host-pathogen interactions and demonstrates a common type V secretion system-dependent mechanism by which bacteria elicit surface morphological changes on mammalian cells. This type V secretion-system mechanism likely contributes bacterial damage to the corneal epithelial layer, and enables access to deeper parts of the tissue that are more susceptible to infection.
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Affiliation(s)
- Kimberly M. Brothers
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Jake D. Callaghan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Nicholas A. Stella
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Julianna M. Bachinsky
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Mohammed AlHigaylan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Kara L. Lehner
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
| | - Jonathan M. Franks
- Center for Biological Imaging, University of Pittsburgh, Pittsburgh, PA United States of America
| | - Kira L. Lathrop
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
| | - Elliot Collins
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Deanna M. Schmitt
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Joseph Horzempa
- Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, WV United States of America
| | - Robert M. Q. Shanks
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA United States of America
- Charles T. Campbell Laboratory of Ophthalmic Microbiology
- * E-mail:
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21
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Astley R, Miller FC, Mursalin MH, Coburn PS, Callegan MC. An Eye on Staphylococcus aureus Toxins: Roles in Ocular Damage and Inflammation. Toxins (Basel) 2019; 11:E356. [PMID: 31248125 PMCID: PMC6628431 DOI: 10.3390/toxins11060356] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/13/2019] [Accepted: 06/15/2019] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is a common pathogen of the eye, capable of infecting external tissues such as the tear duct, conjunctiva, and the cornea, as well the inner and more delicate anterior and posterior chambers. S. aureus produces numerous toxins and enzymes capable of causing profound damage to tissues and organs, as well as modulating the immune response to these infections. Unfortunately, in the context of ocular infections, this can mean blindness for the patient. The role of α-toxin in corneal infection (keratitis) and infection of the interior of the eye (endophthalmitis) has been well established by comparing virulence in animal models and α-toxin-deficient isogenic mutants with their wild-type parental strains. The importance of other toxins, such as β-toxin, γ-toxin, and Panton-Valentine leukocidin (PVL), have been analyzed to a lesser degree and their roles in eye infections are less clear. Other toxins such as the phenol-soluble modulins have yet to be examined in any animal models for their contributions to virulence in eye infections. This review discusses the state of current knowledge of the roles of S. aureus toxins in eye infections and the controversies existing as a result of the use of different infection models. The strengths and limitations of these ocular infection models are discussed, as well as the need for physiological relevance in the study of staphylococcal toxins in these models.
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Affiliation(s)
- Roger Astley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Frederick C Miller
- Department of Cell Biology and Department of Family and Preventive Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Md Huzzatul Mursalin
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Phillip S Coburn
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Michelle C Callegan
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
- Dean McGee Eye Institute, 608 Stanton L. Young Blvd., DMEI PA-418, Oklahoma City, OK 73104, USA.
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22
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Mancini S, Oechslin F, Menzi C, Que YA, Claes J, Heying R, Veloso TR, Vanassche T, Missiakas D, Schneewind O, Moreillon P, Entenza JM. Marginal role of von Willebrand factor-binding protein and coagulase in the initiation of endocarditis in rats with catheter-induced aortic vegetations. Virulence 2019; 9:1615-1624. [PMID: 30280967 PMCID: PMC7000203 DOI: 10.1080/21505594.2018.1528845] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus is the leading cause of infective endocarditis (IE). While the role of S. aureus cell-wall associated protein clumping factor A (ClfA) in promoting IE has been already demonstrated, that of the secreted plasma-clotting factors staphylocoagulase (Coa) and von Willebrand factor-binding protein (vWbp) has not yet been elucidated. We investigated the role of Coa and vWbp in IE initiation in rats with catheter-induced aortic vegetations, using Lactococcus lactis expressing coa, vWbp, clfA or vWbp/clfA, and S. aureus Newman Δcoa, ΔvWbp, ΔclfA or Δcoa/ΔvWbp/ΔclfA mutants. vWbp-expression increased L. lactis valve infection compared to parent and coa-expressing strains (incidence: 62%, versus 0% and 13%, respectively; P < 0.01). Likewise, expression of clfA increased L. lactis infectivity (incidence: 80%), which was not further affected by co-expression of vWbp. In symmetry, deletion of the coa or vWbp genes in S. aureus did not decrease infectivity (incidence: 68 and 64%, respectively) whereas deletion of clfA did decrease valve infection (incidence: 45%; P = 0.03 versus parent), which was not further affected by the triple deletion Δcoa/ΔvWbp/ΔclfA (incidence: 36%; P > 0.05 versus ΔclfA mutant). Coa does not support the initial colonization of IE (in L. lactis) without other key virulence factors and vWbp contributes to initiation of IE (in L. lactis) but is marginal in the present of ClfA.
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Affiliation(s)
- Stefano Mancini
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
| | - Frank Oechslin
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
| | - Carmen Menzi
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
| | - Yok Ai Que
- b Department of Intensive Care Medicine , Bern University Hospital , Bern , Switzerland
| | - Jorien Claes
- c Cardiovascular Developmental Biology, Department of Cardiovascular Sciences , KU Leuven , Leuven , Belgium.,d Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences , KU Leuven , Leuven , Belgium
| | - Ruth Heying
- c Cardiovascular Developmental Biology, Department of Cardiovascular Sciences , KU Leuven , Leuven , Belgium
| | - Tiago Rafael Veloso
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
| | - Thomas Vanassche
- d Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences , KU Leuven , Leuven , Belgium
| | | | - Olaf Schneewind
- e Department of Microbiology , University of Chicago , Chicago , IL , USA
| | - Philippe Moreillon
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
| | - José Manuel Entenza
- a Department of Fundamental Microbiology , University of Lausanne , Lausanne , Switzerland
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Tam K, Torres VJ. Staphylococcus aureus Secreted Toxins and Extracellular Enzymes. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0039-2018. [PMID: 30873936 PMCID: PMC6422052 DOI: 10.1128/microbiolspec.gpp3-0039-2018] [Citation(s) in RCA: 192] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus is a formidable pathogen capable of causing infections in different sites of the body in a variety of vertebrate animals, including humans and livestock. A major contribution to the success of S. aureus as a pathogen is the plethora of virulence factors that manipulate the host's innate and adaptive immune responses. Many of these immune modulating virulence factors are secreted toxins, cofactors for activating host zymogens, and exoenzymes. Secreted toxins such as pore-forming toxins and superantigens are highly inflammatory and can cause leukocyte cell death by cytolysis and clonal deletion, respectively. Coagulases and staphylokinases are cofactors that hijack the host's coagulation system. Exoenzymes, including nucleases and proteases, cleave and inactivate various immune defense and surveillance molecules, such as complement factors, antimicrobial peptides, and surface receptors that are important for leukocyte chemotaxis. Additionally, some of these secreted toxins and exoenzymes can cause disruption of endothelial and epithelial barriers through cell lysis and cleavage of junction proteins. A unique feature when examining the repertoire of S. aureus secreted virulence factors is the apparent functional redundancy exhibited by the majority of the toxins and exoenzymes. However, closer examination of each virulence factor revealed that each has unique properties that have important functional consequences. This chapter provides a brief overview of our current understanding of the major secreted virulence factors critical for S. aureus pathogenesis.
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Affiliation(s)
- Kayan Tam
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, New York, NY 10016
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24
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Minasyan H, Flachsbart F. Blood coagulation: a powerful bactericidal mechanism of human innate immunity. Int Rev Immunol 2019; 38:3-17. [DOI: 10.1080/08830185.2018.1533009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Hayk Minasyan
- Private laboratory, Immunology Microbiology, Yerevan, Armenia
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25
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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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The Role of Platelets in Antimicrobial Host Defense. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00029-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Jin Y, Li M, Shang Y, Liu L, Shen X, Lv Z, Hao Z, Duan J, Wu Y, Chen C, Pan J, Yu F. Sub-Inhibitory Concentrations of Mupirocin Strongly Inhibit Alpha-Toxin Production in High-Level Mupirocin-Resistant MRSA by Down-Regulating agr, saeRS, and sarA. Front Microbiol 2018; 9:993. [PMID: 29867891 PMCID: PMC5962727 DOI: 10.3389/fmicb.2018.00993] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 04/27/2018] [Indexed: 11/13/2022] Open
Abstract
Mupirocin, a topical antibiotic, has been utilized for decades to treat Staphylococcus aureus skin infections, as well as to decolonize patients at risk of methicillin-resistant S. aureus (MRSA) infection. The aims of this study were to investigate the expression of α-toxin (encoded by the hla gene) in ten clinical MRSA strains (MIC = 1024 μg/ml) in response to a sub-inhibitory concentration of mupirocin (1/32 minimum inhibitory concentration [MIC]) (32 μg/ml) by using α-toxin activity determination and enzyme-linked immune sorbent assay (ELISA). Subsequently, real-time polymerase chain reaction (RT-PCR) was used to examine the expression of saeR, agrA, RNAIII, and sarA genes under sub-inhibitory concentration of mupirocin in order to investigate the mechanism of action of this treatment regarding its strong inhibition of α-toxin expression. For all the strains tested, mupirocin dramatically reduced mRNA levels of α-toxin. The results indicated that α-toxin activity in mupirocin-treated groups was significantly lower than that in untreated groups. The results show that the levels of agrA, RNAIII, saeR, and sarA expression significantly decrease by 11.82- to 2.23-fold (P < 0.01). Moreover, we speculate that mupirocin-induced inhibition of α-toxin expression may be related to the inhibition of regulatory loci, such as agr, sarA and saeRS. More specifically, we found that the mechanism involves inhibiting the expression of agrA and RNAIII. In conclusion, sub-inhibitory concentrations of mupirocin strongly inhibit alpha-toxin production in high-level mupirocin-resistant MRSA by down-regulating agr, saeRS and sarA, which could potentially be developed as a supplemental treatment to control high-level mupirocin-resistant MRSA infection and reduce the risk of infection and colonization.
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Affiliation(s)
- Ye Jin
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Meilan Li
- Emergency Intensive Care Unit, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yongpeng Shang
- Key Laboratory of Medicine Molecular Virology, Ministry of Education and Ministry of Public Health, Shanghai Medical College, Fudan University, Shanghai, China
| | - Li Liu
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiaofei Shen
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhihui Lv
- Key Laboratory of Medicine Molecular Virology, Ministry of Education and Ministry of Public Health, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhihao Hao
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jingjing Duan
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yang Wu
- Key Laboratory of Medicine Molecular Virology, Ministry of Education and Ministry of Public Health, Shanghai Medical College, Fudan University, Shanghai, China
| | - Chun Chen
- Department of Respiratory Medicine, Zhejiang Provincial People's Hospital, Hangzhou Medical College, Hangzhou, China
| | - Jingye Pan
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Fangyou Yu
- Department of Laboratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
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Prevalence of IgG and Neutralizing Antibodies against Staphylococcus aureus Alpha-Toxin in Healthy Human Subjects and Diverse Patient Populations. Infect Immun 2018; 86:IAI.00671-17. [PMID: 29263109 DOI: 10.1128/iai.00671-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/17/2017] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus causes an array of serious infections resulting in high morbidity and mortality worldwide. This study evaluated naturally occurring serum anti-alpha-toxin (anti-AT) antibody levels in human subjects from various age groups, individuals with S. aureus dialysis and surgical-site infections, and S. aureus-colonized versus noncolonized subjects. Anti-AT immunoglobulin G (IgG) and neutralizing antibody (NAb) levels in infants (aged ≤1 year) were significantly lower than those in other populations. In comparison to adolescent, adult, and elderly populations, young children (aged 2 to 10 years) had equivalent anti-AT IgG levels but significantly lower anti-AT NAb levels. Therefore, the development of anti-AT NAbs appears to occur later than that of AT-specific IgG, suggesting a maturation of the immune response to AT. Anti-AT IgG levels were slightly higher in S. aureus-colonized subjects than in noncolonized subjects. The methicillin susceptibility status of colonizing isolates had no effect on anti-AT antibody levels in S. aureus-colonized subjects. The highest anti-AT IgG and NAb levels were observed in dialysis patients with acute S. aureus infection. Anti-AT IgG and NAb levels were well correlated in subjects aged >10 years, regardless of colonization or infection status. These data demonstrate that AT elicits a robust IgG humoral response in infants and young children that becomes stable prior to adolescence, matures into higher levels of NAbs in healthy adolescents, and becomes elevated during S. aureus infection. These findings may assist in identifying subjects and patient populations that could benefit from vaccination or immunoprophylaxis with anti-AT monoclonal antibodies.
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Ruzin A, Wu Y, Yu L, Yu XQ, Tabor DE, Mok H, Tkaczyk C, Jensen K, Bellamy T, Roskos L, Esser MT, Jafri HS. Characterisation of anti-alpha toxin antibody levels and colonisation status after administration of an investigational human monoclonal antibody, MEDI4893, against Staphylococcus aureus alpha toxin. Clin Transl Immunology 2018; 7:e1009. [PMID: 29484186 PMCID: PMC5822409 DOI: 10.1002/cti2.1009] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/20/2017] [Accepted: 12/29/2017] [Indexed: 01/07/2023] Open
Abstract
Objectives MEDI4893 is a novel, long‐acting human monoclonal antibody targeting Staphylococcus aureus (SA) alpha toxin (AT). This report presents the results of the exploratory analyses from a randomised phase 1 dose‐escalation study in healthy human subjects receiving single intravenous MEDI4893 doses or placebo. Methods Anti‐AT antibodies and AT expression were measured as described previously. Nasal swabs were analysed by culture and PCR. Data were summarised by treatment groups and visits by using SAS System Version 9.3. Results Subjects receiving 2250 or 5000 mg of MEDI4893 had the highest serum anti‐AT neutralising antibody (NAb) levels: approximately 180‐ to 240‐, 70‐ to 100‐ and sevenfold to 10‐fold higher than respective baseline levels at peak, 30 and 360 days, respectively. In these subjects, levels of serum anti‐AT NAbs were >3.2 International Units (IU) mL−1 for at least 211 days. In the upper respiratory tract, anti‐AT NAb levels increased with MEDI4893 dose. No apparent effect of MEDI4893 on SA nasal colonisation, hla gene sequence or AT expression was observed. Five AT variants were detected, their lytic activity was fully neutralised by MEDI4893. Discussion Our results indicate that (1) MEDI4893 administration at 2250 and 5000 mg would provide effective immunoprophylaxis against systemic SA disease; (2) MEDI4983 distributes to the upper respiratory tract and retains neutralising activity against AT; and (3) potential for emergence of MEDI4893 resistance is low. Conclusion Intravenous administration of MEDI4893 maintained levels of anti‐AT NAbs in serum and nasal mucosa that may provide effective immunoprophylaxis against SA disease and support continued clinical development of MEDI4893.
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Affiliation(s)
| | | | - Li Yu
- MedImmune Gaithersburg MD USA
| | - Xiang-Qing Yu
- MedImmune Gaithersburg MD USA.,Present address: Janssen Pharmaceuticals, Inc. Johnson & Johnson Spring House PA USA
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30
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Moser C, Pedersen HT, Lerche CJ, Kolpen M, Line L, Thomsen K, Høiby N, Jensen PØ. Biofilms and host response - helpful or harmful. APMIS 2017; 125:320-338. [PMID: 28407429 DOI: 10.1111/apm.12674] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 01/14/2017] [Indexed: 01/09/2023]
Abstract
Biofilm infections are one of the modern medical world's greatest challenges. Probably, all non-obligate intracellular bacteria and fungi can establish biofilms. In addition, there are numerous biofilm-related infections, both foreign body-related and non-foreign body-related. Although biofilm infections can present in numerous ways, one common feature is involvement of the host response with significant impact on the course. A special characteristic is the synergy of the innate and the acquired immune responses for the induced pathology. Here, we review the impact of the host response for the course of biofilm infections, with special focus on cystic fibrosis, chronic wounds and infective endocarditis.
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Affiliation(s)
- Claus Moser
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Hannah Trøstrup Pedersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Christian Johann Lerche
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Mette Kolpen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Costerton Biofilm Center, Institute of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Laura Line
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Kim Thomsen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Costerton Biofilm Center, Institute of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Peter Østrup Jensen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Costerton Biofilm Center, Institute of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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31
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Le VTM, Le HN, Pinheiro MG, Hahn KJ, Dinh ML, Larson KB, Flanagan SD, Badiou C, Lina G, Tkaczyk C, Sellman BR, Diep BA. Effects of Tedizolid Phosphate on Survival Outcomes and Suppression of Production of Staphylococcal Toxins in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia. Antimicrob Agents Chemother 2017; 61:e02734-16. [PMID: 28137816 PMCID: PMC5365717 DOI: 10.1128/aac.02734-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 01/24/2017] [Indexed: 01/30/2023] Open
Abstract
The protective efficacy of tedizolid phosphate, a novel oxazolidinone that potently inhibits bacterial protein synthesis, was compared to those of linezolid, vancomycin, and saline in a rabbit model of Staphylococcus aureus necrotizing pneumonia. Tedizolid phosphate was administered to rabbits at 6 mg/kg of body weight intravenously twice daily, which yielded values of the 24-h area under the concentration-time curve approximating those found in humans. The overall survival rate was 83% for rabbits treated with 6 mg/kg tedizolid phosphate twice daily and 83% for those treated with 50 mg/kg linezolid thrice daily (P = 0.66 by the log-rank test versus the results obtained with tedizolid phosphate). These survival rates were significantly greater than the survival rates of 17% for rabbits treated with 30 mg/kg vancomycin twice daily (P = 0.003) and 17% for rabbits treated with saline (P = 0.002). The bacterial count in the lungs of rabbits treated with tedizolid phosphate was significantly decreased compared to that in the lungs of rabbits treated with saline, although it was not significantly different from that in the lungs of rabbits treated with vancomycin or linezolid. The in vivo bacterial production of alpha-toxin and Panton-Valentine leukocidin, two key S. aureus-secreted toxins that play critical roles in the pathogenesis of necrotizing pneumonia, in the lungs of rabbits treated with tedizolid phosphate and linezolid was significantly inhibited compared to that in the lungs of rabbits treated with vancomycin or saline. Taken together, these results indicate that tedizolid phosphate is superior to vancomycin for the treatment of S. aureus necrotizing pneumonia because it inhibits the bacterial production of lung-damaging toxins at the site of infection.
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Affiliation(s)
- Vien T M Le
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
| | - Hoan N Le
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
| | - Marcos Gabriel Pinheiro
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
| | - Kenneth J Hahn
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
| | - Mary L Dinh
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
| | | | | | - Cedric Badiou
- INSERM U1111, Université Lyon 1, CNRS UMR5308, ENS Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Bron, France
| | - Gerard Lina
- INSERM U1111, Université Lyon 1, CNRS UMR5308, ENS Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Bron, France
| | - Christine Tkaczyk
- Department of Infectious Diseases, MedImmune, Gaithersburg, Maryland, USA
| | - Bret R Sellman
- Department of Infectious Diseases, MedImmune, Gaithersburg, Maryland, USA
| | - Binh An Diep
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco, California, USA
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Abstract
Infective endocarditis (IE) is a rare, life-threatening disease that has long-lasting effects even among patients who survive and are cured. IE disproportionately affects those with underlying structural heart disease and is increasingly associated with health care contact, particularly in patients who have intravascular prosthetic material. In the setting of bacteraemia with a pathogenic organism, an infected vegetation may form as the end result of complex interactions between invading microorganisms and the host immune system. Once established, IE can involve almost any organ system in the body. The diagnosis of IE may be difficult to establish and a strategy that combines clinical, microbiological and echocardiography results has been codified in the modified Duke criteria. In cases of blood culture-negative IE, the diagnosis may be especially challenging, and novel microbiological and imaging techniques have been developed to establish its presence. Once diagnosed, IE is best managed by a multidisciplinary team with expertise in infectious diseases, cardiology and cardiac surgery. Antibiotic prophylaxis for the prevention of IE remains controversial. Efforts to develop a vaccine that targets common bacterial causes of IE are ongoing, but have not yet yielded a commercially available product.
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Affiliation(s)
- Thomas L Holland
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Room 185 Hanes Building, 315 Trent Drive, Durham, North Carolina 27710, USA
- Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Larry M Baddour
- Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Arnold S Bayer
- Department of Medicine, David Geffen School of Medicine at UCLA, Torrance, California, USA
| | - Bruno Hoen
- Department of Infectious Diseases, University Hospital of Pointe-Pitre, Pointe-Pitre, France
| | - Jose M Miro
- Infectious Diseases Service, Hospital Clinic - IDIBAPS, University of Barcelona, Barcelona, Spain
| | - Vance G Fowler
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Room 185 Hanes Building, 315 Trent Drive, Durham, North Carolina 27710, USA
- Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina, USA
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Kathirvel M, Buchad H, Nair M. Enhancement of the pathogenicity of Staphylococcus aureus strain Newman by a small noncoding RNA SprX1. Med Microbiol Immunol 2016; 205:563-574. [PMID: 27438010 DOI: 10.1007/s00430-016-0467-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 07/12/2016] [Indexed: 01/22/2023]
Abstract
The pathogenesis of Staphylococcus aureus from local infection to systemic dissemination involves a range of virulence factors including structural and secreted products. Among various control mechanisms, small noncoding RNAs are involved in the regulation of multiple pathogenicity factors in S. aureus. The sRNA SprX which is encoded in the pathogenicity island of methicillin-susceptible S. aureus strain Newman and was shown to influence antibiotic resistance previously, upregulated the expression of virulence genes, especially the cell wall-associated clumping factor B (ClfB) and delta hemolysin (Hld). Bioinformatic analysis revealed several multiple mRNAs associated with pathogenicity as targets for SprX1, one of the three copies of sprX. Both overexpression and chromosomal disruption of sprX1 supported the scheme of upregulation of clfB and hld expression. Altered expression of SprX1 altered the levels of Hld and ClfB mRNAs, hemolysis, clumping of cells, biofilm formation by plate adhesion studies and confocal microscopic analysis as well as infection pathology of modified strains in mice models. ClfB and Hld mRNAs interacted directly with SprX1 in in vitro assays. Increased level of the regulatory RNA, namely RNAIII, that comprises Hld mRNA and also regulates the biofilm formation, indicates that SprX1 may also function through RNAIII for regulating virulence factors. An immunodominant protein, antigen A, was downregulated by SprX1 in two-dimensional electrophoresis. Taken together, these results signify the role of sRNA SprX in the pathogenicity of S. aureus Newman.
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Affiliation(s)
- Manikandan Kathirvel
- Department of Microbiology and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India
| | - Hasmatbanu Buchad
- Department of Microbiology and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India
| | - Mrinalini Nair
- Department of Microbiology and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India.
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Powers ME, Becker REN, Sailer A, Turner JR, Bubeck Wardenburg J. Synergistic Action of Staphylococcus aureus α-Toxin on Platelets and Myeloid Lineage Cells Contributes to Lethal Sepsis. Cell Host Microbe 2016; 17:775-87. [PMID: 26067604 DOI: 10.1016/j.chom.2015.05.011] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 04/15/2015] [Accepted: 05/22/2015] [Indexed: 02/06/2023]
Abstract
Multi-organ failure contributes to mortality in bacterial sepsis. Platelet and immune cell activation contribute to organ injury during sepsis, but the mechanisms by which bacterial virulence factors initiate these responses remain poorly defined. We demonstrate that during lethal sepsis, Staphylococcus aureus α-toxin simultaneously alters platelet activation and promotes neutrophil inflammatory signaling through interactions with its cellular receptor ADAM10. Platelet intoxication prevents endothelial barrier repair and facilitates formation of injurious platelet-neutrophil aggregates, contributing to lung and liver injury that is mitigated by ADAM10 deletion on platelets and myeloid lineage cells. While platelet- or myeloid-specific ADAM10 knockout does not alter sepsis mortality, double-knockout animals are highly protected. These results define a pathway by which a single bacterial toxin utilizes a widely expressed receptor to coordinate progressive, multi-organ disease in lethal sepsis. As an expression-enhancing ADAM10 polymorphism confers susceptibility to severe human sepsis, these studies highlight the importance of understanding molecular host-microbe interactions.
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Affiliation(s)
- Michael E Powers
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | - Russell E N Becker
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | - Anne Sailer
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Jerrold R Turner
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Juliane Bubeck Wardenburg
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA; Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA.
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35
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Diosmetin inhibits the expression of alpha-hemolysin in Staphylococcus aureus. Antonie van Leeuwenhoek 2015; 108:383-9. [DOI: 10.1007/s10482-015-0491-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/21/2015] [Indexed: 11/26/2022]
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Differential expression and roles of Staphylococcus aureus virulence determinants during colonization and disease. mBio 2015; 6:e02272-14. [PMID: 25691592 PMCID: PMC4337569 DOI: 10.1128/mbio.02272-14] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Staphylococcus aureus is a Gram-positive, commensal bacterium known to asymptomatically colonize the human skin, nares, and gastrointestinal tract. Colonized individuals are at increased risk for developing S. aureus infections, which range from mild skin and soft tissue infections to more severe diseases, such as endocarditis, bacteremia, sepsis, and osteomyelitis. Different virulence factors are required for S. aureus to infect different body sites. In this study, virulence gene expression was analyzed in two S. aureus isolates during nasal colonization, bacteremia and in the heart during sepsis. These models were chosen to represent the stepwise progression of S. aureus from an asymptomatic colonizer to an invasive pathogen. Expression of 23 putative S. aureus virulence determinants, representing protein and carbohydrate adhesins, secreted toxins, and proteins involved in metal cation acquisition and immune evasion were analyzed. Consistent upregulation of sdrC, fnbA, fhuD, sstD, and hla was observed in the shift between colonization and invasive pathogen, suggesting a prominent role for these genes in staphylococcal pathogenesis. Finally, gene expression data were correlated to the roles of the genes in pathogenesis by using knockout mutants in the animal models. These results provide insights into how S. aureus modifies virulence gene expression between commensal and invasive pathogens. Many bacteria, such as Staphylococcus aureus, asymptomatically colonize human skin and nasal passages but can also cause invasive diseases, such as bacteremia, pneumonia, sepsis, and osteomyelitis. The goal of this study was to analyze differences in the expression of selected S. aureus genes during a commensal lifestyle and as an invasive pathogen to gain insight into the commensal-to-pathogen transition and how a bacterial pathogen adapts to different environments within a host (e.g., from nasal colonization to invasive pathogen). The gene expression data were also used to select genes for which to construct knockout mutants to assess the role of several proteins in nasal colonization and lethal bacteremia. These results not only provide insight into the factors involved in S. aureus disease pathogenesis but also provide potential therapeutic targets.
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37
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Hanses F, Roux C, Dunman PM, Salzberger B, Lee JC. Staphylococcus aureus gene expression in a rat model of infective endocarditis. Genome Med 2014; 6:93. [PMID: 25392717 PMCID: PMC4228149 DOI: 10.1186/s13073-014-0093-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/20/2014] [Indexed: 01/04/2023] Open
Abstract
Background Diabetes mellitus is a frequent underlying comorbidity in patients with Staphylococcus aureus endocarditis, and it represents a risk factor for complications and a negative outcome. The pathogenesis of staphylococcal endocardial infections in diabetic hosts has been poorly characterized, and little is known about S. aureus gene expression in endocardial vegetations. Methods We utilized a rat model of experimental S. aureus endocarditis to compare the pathogenesis of staphylococcal infection in diabetic and nondiabetic hosts and to study the global S. aureus transcriptome in endocardial vegetations in vivo. Results Diabetic rats had higher levels of bacteremia and larger endocardial vegetations than nondiabetic control animals. Microarray analyses revealed that 61 S. aureus genes were upregulated in diabetic rats, and the majority of these bacterial genes were involved in amino acid and carbohydrate metabolism. When bacterial gene expression in vivo (diabetic or nondiabetic endocardial vegetations) was compared to in vitro growth conditions, higher in vivo expression of genes encoding toxins and proteases was observed. Additionally, genes involved in the production of adhesins, capsular polysaccharide, and siderophores, as well as in amino acid and carbohydrate transport and metabolism, were upregulated in endocardial vegetations. To test the contribution of selected upregulated genes to the pathogenesis of staphylococcal endocarditis, isogenic deletion mutants were utilized. A mutant defective in production of the siderophore staphyloferrin B was attenuated in the endocarditis model, whereas the virulence of a surface adhesin (ΔsdrCDE) mutant was similar to that of the parental S. aureus strain. Conclusions Our results emphasize the relevance of diabetes mellitus as a risk factor for infectious endocarditis and provide a basis for understanding gene expression during staphylococcal infections in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s13073-014-0093-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Frank Hanses
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA ; Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Christelle Roux
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642 USA
| | - Bernd Salzberger
- Department of Internal Medicine I, University Hospital Regensburg, Franz-Josef-Strauss Allee 11, Regensburg, 93049 Germany
| | - Jean C Lee
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115 USA
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Mohan K, Sainath Rao S, Gao Y, Atreya C. Enhanced antimicrobial activity of peptide-cocktails against common bacterial contaminants of ex vivo stored platelets. Clin Microbiol Infect 2014; 20:O39-46. [DOI: 10.1111/1469-0691.12326] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 06/05/2013] [Accepted: 07/01/2013] [Indexed: 11/30/2022]
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Abstract
Staphylococcus aureus secretes a number of host-injurious toxins, among the most prominent of which is the small β-barrel pore-forming toxin α-hemolysin. Initially named based on its properties as a red blood cell lytic toxin, early studies suggested a far greater complexity of α-hemolysin action as nucleated cells also exhibited distinct responses to intoxication. The hemolysin, most aptly referred to as α-toxin based on its broad range of cellular specificity, has long been recognized as an important cause of injury in the context of both skin necrosis and lethal infection. The recent identification of ADAM10 as a cellular receptor for α-toxin has provided keen insight on the biology of toxin action during disease pathogenesis, demonstrating the molecular mechanisms by which the toxin causes tissue barrier disruption at host interfaces lined by epithelial or endothelial cells. This review highlights both the historical studies that laid the groundwork for nearly a century of research on α-toxin and key findings on the structural and functional biology of the toxin, in addition to discussing emerging observations that have significantly expanded our understanding of this toxin in S. aureus disease. The identification of ADAM10 as a proteinaceous receptor for the toxin not only provides a greater appreciation of truths uncovered by many historic studies, but now affords the opportunity to more extensively probe and understand the role of α-toxin in modulation of the complex interaction of S. aureus with its human host.
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Affiliation(s)
- Bryan J. Berube
- Department of Microbiology, The University of Chicago, 920 E. 58th Street Chicago, IL 60637, USA; E-Mail:
| | - Juliane Bubeck Wardenburg
- Department of Microbiology, The University of Chicago, 920 E. 58th Street Chicago, IL 60637, USA; E-Mail:
- Department of Pediatrics, The University of Chicago, 5721 S. Maryland Ave. Chicago, IL 60637, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-773-834-9763; Fax: +1-773-834-8150
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Assessment of an anti-alpha-toxin monoclonal antibody for prevention and treatment of Staphylococcus aureus-induced pneumonia. Antimicrob Agents Chemother 2013; 58:1108-17. [PMID: 24295977 DOI: 10.1128/aac.02190-13] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Alpha-toxin (AT) is a major virulence factor in the disease pathogenesis of Staphylococcus aureus. We previously identified a monoclonal antibody (MAb) against AT that reduced disease severity in a mouse dermonecrosis model. Here, we evaluate the activity of an affinity-optimized variant, LC10, in a mouse model of S. aureus pneumonia. Passive immunization with LC10 increased survival and reduced bacterial numbers in the lungs and kidneys of infected mice and showed protection against diverse S. aureus clinical isolates. The lungs of S. aureus-infected mice exhibited bacterial pneumonia, including widespread inflammation, whereas the lungs of mice that received LC10 exhibited minimal inflammation and retained healthy architecture. Consistent with reduced immune cell infiltration, LC10-treated animals had significantly lower (P < 0.05) proinflammatory cytokine and chemokine levels in the bronchoalveolar lavage fluid than did those of the control animals. This reduction in inflammation and damage to the LC10-treated animals resulted in reduced vascular protein leakage and CO2 levels in the blood. LC10 was also assessed for its therapeutic activity in combination with vancomycin or linezolid. Treatment with a combination of LC10 and vancomycin or linezolid resulted in a significant increase (P < 0.05) in survival relative to the monotherapies and was deemed additive to synergistic by isobologram analysis. Consistent with improved survival, the lungs of animals treated with antibiotic plus LC10 exhibited less inflammatory tissue damage than those that received monotherapy. These data provide insight into the mechanisms of protection provided by AT inhibition and support AT as a promising target for immunoprophylaxis or adjunctive therapy against S. aureus pneumonia.
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41
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Speth C, Löffler J, Krappmann S, Lass-Flörl C, Rambach G. Platelets as immune cells in infectious diseases. Future Microbiol 2013; 8:1431-51. [DOI: 10.2217/fmb.13.104] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Platelets have been shown to cover a broad range of functions. Besides their role in hemostasis, they have immunological functions and thus participate in the interaction between pathogens and host defense. Platelets have a broad repertoire of receptor molecules that enable them to sense invading pathogens and infection-induced inflammation. Consequently, platelets exert antimicrobial effector mechanisms, but also initiate an intense crosstalk with other arms of the innate and adaptive immunity, including neutrophils, monocytes/macrophages, dendritic cells, B cells and T cells. There is a fragile balance between beneficial antimicrobial effects and detrimental reactions that contribute to the pathogenesis, and many pathogens have developed mechanisms to influence these two outcomes. This review aims to highlight aspects of the interaction strategies between platelets and pathogenic bacteria, viruses, fungi and parasites, in addition to the subsequent networking between platelets and other immune cells, and the relevance of these processes for the pathogenesis of infections.
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Affiliation(s)
- Cornelia Speth
- Division of Hygiene & Medical Microbiology, Innsbruck Medical University Fritz-Pregl-Straße 3, A-6020 Innsbruck, Austria
| | - Jürgen Löffler
- Laboratory of Innate Immunity, Infection, Inflammation, University Hospital Würzburg, Würzburg, Germany
| | - Sven Krappmann
- Microbiology Institute – Clinical Microbiology, Immunology & Hygiene, University Hospital of Erlangen & Friedrich-Alexander-University Erlangen-Nürnberg, Germany
| | - Cornelia Lass-Flörl
- Division of Hygiene & Medical Microbiology, Innsbruck Medical University Fritz-Pregl-Straße 3, A-6020 Innsbruck, Austria
| | - Günter Rambach
- Division of Hygiene & Medical Microbiology, Innsbruck Medical University Fritz-Pregl-Straße 3, A-6020 Innsbruck, Austria
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Abstract
Infective endocarditis (IE) is an uncommon infection, occurring as a complication in varying percentages of bacteremic episodes. The ability of an organism to cause endocarditis is the result of an interplay between the predisposing structural abnormalities of the cardiac valve for bacterial adherence, the adhesion of circulating bacteria to the valvular surface, and the ability of the adherent bacteria to survive on the surface and propagate as vegetation or systemic emboli. Certain bacteria, if present in the bloodstream, may colonize the initially sterile vegetation composed of fibrin and platelets; bacterial growth enlarges the vegetation, further impeding blood flow and inciting inflammation that involves the vegetation and adjacent endothelium. The true incidence of endocarditis complicating each of the bacterial species causing IE is difficult to estimate. About 20 %-30 % of individuals with community-acquired staphylococcal bacteremia develop IE [1, 2].
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Yang J, Liang X, Ji Y. The mutated staphylococcal H35A α-toxin inhibits adhesion and invasion of Staphylococcus aureus and group A streptococci. Virulence 2013; 4:77-81. [PMID: 23314570 DOI: 10.4161/viru.22719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In previous studies we demonstrated that the staphylococcal α-toxin inhibits adhesion and invasion of S. aureus by epithelial cells through binding to α5β1 integrin, a receptor of fibronectin. Moreover, we revealed that a H35A mutation abolishes the cytotoxicity of α-toxin completely. These findings led us to hypothesize that the H35A mutated α-toxin may be explored as a potential inhibitor for bacterial adhesion and invasion of epithelial cells. In this study, we examined the impact of the H35A α-toxin on staphylococcal capacity of adhering to and invading into epithelial cells and found that the addition of H35A α-toxin in the culture medium dramatically inhibited S. aureus' ability to adhere to and internalize into epithelial cells. Importantly, we demonstrated that both the staphylococcal α-toxin and H35A mutated α-toxin are capable of retarding the adhesion and invasion of epithelial cells by Streptococcus pyogenes. These findings suggest that the H35A toxoid has the potential to be utilized as an inhibitor of S. aureus and S. pyogenes ability to adhere to and invade epithelial cells.
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Affiliation(s)
- Junshu Yang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
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Parimon T, Li Z, Bolz DD, McIndoo ER, Bayer CR, Stevens DL, Bryant AE. Staphylococcus aureus α-hemolysin promotes platelet-neutrophil aggregate formation. J Infect Dis 2013; 208:761-70. [PMID: 23698812 DOI: 10.1093/infdis/jit235] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) causes severe hemorrhagic necrotizing pneumonia associated with high mortality. Exotoxins have been implicated in the pathogenesis of this infection; however, the cellular mechanisms responsible remain largely undefined. Because platelet-neutrophil aggregates (PNAs) can dysregulate inflammatory responses and contribute to tissue destruction, we investigated whether exotoxins from MRSA could stimulate formation of PNAs in human whole blood. Strong PNA formation was stimulated by toxins from stationary phase but not log phase CA-MRSA, and α-hemolysin was singularly identified as the mediator of this activity. MRSA exotoxins also caused neutrophil (polymorphonuclear leukocyte) activation, as measured by increased CD11b expression, although platelet binding was not driven by this mechanism; rather, α-hemolysin-induced PNA formation was solely platelet P-selectin dependent. These findings suggest a role for S. aureus α-hemolysin-induced PNA formation in alveolar capillary destruction in hemorrhagic/necrotizing pneumonia caused by CA-MRSA and offer novel targets for intervention.
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Affiliation(s)
- Tanyalak Parimon
- Research and Development Service, Infectious Diseases Section, Veterans Affairs Medical Center, Boise, Idaho 83702, USA. (
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Oganesyan V, Barnes A, Tkaczyk C, Ferguson A, Wu H, Dall'Acqua WF. Crystallization and preliminary X-ray diffraction analysis of the complex between a human anti-alpha toxin antibody fragment and alpha toxin. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:302-5. [PMID: 23519809 PMCID: PMC3606579 DOI: 10.1107/s1744309113002881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/28/2013] [Indexed: 12/18/2022]
Abstract
Staphylococcus aureus alpha toxin (AT) has been crystallized in complex with the Fab fragment of a human antibody (MEDI4893). This constitutes the first reported crystals of AT bound to an antibody. The monoclinic crystals belonged to space group P2₁, with unit-cell parameters a=85.52, b=148.50, c=93.82 Å, β=99.82°. The diffraction of the crystals extended to 2.56 Å resolution. The asymmetric unit contained two MEDI4893 Fab-AT complexes. This corresponds to a crystal volume per protein weight (VM) of 2.3 Å3 Da(-1) and a solvent content of 47%. The three-dimensional structure of this complex will contribute to an understanding of the molecular basis of the interaction of MEDI4893 with AT. It will also shed light on the mechanism of action of this antibody, the current evaluation of which in the field of S. aureus-mediated diseases makes it a particularly interesting case study. Finally, this study will provide the three-dimensional structure of AT in a monomeric state for the first time.
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Affiliation(s)
- Vaheh Oganesyan
- Department of Antibody Discovery and Protein Engineering, MedImmune, One MedImmune Way, Gaithersburg, MD 20878, USA
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46
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Genetic elimination of the binding motif on fibrinogen for the S. aureus virulence factor ClfA improves host survival in septicemia. Blood 2013; 121:1783-94. [PMID: 23299312 DOI: 10.1182/blood-2012-09-453894] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Fibrinogen can support host antimicrobial containment/clearance mechanisms, yet selected pathogens appear to benefit from host procoagulants to drive bacterial virulence. Here, we explored the hypothesis that host fibrin(ogen), on balance, supports Staphylococcus aureus infection in the context of septicemia. Survival studies following intravenous infection in control and fibrinogen-deficient mice established the overall utility of host fibrin(ogen) to S. aureus virulence. Complementary studies in mice expressing mutant forms of fibrinogen-retaining clotting function, but lacking either the bacterial ClfA (Fibγ(Δ5)) binding motif or the host leukocyte integrin receptor αMβ2 (Fibγ(390-396A)) binding motif, revealed the preeminent importance of the bacterial ClfA-fibrin(ogen) interaction in determining host survival. Studies of mice lacking platelets or the platelet integrin receptor subunit αIIb established that the survival benefits observed in Fibγ(Δ5) mice were largely independent of platelet αIIbβ3-mediated engagement of fibrinogen. Fibγ(Δ5) mice exhibited reduced bacterial burdens in the hearts and kidneys, a blunted host proinflammatory cytokine response, diminished microscopic tissue damage, and significantly diminished plasma markers of cardiac and other organ damage. These findings indicate that host fibrin(ogen) and bacterial ClfA are dual determinants of virulence and that therapeutic interventions at the level of fibrinogen could be advantageous in S. aureus septicemia.
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47
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Multicenter evaluation of the clinical outcomes of daptomycin with and without concomitant β-lactams in patients with Staphylococcus aureus bacteremia and mild to moderate renal impairment. Antimicrob Agents Chemother 2012; 57:1192-200. [PMID: 23254428 DOI: 10.1128/aac.02192-12] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Patients with underlying renal disease may be vulnerable to vancomycin-mediated nephrotoxicity and Staphylococcus aureus bacteremia treatment failure. In light of recent data demonstrating the successful use of β-lactam plus daptomycin in very difficult cases of S. aureus bacteremia, we examined safety and clinical outcomes for patients who received daptomycin with or without concomitant β-lactams. We identified 106 patients who received daptomycin for S. aureus bacteremia, had mild or moderate renal insufficiency according to FDA criteria, and enrolled in the Cubicin Outcomes Registry and Experience (CORE), a multicenter registry, from 2005 to 2009. Daptomycin treatment success was 81%. Overall treatment efficacy was slightly enhanced with the addition of a β-lactam (87% versus 78%; P = 0.336), but this trend was most pronounced for bacteremia associated with endocarditis or bone/joint infection or bacteremia from an unknown source (90% versus 57%; P = 0.061). Factors associated with reduced daptomycin efficacy (by logistic regression) were an unknown source of bacteremia (odds ratio [OR] = 7.59; 95% confidence interval [CI] = 1.55 to 37.2), moderate renal impairment (OR = 9.11; 95% CI = 1.46 to 56.8), and prior vancomycin failure (OR = 11.2; 95% CI = 1.95 to 64.5). Two patients experienced an increase in creatine phosphokinase (CPK) that resolved after stopping daptomycin. No patients developed worsening renal insufficiency related to daptomycin. In conclusion, daptomycin appeared to be effective and well tolerated in patients with S. aureus bacteremia and mild to moderate renal insufficiency. Daptomycin treatment efficacy might be enhanced with β-lactam combination therapy in primary endovascular and bone/joint infections. Additional studies will be necessary to confirm these findings.
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48
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Spaulding AR, Lin YC, Merriman JA, Brosnahan AJ, Peterson ML, Schlievert PM. Immunity to Staphylococcus aureus secreted proteins protects rabbits from serious illnesses. Vaccine 2012; 30:5099-109. [PMID: 22691432 DOI: 10.1016/j.vaccine.2012.05.067] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 10/28/2022]
Abstract
Staphylococcus aureus causes significant illnesses throughout the world, including toxic shock syndrome (TSS), pneumonia, and infective endocarditis. Major contributors to S. aureus illnesses are secreted virulence factors it produces, including superantigens and cytolysins. This study investigates the use of superantigens and cytolysins as staphylococcal vaccine candidates. Importantly, 20% of humans and 50% of rabbits in our TSS model cannot generate antibody responses to native superantigens. We generated three TSST-1 mutants; G31S/S32P, H135A, and Q136A. All rabbits administered these TSST-1 toxoids generated strong antibody responses (titers>10,000) that neutralized native TSST-1 in TSS models, both in vitro and in vivo. These TSST-1 mutants lacked detectable residual toxicity. Additionally, the TSST-1 mutants exhibited intrinsic adjuvant activity, increasing antibody responses to a second staphylococcal antigen (β-toxin). This effect may be due to TSST-1 mutants binding to the immune co-stimulatory molecule CD40. The superantigens TSST-1 and SEC and the cytolysin α-toxin are known to contribute to staphylococcal pneumonia. Immunization of rabbits against these secreted toxins provided complete protection from highly lethal challenge with a USA200 S. aureus strain producing all three exotoxins; USA200 strains are common causes of staphylococcal infections. The same three exotoxins plus the cytolysins β-toxin and γ-toxin contribute to infective endocarditis and sepsis caused by USA200 strains. Immunization against these five exotoxins protected rabbits from infective endocarditis and lethal sepsis. These data suggest that immunization against toxoid proteins of S. aureus exotoxins protects from serious illnesses, and concurrently superantigen toxoid mutants provide endogenous adjuvant activity.
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Affiliation(s)
- Adam R Spaulding
- Department of Microbiology, Medical School, University of Minnesota, Minneapolis, MN 55455, USA.
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49
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Eisen DP. Manifold beneficial effects of acetyl salicylic acid and nonsteroidal anti-inflammatory drugs on sepsis. Intensive Care Med 2012; 38:1249-57. [DOI: 10.1007/s00134-012-2570-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 03/19/2012] [Indexed: 12/31/2022]
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50
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Thurlow LR, Joshi GS, Richardson AR. Virulence strategies of the dominant USA300 lineage of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). ACTA ACUST UNITED AC 2012; 65:5-22. [PMID: 22309135 DOI: 10.1111/j.1574-695x.2012.00937.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 01/19/2012] [Accepted: 01/26/2012] [Indexed: 11/28/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious threat to worldwide health. Historically, MRSA clones have strictly been associated with hospital settings, and most hospital-associated MRSA (HA-MRSA) disease resulted from a limited number of virulent clones. Recently, MRSA has spread into the community causing disease in otherwise healthy people with no discernible contact with healthcare environments. These community-associated MRSA clones (CA-MRSA) are phylogenetically distinct from traditional HA-MRSA clones, and CA-MRSA strains seem to exhibit hypervirulence and more efficient host : host transmission. Consequently, CA-MRSA clones belonging to the USA300 lineage have become dominant sources of MRSA infections in North America. The rise of this successful USA300 lineage represents an important step in the evolution of emerging pathogens and a great deal of effort has been exerted to understand how these clones evolved. Here, we review much of the recent literature aimed at illuminating the source of USA300 success and broadly categorize these findings into three main categories: newly acquired virulence genes, altered expression of common virulence determinants and alterations in protein sequence that increase fitness. We argue that none of these evolutionary events alone account for the success of USA300, but rather their combination may be responsible for the rise and spread of CA-MRSA.
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Affiliation(s)
- Lance R Thurlow
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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