Comprehensive analysis of voltage balancing techniques for 5L NPC converters

The reduced capability of the 5L-NPC Inverter to balance the voltages of the four DC-bus capacitors makes this converter unattractive for real power applications. This is especially true if the load demands active power. The Back-to-Back (B2B) configuration of two 5L-NPC converters and the use of a Space Vector Modulation (SVM) that exploits the voltage balancing capabilities of the redundant switching vectors, extend the operating conditions range in which a proper voltage balance can be achieved. However, if practical modulation restrictions are considered (limitation of voltage steps, dead times, switching losses, etc.) the voltage balance cannot be achieved for all operation conditions. This paper introduces the main restrictions that should be considered for the 5L-NPC modulation strategy. The voltage balancing limits of the proposed SVM scheme are shown and additional considerations to improve the voltage balancing capability are proposed and evaluated

Implant Removal in the Management of Prosthetic Joint Infection by Staphylococcus aureus: Outcome and Predictors of Failure in a Large Retrospective Multicenter Study

Objectives: To compare the characteristics and outcomes of cases with acute prosthetic joint infection (PJI; early post-surgical or hematogenous) by Staphylococcus aureus managed with implant removal (IRm) or debridement and retention (DAIR). To analyze the outcomes of all cases managed with IRm (initially or after DAIR failure). Methods: Retrospective, multicenter, cohort study of PJI by S. aureus (2003–2010). Overall failure included mortality within 60 days since surgery and local failure due to staphylococcal persistence/relapse. Results: 499 cases, 338 initially managed with DAIR, 161 with IRm. Mortality was higher in acute PJI managed initially with IRm compared to DAIR, but not associated with the surgical procedure, after propensity score matching. Underlying conditions, hemiarthroplasty, and methicillin-resistant S. aureus were risk factors for mortality. Finally, 249 cases underwent IRm (88 after DAIR failure); overall failure was 15.6%. Local failure (9.3%) was slightly higher in cases with several comorbidities, but independent of previous DAIR, type of IRm, and rifampin treatment. Conclusions: In a large multicenter study of S. aureus PJI managed with IRm, failure was low, but mortality significant, especially in cases with acute PJI and underlying conditions, but not associated with the IRm itself. Rifampin efficacy was limited in this setting.Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y CompetitividadMinisterio Educación Españ

Resumen ejecutivo de tratamiento de las infecciones de prótesis articulares. Guia clínica práctica de la Sociedad Española de Enfermedades Infecciosas y Microbiologia Clínica

[EN] The incidence of prosthetic joint infection (PJI) is expected to increase in the coming years. PJI has serious consequences for patients, and high costs for the health system. The complexity of these infections makes it necessary to organize the vast quantity of information published in the last several years. The indications for the choice of a given surgical strategy and the corresponding antimicrobial therapy are specifically reviewed. The authors selected clinically relevant questions and then reviewed the available literature in order to give recommendations according to a pre-determined level of scientific evidence. The more controversial aspects were debated, and the final composition was agreed at an ad hoc meeting. Before its final publication, the manuscript was made available online in order that all SEIMC members were able to read it and make comments and suggestions.[ES] Se prevé un incremento de la incidencia de infección de las prótesis articulares (IPA) en los próximos años. Las IPA plantean graves consecuencias para los pacientes y un alto coste el sistema sanitario. La complejidad de estas infecciones hace que sea necesario organizar la inmensa cantidad de información publicada en los últimos años. En estas guías se revisan específicamente las indicaciones para la elección de una estrategia quirúrgica dada y el tratamiento antimicrobiano correspondiente. Los autores seleccionaron las preguntas clínicamente relevantes y revisaron la literatura disponible con el fin de proporcionar recomendaciones de acuerdo con un grado de evidencia científica predeterminada. Los aspectos más controvertidos fueron debatidos y la redacción final se acordó en una reunión ad hoc. Antes de su publicación, el manuscrito estuvo abierto a comentarios y sugerencias de los miembros de la Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica.Peer reviewe

The Different Microbial Etiology of Prosthetic Joint Infections According to Route of Acquisition and Time After Prosthesis Implantation, Including the Role of Multidrug-Resistant Organisms

The aim of our study was to characterize the etiology of prosthetic joint infections (PJIs)-including multidrug-resistant organisms (MDRO)-by category of infection. A multicenter study of 2544 patients with PJIs was performed. We analyzed the causative microorganisms according to the Tsukayama's scheme (early postoperative, late chronic, and acute hematogenous infections (EPI, LCI, AHI) and "positive intraoperative cultures" (PIC)). Non-hematogenous PJIs were also evaluated according to time since surgery: 12 months. AHIs were mostly caused by Staphylococcus aureus (39.2%) and streptococci (30.2%). EPIs were characterized by a preponderance of virulent microorganisms (S. aureus, Gram-negative bacilli (GNB), enterococci), MDROs (24%) and polymicrobial infections (27.4%). Conversely, coagulase-negative staphylococci (CoNS) and Cutibacterium species were predominant in LCIs (54.5% and 6.1%, respectively) and PICs (57.1% and 15.1%). The percentage of MDROs isolated in EPIs was more than three times the percentage isolated in LCIs (7.8%) and more than twice the proportion found in AHI (10.9%). There was a significant decreasing linear trend over the four time intervals post-surgery for virulent microorganisms, MDROs, and polymicrobial infections, and a rising trend for CoNS, streptococci and Cutibacterium spp. The observed differences have important implications for the empirical antimicrobial treatment of PJIs.Acknowledgments: This work was supported by the Instituto de Salud Carlos III, Spanish Ministry of Economy and Competitiveness (grant number PI15/1026) (Co-funded by European Regional Development Fund/European Social Fund "Investing in your future"). REIPI (Spanish Network for Research in Infectious Disease) is supported by the Instituto de Salud Carlos III, Spanish Ministry of Economy and Competitiveness, and by the European Development Regional Fund “A way to achieve Europe”

Implant Removal in the Management of Prosthetic Joint Infection by Staphylococcus aureus: Outcome and Predictors of Failure in a Large Retrospective Multicenter Study

Staphylococcus aureus; Implant removal; Prosthetic joint infectionStaphylococcus aureus; Extracción de implantes; Infección de la articulación protésicaStaphylococcus aureus; Eliminació d’implants; Infecció de l'articulació protèsicaObjectives: To compare the characteristics and outcomes of cases with acute prosthetic joint infection (PJI; early post-surgical or hematogenous) by Staphylococcus aureus managed with implant removal (IRm) or debridement and retention (DAIR). To analyze the outcomes of all cases managed with IRm (initially or after DAIR failure). Methods: Retrospective, multicenter, cohort study of PJI by S. aureus (2003–2010). Overall failure included mortality within 60 days since surgery and local failure due to staphylococcal persistence/relapse. Results: 499 cases, 338 initially managed with DAIR, 161 with IRm. Mortality was higher in acute PJI managed initially with IRm compared to DAIR, but not associated with the surgical procedure, after propensity score matching. Underlying conditions, hemiarthroplasty, and methicillin-resistant S. aureus were risk factors for mortality. Finally, 249 cases underwent IRm (88 after DAIR failure); overall failure was 15.6%. Local failure (9.3%) was slightly higher in cases with several comorbidities, but independent of previous DAIR, type of IRm, and rifampin treatment. Conclusions: In a large multicenter study of S. aureus PJI managed with IRm, failure was low, but mortality significant, especially in cases with acute PJI and underlying conditions, but not associated with the IRm itself. Rifampin efficacy was limited in this setting.This study was supported by Plan Nacional I+D+I 2013–2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/0005), co-financed by the European Development Regional Fund “A way to achieve Europe”, Operative program Intelligent Growth 2004–2020. J. G-J was supported by a grant from the Spanish Ministry of Education (FPU 14/03124)

A case of septic arthritis caused by Capnocytophaga canimorsus in an HIV patient

Invasive infections caused by Capnocytophaga canimorsus , a Gram-negative rod found in the oral cavity of healthy dogs and cats, are rare but they are increasing worldwide. We report a case of septic arthritis in a native knee joint due to this micro-organism. A 57-year-old man, with a well-controlled chronic HIV infection, attended the Emergency Department because of left knee pain and shivering without measured fever. A knee arthrocentesis and a computed tomography scan were performed, revealing septic arthritis with collections in the left leg posterior musculature. He was admitted to the Infectious Diseases Department for antibiotic treatment. Initial synovial fluid was inoculated in blood culture bottles, and the anaerobic one was positive after 63 h. Gram stain revealed fusiform Gram-negative rods, identified as C. canimorsus by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) directly from the bottle. Identification was confirmed by 16S rRNA sequencing and serotyping was performed by PCR, with serovar A as the outcome. Due to an unfavourable clinical course, the patient required two surgical cleanings and after appropriate antibiotic treatment he was discharged 2 months later