Particle Acceleration in Pulsar Wind Nebulae: PIC modelling

We discuss the role of particle-in-cell (PIC) simulations in unveiling the origin of the emitting particles in PWNe. After describing the basics of the PIC technique, we summarize its implications for the quiescent and the flaring emission of the Crab Nebula, as a prototype of PWNe. A consensus seems to be emerging that, in addition to the standard scenario of particle acceleration via the Fermi process at the termination shock of the pulsar wind, magnetic reconnection in the wind, at the termination shock and in the Nebula plays a major role in powering the multi-wavelength signatures of PWNe.Comment: 32 pages, 16 figures, to appear in the book "Modelling Nebulae" edited by D. Torres for Springer, based on the invited contributions to the workshop held in Sant Cugat (Barcelona), June 14-17, 201

Etiology of severe community-acquired pneumonia in adults: Results of the first Russian multicenter study [Этиология тяжелой внебольничной пневмонии у взрослых: результаты первого российского многоцентрового исследования]

Aim: to study the etiology of severe community-acquired pneumonia (SCAP) in adults in Russian Federation. SCAP is distinguished by high mortality and socio-economic burden. Both etiology and antimicrobial resistance are essential for appropriate antibiotic choice. Materials and methods. A prospective cohort study recruited adults with confirmed diagnosis of SCAP admitted to multi-word hospitals of six Russian cities in 2014-2018. Etiology was confirmed by routine culture of blood, respiratory (sputum, endotracheal aspirate or bronchoalveolar lavage) and when appropriate, autopsy samples, urinary antigen tests (L. pneumophila serogroup 1, S. pneumoniae); real-time PCR for identification of “atypical” bacterial pathogens (M. pneumoniae, C. pneumoniae, L. pneumophila) and respiratory viruses (influenza viruses A and B, parainfluenza, human metapneumovirus, etc.) was applied. Results. Altogether 109 patients (60.6% male; mean age 50.8±18.0 years old) with SCAP were enrolled. Etiological agent was identified in 65.1% of patients, S. pneumoniae, rhinovirus, S. aureus and K. pneumoniae were the most commonly isolated pathogens (found in 43.7, 15.5, 14.1 and 11.3% of patients with positive results of microbiological investigations, respectively). Bacteriemia was seen in 14.6% of patients and most commonly associated with S. pneumoniae. Co-infection with 2 or more causative agents was revealed in 36.6% of cases. Combination of bacterial pathogens (mainly S. pneumoniae with S. aureus or/and Enterobacterales) prevailed - 57.7% of cases; associations of bacteria and viruses were identified in 38.5% of patients, different viruses - in one case. Conclusion. S. pneumoniae was the most common pathogen in adults with SCAP. A high rate of respiratory viruses (mainly rhinovirus and influenza viruses) identification both as mixt infection with bacteria and mono-infection should be taken into account. © 2020 Consilium Medikum. All rights reserved

Этиология тяжелой внебольничной пневмонии у взрослых: результаты первого российского многоцентрового исследования

Aim: to study the etiology of severe community - acquired pneumonia (SCAP) in adults in Russian Federation. SCAP is distinguished by high mortality and socio - economic burden. Both etiology and antimicrobial resistance are essential for appropriate antibiotic choice. Materials and methods. A prospective cohort study recruited adults with confirmed diagnosis of SCAP admitted to multi - word hospitals of six Russian cities in 2014-2018. Etiology was confirmed by routine culture of blood, respiratory (sputum, endotracheal aspirate or bronchoalveolar lavage) and when appropriate, autopsy samples, urinary antigen tests (L. pneumophila serogroup 1, S. pneumoniae); real - time PCR for identification of “atypical” bacterial pathogens (M. pneumoniae, C. pneumoniae, L. pneumophila) and respiratory viruses (influenza viruses A and B, parainfluenza, human metapneumovirus, etc.) was applied. Results. Altogether 109 patients (60.6% male; mean age 50.8±18.0 years old) with SCAP were enrolled. Etiological agent was identified in 65.1% of patients, S. pneumoniae, rhinovirus, S. aureus and K. pneumoniae were the most commonly isolated pathogens (found in 43.7, 15.5, 14.1 and 11.3% of patients with positive results of microbiological investigations, respectively). Bacteriemia was seen in 14.6% of patients and most commonly associated with S. pneumoniae. Co - infection with 2 or more causative agents was revealed in 36.6% of cases. Combination of bacterial pathogens (mainly S. pneumoniae with S. aureus or/and Enterobacterales) prevailed - 57.7% of cases; associations of bacteria and viruses were identified in 38.5% of patients, different viruses - in one case. Conclusion. S. pneumoniae was the most common pathogen in adults with SCAP. A high rate of respiratory viruses (mainly rhinovirus and influenza viruses) identification both as mixt infection with bacteria and mono - infection should be taken into account.Цель - изучить структуру возбудителей тяжелой внебольничной пневмонии (ТВП) у взрослых больных в Российской Федерации (РФ). ТВП относится к заболеваниям с высокой летальностью и отличается значимым социально - экономическим бременем для общества. Адекватная эмпирическая антибактериальная терапия должна основываться на знании спектра ключевых возбудителей и их чувствительности к антимикробным препаратам. Материалы и методы. В проспективное исследование, выполнявшееся в многопрофильных стационарах 6 городов РФ в 2014-2018 гг., включались взрослые пациенты с подтвержденным диагнозом ТВП. Для верификации этиологии культуральным методом исследовались кровь, респираторные образцы (мокрота, эндотрахеальный аспират, бронхоальвеолярный лаваж), аутопсийные образцы у умерших пациентов; использовались экспресс - тесты для выявления антигенурии (L. pneumophila cерогруппа 1 и S. pneumoniae). «Aтипичные» бактериальные патогены (M. pneumoniae, C. pneumoniae, L. pneumophila) и респираторные вирусы (вирусы гриппа А и В, парагриппа, риновирус, метапневмовирус человека и др.) выявлялись методом полимеразной цепной реакции в режиме реального времени с помощью коммерческих тестов. Результаты. Всего в исследование включено 109 пациентов (мужчин - 60,6%, средний возраст 50,8±18,0 лет) с ТВП. Этиологически значимые возбудители ТВП обнаружены в 65,1% случаев; наиболее часто выявлялись S. pneumoniae, риновирусы, S. aureus и K. pneumoniae (43,7, 15,5, 14,1 и 11,3% пациентов c положительными результатами микробиологического исследования соответственно). Бактериемия выявлена в 14,6% случаев, S. pneumoniae являлся наиболее часто идентифицируемым патогеном. Два и более возбудителя ТВП выявлены в 36,6% случаев. Среди комбинаций превалировало сочетание бактериальных возбудителей (чаще всего S. pneumoniae с S. aureus или/и Enterobacterales) - 57,7%; ассоциации бактериальных возбудителей и вирусов выявлены у 38,5% пациентов, в 1 случае выявлена ко - инфекция двумя респираторными вирусами. Заключение. В структуре этиологии ТВП у госпитализированных взрослых больных преобладал S. pneumoniae. Следует отметить высокую частоту выявления респираторных вирусов (преимущественно риновирус и вирусы гриппа) как в ассоциации с бактериальными возбудителями, так и в монокультуре