Epidemiology and impact of colonization by multidrug-resistant Gram-negative bacteria on bloodstream infections in early phase of allogeneic hematopoietic stem cell transplantation

Objective. To study epidemiology and impact of colonization by multidrug-resistant Gram-negative bacteria (MDRGNB) on bloodstream infections (BSI) during allogeneic hematopoietic stem cell transplantation (allo-HSCT). Materials and Methods. The retrospective study included 288 patients received the first allo-HSCT between 2018 and 2019. The median age was 32 (18–66) years, male – 53% (n = 152). The majority of patients had acute leukemia – 62% (n = 178) and received transplant from matched unrelated – 42% (n = 120) or haploidentical donor – 26% (n = 75). Relapse of underlying disease at the moment of all-HSCT was registered in 23% (n = 66) of patients. Results. Colonization of non-sterile sites before allo-HSCT by at least one MDRGNB was detected in 28% (n = 64). In most cases resistance is due to extended spectrum beta-lactamases (ESBL) – 86% (n = 55), while carbapenemases in combination with ESBL were detected in 14% (n = 9) of patients. After allo-HSCT the colonization was significantly higher than before transplantation (n = 161, 56%, p = 0.001), mainly due to carbapenemase- and ESBL-producing bacteria – 73% (n = 118) (p = 0.001). BSI in the early period after transplantation developed in 26% (n = 76), and in 56% (n = 43) was caused by MDRGNB. The etiology of BSI included K. pneumoniae – 51% in mostly cases. The etiology of BSI was the same bacteria that colonized non-sterile sites 2 weeks before the detection bacteria in bloodstream in 69% (n = 30) patients. Colonization by MDRGNB was associated with the development of BSI (p < 0.0001). The 100-day overall survival (OS) after all-HSCT was significantly lower in patients with colonization of non-sterile sites by MDRGNB compared with patients without colonization (60.6% vs 88.2%, p = 0.001). Conclusions. Colonization of MDRGNB after allo-HSCT reached 56%. K. pneumoniae was predominant etiology in both colonization and bloodstream infections. Colonization by MDRGNB was associated with the development of BSI and decreased OS after allo-HSCT

First measurement of the Sivers asymmetry for gluons using SIDIS data

The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. For quarks, it was studied in previous measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it was found to be non-zero. In this letter the evaluation of the Sivers asymmetry for gluons is presented. The contribution of the photon-gluon fusion subprocess is enhanced by requiring two high transverse-momentum hadrons. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon-gluon fusion, QCD Compton scattering and the leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/c muon beam scattered off transversely polarised deuterons and protons. With a significance of about two standard deviations, a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero. (C) 2017 The Author(s). Published by Elsevier B.V