Effect of colchicine on physiological and biochemical properties of Rhodococcus qingshengii

The genus Rhodococcus includes polymorphic non-spore-forming gram-positive bacteria belonging to the class Actinobacteria. Together with Mycobacterium and Corynebacterium, Rhodococcus belongs to the Mycolata group. Due to their relatively high growth rate and ability to form biof ilms, Rhodococcus are a convenient model for studying the effect of biologically active compounds on pathogenic Mycolata. Colchicine was previously found to reduce biof ilm formation by P. carotovorum VKM B-1247 and R. qingshengii VKM Ac-2784D. To understand the mechanism of action of this alkaloid on the bacterial cell, we have studied the change in the fatty acid composition and microviscosity of the R. qingshengii VKM Ac-2784D membrane. Nystatin, which is known to reduce membrane microviscosity, is used as a positive control. It has been found that colchicine at concentrations of 0.01 and 0.03 g/l and nystatin (0.03 g/l) have no signif icant effect on the survival of R. qingshengii VKM Ac-2784D cultivated in a buffered saline solution with 0.5 % glucose (GBSS). However, colchicine (0.03 g/l) signif icantly inhibits biof ilm formation. Rhodococcus cells cultivated for 24 hours in GBSS with colchicine acquire a rounded shape. Colchicine at 0.01 g/l concentration increases C16:1(n-7), C17:0, C20:1(n-9) and C21:0 fatty acids. The microviscosity of the membrane of individual cells was distributed from the lowest to the highest values of the generalized laurdan f luorescence polarization index (GP), which indicates a variety of adaptive responses to this alkaloid. At a higher concentration of colchicine (0.03 g/l) in the membranes of R. qingshengii VKM Ac-2784D cells, the content of saturated fatty acids increases and the content of branched fatty acids decreases. This contributes to an increase in membrane microviscosity, which is conf irmed by the data on the GP f luorescence of laurdan. All of the above indicates that colchicine induces a rearrangement of the Rhodococcus cell membrane, probably in the direction of increasing its microviscosity. This may be one of the reasons for the negative effect of colchicine on the formation of R. qingshengii VKM Ac-2784D biof ilms.

Necrotizing enterocolitis in newborns with congenital heart defects: incidence and risk factors

Necrotizing enterocolitis (NEC) is a serious complication in newborns with critical congenital heart disease (CHD), prolonging hospital stay, worsening neurological prognosis, and increasing mortality. The leading role in the pathogenesis of NEC in these infants is the violation of mesenteric perfusion. A decrease in arterial blood oxygenation may be an additional risk factor for intestinal hypoxia. Objective. To assess the incidence and risk factors for NEC in full-term newborns with CHD born in 2019–2021 at the Perinatal Center of Almazov National Research Medical Center. Patients and methods. The article presents an analysis of the frequency and risk factors of NEC in children with CHD born at the Almazov National Medical Research Centre in 2019–2021. In the group of critical and duct-dependent CHD (n = 264), the overall incidence of NEC was 15.9% (42 cases). The frequency of surgical stages of NEC (IIIA) was 1.1% (3 cases). In the preoperative period, there was a trend towards a higher frequency of inotropic therapy in a subgroup of children who subsequently developed NEC. NEC in newborns with duct-dependent CHD developed mainly in the early postoperative period after cardiac surgery. In children with duct-dependent pulmonary blood flow, a higher incidence of NEC after surgery was noted compared to children with duct-dependent systemic blood flow. Conclusion. Risk factors for NEC in the postoperative period were arterial hypotension and hemodynamically significant cardiac arrhythmias. Dysbiosis of the gut microbiota and changes in microbial metabolism may be additional risk factors for NEC in children with CHD. Key words: necrotizing enterocolitis, risk factors, congenital heart disease, cardiopulmonary bypass, intestinal microbiome, metabolomics