Sensitivity of <i>Streptococcus</i> <i>viridans</i> to antibacterial agents in HIV-positive patients coupled to respiratory diseases

The streptococcus group consists of multiple species of globular Gram-positive facultative anaerobic bacteria, the classification of which is based on assessing their capacity to erythrocyte hemolysis. The viridans group streptococci produce a green coloration being a part of normal microflora in the oral cavity. However, in case of developing immunodeficiency states, oncology, and neutropenia, this pathogen can cause diseases such as bacteremia, sepsis, endocarditis, as well as pneumonia in some cases. Respiratory diseases commonly require medical assistance in HIV-infected patient cohort. The role of commensal S. viridans in development of bacterial diseases in HIV-infected patients remains poorly examined. A potential association between S. viridans and other bacterial communities, including pathogenic microorganisms is obscure. In addition, it might be worth evaluating sensitivity of S. viridans to antibacterial agents in regions with high HIV infection incidence. The aim of the study was to evaluate sensitivity to antibiotics in sputum viridans group streptococci collected from HIV-infected patients with symptomatic pneumonia. Materials and methods. The data on sputum microbiological study conducted within the 01.01.2012—01.01.2019 interval were collected from all HIV-infected patients with suspected pneumonia (n = 684) and analyzed at the Infectious Clinical Hospital No. 1 named after D.M. Dalmatov, among which S. viridans was detected in 193 patients (28.2%). Bacteriological examination of patient samples was conducted to isolate pure bacterial culture by using standard methods. Next, S. viridans was assessed for sensitivity to antibacterial agents (n = 78) according to the 2018 clinical recommendations. Initially, antibiotic resistance was assessed by disk-diffusion method as a routine approach broadly used in clinical laboratory. After that, the minimal inhibitory concentration was measured by using AutoScan 4 Microscan analyzer (bacteriological semi-automatic analyzer, Beckman Coulter, USA) to identify and determine antibacterial sensitivity. Results. A disk-diffusion method allowed to find in sputum samples streptococci resistant to penicillin in 28.2% cases, ampicillin — in 42.3% and cefazolin — in 43.6%. While assessing the minimal inhibitory concentration for antibacterial agents, similar data were obtained. Good sensitivity was found for cefotaxime, ceftriaxone, cefepime, fluoroquinolones and vancomycin

Ледовые водоросли в условиях современного состояния водно-ледовой среды Арктического бассейна

 In the Arctic Ocean (AO) of today, there are noticeable changes in the composition and structure of biological communities inhabiting the water-ice environment. Over the past two decades, a decrease in the number of species of the sea ice flora and fauna has been noted in the central regions of the AO due to the changing physical environment of their habitat. In view of the current climatic instability in the AO, it is important to monitor and evaluate their composition, structure and dynamics of development. It is also important to preserve the methods of processing the materials collected in order to compare the state of the water-ice biota on similar spatial and temporal scales of the basin. In the present study, centric and pennate diatoms dominating in ice floristic communities were selected as indicators of changes. The aim of the work is to analyze the physical state of the water-ice environment and the species composition of ice diatoms based on the materials of the expeditions within the NABOS program at the Research Vessel (R/V) “Akademik Treshnikov” in the Arctic Basin in 2018 and 2021. The field work included observations of the state of the sea-ice cover in the area of the expeditions, the selection of ice cores to assess the salt composition and species composition of the algae, as well as CTD-sounding of the under ice — water layer. The analysis of the materials collected showed significant differences in the species composition and abundance of algae between the seasons, which indicates the formation of independent floristic communities in the current conditions of unstable physical environment in the central regions of the AO, which confirms the previously obtained results in the period 2007–2015. The materials under discussion were obtained in a short period of time and in limited spaces in the zones of production of annual ice in the waters of the shelf seas and zones of removal to the central regions of the AO. At the same time, short-term observations provide “instant” information about the qualitative and quantitative state of sea-ice biological communities. In order to obtain reliable estimates, long-term observations are needed, which may be organized in the near future based on new logistical approaches to the study of the marine Arctic. В современном Северном Ледовитом океане (СЛО) наблюдаются заметные изменения в составе и структуре биологических сообществ, населяющих водно-ледовую среду. За последние два десятилетия в центральных районах СЛО отмечено снижение численности видового состава ледовой флоры и фауны на фоне изменяющейся физической среды их обитания. В условиях современной климатической нестабильности в СЛО важно отслеживать и оценивать их состав, структуру и динамику развития. Важно также сохранять методы обработки собранных материалов для сравнения состояния водно-ледовой биоты в сходных пространственно-временных масштабах бассейна. В настоящем исследовании в качестве индикаторов изменений выбраны центрические и пеннатные диатомовые водоросли, доминирующие в ледовых флористических сообществах. Целью настоящей работы является анализ физического состояния водно-ледовой среды и видового состава ледовых диатомовых водорослей по материалам экспедиций в рамках программы NABOS на НЭС «Академик Трёшников» в Арктическом бассейне в 2018 и 2021 гг. В задачу полевых работ входили наблюдения за состоянием ледяного покрова в районе проведения экспедиций, отбор ледяных кернов на предмет оценки солевого состава и видового состава водорослей, а также СТD-зондирование подледного водного слоя. Анализ собранных материалов показал значительные различия в видовом составе и обилии водорослей между сезонами, что свидетельствует о формировании независимых друг от друга флористических сообществ в современных условиях нестабильной физической среды в центральных районах СЛО, что подтверждает ранее полученные результаты в период 2007–2015 гг. Обсуждаемые материалы получены в короткий период времени и на ограниченных пространствах в зонах продуцирования однолетних льдов на акваториях шельфовых морей и зонах выноса в центральные районы СЛО. Вместе с тем краткосрочные наблюдения дают «мгновенную» информацию о качественном и количественном состоянии ледовых биологических сообществ. Для получения достоверной оценки необходимы длительные наблюдения, которые, возможно, будут организованы в ближайшее время на новых логистических подходах в изучении морской Арктики