General characteristics and clinical significance of Nocardia and Gordonia genera

Over the last years, an increasing attention in modern medical microbiology has been paid to examining Actinomycetaceae, Corynebacteriaceae, Mycobacteriaceae, Nocardiaceae, Gordoniaceae sps. Members of the Mycobacteriaceae family are increasingly examined in research and real-life practice, whereas bacteria belonging to families such as Nocardiaceae and Gordoniaceae remain poorly investigated despite novel methods emerging in practical microbiology that allow to more accurately identify microorganisms. According to the current classification, the genus Nocardia includes over 80 species, most of which rarely result in human disease development. Most often, members of the genus Nocardia cause lesions in bronchopulmonary system, which, however, may also cause development of pathological processes in other anatomical sites. Likewise, members of the genus Gordonia may also trigger infectious lesions in human, which were previously often incorrectly identified as other actinomycetes or mycobacteria. Owing to use of 16S rRNA sequencing, it substantially improved identification of these bacteria. Currently, an increasing number of microorganisms with potential clinical significance has been recorded. In addition, similar to nocardiosis, diverse primary and secondary immunodeficiencies play a primary role in gordonii-associated development of pathological processes. However, an additional risk factor may be represented by pathological conditions associated with ingestion of foreign bodies colonized by such microorganisms. Most often, members the genus Nocardia cause lesions in the bronchopulmonary system able, however, affect other anatomical areas. Half of all cases of pulmonary nocardiosis are accompanied by pathological processes of extrapulmonary localization, whereas as low as 20% of patients manifest with extrapulmonary form of the disease usually occurring when the pathogen spreads hematogenously or via other routes also highlighted by primary pulmonary lesion. Moreover, members of the genus Gordonia may result in similar infectious lesions. Currently, the number of aerobic actinomycetes of potential clinical significance is increasing that may be due to their role in diverse pathological processes of various etiologies, which have been more often reported in scientific publications. Few reports regarding infections caused by the genus Gordonia ara available which may be due to a paucity of microorganisms isolated from clinical material or false identification as mycobacteria or Nocardia. Similar to nocardiosis, diverse immunodeficiencies play a primary role in the development of pathological processes associated with Gordonia. However, an additional risk factor may be linked to pathological conditions associated with the ingestion of foreign bodies colonized by these microorganisms. Available publications allows to underline etiological significance of Gordonia in development of cholecystitis, granulomatous skin lesions, eyelid abscess of other soft tissues, granulomatous mastitis, brain abscess and meningitis, as well as external otitis, bronchitis, endocarditis and mediastinitis. In addition, all these microorganisms can cause bacteremia associated with use of a central venous catheter. Owing to emergence of new detection methods as well as elevated rate of immunocompromised patients, and subsequently increased amount of new cases caused by members of the Nocardiaceae and Gordoniaceae families, an interest they rise will grow progressively

Динамика резистентности к антибактериальным препаратам штаммов Streptococcus pneumoniae за период 2015–2019 гг. в Самаре и возможности ее преодоления

According to the World Health Organization (WHO), diseases caused by Streptococcus pneumoniae are one of the most dangerous diseases, that can be completely prevented by vaccination. Studies conducted in various regions of the Russian Federation and other countries have revealed certain features in the prevalence of pneumococcus strains, resistant to different antibacterial drugs, which requires local studies among patients of different age groups.The aim of the study was to determine the level of sensitivity of S. pneumoniae, isolated from adult patients, to antibacterial drugs (ABD) and the dynamics of resistance to ABD in Samara for the period of 2015–2019.Methods. A retrospective analysis of data from the microbiological department of clinical diagnostic laboratories of the Clinics of Samara State Medical University, Healthcare Ministry of Russia for 2015–2019 was carried out. The microorganism resistance to several groups of ABD was studied – macrolides (erythromycin, azithromycin, clarithro mycin), cephalosporins (ceftriaxone, cefotaxime), fluoroquinolones (levofloxacin) and penicillin. The sensitivity was determined by the disk diffusion method. Statistical processing was performed using the SPSS Statistic 22.0 program. When comparing groups, the χ2 criterion was used; to compare small groups (n < 5), the exact Fisher test was used.Results. Since 2017, there has been a tendency to increase the frequency of pneumococcus isolation in the carrier group. At the same time, a 3-fold decrease in S. pneumoniae excretion from patients with ENT pathology occurred. The highest sensitivity was detected for cephalosporins – 100% sensitivity of all S. pneumoniae strains, detected from ENT organs and during carriage. There is a low level of pneumococcus resistance to levofloxacin. The general sensitivity to ABD from penicillin group is 96.4–98.8%, while the most common resistant strains were found in patients with respiratory tract damage. The highest resistance of S. pneumoniae was revealed to ABD from the macrolide group with a tendency to increase from 4.6% in 2016 to 14.0% in 2019.Conclusion. According to the study results, a rather low level of resistance of S. pneumoniae to most ABD groups, with the exception of macrolides, was demonstrated in Samara. The greatest number of ABD-insensitive pathogens was isolated in patients with pathology of the bronchopulmonary system. A mandatory microbiological examination of the sputum of such patients is necessary with a determination of the sensitivity of the isolated microorganisms to ABD and subsequent correction of therapy upon the identification of resistant strains. Given the increasing resistance of S. pneumoniae in carriers, it is necessary to vaccinate patients in this group. По данным Всемирной организации здравоохранения (ВОЗ), заболевания, вызываемые Streptococcus pneumoniae, являются одними из самых опасных, однако полностью предупреждаемых при проведении вакцинопрофилактики болезней. В исследованиях, проведенных в различных регионах Российской Федерации и других странах, выявлены определенные особенности распространенности штаммов пневмококка, резистентных к разным антибактериальным препаратам (АБП), при этом требуется проведение локальных исследований у пациентов различных возрастных групп.Целью исследования явилось определение уровня чувствительности S. pneumoniae, выделенных от взрослых пациентов, к АБП, и динамика резистентности к АБП в Самаре за 2015–2019 гг.Материалы и методы. Проведен ретроспективный анализ данных микробиологического отдела клинико-диагностической лаборатории Федерального государственного бюджетного образовательного учреждения высшего образования «Самарский государственный медицинский университет» Мини стерства здравоохранения Российской Федерации (2015–2019). Изучена устойчивость микроорганизма к нескольким группам АБП – макролидам (эритромицин, азитромицин, кларитромицин), цефалоспоринам (цефтриаксон, цефотаксим), фторхинолонам (левофлоксацин) и пенициллину. Определение чувствительности проводилось дискодиффузионным методом. Статистическая обработка проведена в программе SPSS Statistic 22.0. При сравнении групп использовался критерий χ2 , для сопоставления малых групп (n < 5) – точный критерий Фишера.Результаты. Начиная с 2017 г., отмечается тенденция к увеличению частоты выделения пневмококка в группе носителей. При этом произошло 3-кратное снижение выделения S. pneumoniae от пациентов с ЛОР-патологией. Наибольшая (100%-ная) чувствительность всех штаммов S. pneumoniae, выявленных из ЛОР-органов и при носительстве, установлена к цефалоспоринам. Отме чается низкий уровень устойчивости пневмококка к левофлоксацину. Общая чувствительность к АБП группы пенициллина составляет 96,4–98,8 %, при этом наиболее часто резистентные штаммы встречались у больных с поражением респираторного тракта. Наибольшая резистентность S. pneumoniae выявлена к АБП из группы макролидов с тенденцией к нарастанию от 4,6 (2016) до 14,0 % (2019).Заключение. По результатам исследования в Самаре продемонстрирован достаточно низкий уровень устойчивости S. pneumoniae к большинству АБП, за исключением группы макролидов. Наибольшее количество нечувствительных к АБП возбудителей выделено у больных с патологией бронхолегочной системы. У таких пациентов необходимо обязательное микробиологическое исследование мокроты с определением чувствительности выделенных микроорганизмов к АБП и последующей коррекцией терапии при выявлении устойчивых штаммов. Учитывая нарастание устойчивости S. pneumoniae у носителей, необходимо проводить вакцинацию пациентов данной группы.