Фенотипни и генотипни проучвания върху ванкомицин-резистентни ентерококи при пациенти с висок риск за колонизация и инфекция с проблемни микроорганизми   //   Phenotypic and genotypic studies on vancomycin-resistant enterococci in patients at high risk of colonization and infection with problematic microorganisms

Христова-Трифонова, Преслава Михайлова  // Hristova-Trifonova, Preslava Mihaylova

Фенотипни и генотипни проучвания върху ванкомицин-резистентни ентерококи при пациенти с висок риск за колонизация и инфекция с проблемни микроорганизми // Phenotypic and genotypic studies on vancomycin-resistant enterococci in patients at high risk of colonization and infection with problematic microorganisms

dc.contributor.author	Христова-Трифонова, Преслава Михайлова // Hristova-Trifonova, Preslava Mihaylova
dc.date.accessioned	2023-11-17T12:35:24Z
dc.date.available	2023-11-17T12:35:24Z
dc.date.issued	2022
dc.description.abstract	ЦЕЛ И ЗАДАЧИ ЦЕЛТА на настоящата дисертационна работа е да се проучат фенотипните и генотипни характеристики на клинични и интестинални ванкомицин-резистентни ентерококи (VRE) и рисковите фактори за колонизация и инфекция с тези бактерии при хоспитализирани пациенти. За реализиране на тази цел бяха поставени следните ЗАДАЧИ: 1. Да се оценят възможностите на различни видове селективни хранителни среди за първично изолиране и идентифициране на интестинални VRE. 2. Да се проучи интестиналната колонизация с VRE при групи пациенти с висок риск за колонизация и инфекция с проблемни микроорганизми. 3. Да се анализира разпространението на клинични VRE в УМБАЛ „Д-р Г. Странски“, Плевен. 4. Да се определи антимикробната чувствителност и гените, кодиращи резистентност към гликопептиди и аминогликозиди при изолираните клинични и интестинални VRE. 5. Да се проучат гените, кодиращи фактори на вирулентност, при изолираните клинични и интестинални VRE. 6. Да се извърши епидемиологично типизиране на изолираните клинични и интестинални VRE. // SUMMARY. The objectives of the current work were to study the phenotypic and genotypic characteristics of 186 non-repetitive clinical (n=117) and intestinal (n=69) vancomycin-resistant enterococci (VRE) and the risk factors for colonization and infection with these bacteria in hospitalized patients. Results: The three tested chromogenic agars for isolation and preliminary identification of intestinal VRE showed equal sensitivity (85.7%). Brilliance VRE and chromID VRE demonstrated identical specificity (98.7%), while the specificity of HiCrome VRE Modified was with minimal differences (96.7%). The sensitivity and specificity of BEAV broth were 100% and 81.6%, respectively. The frequency of intestinal colonization with VRE was the highest in patients in the Hemodialysis ward (27.8%), followed by the ICU (24.2%) and the Hematology ward (15.1%). Among the three groups of high-risk patients E. gallinarum and E. casseliflavus species (78.3%) were the dominant intestinal isolates. Risk factors, statistically significant, for intestinal colonization with VRE in patients undergoing hemodialysis were duration of hemodialysis between 13-60 months, the vascular access through an indwelling tunneled catheter and the use of vancomycin; in intensive care patients the risk factors were the need for postoperative cares, the cardiovascular diseases and the presence of an endotracheal tube; in patients with hematological malignancies the risk factors for colonization with VRE were the aged 70-79 years and the multiple myeloma. For the period 2016 – 2020 in UMHAT "Dr. G. Stranski", Pleven 3% of the enterococcal isolates were VRE with prevalence of VR E. faecium (90.4%). The VR E. faecium was circulating mainly in the intensive care units and their adjacent surgical units. Among the VR E. faecium isolates, the vanA genotype was prevalent and confirmed in 98.2% of clinical and 92.9% of intestinal isolates. A correlation between the phenotype and genotype of glycopeptide resistance was found in all E. gallinarum, E. casseliflavus, vanB E. faecium isolates and in 13 vanA E. faecium, whereas 106 E. faecium showed VanD-vanA type. The bifunctional aminoglycoside gene aac(6')-Ie-aph(2")-Ia was demonstrated in all VRE with HLGR and in 6 VR E. faecium with low-level gentamicin resistance. One or more virulence determinants were founded in all VR E. faecium and VR E. faecalis, 6 intestinal E. gallinarum and 1 VR E. durans. The predominant genes were acm and esp. 85.7% of the clinical and 76.9% of the intestinal vanA E. faecium from UMHAT "Dr. G. Stranski", as well as 77.3% of vanA E. faecium from other clinical centers belong to MT11. They all expressed similar antibiotic resistance profiles and share common virulence genes. Conclusions: The current detailed phenotypic and genotypic study of large number of clinical and intestinal VRE might be useful for prediction of the type of circulating enterococci in the UMHAT "Dr. G. Stranski", Pleven. In addition, the evaluation of frequency of colonization/infection with VRE among the hospitalized patients and the contributing risk factors is an advanced approach to prevent spreading of these problematic microorganisms in hospitals.
dc.identifier.uri	http://hdl.handle.net/10861/2060
dc.language.iso	other
dc.publisher	Медицински университет - София // Medical University - Sofia
dc.subject	медицинска микробиология; ентерококи; фенотип; медицинска генетика; лекарствена резистентност; бактериални инфекции и микози - микробиологична диагностика // microbiology; enterobacteriacae; phenotype; medical genetics; drug resistance; bacterial infections and mycoses - microbiology
dc.title	Фенотипни и генотипни проучвания върху ванкомицин-резистентни ентерококи при пациенти с висок риск за колонизация и инфекция с проблемни микроорганизми // Phenotypic and genotypic studies on vancomycin-resistant enterococci in patients at high risk of colonization and infection with problematic microorganisms
dc.title.alternative	Phenotypic and genotypic studies on vancomycin-resistant enterococci in patients at high risk of colonization and infection with problematic microorganisms
dc.type	Thesis