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  • Küçük Resim
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    CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF MENTHA PIPERITA VAR. CITRATA EXTRACTS OBTAINED BY DIFFERENT EXTRACTION SOLVENTS
    (2022) Kürekci, Cemil; Beyazit, Neslihan
    The main aim of this study was to evaluate the phytochemical composition of extracts of Mentha piperita var. citrata obtained by using three different solvents as well as their antimicrobial activity against a panel of Gram positive and Gram negative bacteria. The antibacterial activities of the extracts (hexane, chloroform, and 70% aqueous methanol) were tested against a panel of bacteria using broth microdilution method. Rosmarinic acid (10.505 mg/g extract), cynaroside (8.545 mg/g extract) and cosmosiin (8.489 mg/g extract) appeared to be the major components of methanolic extract, whereas acacetin was the most abundant (8.438 mg/g extract) component of chloroform extract. M. citrata extracts showed significant antimicrobial activity against Gram positive bacteria at different concentrations. Chloroform extract from M. citrata showed antimicrobial activity at concentration of 512-4096 µg/mL, whereas hexane and methanolic extracts had activity at 1024-4096 µg/mL and 2048-4096 µg/mL, respectively. This study shows the different chemical composition and antimicrobial activities of M. citrata extracts obtained by using different extraction solvents.
  • Küçük Resim
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    A COMPARISON OF SOLID-PHASE EXTRACTION METHODS FOR BISPHENOL A IN CHEESE SAMPLES
    (2021) Kürekci, Cemil; Tan, Sait; Arslan, Ali; Özgen, Sara Betül; Sakin, Fatih
    In this study, four different solid phase extraction (SPE) methods were compared for the determination of bisphenol A (BPA) in cheese samples using HPLC-FD. All methods were validated according to the parameters; linearity, recovery, precision, detection and quantification limits (LOD-LOQ). Subsequently, BPA levels were determined in twenty cheese samples commercially available in Elazığ province. All the extraction methods showed good performances for quantitative analysis of PBA, achieving very low LOD (0.16-0.39 ?g/kg) and LOQ (0.53-1.30 ?g/ kg) values. The average fortification recoveries for spiked BPA (3-30 ?g/kg) ranged between 93.1 and 100.8%. 55% of cheese samples had BPA concentration ranging from 0.75 ?g/kg to 8.46 ?g/kg and estimated daily intake (EDI) was measured as 0,001 ?g/kg BW per day. On the basis of EDI, the consumption of cheese itself cannot be considered as significant health problem, but results impose a systematic monitoring of dairy products.
  • [ N/A ]
    Öğe
    Emergence and Characterization of Tigecycline Resistance Gene tet(X4) in ST609 Escherichia coli Isolates from Wastewater in Turkey
    (Amer Soc Microbiology, 2022) Kürekci, Cemil; Lu, Xiaoyu; Celil, Busra Gulay; Disli, Huseyin Burak; Mohsin, Mashkoor; Wang, Zhiqiang; Li, Ruichao
    Emergence of pathogens harboring tigecycline resistance genes incurs great concerns. Wastewater is recognized as the important reservoir of antimicrobial resistance genes. Here we characterized the phenotypes and genotypes of bacteria carrying tet(X4) from wastewater in Turkey for the first time. Four tet(X4)-positive Escherichia coli isolates were identified and characterized by PCR, Sanger sequencing, antimicrobial susceptibility testing, conjugation assays, Illumina sequencing, nanopore sequencing and bioinformatic analysis. Four tet(X4)-harboring isolates were multidrug-resistant (MDR) bacteria and the tet(X4) gene was nontransferable in four isolates. Genetic analysis revealed that tet(X4) genes in four isolates were located on plasmids co-harboring two replicons IncFIA(HI1) and IncFIB(K). However, none of the four plasmids carried genes associated with horizontal transfer of plasmids. The coexistence of bla(SHV-12)-bearing IncX3-type plasmid and tet(X4)harboring plasmid was also found in one isolate. These findings indicate that continuous surveillance of the tet(X4)-bearing isolates in different environments worldwide should be strengthened. IMPORTANCE The emergence of tigecycline resistance genes in humans and animals in China seriously threatens the clinical utility of tigecycline, but the molecular epidemiology of tigecycline-resistant bacteria in other countries remained largely unknown. Therefore, it is necessary to learn the prevalence and molecular characteristics of bacteria carrying tigecycline resistance genes, particularly the mobilizable tet(X4), in other countries. In the study, we first described the presence and molecular characteristics of the tet(X4)-positive E. coli isolates from wastewater in Turkey. Four tet(X4)-bearing isolates belonged to ST609, an E. coli clone commonly found from humans, animals and the environment. These findings highlight the importance of monitoring the tet(X4) gene in different settings globally.
  • Küçük Resim
    Öğe
    Salmonella Infantis
    (2023) Kürekci, Cemil; Şahin, Seyda
    Salmonella enterica subsp. enterica serovar Infantis (S. Infantis) izolatlarının tespiti ve küresel yayılımı Türkiye’de dahil olmak üzere bir çok ülkede kanatlı ve kanatlı et örneklerinde artan oranda rapor edilmektedir. Ayrıca, S. Infantis Avrupa Birliği ülkelerinde ve Türkiye’de insanda salmonelloza neden olan en yaygın serotiplerden birisidir, bu nedenle de insan sağlığı açısından risk teşkil etmektedir. Bu durum genellikle çeşitli antimikrobiyal direnç ve virulens genleri ile ilişkilendirilen pESI (?280 kb) olarak adlandırılan büyük bir megaplazmidin varlığı ile açıklanmaktadır. S. Infantis izolatlarında çoklu ilaç direnci belirlenmiş olup bu da insanlarda vakaların tedavisi sorusunu gündeme getirmektedir. Dolayısıyla, bu derlemede yeni ortaya çıkan problem epidemiyolojik ve genomik açıdan değerlendirildi. Sonuç olarak, insan olgularındaki S. Infantis’in gerçek prevalansının tam olarak açıklığa kavuşturulması gerektiği söylenebilir. Türkiye’de S. Infantis’in insanlara bulaşma yolunu araştıran herhangi bir çalışma olmamasına rağmen, asıl bulaşma kaynağının tavuk eti tüketimi olduğuna inanılmaktadır. Bu yüzden, insan ve hayvan kökenli izolatlarda tüm genom analizi yapılması ile S. Infantis epidemiyolojisinin anlaşılmasına katkı sağlayacaktır. Sonuçta, S. Infantis’in kanatlı hayvanların bağırsaklarında taşınmasını kontrol etmek için yeni politikalar başlatılabilir.