Yazar "Demirci, Mehmet" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Antimicrobial peptides: Could cecropin A and nisin be new promising agents for the treatment of anaerobic infections(2024) Kurt, Zeynep; Demirci, Mehmet; Arı, Şule; Tokuç, Edip; Kılınçaslan, Ayşe Ceylan; Ziyad, Muhuyedin Abdirahman; Kocazeybek, Bekir Sami; Toman, Hrisi BaharAntimicrobial peptides (AMPs) may mitigate the danger of increasing antimicrobial resistance. We aimed to determine the activities of catestatin, temporin A, nisin and cecropin A against Bacteroides fragilis ATCC 25285, Prevotella melaninogenica ATCC 25845, Cutibacterium acnes ATCC 6919, Peptostreptococcus anaerobius ATCC 27337 and Peptostreptococcus stomatis DSM 17678. strains. The susceptibility of all anaerobic bacteria was determined by Kirby-Bauer disc diffusion method, agar dilution and broth microdilution method, recommended by CLSI. By broth microdilution the MIC of temporin A for P. anaerobius was 500µg/mL, and MBC >500µg/mL. The MIC of nisin for P. melaninogenica was 200µg/mL, with a MBC of 400µg/mL, for C. acnes, P. anaerobius, and P. stomatis, MIC were 40mg/mL. The MIC of cecropin A for B. fragilis was 50µg/mL, MBC was 500µg/mL. For C. acnes, the MIC was 4µg/mL, MBC was 8µg/mL. The MIC for P. melaninogenica, P. anaerobius and P. stomatis were 8µg/mL, with corresponding MBC values of 16, 32 and 50µg/mL, respectively. Conversely, catestatin proved ineffective against all strains. In conclusion, our study, demonstrated that cecropin A and nisin showed promising results against anaerobic standard strains. We believe thatfurther research conducted to explore those AMPs could hold promise as a treatment option for anaerobic bacterial infections.Öğe Bruselloz şüpheli olgularda brusella seropozitifliğinin araştırılması: dört yıllık retrospektif bir değerlendirme(2019) Taner, Zeynep; Dinç, Harika Öykü; Demirci, Mehmet; Gareayaghi, Nesrin; Kurt, Aykut; Özbey, Doğukan; Kocazeybek, Bekir SamiAmaç: Brucella cinsi bakterilerle oluşan bruselloz, sistemik bir enfeksiyon hastalığı olup dünyanın birçok ülkesinde yaygın olarak saptanmakta ve ülkemizde de oldukça sık görülmektedir. Çalışmamızın amacı, İstanbul ve çevre illerdeki yerleşim bölgelerinden dört yıllık dönemde bruselloz kuşkusu ile merkezimize başvuran 6.045 olgudan alınan serum örneklerinde bruselloz serolojik göstergelerini retrospektif olarak değerlendirmek ve sonuçları yine merkezimizde 2005-2011 yılları arasında gerçekleştirilmiş çalışmanın verileriyle karşılaştırarak değişkenlikleri irdelemektedir. Yöntem: Çalışmamıza Mart 2013- Mart 2017 tarihleri arasında İstanbul Üniversitesi-Cerrahpaşa, Cerrahpaşa Tıp Fakültesi Hastanesi Tıbbi Mikrobiyoloji Laboratuvarı Seroloji/ELISA birimine gönderilen bruselloz şüpheli olgulara ait serum örnekleri dahil edilmiştir. Örneklerden Brucella Serum Aglütinasyon (SAT), Coombs’lu Wright (CT) ve Rose-Bengal (RB) testleri yapılmıştır. Bulgular: Dört yıllık değerlendirme sonucunda, bruselloz şüpheli 6045 olgunun 107 (%1.8)’si seropozitif, 5938 (%98.2)’i seronegatif bulunmuştur. Brusella seropozitif 107 olgunun 73 (%68.2)’ü RB ve SAT ile eş zamanlı pozitif bulunmuş, 34 (%31.7) olgu ise RB ve SAT test sonuçları arasında uyumsuzluk görülmesi nedeniyle, CT sonucuna göre brusella seropozitif olarak belirlenmiştir. Brusella seropozitiflik oranı kadınlarda (%58) erkeklere (%42) göre daha yüksek olsa da istatistiksel olarak anlamlı bir fark bulunmamıştır. Olguların %28’inde aile içi aynı kaynaktan bulaş, %48’inde kırsal kesimde yaşama öyküsü saptanmıştır. Sonuç: Verilerimizin retrospektif değerlendirmesi sonucunda, bu çalışmada İstanbul ve çevre illerinde saptadığımız bruselloz seropozitiflik oranı (%1.8), aynı merkezde bir önceki dönem elde edilen orana göre (%3) düşük bulunmuştur. Bruselloz seropozitifliğinin oransal düşüklüğünde, son yıllarda görsel ve yazılı iletişim araçlarındaki artışla hayvansal kaynaklı beslenme konusunda daha bilinçli ve hijiyen kurallarına uyan insan kitlelerindeki artışın rolü olabileceğini düşünmekteyiz.Öğe Enterotoksijenik bacteroides fragilis ve fusobacterium nucleatum bağırsak kolonizasyonunun kolorektal kanser ile ilişkisi: kolon biyopsileri ile yapılan bir olgu kontrol çalışması(2023) Öztürk Bakar, Yeşim; Demiryas, Süleyman; Kılınçarslan, Ayşe Ceylan; Demirci, Mehmet; Kepil, Nuray; Bakar, Murat Tuğberk; Taner, Zeynep; Tokuç, Edip; Ziyad, Muhuyedin Abdırahman; Taşkı, İhsan; Kocazeybek, Bekir Sami; Tokman, Hrisi BaharIn recent years, it has been shown that some bacteria may be associated with colorectal cancer (CRC). In this study, it was aimed to investigate the role of Fusobacterium nucleatum and enterotoxigenic Bacteroides fragilis (ETBF) in the etiology of CRC by comparing the amounts of these bacteria in colon biopsy tissues of patients with CRC and healthy individuals. The amounts of F.nucleatum and ETBF were determined by quantitative polymerase chain reaction (qPCR) in colon biopsy samples taken from 35 CRC and 35 healthy individuals, and the results were compared in the patient and control groups. The detection rate and amounts of F.nucleatum were found to be statistically significantly higher in tissues of female patients with CRC compared to male patients (p= 0.003, p= 0.013, respectively). There was no statistically significant difference between the tissues of female and male patients with CRC in terms of detection rate and amount of ETBF (p= 0.521, p= 0.515, respectively). It was found that in the 50-74 age group, the amount of ETBF was statistically significantly higher in women and men with CRC compared to the controls (p= 0.005, p= 0.047, respectively), while the amount of F.nucleatum was statistically significantly higher in female patients compared to controls. However, no difference was found between male patients and controls (p= 0.009, p= 0.083). It was determined that the detection rate and amount of F.nucleatum in the tissues of patients with CRC, regardless of age and gender, were not statistically different from the controls (p= 0.473, p= 0.995, respectively), however, the detection rate of ETBF and the amount of ETBF were found to be statistically significantly higher (p= 0.002, p= 0.004, respectively). It has been determined that ETBF can play a role in the etiology of CRC in both men and women, and F.nucleatum only in women, in the age range of 50-74 years, when routine screenings for CRC are performed.Öğe Firmicutes/Bacteroidetes Ratio in the Gut Microbiota and IL-10, IL-6, IL-8, TLR2, TLR4, TLR5 Gene Expressions in Type 2 Diabetes(Clin Lab Publ, 2022) Bahar-Tokman, Hrisi; Demirci, Mehmet; Keskin, Fatma E.; Cagatay, Penbe; Taner, Zeynep; Ozturk-Bakar, Yesim; Ozyazar, MucahitBackground: The aim of this study was to determine the Firmicutes/Bacteroidetes ratio in the gut microbiota and IL-1 beta, IL-6, IL-8, TLR2, TLR4 and TLR5 gene expression levels in the blood of adult type 2 diabetes (T2D) patients and compare it with that of adult nondiabetic healthy controls (HC). Methods: Between May 2016 and April 2017, 99 T2D patients and 99 HCs were enrolled in the study. Bacteroidetes and Firmicutes levels were assessed from stool sample DNA and IL-1 beta, IL-6, IL-8, TLR2, TLR4, and TLR5 gene expression levels assesed from blood sample RNA via gPCR from both T2D patients and healthy controls. Results: The Firmicutes/Bacteroidetes ratio detected in the stool of type 2 diabetes patients was found to be higher with a statistically significant difference (p < 0.0001). Gene expression levels of IL-1 beta, IL-6, IL-8, TLR2, TLR4, and TLR5 were found to be upregulated. Conclusions: The highest upregulation was detected in IL-6 with 11 fold in T2D patients comparing with HCs. F/B ratio and gene expression levels were elevated in T2D patients. Firmicutes were positively correlated with studied gene expressions. A better understanding of the complex interaction between gut microbiota, environment, and diabetes will allow for more effective prevention and treatment strategies for T2D.Öğe Human papillomavirus prevalence and genotype distribution among Turkish women with or without cervical lesion(Wolters Kluwer Medknow Publications, 2018) Demirci, Mehmet; Güzel, Aylin Dağ; Erşahin, Aynur Adeviye; Yorulmaz, Eda; Erşahin, Suat Süphan; Borsa, Barış AtaContext: Human papillomavirus (HPV) infection is the main cause of cervical cancer, but the risk is associated with the various HPV genotypes which may be found in women with or without clinical findings. Aims: We aimed to identify HPV prevalence and genotype distribution in women with or without cervical lesions admitted to Gynaecology and Obstetrics Clinics of one of the largest private hospitals in Istanbul between 2013 and 2017. Subjects and Methods: In the present study, cervical cytobrush samples collected from 2464 women with different cytological conditions, and investigated for the presence of HPV, and the different genotypes. Results were evaluated based on the HPV positivity in different cytological findings, and ages. Furthermore, distribution of high-risk (HR) and low-risk (LR) genotypes in different groups was investigated. Results: Among all participants, 1925 (78.1%) was with the normal cytological condition, 354 (14.4%) with ASC-US; 151 (6.1%) with low-grade squamous intraepithelial lesion (LSIL), and 34 (1.4%) with high-grade squamous intraepithelial lesion (HSIL). Our results showed that 649 out of 2464 patients (26.3%) were positive, and 1815 (73.7%) were negative for the presence of HPV. Among 649 positive patients, 223 (34.3%) were found positive for more than one genotype. HPV 16 was found the most common HR-HPV type in ASC-US and LSIL whereas HPV 18 was the most common in HSIL. HPV 6 was found the most common LR-HPV type in ASC-US and LSIL whereas HPV 11 was the most common in HSIL. 26.9% of women <50 years old, and 22.3% of women >= 50 years old was positive for HPV. The most common HR-HPV genotype was 16 in both groups with (19%) or without (17%) abnormal cytology. Conclusions: We concluded that HPV prevalence and genotype distribution in women with or without clinical findings is an important predictor of cervical cancer.Öğe Molecular mechanisms of colistin resistance among klebsiella pneumoniae strains(Clin Lab Publ, 2019) Borsa, Barış Ata; Demirci, Mehmet; Güngördü-Dalar, Zeynep; Karabıyık, Göktuğ; Aygün, Gökhan; Küçükbasmacı, ÖmerBackground: The increasing rate of infections caused by multiple drug resistant gram-negative bacteria has led to resuscitation of colistin. As a result, colistin resistance, mainly among Klebsiella pneumoniae strains has also been increased. The aim of this study was to investigate molecular mechanisms behind colistin resistance. Methods: Twenty colistin-resistant K. pneumoniae strains isolated from clinical samples of different patients were involved in this study. VITEK2 automated ID/AST system (Biomeriux, France) was used for the identification and also the susceptibility testing for antibiotics other than colistin. Colistin susceptibility was determined by broth microdilution method. To identify the mechanisms of resistance, mutations on mgrB genes, expression levels of pmrA, pmrB, pmrC, pmrD, pmrE, pmrK, phoQ, and phoP genes, and the presence of plasmid mediated colistin resistance genes, mcr-1 and mcr-2 were investigated. Results: As a result of the study, increased expression levels of the pmrA, pmrB, pmrD, pmrK, phoP, and phoQ genes were observed. All colistin resistant strains were found wild type for the mgrB gene which is thought to be responsible for colistin resistance. Also, no mcr-1 or mcr-2 genes which are the causes of plasmid mediated colistin resistance have been detected in any of the strains. Conclusions: Among the colistin resistant K. pneumoniae strains included in our study, increased expression levels of the genes responsible for cell membrane modifications related with colistin resistance were the most common mechanisms.Öğe Prevalence and antimicrobial susceptibilities of anaerobic bacteria isolated from perforated corneal ulcers by culture and multiplex PCR: An evaluation in cases with keratitis and endophthalmitis(Clin Lab Publ, 2014) Tokman, Hrisi Bahar; İskeleli, Güzin; Dalar, Zeynep Güngördü; Kangaba, Achille Aime; Demirci, Mehmet; Akay, Hatice K.; Kiraz, Nuri; Borsa, Barış AtaBackground: Anaerobic bacteria play an important role in eye infections; however, there is limited epidemiologic data based on the the role of these bacteria in the etiology of keratitis and endophthalmitis. The aim of this research is to determine the prevalence of anaerobic bacteria in perforated corneal ulcers of patients with keratitis and endophthalmitis and to evaluate their antimicrobial susceptibilities. Methods: Corneal scrapings were taken by the ophthalmologist using sterile needles. For the isolation of anaerobic bacteria, samples were inoculated on specific media and were incubated under anaerobic conditions obtained with Anaero-Gen (Oxoid & Mitsubishi Gas Company) in anaerobic jars (Oxoid USA, Inc. Columbia, MD, USA). The molecular identification of anaerobic bacteria was performed by multiplex PCR and the susceptibilities of anaerobic bacteria to penicillin, chloramphenicol, and clindamycin were determined with the E test (bioMerieux). Results: 51 strains of anaerobic bacteria belonging to four different genuses were detected by multiplex PCR and only 46 strains were isolated by culture. All of them were found susceptible to chloramphenicol whereas penicillin resistance was found in 13.3% of P.anaerobius strains, clindamycin resistance was found in 34.8% of P.acnes and 13.3% of P.anaerobius strains. Additionnaly, one strain of P.granulosum was found resistant to clindamycin, one strain of B.fragilis and one strain of P.melaninogenica were found resistant to penicillin and clindamycin. Conclusions: Routine analyses of anaerobes in perforated corneal ulcers is inevitable and usage of appropriate molecular methods, for the detection of bacteria responsible from severe infections which might not be determined by cultivation, may serve for the early decision of the appropriate treatment. Taking into account the increasing antimicrobial resistance of anaerobic bacteria, alternative eye specific antibiotics effective against anaerobes are needed to achieve a successful treatment.Öğe Similar bacterial signatures in the gut microbiota of type 1 and type 2 diabetes patients and its association with G protein-coupled receptor 41 and 43 gene expression(Springer Science and Business Media Deutschland GmbH, 2022) Demirci, Mehmet; Taner, Zeynep; Keskin, Fatma E.; Ozyazar, Mucahit; Kiraz, Nuri; Kocazeybek, Bekir S.; Tokman, Hrisi BaharPurpose: There are conficting reports regarding the abundance of short-chain fatty acids producing bacteria in the gut microbiota in patients with type 1 and type 2 diabetes. We aimed to determine the amount of Akkermansia muciniphila, Anaerobutyricum hallii, Bifdobacterium adolescentis, Bifdobacterium longum, Collinsella aerofaciens, Faecalibacterium prausnitzii, Lacticaseibacillus rhamnosus, and Parabacteroides distasonis in the gut microbiota in patients with type1 and type2 diabetes, compared with the healthy controls and analyze the correlation between the gene expression levels of two short-chain fatty acids receptors GPR41 and GPR43. Methods: Forty type 1, 40 type 2 stool and blood samples of diabetes patients, and 40 healthy control samples were studied. DNA and RNA were extracted, and bacteria were detected using a Microbial DNA qPCR Assay kit. Gene expressions were detected with GPR41 and GPR43 primers via in-house qPCR. Results: Compared with healthy controls, B.longum and F.prausnitzii abundance were signifcantly decreased in patients with type1 and type2 diabetes, A.hallii abundance was increased in patients with type1 and decreased in type2 diabetes contrarily A.muciniphila abundance was decreased in patients with type1 and increased in type2 diabetes. GPR43 gene expression was upregulated in both patients group, however GPR41 was upregulated only in patients with type2 diabetes. Conclusions: Elevated B. longum and F. prausnitzii abundances were detected in the gut microbiota of patients with type1 and type2 diabetes and compared with healthy controls. B. longum and F.prausnitzii abundances were also correlated with the GPR43 gene expression level in type1 diabetes patients. Extensive studies determining bacteria producing short-chain fatty acids in gut microbiota, and their contribution in the pathogenesis of diabetes, are needed to understand better the mechanism of these diseases.Öğe The relationship between bifidobacteria and allergic asthma and/or allergic dermatitis: A prospective study of 0-3 years-old children in Turkey(Elsevier Sci Ltd, 2014) Akay, Hatice Kubra; Tokman, Hrisi Bahar; Hatipoğlu, Nevin; Hatipoğlu, Huseyin; Siraneci, Rengin; Demirci, Mehmet; Kocazeybek, Bekir S.; Borsa, Barış AtaBifidobacteria are beneficial bacteria for humans. These bacteria are particularly effective at protecting against infectious diseases and modulating the immune response. It was shown that in newborns, the fecal distribution of the colonizing Bifidobacterium species influences the prevalence of allergic diseases. This study aimed to compare the faecal Bifidobacterium species of allergic children to those of healthy children to detect species level differences in faecal distribution. Stool samples were obtained from 99 children between 0 and 3 years of age whose clinical symptoms and laboratory reports were compatible with atopic dermatitis and allergic asthma. Samples were also obtained from 102 healthy children who were similar to the case group with respect to age and sex. Bifidobacteria were isolated by culture and identified at the genus level by API 20 A. In addition, 7 unique species-specific primers were used for the molecular characterization of bifidobacteria. The McNemar test was used for statistical analyses, and p < 0.05 was accepted as significant. Bifidobacterium longum was detected in 11(11.1%) of the allergic children and in 31 (30.3%) of the healthy children. Statistical analysis revealed a significant difference in the prevalence of B. longum between these two groups (X-2: 11.2, p < 0.001). However, no significant differences in the prevalence of other Bifidobacterium species were found between faecal samples from healthy and allergic children. (p > 0.05). The significant difference in the isolation of B. longum from our study groups suggests that this species favors the host by preventing the development of asthma and allergic dermatitis. Based on these results, we propose that the production of probiotics in accordance with country-specific Bifidobacterium species densities would improve public health. Thus, country-specific prospective case control studies that collect broad data sets are needed. (C) 2014 Elsevier Ltd. All rights reserved.
