Researcher:
Nurtop, Elif

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Master Student

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Elif

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Nurtop

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Nurtop, Elif

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2016 - 201932020 - 20223

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Researcher Of Publications: search.filters.isAuthorOfPublication.38849459-cee5-4778-90e6-e101d0b74242

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    Promoters of colistin resistance in acinetobacter baumannii infections
    (2019) Bilman, Fulya Bayındır; Menekşe, Şirin; Azap, Özlem Kurt; N/A; Department of Industrial Engineering; N/A; N/A; Nurtop, Elif; Gönen, Mehmet; Ergönül, Önder; Can, Füsun; Master Student; Faculty Member; Faculty Member; Faculty Member; Department of Industrial Engineering; Graduate School of Health Sciences; College of Engineering; School of Medicine; School of Medicine; N/A; 237468; 110398; 103165
    Objectives: We aimed to describe the mechanisms of colistin resistance in Acinetobacter baumannii. Materials and Methods: Twenty-nine patients diagnosed with colistin-resistant A. baumannii infection were included to the study. The mutations in pmrCAB, lpxA, lpxC, and lpxD genes, expression of pmrCAB, carbapenemases, and mcr-1 positivity were studied. Results: Twenty-seven (93%) of the patients received IV colistin therapy during their stay, and the case fatality rate was 45%. All mutations in pmrC and pmrB were found to be accompanied with a mutation in lpxD. The most common mutations were I42V and L150F in pmrC (65%), E117K in lpxD (65%), and A138T in pmrB (58.6%). The colistin minimum inhibitory concentrations (MICs) of the isolates having any of these four mutations were higher than the isolates with no mutations (p < 0.001). The two most common mutations in pmrC (I42V and L150F) were found to be associated with higher expressions of pmrA and pmrC and higher colistin MIC values (p = 0.010 and 0.031). All isolates were bla(OXA-23) positive. Conclusion: Coexistence of the lpxD mutation along with mutations in pmrCAB indicates synergistic function of these genes in development of colistin resistance in A. baumannii.
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    The clinical impact of ST131 H30-Rx subclone in urinary tract infections due to multidrug-resistant Escherichia coli
    (Elsevier, 2016) Kurt-Azap, Özlem; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Can, Füsun; İspir, Pelin; Nurtop, Elif; Şeref, Ceren; Loçlar, İlayda; Aktaş, Özge Nur; Orhan, Yelda Ceren; Ergönül, Önder; Faculty Member; Master Student; Master Student; PhD Student; Undergraduate Student; Undergraduate Student; Undergraduate Student; Faculty Member; School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; Graduate School of Health Sciences; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 103165; N/A; N/A; N/A; N/A; N/A; N/A; 110398
    In this study, risk factors for ST131 H30 and H30-Rx subclones among urinary tract infections (UTIs) caused by multidrug-resistant (MDR) Escherichia coli were described. Urine samples were collected from consecutive outpatients registered to the outpatient clinics of Bas, kent University Hospital (Ankara, Turkey) with complaints of acute cystitis in 2011. A total of 107 MDR E. coli isolates were included in the study. of the 107 isolates studied, 26 (24.3%) were typed as ST131 clone. Extended-spectrum beta-lactamase (ESBL)-producers accounted for 59 (55.1%) of the 107 isolates. Among the 59 ESBL-positive isolates, 18 (31%) were found to belong to the ST131 clone. of the 18 ESBL-positive ST131 isolates, 17 (94%) were defined as H30 subclone, among which 16 (94%) represented the H30-Rx subclone. Among the 48 ESBL-negative isolates, 8 (17%) ST131 isolates were detected, 7 (88%) of which belonged to H30 subclone; 5 (71%) of the H30 subclone isolates were classified under H30-Rx subclone. In multivariate analysis, hospitalisation within last year was the only host risk factor associated with MDR E. coli ST131 H30-Rx subclone UTI (OR = 3.5, 95% CI 1.04-12.17; P = 0.042). CTX-M-15 production was found to be highly associated with the presence of ST131 H30-Rx subclone (OR = 4.8, 95% CI 1.54-15.32; P = 0.007). In conclusion, urinary MDR E. coli ST131 H30-Rx subclone was found to be important in the dissemination of MDR UTIs in the community. Approximately 20% of the MDR isolates were H30-Rx subclone. Infection with this subclone was found to be healthcare-associated. (C) 2015 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.
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    Molecular epidemiology of bloodstream-associated Escherichia coli ST131 H30-Rx subclone infection in a region with high quinolone resistance
    (Microbiology Society, 2016) Kurt-Azap, Özlem; N/A; N/A; N/A; N/A; N/A; Can, Füsun; Nurtop, Elif; İspir, Pelin; Şeref, Ceren; Ergönül, Önder; Faculty Member; Master Student; Master Student; PhD Student; Faculty Member; School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; Graduate School of Health Sciences; School of Medicine; 103165; N/A; N/A; N/A; 110398
    Bloodstream infections caused by Escherichia coli ST131 and ST131 H30-Rx subclones have emerged worldwide. This study was carried out to evaluate the prevalence of the ST131-Rx subclone and characterize the virulence properties of the Rx isolates among the bloodstream E. coli isolates. A total of 297 non-duplicated E. coli bloodstream isolates were studied. Antibiotic susceptibilities were tested using the disc diffusion method. PCR amplification and sequencing was used to identify ST131 and H30-Rx, the virulence gene, the beta-lactamase and virotype. Quinolone resistance among bacteraemic E. coli strains was 51 %, and it was 98% among E. coli ST131 isolates. The ST131 isolates accounted for 16% (49) of all isolates and all ST131 isolates belonged to the extraintestinal pathogenic E. coli. The proportion of H30 subclone among the ST131 isolates was 98%, and 75 % of H30 isolates belonged to the H30-Rx subclone. The prevalence of ST131 increased from 13 to 23 % in 4 years; however, there was a decrease in the ratio of H30-Rx infections. CTX-M-15 was detected in 85% of ST131 and all of the H30-Rx isolates. The virulence genes associated with adhesion, cell protection, iron uptake and toxins (papA, iha, kpsMTII, iut and sat) were more common in ST131 than in non-ST131 isolates. Most of the ST131 and H30-Rx isolates were of the C virotype. All papA-positive isolates were in virotype C. The E. coli ST131 clone has increased rapidly among bloodstream isolates. However, a decrease in the proportion of the H30-Rx subclone in the quinolone-resistant population suggests the possibility of dissemination of other virulent and quinolone-resistant subclones in hospital settings.
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    PublicationOpen Access
    Infectivity of adult and pediatric COVID-19 patients
    (Design Oriented Community (DOC), 2021) İncir, Said; Doğan, Özlem; Özer, Berna; Nurtop, Elif; Vatansever, Cansel; Özcan, Gülin; Çelikyurt, Aydın; Khalilova, Fidan; Okan, Ayşe; Saçkesen, Cansın; Can, Füsun; Ergönül, Önder; Faculty Member; Faculty Member; Master Student; Undergraduate Student; Doctor; Faculty Member; Faculty Member; Faculty Member; Koç Üniversitesi İş Bankası Enfeksiyon Hastalıkları Uygulama ve Araştırma Merkezi (EHAM) / Koç University İşbank Center for Infectious Diseases (KU-IS CID); School of Medicine; Graduate School of Health Sciences; Koç University Hospital; 175430; 170418; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 182537; 103165; 110398
    Objective: we aimed to describe the infectivity of adult and pediatric COVID-19 patients in the presence of viral shedding and anti-SARS-CoV-2 antibody response. Materials and methods: a total of 408 consequent samples from eleven adults and five pediatric patients with SARS-CoV-2 infection were included. Reverse transcription-polymerase chain reaction (RT-PCR) and viral culture were performed for the samples obtained every other day from saliva, nasopharynx, feces, serum, urine, and tear. Anti-SARS-CoV-2 antibodies were measured. Results: the median duration of RNA shedding in all specimens was 7 (2-15) days in adults and 5 (3-19) days in children. The median duration from symptom onset to admission was three days. The viral RNA was positive in 44.7 % of the nasopharynx and 37.6% of saliva samples up to 16 days in adults and 19 days in children. We detected the latest viral culture positivity in the nasopharynx on day eight of symptoms. The viral RNA was found in 6.1% of feces, 4.4% of serum, 4.3 % of tear, 2.9% of urine. The earliest seroconversion was the seventh day for adults and the eighth day for children. On the 14th day, total antibody positivity was 78% in adults and 80% in children. After seroconversion, the viral RNA was still detected in the nasopharynx and saliva of three patients; however, the infectious virus was not present. Conclusion: the infectivity of a positive patient is low after eight days of symptoms. The risk of fecal-oral transmission is very low, and strict hand hygiene measures could be preventive.
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    PublicationOpen Access
    Evaluation of protective effect of L-carnitine and N-acetylcysteine in mesenteric ischemia-reperfusion injury model in rats
    (Bayrakol Medical Publishing, 2021) Kalafat, Murat Utku; Bildik, Büşra; Doğan, Serkan; Tapkan, Birsen Rabia; Dörter, Melis; Kalafat, Ayşe Fethiye Başa; Tapkan, Baheddin; Cander, Başar; İncir, Said; Doğan, Özlem; Özer, Berna; Nurtop, Elif; Vatansever, Cansel; Özcan, Gülin; Çelikyurt, Aydın; Khalilova, Fidan; Okan, Ayşe; Saçkesen, Cansın; Can, Füsun; Ergönül, Önder; Faculty Member; Faculty Member; Master Student; Undergraduate Student; Doctor; Faculty Member; Faculty Member; Faculty Member; School of Medicine; 175430; 170418; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 182537; 103165; 110398
    Aim: ischemia-reperfusion injury is an important dilemma in surgical modalities. The mechanism of IR damage is related to oxidative stress mediators. L-carnitine and N-acetylcysteine are thought to have antioxidant activity. In our study, we aimed to evaluate the effects of short-term administration of these two drugs and to compare their effects on oxidative stress parameters in the experimental mesenteric ischemia-reperfusion model in rats. Materials and methods: twenty-four female Sprague-Dawley rats were allocated into 3 experimental groups. In Group 1 (CG) (n=8), rats underwent occlusion of the superior mesenteric artery for 30 minutes and were not given any medications. In Group 2 (NG) and Group 3 (LG), rats underwent occlusion as CG. Rats were given 150 mg/kg (IP) N-acetylcysteine and 300 mg/kg IP L-carnitine according to their groups 15 minutes before reperfusion. Rats were sacrificed with high dose anesthetic drugs after 60 minutes of reperfusion. Blood and liver tissue samples were obtained to investigate total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI). Results: by biochemical examination, all groups showed similar levels of TOS. There was no statistically significant difference between the level of TAS and OSI in all groups (p>0,05). There was no any statistically significant difference between the groups for TAS measurements (p=0.061; p>0.05); however, higher measurement values in the L-Carnitine group is considerable.Discussion: although the use of drugs with proven antioxidant efficiency after ischemia may cause a histologically significant difference in IR injury, there was no significant efficiency in the reduction of superoxides in the circulation. Therefore, we believe that the use of NAC and L-carnitine as antioxidants after the development of ischemia does not help to prevent intestinal IR injury.
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    PublicationOpen Access
    Protein scaffold-based multimerization of soluble ACE2 efficiently blocks SARS-CoV-2 infection in vitro and in vivo
    (Wiley, 2022) Ulbegi Polat, Hivda; Yıldırım, İsmail Selim; Kayabölen, Alişan; Akcan, Uğur; Özturan, Doğancan; Şahin, Gizem Nur; Değirmenci, Nareg Pınarbaşı; Bayraktar, Canan; Söyler, Gizem; Sarayloo, Ehsan; Nurtop, Elif; Özer, Berna; Esken, Gülen Güney; Barlas, Tayfun; Doğan, Özlem; Karahüseyinoğlu, Serçin; Lack, Nathan Alan; Kaya, Mehmet; Albayrak, Cem; Can, Füsun; Solaroğlu, İhsan; Önder, Tuğba Bağcı; PhD Student; PhD Student; Master Student; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Health Sciences; School of Medicine; Koç University Hospital; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 170418; 110772; 120842; 10486; N/A; 103165; 102059; 184359
    Soluble ACE2 (sACE2) decoys are promising agents to inhibit SARS-CoV-2, as their efficiency is unlikely to be affected by escape mutations. However, their success is limited by their relatively poor potency. To address this challenge, multimeric sACE2 consisting of SunTag or MoonTag systems is developed. These systems are extremely effective in neutralizing SARS-CoV-2 in pseudoviral systems and in clinical isolates, perform better than the dimeric or trimeric sACE2, and exhibit greater than 100-fold neutralization efficiency, compared to monomeric sACE2. SunTag or MoonTag fused to a more potent sACE2 (v1) achieves a sub-nanomolar IC50, comparable with clinical monoclonal antibodies. Pseudoviruses bearing mutations for variants of concern, including delta and omicron, are also neutralized efficiently with multimeric sACE2. Finally, therapeutic treatment of sACE2(v1)-MoonTag provides protection against SARS-CoV-2 infection in an in vivo mouse model. Therefore, highly potent multimeric sACE2 may offer a promising treatment approach against SARS-CoV-2 infections.