Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/11727/4809
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Item Investigation of anti-cholinesterase and anti-amyloidogenic activities of beta-lactam antibiotics(2022) Ozer, Eda Ozturan; Mirza, Hasan Cenk; Tan, Oya Unsal; Turkoglu, Suna; 0000-0002-8853-3893; 0000-0003-4805-1918; F-1232-2015; AAJ-2243-2021Objectives: Neuroinflammation is an important factor in the pathogenesis of neurodegenerative disesases. The following study aimed to clarify the effects of beta-lactam antibiotics to the cholinergic system, on acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) activities, considering the structural differences of antibiotics, to evaluate the underlying mechanism of effects provided by protein-antibiotic interactions, and to clarify possible effects of the antibiotics on the aggregation of A beta-peptides. Methods: The inhibition/activation mechanisms for each antibiotic were examined kinetically by Ellman method. Destabilization effects of them on amyloid peptide fibrillation were examined and protein-ligand interactions were evaluated with most potent antibiotics by molecular docking studies. Results: The most powerful inhibitions were detected by the inhibition studies of AChE with ceftazidime (CAZ) and BuChE with amoxicillin (AMX). CAZ was exhibited dose-related dual effect on AChE activity. CAZ was actually the dose-related modifier of AChE. At higher concentrations, CAZ was a nonessential activator of AChE. Molecular docking studies have been confirmed by kinetic studies. Interested beta-lactam antibiotics did not prevent fibrillation rate as rifampicin. Conclusion: Inhibition/activation behaviours of studied beta-lactam antibiotics on both cholinesterases may suggest that cholinergic transmission is one of the crucially important components of the beta-lactam antibiotics-induced central nervous system adverse reactions.Item Comparison of in vitro activities of plazomicin and other aminoglycosides against clinical isolates of Klebsiella pneumoniae and Escherichia coli(2021) Ince, Gizem; Mirza, Hasan Cenk; Guclu, Aylin Uskudar; Gumus, Hale; Erol, Cigdem; Basustaoglu, Ahmet; 0000-0001-9071-9606; 0000-0002-1872-028X; 0000-0002-2535-2534; 0000-0002-8853-3893; 34499728; AAJ-2108-2021; AAU-6196-2020; AAJ-1219-2021; F-1232-2015Objectives: To compare the in vitro activity of plazomicin and two older aminoglycosides (gentamicin and amikacin) against 180 isolates of Escherichia coli and Klebsiella pneumoniae, including subsets of 60 non-ESBL-producing, 60 ESBL-producing and 60 carbapenem-resistant (46 carrying bla(OXA-48), 11 carrying bla(NDM) and 3 carrying bla(OXA-48) and bla(NDM)) strains. Methods: MICs of plazomicin, gentamicin and amikacin were determined by a gradient diffusion method. Gentamicin and amikacin MICs were interpreted according to CLSI criteria and EUCAST breakpoint tables. Plazomicin MICs were interpreted using FDA-defined breakpoints. Results: All non-ESBL-producing and ESBL-producing isolates were susceptible to plazomicin. The plazomicin susceptibility rate (71.7%) in carbapenem-resistant isolates was significantly higher than those observed for gentamicin (45%) and amikacin (56.7% and 51.7% according to CLSI and EUCAST breakpoints, respectively). Gentamicin, amikacin and plazomicin susceptibility rates (35.6% for gentamicin; 44.4% and 37.8% for amikacin according to CLSI and EUCAST breakpoints, respectively; 64.4% for plazomicin) in carbapenem-resistant K. pneumoniae were significantly lower than those observed for carbapenem-resistant E. coli isolates (73.3% for gentamicin; 93.3% for amikacin and plazomicin). Gentamicin, amikacin and plazomicin susceptibility rates for bla(NDM)-positive isolates were lower than those observed for bla(OXA-48)-positive isolates, but differences were not statistically significant. Among the isolates that were non-susceptible to both gentamicin and amikacin, the plazomicin susceptibility rate was less than 30%. Conclusions: Although plazomicin showed excellent in vitro activity against carbapenem-susceptible isolates, the plazomicin resistance rate increased to 35.6% among carbapenem-resistant K. pneumoniae and further increased to 45.5% among bla(NDM)-positive isolates.Item In vitro activity of ceftolozane-tazobactam and ceftazidime-avibactam against clinical isolates of meropenem-non-susceptible Pseudomonas aeruginosa: A two-centre study(2020) Mirza, Hasan Cenk; Hortac, Elvan; Kocak, Aylin Altay; Demirkaya, M. Hamiyet; Yayla, Buket; Guclu, Aylin Uskudar; Bustaoglu, Ahmet; 0000-0002-1872-028X; 0000-0002-8853-3893; 0000-0002-0451-0142; 0000-0002-4335-6897; 31568882; AAU-6196-2020; F-1232-2015; AAI-8012-2021Objectives: This study aimed to compare the activity of ceftazidime-avibactam (C/A), ceftolozane-tazobactam (C/T) and three anti-pseudomonal beta-lactams (piperacillin-tazobactam, ceftazidime and cefepime) against a collection of meropenem-non-susceptible Pseudomonas aeruginosa (P. aeruginosa) clinical isolates recovered from two centres in Turkey. Methods: A total of 102 unique patient isolates of meropenem-non-susceptible P. aeruginosa were included in the study. MICs of antimicrobials were determined by the gradient diffusion method. Results: Overall susceptibility rates for C/A and C/T were 83.3% and 82.4%, respectively. Both C/A and C/T had better activity than any one of the three anti-pseudomonal beta-lactams. According to the MIC50 values, C/T was the most potent agent against isolates. Although the susceptibility rates of isolates to C/T and C/A were similar, C/T (MIC50, 1 mg/mL) was four-fold more potent than C/A (MIC50, 4 mg/mL). The MIC50 values of C/A and C/T for the isolates that were non-susceptible to three beta-lactams were significantly higher than those for isolates that were non-susceptible to zero, one or two beta-lactams. Also, the C/A MIC50 value for the isolates that were non-susceptible to two beta-lactams was higher than that for isolates which were non-susceptible to one beta-lactam. Conclusions: C/A and C/T showed good activity against meropenem-non-susceptible P. aeruginosa isolates. However, resistance to these agents was not uncommon among these isolates. The overall beta-lactam susceptibility profile of isolates seems to have an effect on the probability of susceptibility to C/A and C/T. Antimicrobial susceptibility testing should be performed for C/A and C/T if these agents are considered for treatment of infections caused by meropenem-non-susceptible P. aeruginosa. (C) 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd.Item Prevention of Candida biofilm formation over polystyrene by plasma polymerization technique(2020) Kaleli-Can, Gizem; Hortac-Istar, Elvan; Ozguzar, Hatice Ferda; Mutlu, Mehmet; Mirza, Hasan Cenk; Basustaoglu, Ahmet; Gocmen, Julide Sedef; 0000-0002-8853-3893; 0000-0002-2571-0637; F-1232-2015; AAI-8926-2021This work investigates the antifungal effect of plasma polymer films produced by low-pressure RF-generated plasma system using acrylic acid, 2-hydroxyethyl methacrylate, and diethyl phosphite (DEP). Unmodified and plasma-modified polystyrene (PS) microplate wells were tested by 30 biofilm-positive Candida spp. isolated from blood samples and two control strains using a quantitative plaque assay method. Regardless of the precursors and plasma parameters, biofilm formation was inhibited for all plasma-modified microplate wells. The most significant anti-biofilm effect was observed on PS modified by DEP at 90 W plasma power with the inhibition of all Candida species' biofilm formation.Item Comparison of Antimicrobial Susceptibilities of Escherichia coli Isolated From Urinary Cultures of Different Patient Groups: A University Hospital Experience(2020) Mirza, Hasan Cenk; Sancak, Banu; F-1232-2015Objective: Our objective was to investigate the antimicrobial susceptibilities of Escherichia coli isolated from urinary cultures in Central Laboratory of Hacettepe University Faculty of Medicine Hospital and to examine the differences between antimicrobial susceptibilities of E. coli isolated from different patient groups. Methods: E. coli isolated from urinary cultures between January 1, 2017 and April 30, 2018 were included in our study. Automated systems, i.e. VITEK (R) 2 Compact (bioMerieux, Marcy l'Etoile, France) and BD Phoenix (Becton Dickinson, Sparks, MD, USA) and disk diffusion test were used for the determination of antimicrobial susceptibilities. The patients from whom the bacteria were isolated were divided into groups according to age (<18 years, 18-64 years, and >64 years), gender and patient care (outpatients/inpatients). Results: The highest susceptibility rates were observed for carbapenems (>99%), fosfomycin (98.5%), nitrofurantoin (98.3%) and amikacin (94.2%), whereas the highest resistance rates were observed for ampicillin (61.3%) and amoxicillin-clavulanate (37.5-45.7%). Antimicrobial resistance rates of isolates from patients aged 65 years and over were higher than those of patients in other age groups, with the exception of piperacillintazobactam, amikacin and ertapenem. The resistance rates of isolates belonging to male patients were higher than those belonging to female patients for all antimicrobials. Also, the resistance rates of isolates belonging to inpatients were higher than those belonging to outpatients for all antimicrobials. When the rates of extended-spectrum beta-lactamase (ESBL)-producing E. coli from different age groups were compared, the highest rate (34.2%) was observed among the isolates from patients aged 65 years and over. The rates of ESBL-producing E. coli from males (33.9%) and inpatients (36.3%) were higher than those from females (23.8%) and outpatients (23.3%), respectively. Conclusions: Antimicrobial susceptibilities of E. coli isolates may vary among different patient groups. Demographic features of patients may guide for selecting the antimicrobials for empiric treatment of urinary tract infections.