Browsing by Author "Uskudar-Guclu, Aylin"

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Antibacterial, Antifungal and Antibiofilm Activity of Methylglyoxal: A Phytochemical from Manuka Honey Metilglioksalin Antibakteriyel, Antifungal ve Antibiyofilm Aktivitesi: Manuka Balindan Bir Fitokimyasal
(2021) Uskudar-Guclu, Aylin; Simsek, Derya; Ata-Vural, Ilgin; Unlu, Sezin; Basustaoglu, Ahmet; 0000-0002-1872-028X; AAU-6196-2020
Introduction: Honey has been known for its ability to promote wound healing for a long time. It is utilized for several skin and soft tissue infections caused by a wide range of microorganisms due to its antimicrobial property. Methylglyoxal (MGO), the unique antibacterial compound contained by Manuka honey, is believed as the reason for the antimicrobial activity of Manuka honey. This study aims to identify the antibacterial, antifungal and anti-adherent activity of MGO in changing concentrations and determine the viable number of bacteria and fungi in biofilm after the treatment of MGO. Materials and Methods: Antibacterial and antifungal activity of MGO was determined by broth microdilution method for identifying minimum inhibitory and bactericidal and fungicidal concentrations (MIC, MBC and MFC, respectively). Percentage of biofilm formation inhibition and the number of viable microorganisms in biofilm after the MGO treatment was determined by the colony-forming unit method. Results: Minimum inhibitory concentration values for the bacterial strains ranged from 0.0078 to 0.125010 (v/v), while MBC ranged from 0.0312 to 2010 (v/v). Among fungi, MIC and MFC values were higher than those for tested bacterial strains; MIC values ranged from 0.0156 to 1010 (v/v), while MFC values ranged from 0.0625 to 2010 (v/v). Methylglyoxal was able to prevent biofilm formation in the all tested biofilm forming isolates. Number of viable bacteria, even in the sub-inhibitory doses of MGO, reduced remarkably. Conclusion: Unique compound of Manuka honey, MGO, exerts significant antimicrobial and antibiofilm activity against clinically important strains of both bacteria and fungi which may be utilized for the search of promising alternatives for antibiotics and may lead to combat antibiotic resistance.
Arising Prevalence of OXA-48 producer Escherichia coli and OXA-48 with NDM co-producer Klebsiella pneumoniae Strains
(2019) Uskudar-Guclu, Aylin; Guney, Mustafa; Sig, Ali Korhan; Kilic, Selcuk; Baysallar, Mehmet; AAU-6196-2020
Background/aim: This prospective study aimed to determine the presence of the most common carbapenemase genes, blaOXA-48, blaKPC, blaIMP, blaVIM and blaNDM on carbapenem resistant clinical K.pneumoniae and E.coli isolates. Materials and methods: Isolates were selected according to EUCAST guideline; gradient test and disc diffusion with both meropenem and ertapenem discs. Resistance rates of these isolates to other antimicrobial agents were also examined by disc diffusion method. Carbapenem resistance gene were investigated by using Real-Time PCR. Results: A total of 3845 E. coli and 1689 K. pneumoniae isolates from clinical samples between January 2015 and April 2017 were evaluated. The 419 isolates were found as carbapenem resistant but only the first resistant isolate (n=155; 126 K. pneumoniae and 29 E.coli) of each patient were included. Carbapenem resistant isolates were most frequently isolated from intensive care units (48.8%). Colistin was the most effective antibiotic (91.0%). The 121 (78.1%) of the tested isolates were positive for OXA-48 (103 K. pneumoniae and 18 E. coli) and 9 K. pneumoniae carrying blaNDM were also positive for blaOXA-48. VIM, IMP and KPC type carbapenemases were not detected in any isolates. Conclusion: Carbapenem-resistant pathogens have been shown to be able to develop resistance mechanisms with more than one carbapenemase encoding gene.
Co-existence of Multiple Resistance Mechanisms in Clinical Isolates of Carbapenem-Resistant Pseudomonas Aeruginosa
(2022) Uskudar-Guclu, Aylin; Mirza, Hasan Cenk; Unlu, Sezin; https://orcid.org/0000-0002-1872-028X; https://orcid.org/0000-0002-8853-3893; AAU-6196-2020; F-1232-2015
Introduction: Multidrug resistance phenotype of Pseudomonas aeruginosa utilizes several resistant mechanisms to overcome the action of antibiotics. This phenotype is caused by several resistance mechanisms or a combination of thereof. This study aimed to evaluate various resistance mechanisms by phenotypic methods. Materials and Methods: Carbapenem-resistant P. aeruginosa were included in this study. Antimicrobial resistance mechanisms such as efflux pump activity, reduced outer membrane permeability (OMP), various beta-lactamase activities, and biofilm formation ability of clinical P aeruginosa isolates were determined by phenotypic methods. Results: Of the P aeruginosa isolates, 33.7% (n= 33/98) had a positive efflux pump activity. The co-existence of positive efflux pump activity and Metallo beta-lactamase (MBL) production was detected in 30.3% (10/33) of the isolates. In 34.7% of the clinical P. aeruginosa isolates, reduced OMP was detected and 70.6% of them were also biofilm producers. Totally 21.4% (21/98) of P aeruginosa isolates were evaluated as extended-spectrum beta-lactamase (ESBL) positive. AmpC beta-lactamase was detected in 15.3% (n= 15/98) of the clinical P. aeruginosa isolates. MBL activity was detected in 33.7% (n= 33/98) of the clinical P. aeruginosa isolates. Of the MBL-positive isolates, 69.7% were biofilm producers. The co-existence of MBL and reduced OMP was detected in 36.4% (n= 12/33). Conclusion: High resistance of P. aeruginosa was attributed to several resistance mechanisms or a combination of thereof. This infections caused by multidrug-resistant (MDR) P. aeruginosa are difficult to treat due to the co-existence of different resistance mechanisms.
The Impacts of 13 Novel Mutations of SARS-Cov-2 on Protein Dynamics: in Silico Analysis From Turkey
(2022) Unlu, Sezin; Uskudar-Guclu, Aylin; Cela, Isli; 37520163
SARS-CoV-2 inherits a high rate of mutations making it better suited to the host since its fundamental role in evolution is to provide diversity into the genome. This research aims to identify variations in Turkish isolates and predict their impacts on proteins. To identify novel variations and predict their impacts on protein dynamics, in silico methodology was used. The 411 sequences from Turkey were analysed. Secondary structure prediction by Garnier-Osguthorpe-Robson (GOR) was used. To find the effects of identified Spike mutations on protein dynamics, the SARS-CoV-2 structures (PDB:6VYB, 6M0J) were uploaded and predicted by Cutoff Scanning Matrix (mCSM), DynaMut and MutaBind2. To understand the effects of these mutations on Spike protein molecular dynamics (MD) simulation was employed. Turkish sequences were aligned with sequences worldwide by MUSCLE, and phylogenetic analysis was performed via MegaX. The 13 novel mutations were identified, and six of them belong to spike glycoprotein. Ten of these variations revealed alteration in the secondary structure of the protein. Differences of free energy between the reference sequence and six mutants were found below zero for each of six isolates, demonstrating these variations have stabilizing effects on protein structure. Differences in vibrational entropy calculation revealed that three variants have rigidification, while the other three have a flexibility effect. MD simulation revealed that point mutations in spike glycoprotein and RBD:ACE-2 complex cause changes in protein dynamics compared to the wild-type, suggesting possible alterations in binding affinity. The phylogenetic analysis showed Turkish sequences distributed throughout the tree, revealing multiple entrances to Turkey.
An Investigation into Bacterial Bloodstream Infections and Antibiotic Resistance Profiles in a Tertiary Hospital for a Ten-Year Period
(2020) Mataj, Valbona; Guney, Mustafa; Sig, Ali Korhan; Uskudar-Guclu, Aylin; Albay, Ali; Bedir, Orhan; Baysallar, Mehmet; 0000-0002-1872-028X; 32776752; AAU-6196-2020
Background: Bloodstream infections are one of the major causes of healthcare-associated morbidity and mortality. The present study aims to investigate the prevalence of the microorganisms isolated from blood cultures and to evaluate susceptibilities to antimicrobial agents in a tertiary center, Gulhane Training and Research Hospital, Ankara, Turkey. Methods: Blood cultures (BCs) were incubated in BACTEC/9050 (Becton Dickinson, USA) (2007 - 2015) and BacT/ALERT (bio-Merieux, France) (2014 - 2016) automated systems. Phoenix (TM) 100 system (Becton Dickinson, USA) (2007 - 2014), MALDI-TOF MS (Bruker, USA) (2015 - 2016) and conventional techniques were used for the identification of isolated microorganisms. According to CLSI (2007 - 2014) and EUCAST (2015 - 2016) criteria, Kirby-Bauer disc diffusion method, Phoenix (TM) system, and broth microdilution were applied for antimicrobial susceptibility testing. Two five-year periods were statistically compared regarding antibiotic resistance. Results: From the overall evaluated 31,380 BCs, 7,367 cultures (23.5%) were positive, excluding 503 BCs (6.4%), which were interpreted as contamination. Of 7,367 isolated microorganisms, 3,680 (50.0%) were gram-negative, 3,303 (44.8%) were gram-positive bacteria, and 384 (5.2%) were fungi. Coagulase-negative staphylococci (CoNS) were predominantly isolated (n = 2,075; 28.2%) among gram-positives. E.coli (n = 978; 13.3%) was the most frequently isolated gram-negative species. Between the first and the last five-year period, three genera (Enterococcus spp., Acinetobacter spp., Streptococcus spp.) showed significant differences when isolated, and only Enterococcus spp. showed increased isolation rates. In total, 90.3% of CoNS and 32% of S. aureus were methicillin-resistant. Only 75 strains of Enterococcus spp. (12.1%) were vancomycin-resistant. ESBL was detected in 40.6% of E. coli and 30.7% of Klebsiella spp. isolates. Carbapenem resistance showed a significant increase, particularly in K. pneumoniae (> 20%). Conclusions: The findings suggest that there was a threatening condition in antimicrobial resistance rates, especially for some antimicrobials between two periods. Although antimicrobial resistance is usually associated with MRSA, carbapenem resistance, ESBL, and VRE, the problem is far beyond these definitions, consisting of not just medicine, but also commercial companies, food industry, veterinarians, and other areas.