TR-Dizin İndeksli Yayınlar Koleksiyonu

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    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.
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    Biofilm Formation Research of Coagulase-Negative Staphylococci Isolates' Isolated from Blood and Hand Culture at Nanofilm Covered Micro Plaques by Plasma Polymerization Technique: An Experimental Model
    (2017) Hortac Istar, Elvan; Gocmen, Julide Sedef; Cokeliler, Dilek; Mutlu, Mehmet; Kaleli Can, Gizem; Alparaslan, Sezin; Cetin, Ceren; Kartal, Naz; Ozcelik, Ugur Can; Aycan, Cagri; 0000-0002-4335-6897; 0000-0001-6423-7523; AAP-6138-2021
    Introduction: Coagulase-negative staphylococci (CNS) can protect themselves from the effects of antibiotics by producing biofilms through breeding on biomaterials, medical equipment and devices. It is possible to influence biofilm formation with the aid of various surface modifications. In our study, plasma polymerization method, which is a surface modification technique, was used. The plasma polymerization technique is an environmentally-friendly technique that allows you to modify the nanometer level only at the surface without affecting the stack using the fourth state of the material. The possibility to generate surfaces with different properties (hydrophilic, hydrophobic, biocompatible etc.) by the help of various monomers and gases has made this technique more popular. In this study, the effect of the microplate surfaces modified by three different monomers on the biofilm formation of CNS was investigated. Materials and Methods: A total of 60 isolated CNS isolates from blood and hand cultures were included into the study. As control strains, Staphylococcus epidermidis ATCC 35984, known to be biofilm positive, and S. epidermidis ATCC 12228 which do not form biofilm, were used. Slime formation was determined by the quantitative plaque assay method described by Christensen. In microplates, which were plain or modified by three different monomers, the biofilm formation behavior of all strains was investigated simultaneously and comparatively. Results: There was no difference in biofilm positivity between strains isolated from hand and blood. A total of 71.6% biofilm formation was observed on microplates, which were not coated with plasma technique, and on plasma-modified microplated surfaces, 80% (monomer: 3- mercaptopropionic acid), 65% (monomer: 2-hydroxyethyl methacylate) and 31.6% (monomer: ethylene glycol dimethacylate) biofilm formation was observed, respectively. It was found that ethylene glycol dimethacrylate in three monomers significantly inhibited biofilm formation when compared to other monomers. Conclusion: In recent years CNS, especially S. epidermidis has become the most frequently isolated bacteria in catheter infections and responsible for the 28% of nosocomial bacteremia. The widespread use of prosthetic and permanent devices has been shown as a reason for the increase in the frequency of this effect. In 90% of patients with S. epidermidis bacteremia, there is an intravascular catheter history. Biofilm is an extracellular structure containing water, proteins and carbohydrates and is responsible for the unwanted adhesion of microorganisms to host cells and artificial surfaces. The biofilm mechanism can be altered by the interaction between the material surface and the bacterial surface. In our study, in-vitro results were obtained showing the potential to reduce the risk of biofilm-associated infection by microorganism biofilm formation on modified surfaces with appropriate monomer selection.