Person: DAMAR ÇELİK, DAMLA
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DAMAR ÇELİK
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DAMLA
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Publication Metadata only Isolation, characterization, and comparative investigation of novel bacteriophages as phage therapy candidates(2022-06-30) DAMAR ÇELİK, DAMLA; Özbek Çelik B., Damar Çelik D.Publication Metadata only Synergy between Pelargonium endlicherianum essential oil and conventional antibiotics againstNeisseria meningitidis and Haemophilus influenzae(ELSEVIER, 2022) DAMAR ÇELİK, DAMLA; Dumlupinar, Berrak; Celik, Damla Damar; Karatoprak, Gokce Seker; Gueur, Umran SoyogulThis study investigated the bactericidal effects of the essential oil of Pelargonium endlicherianum in combina-tion with four antibiotics commonly used in the treatment of bacterial meningitis (penicillin, ampicillin, cip-rofloxacin, and gentamicin) against the meningitis causative pathogens Neisseria meningitidis and Haemophilus influenzae. The phagocytic effects of these combinations were also tested against human leuko-cyte cells. The bactericidal effect of P. endlicherianum essential oil (PEO) and antibiotic combinations was dynamically detected by time-kill assay. The function of PEO and antibiotic in permeating outer membrane barriers, when used singly or in combination, was analyzed by UV spectrophotometer. The interactions between antibiotic and essential oil were calculated according to the fractional inhibitory concentration (FIC) index. While a synergistic effect of the ciprofloxacin + PEO combination was determined on N. meningitidis (FIC< 0.5), an additive effect was observed on H. influenzae (FIC= 1). Combined use of PEO with gentamicin showed a synergistic effect against N. meningitidis and H. influenzae (FIC < 0.5). The antimi-crobial effect of the penicillin + PEO combination was higher than that of penicillin + PEO used alone. The ampicillin + PEO combination had a synergistic effect on N. meningitidis and an additive effect on H. influen-zae. The results of our study showed that the essential oil increases membrane permeability activity and also has phagocytic activity in human leukocyte cells. Combining antibiotics with essential oils that target resis-tant bacteria may open up new options in combating microbial resistance. (c) 2021 SAAB. Published by Elsevier B.V. All rights reserved.Publication Open Access In vitro activities of ceftazidime/avibactam alone or in combination with antibiotics against multidrugresistant Stenotrophomonas maltophilia isolates(2023-03-30) DAMAR ÇELİK, DAMLA; Damar Çelik D., Çakmak S. M., Mataracı Kara E., Sümbül B., Özbek Çelik B.Objectives: Infections caused by multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) are a growing problem because of the limited options for treatment. The number of antimicrobials that are currently being developed is still insufficient to control this global threat. Combination therapies of antibiotics with different antimicrobial mechanisms have been proposed as the best options for treating MDR A. baumannii infections. The objective of this study was to investigate the in-vitro effectiveness of ceftazidime/avibactam alone or in combination with antibiotics against MDR A. baumannii isolates using time-kill assays. Methods: Forty clinical MDR strains were screened, and minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of ceftazidime/avibactam, colistin, levofloxacin, meropenem, tigecycline, and tobramycin were determined by microbroth dilution method. The in-vitro synergistic activities of ceftazidime/avibactam with antibiotic combinations were determined by timekill assays at 1 MIC and 4 MIC against five MDR A. baumannii isolates. Results: Based on MIC results, all isolates of A. baumannii were resistant to ceftazidime/avibactam, except for AB-5. All isolates were found to be resistant to meropenem and levofloxacin. At 4 MIC, all of the tested antibiotics showed bactericidal effect (3 log10killing). The synergistic activities of ceftazidime/avibactam + colistin, ceftazidime/avibactam + tobramycin and ceftazidime/avibactam + tigecycline combinations at 1 MIC were observed against studied 5/5, 4/5 and 4/5 strains, respectively. Furthermore, all of the tested combinations at 4 MIC were additive at 24 h. No antagonism was observed. Conclusions: The findings of this study suggest that a significant bactericidal effect was seen with all tested combinations. These findings present significant implications for antibiotic choice for the treatment of infections caused by MDR A. baumannii. © 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.Publication Metadata only Synergic potential of Pelargonium endlicherianum Fenzl. Essential oil and antibiotic combinations against Klebsiella pneumoniae(ELSEVIER, 2020) GÜRBÜZ, BURÇAK; Dumlupinar, Berrak; Karatoprak, Gokce Seker; Celik, Damla Damar; Gurer, Umran Soyogul; Demirci, Betul; Gurbuz, Burcak; Rayaman, Pervin; Kurtulus, Eda MerveIn this study we investigated antimicrobial activity against Klebsiella pneumoniae and the phagocytic functions of human leukocyte cells as revealed in an in vitro experimental model combining cefepime and gentamicin with Pelargonium endlicherianum Fenzl. essential oil treatments. The bactericidal effects of this essential oil and antibiotic combinations were dynamically detected by time-kill assay. To examine the function of this essential oil and antibiotics in permeating outer membrane barriers when used singly or in combination, a UV spectrophotometer was used, and morphologic images were captured by scanning electron microscopy. The antibacterial activity of the essential oil and antibiotics was assessed using broth microdilution and agar well diffusion. The combined effects of the essential oils of P. endlicherianum and gentamicin and cefepime were evaluated by means of the checkerboard method against K. pneumoniae. In the assays, fractional inhibitory concentration (FIC) values were calculated to characterize the interactions between the combinations. In the combinations of essential oil and antibiotics, the sensitivity of the bacteria to antibiotics increased and the antibiotics had a synergistic effect, and the antibacterial effect on the microorganisms increased. The cefepime + essential oil pair tested showed a synergistic effect (FIC <= 0.5), but the gentamicin + essential oil pair did not (FIC > 0.5-4.0). Thus, the cefepime + essential oil pair has been found to exhibit a synergistic effect against K. pneumoniae compared to the gentamicin + essential oil pair. According to the results obtained here, the combined use of essential oils with antibiotics can be applied as a treatment strategy to reduce the use of antibiotics, reduce side effects, and possibly reverse antibiotic resistance to these microorganisms in light of the increase in multiple antibiotic resistance. (c) 2020 SAAB. Published by Elsevier B.V. All rights reserved.Publication Metadata only Isolation and charecterization of bacteriophage effective against Escherichia coli and its antibiofilm activitiy(2023-06-01) DAMAR ÇELİK, DAMLA; Damar Çelik D., Özbek Çelik B.