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    Development of besifloxacin HCl loaded nanofibrous ocular inserts for the treatment of bacterial keratitis: In vitro, ex vivo and in vivo evaluation
    (Elsevier, 2020) Polat, H. Kerem; Pehlivan, Sibel Bozdag; Ozkul, Ceren; Calamak, Semih; Ozturk, Naile; Aytekin, Eren; Firat, Aysegul
    Novel drug delivery systems have emerged to treat bacterial keratitis, an acute infection of the cornea. In this study, besifloxacin HCl loaded insert formulations were designed and investigated in vitro, ex vivo and in vivo for the treatment of bacterial keratitis. Besifloxacin HCl (BH) or BH-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) complex containing poly(caprolactone)/polyethylene glycol (PLC/PEG) fibrous inserts were prepared with an electrospinning method. These fibrous inserts were coated with mucoadhesive polymers such as sodium alginate (SA) or thiolated sodium alginate (TSA). Developed inserts compared to commercially available drug and it was found that coating of the insert surfaces with SA and TSA, increases bioadhesion of the formulations. Insert formulations showed a burst release in the first 2 days followed by a slow-release profile. Ex vivo transport studies showed that HP-beta-CD possessed a drug delivery level close to the commercial drug. Both TSA coated inserts as well as inserts containing HP-beta-CD-drug complex were effectively reducing bacterial keratitis in rabbit eyes upon single-dose application compared to multiple dosing with the commercial drug. Consequently, TSA coated inserts as well as the inserts containing HP-beta-CD-drug complex, may be potential alternatives to conventional market product by reducing the application frequency in the clinic leading to increased patient compliance.
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    Exploring bisbenzimidazole-chalcone hybrid compounds: Dual-action as antibacterial agents targeting biofilm formation and E. coli DNA gyrase inhibition
    (Elsevier, 2025) Adal, Ercan; Oksuz, Zehra; Ozkul, Ceren; Nigiz, Seyma; Alagoz, M. Abdulah; Dogen, Aylin; Simsek, Rahime
    The emergence of antibiotic-resistant pathogens has reduced the efficacy of current antimicrobial therapies, emphasizing the need for new therapeutic agents. This study presents the design, synthesis, and evaluation of bisbenzimidazole-chalcone hybrid compounds as potential antimicrobial agents. These compounds were tested for their antimicrobial activity against eleven common pathogens, as well as their ability to inhibit biofilm formation and eradicate preformed biofilms in Escherichia coli. Compounds EA1, EA3, EA4, and EA5 demonstrated antibacterial activity against E. coli comparable to ampicillin (31.25 mu g/mL) and outperformed the other tested compounds. Notably, EA4 and EA5 inhibited biofilm formation at sub-MIC concentrations and effectively eradicated preformed biofilms, as confirmed by the crystal violet assay. The synergistic effects of the most active compounds in combination with ampicillin were assessed using checkerboard synergy testing, with all combinations showing 'indifference' effects. Further analysis of the most potent compounds against E. coli ATCC 25,922 included the inhibition of DNA gyrase using E. coli DNA gyrase and a plasmid-based relaxed DNA kit. Molecular docking and molecular dynamics simulations were conducted to elucidate the binding modes and stability of these compounds within E. coli DNA gyrase enzymes. EA4 exhibited significant affinity for DNA gyrase B subunit (docking score: -4.026 kcal/mol, average RMSD value: 4.4 & Aring;), while EA5 displayed dual affinity for both DNA gyrase B subunit and DNA gyrase A subunit (docking scores: -6.944 and -3.432 kcal/mol, respectively), maintaining stable interactions in the active sites during simulations (average RMSD values of 3.2 & Aring; and 3.1 & Aring;). These results highlight the potential of bisbenzimidazole-chalcone hybrids as promising antibacterial agents, particularly in their dualtargeting capabilities against biofilm formation and DNA gyrase inhibition.
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    Molecular characterization and antibiotic resistance of clinical Bacteroides and related genera from a tertiary care center in Turkiye
    (Elsevier Sci Ltd, 2024) Demir, Mervenur; Soki, Jozsef; Tanriverdi, Elif Seren; Ozkul, Ceren; Mahmood, Bakhtiyar; Otlu, Baris; Hazirolan, Gulsen
    Objectives: This study was conducted to measure the prevalence of antibiotic resistance, and corresponding resistance genes among Bacteroides and related genera in a tertiary hospital. Methods: We examined 138 clinical strains of Bacteroides, Phocaeicola and Parabacteroides species isolated between July 2018 and June 2022. Antibiotic susceptibility tests were conducted using agar dilution. The bft gene and antibiotic resistance genes were targeted by real-time PCR. Results: Resistance rates of all strains against ampicillin, cefoxitin, piperacillin-tazobactam, meropenem, imipenem, clindamycin, metronidazole, and tigecycline were 97.8 %, 28.3 %, 11.6 %, 7.9 %, 5.1 %, 47.8 %, 0 % and 4.3 %, respectively. Non-fragilis Bacteroidales spp. (NFB) exhibited lower susceptibility rates compared to B. fragilis for cefoxitin, clindamycin, and piperacillin-tazobactam. The prevalence of meropenem resistance was higher in B. fragilis (15.5 %) than in NFB (0 %). Among all strains, the rates of cepA, cfxA, cfiA, ermF, ermG, ermB, nim, linA, mefA, msrSA, tetQ, tetX, tetX1 and bft genes were 42.8 %, 44.9 %, 8.7 %, 44.2 %, 10.9 %, 2.2 %, 0.7 %, 29.0 %, 17.4 %, 7.2 %, 76.1 %, 8.0 %, 37.7 % and 16.7 %, respectively. In five B. fragilis strains, insertion sequences [IS1187(n = 3), ISBf6(n = 1), IS612B(n = 1)] were detected in the upstream region of cfiA. NimE with ISBf6 on plasmid pBFM29b was detected in one B. fragilis strain, intermediate to metronidazole (MIC = 16 mu g/mL). ErmF was the most abundant gene responsible for clindamycin resistance. TetQ and tetX1 genes exhibited a higher frequency in strains that were not susceptible to tigecycline (MIC >= 8 mu g/ml). Conclusions: Monitoring the resistance trends of Bacteroides and related genera is crucial given the observed resistance to all classes of antibiotics and the presence of various resistance mechanisms.