Pasteur Institute of Iran

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Introduction: Antibiotic resistance, especially in Gram-negative uropathogens such as Escherichia coli, is the main barrier to treat urinary tract infection (UTI). In recent years, the dramatically increased resistance of E. coli to quinolones, a group of widely used antibiotics, has become a significant concern. Methods: In this descriptive cross-sectional study, we collected 261 E. coli isolates from the urine and stool samples of patients, referred to or hospitalized at Loghman hospital in Tehran, Iran, with either acute or recurrent UTI. The susceptibility testing for quinolones was performed by the disk diffusion method according to the recent protocols. Results: The frequency of resistant E. coli isolates was higher against nalidixic acid than ciprofloxacin and norfloxacin (67.8% vs. 48.7% and 44.1% respectively). When comparing acute and recurrent phases of UTI, in the urine samples, no significant difference was seen in the frequency of resistant isolates against nalidixic acid and norfloxacin, while this frequency against ciprofloxacin was significantly higher in recurrent UTI (68% vs. 48.2%). However, in the stool samples, the frequency of resistant isolates against nalidixic acid was higher in recurrent UTI (77.1% vs. 55.7%), while no significant difference was seen against ciprofloxacin and norfloxacin in these phases. Conclusion: Regarding the antibiotic type and frequency of the administration, the resistance pattern of E. coli to quinolones seems to differ in acute and recurrent phases of UTI.

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Introduction: Staphylococcus aureus is a source of nosocomial infections and one of the significant concerns in patients with indwelling devices. Lysostaphin is a bacterially produced endopeptidase with a unique activity on S. aureus. Plasma, the fourth state of the material, consists of charged ions, free electrons, and activated neutral species. Biomedical applications of cold plasma are rapidly growing due to its capacity to treat heat-sensitive objects such as polymeric materials and biological samples. It activates surfaces by etching them to stabilize proteins. The direct effect of cold atmospheric plasma on the eradication of microorganisms have been investigated. However, there is no report on immobilizing antibiotic agents. Methods: In this study, the lysostaphin protein was expressed and purified using Ni-NTA column, then the purified enzyme was immobilized on glass surfaces pretreated with cold atmospheric plasma for 150 s, 200 s, and 300 s. The antimicrobial activity of immobilized lysostaphin on S. aureus was approved by in vitro analysis. Results: The 300 s plasma treatment confirmed to be the best time arrangement for more lysostaphin immobilization, shown by Atomic Force Microscopy. Conclusion: Our results showed that passive adsorption to the treated surface does not affect the structure and subsequent antimicrobial function of the recombinant protein compared to the standard proteins.