Study for antibacterial activity of Fluoroquinolone-loaded non-ionic surfactant vesicles against Fluoroquinolone resistant staphylococcus biofilms forming bacteria / Nehal Mohamed Saleh Mohamed ; Supervised Mohamed Abdelhalim Ramadan , Mona Tawfik Kashef , Nouran Hamed Assar

Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Purpose: The threat of Staphylococcus aureus antimicrobial resistance is increasing worldwide. Niosomes are new drug delivery system that enhances the antimicrobial potential of antibiotics. We hereby set to evaluate the antimicrobial and antibiofilm activity of ciprofloxacin-loaded niosomes. Methods: The antimicrobial susceptibility of clinical S. aureus isolates (n=59) was determined by the Kirby-Bauer disk diffusion method. Their biofilm formation activity was tested by Christensen{u2019}s method, and the presence of icaA and icaD genes was detected by the polymerase chain reaction (PCR). Two ciprofloxacin-loaded niosomal formulations were prepared by the thin-film hydration method, and their minimum inhibitory concentrations (MIC) were determined by agar dilution method against ciprofloxacin-resistant and biofilm-forming isolates (n=24). Their ability to inhibit biofilm formation and eradicate already-formed biofilms was evaluated and further confirmed by scanning electron microscopy. Non-synonomous mutations in quinolone resistance determining regions of S. aureus isolates were detected by PCR.Results: Most isolates were methicillin (47/59) and ciprofloxacin- resistant (45/59). All except two isolates were capable of biofilm production. Results of PCR revealed that 58.3 % of S. aureus isolates possessed both icaA and icaD genes. Niosomal preparation I reduced the ciprofloxacin MIC by two-fold in four isolates only, while preparation II reduced ciprofloxacin MIC of most isolates by eight- to 32-fold with three isolates becoming ciprofloxacin susceptible

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