Diploma Thesis from the year 2017 in the subject Medicine - Pharmacology, Pharmacy, grade: 4,0, University of Veterinary Medicine Budapest, course: Veterinary Medicine, language: English, abstract: This study is concerned with a comparison between the antibiotic agents marbofloxacin and gatifloxacin in fluoroquinolones and their efficiency in the treatment of Pseudomas aeruginosa. Pseudomonas aeruginosa, a major cause of extremely dangerous nosocomial infection, has become problematic in both human and veterinary medicine due to it s resistance to multiple drugs. Several experiments within research concerning development of bacterial resistance in P.aeruginosa have been reported. Imported resistance mechanism of P.aeruginosa is linked to mutations of DNA gyrase, the fluoroquinolone target, as well as overexpression of efflux pump. The worldwide, frequent use of different antibiotics contributes to a significant reduction in the bactericidal and bacteriostatic effect of different antibiotics. P.aeruginosa is represented as a ubiquitous organism present in environmental surroundings, and can be isolated from various living sources, including plants, animals, and humans. The ability of P. aeruginosa to survive on minimal nutritional requirements and to tolerate a variety of physical conditions has allowed this organism to persist in both community and hospital settings. Within hospitals, P. aeruginosa can be isolated from a variety of sources such as respiratory therapy equipment, antiseptics, soap, sinks, mops and medicines. As resistance to antibiotic is a relevant topic within today s global health care concerning both human and veterinary medicine, the curiosity for this expanding health problem resulted in a 9 days serial passage of P.aeruginosa in broth, investigating the susceptibility to marbofloxacin and gatifloxacin. The aim in this study was, therefore, to demonstrate that 4th generation fluoroquinolones appears to be more beneficial and efficient in the treatment of P.aeruginosa infections, than 2nd generation fluoroquinolones. In other words, the aim is to prove that gatifloxacin is of better use than marbofloxacin, due its antibiotic activity.