Background and aim: Pseudomonas putida is a non-capsulated, rod-shaped, oxidative, gram-negative Bacterium. The aim of the study was to isolate the pathogenic P. putida from a cow with respiratory infection and to evaluate pharmacodynamics indices of cinnamon oil against isolated bacteria in order to determine its the in vitro antibacterial efficacy for the first time in Iraq. Materials and methods: divided into two parts: first part involved the isolation and identification of pathogenic P. putida from cow with respiratory infection, swab samples were cultured on different media and examined microscopically. Results: The isolates were identified based on the production of pyoverdine dye on nutrient agar, beta-hemolysis on blood agar and pale-mucoid on MacConkey agar, the identification was further confirmed using the VITEK 2 system. The second part evaluated the in vitro antibacterial activity of cinnamon oil against bacterium, the minimum inhibitory concentration was about (0.5 mg/mL) and minimum bactericidal concentration was approximately (0.1 mg/L), the sensitivity test demonstrated increasing inhibition zones with higher concentration of extract. Time-kill experiments revealed a complete lysis after 60 minutes, while 50% of bacterial cells were lysed with 10 minutes at 4× MIC. Conclusions: intracellular components were released in a concentration- and time-dependent manner by UV spectrophotometry indicating membrane disruption.
