Pseudomonas aeruginosa gram-negative, bacilli and facultative aerobic, P. aeruginosa cause cystic fibrosis patients, wounds, burns, and immunodeficienct patients, that have many virulence factors such as pyocyanin , cytotoxic ,biofilm formation and motility, Eighty-eight isolates belonging to P. aeruginosa were collected including the 66 clinical isolates obtained from different hospitals in Baghdad and were from different sources and 22 environmental isolates from previous studies of soil near oil fields. Microscopical and cultural characteristics were studied and diagnosed using biochemical tests, VITEC device, their ability to adhere to non-living (Polystyrene), living cell line (A549) and cytotoxicity of bacterial filtrate by MTT method. The results displayed that all isolates belonged to P. aeruginosa. The pigment-forming (pe26 – pc36) isolates and (PE33 – PC31) non-pigment-forming isolates were selected. That all selected bacteria were able to adhere to the Polystyrene and an epithelial carcinoma of lung (A549) was of more than 300 colony formation units in dilution (1:10) ,(1:1000), and (1:10000). The toxicity of the P. aeruginosa filtrate (pc36) isolated from clinical sources and producing pigments was 15.7, 34.5, 44 % at a concentration of 40, 60, 80 % respectively, while the isolate (pc31) that was isolated from clinical sources and non-producing pigment was 28.1, 75.2, 80.9 % at the same concentrations. As for the isolate (pe26),isolated from environmental sources and forming the pigment, the inhibition rate was 38.5, 83.1, 48.8 % at concentrations of 40, 60, 80) % respectively, and the isolate (PE33) that was isolated from environmental sources was 42, 73.4, 74.1 % at concentrations of 40, 60, 80 % respectively. The study will be helpful in evaluating the effect of pigment formation in P. aeruginosa on adhesion.
