Abstract :
P. aeruginosa was cultured on nutrient agar containing different antibiotics,the growth and pigment of bacterial colonies were treated. Azithromycin killed the bacteria on low concentration,colonies of P. aeruginosa treated with Ampicillin,Amoxycillin,and Cefixime appeared light green .Cephalexin and Azithromycin led to formation of light green-yellow colonies,while Doxycillin ,and Clindamycin appeared green ,but there was slight change in colonies color.The pigment(pyocyanin) was extracted from the untreated cells of bacteria and its effect as antibiotic used against many different pathogenic bacteria have been studied,the pigment inhibited E. coli, Acinetobacter,Staphylococcus auraus ,and Streptococcus pneumoniae but not Klebsiella pneumoniae ,and Proteus vulgaris