Concern over the development of antibiotic resistance is increasing among healthcare providers who offer their services globally. This study aims to detect the resistance pattern of some widespread microorganisms by calculating their zone of inhibition against some typically prescribed broad spectrum antibiotics. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were among the prevalent clinical isolates that were gathered from a  pathological laboratory in Karachi. Additionally, the pattern of their resistance to various broad spectrum antibiotics such as Ciprofloxacin (5µg), Amoxicillin (25µg), Gentamycin (10µg), Cefotaxime (30µg), Ceftriaxone (30µg), and Clarithromycin (15µg) was investigated by using disc diffusion method. The results revealed that all three selected strains were resistant to all the antibiotics in spite of the fact that zones of inhibition were observed in the antibiotics ciprofloxacin and gentamycin against pseudomonas aeruginosa strains. 

Keywords: Escherichia coli, Staphylococcus aureus, Pseudomonas, Staphylococcus aureus clinical isolates.