In recent years there has been a growing interest in the marine environment as a promising source of new microorganisms with novel bioactive compounds against multi-drug resistant bacteria. The present study aimed to determine the antibacterial activity of marine Bacillus pumilus extract against Gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis as well as Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa and Klebsilla pneumoniae. These bacteria were isolated from field samples using routine isolation methods. A disc diffusion assay was performed to determine the antibacterial effect of B. pumilus extract against the selected pathogens. The extract exhibited a broad inhibitory spectrum against all tested bacteria with inhibitory diameter ranging from 19 to 30 mm. These pathogens were further screened against 10 different antimicrobial discs. The result of antimicrobial susceptibility demonstrated that the tested organisms were resistant to many of the used antimicrobials with MAR index ranging from 0.3-0.6. Moreover, the antibacterial effect of B. pumilus extract was tested using the transmission electron microscope that revealed significant damage in all treated compared to untreated bacteria. These results suggest an antibacterial potential of B. pumilus extract against some pathogenic bacteria comparable to that of commercial antimicrobials and could be possibly used as a promising antibacterial agent.