Spirulina as many other cyanobacteria species have the potential to produce a large number of antimicrobial substances, so they are considered as suitable organisms for exploitation as biocontrol agents of  pathogenic bacteria. In the present study, antimicrobial activity of Spirulina platensis phenolic acid extract was investigated against pathogenic bacteria which cause sepsis in neonates. The algal extract was tested in vitro for their antibacterial effect against (Bacillus cereus, Enterococcus casseliflavus, Kocuria kristinae, Staphylococcus aureus, Alloiococcus otitis, Rosemonas gilardii,and Aeromonas hydrophila) using paper disc diffusion method and observed all these bacteria showed inhibition in growth by this extract. The bioactive components of Spirulina platensis have been assessed using GC-MS analysis. Eleven compounds in phenolic acid extract of the alga were identified. Bis(2-ethylhexyl) Phthatate (25.899%), Palmitic acid (14.263%) ,were the most prevailing compounds in phenolic acid extract.