iajabmsIAJABMSIAJABMS2709-3298https://doi.org/10.47310/iajabms.2021.v02i01.017Bacterial Isolates and Their Ability to Produce HemolysinAliHusseinHumaidanSample collection 180 collect samples were collected equally between males and females, from patients attending consulting clinics and suffering from UTI for different ages and both sexes. Urine samples were collected in sterile and sealed plastic tubes and then the tubes were marked with numbers and urine samples were transferred to the laboratory within a period not exceeding 30 minutes. Staphylococcus aureus is one of the most important and most common pathogenic species for humans. Species belonging to the genus are responsible for a wide range of diseases such as boils, impetigo and wound abscesses resulting from surgery. Pathogenicity and its ability to invade the host's tissue and spread in it is due to its possession of many virulence factors. Genetic elements called plasmids are in the form of circular ring structures of a double strand of DNA. They have the ability to be inherited steadily and spread widely in the cells of different bacteria. PCR technique was used to investigate the hemolysin gens possessed by bacterial isolates. The HLA gene is the main virulence factor encoding its pathogenicity. It is active against a group of host cells, including red blood cells. It gives an indication of the role of these genes in the pathogenesis of Staphylococcus aureus among hospitalized patients. Hemolysin is one of the most important virulent agents for bacteria that cause infections outside the intestine. The hemolysin enzyme breaks down the membranes of the red blood cells by making small holes in their membranes. It provides the bacteria with the iron they need, and as a result of its toxicity to the cells, leads to the destruction of the host's kidney tissues.