Escherichia coli (E. coli), Pseudomonas aeruginosa, and Staphylococcus aureus are three bacteria of significant importance in microbiology and healthcare. E. coli, a gram-negative bacterium, resides in the human intestine and serves as a model organism for genetic research. However, certain pathogenic strains can cause gastrointestinal and urinary tract infections. Pseudomonas aeruginosa, another gram-negative bacterium, is highly adaptable and often found in various environments. It poses a challenge due to its antibiotic resistance and causes opportunistic infections, particularly in immunocompromised individuals. Staphylococcus aureus, a gram-positive bacterium, inhabits the skin and mucous membranes and can lead to a range of infections, from skin issues to severe conditions like bloodstream infections. Understanding these bacteria is crucial for managing and preventing associated diseases, including antibiotic-resistant strains.