Final answer:
Staphylococcus aureus and Pseudomonas aeruginosa are the most common bacteria found in prosthetic joints, forming biofilms that can lead to infections.
Step-by-step explanation:
The bacteria commonly found in prosthetic joints are Staphylococcus aureus and Pseudomonas aeruginosa. These bacteria form biofilms, which are complex colonies of bacteria that exchange chemical signals to coordinate the release of toxins. When biofilms invade implants such as hip or knee replacements, they can cause serious infections.