Final answer:
The most likely organisms to cause septic arthritis in multiple joints at the same time are Staphylococcus aureus and Neisseria gonorrhoeae, which can be diagnosed by testing synovial fluid from the affected joints and treated with appropriate antibiotics.
Step-by-step explanation:
The two organisms likely to cause septic arthritis in two or more joints simultaneously are Staphylococcus aureus and Neisseria gonorrhoeae. These bacteria can cause a rapid onset of moderate to severe joint pain and swelling, limiting the motion of the affected joints.
Staphylococcus aureus is the most common cause of acute septic arthritis in the general population, and Neisseria gonorrhoeae is a notable cause in sexually active individuals. Infections can be introduced directly through injury or circulatory system and often occur in patients with an impaired immune system. Diagnosis involves aspiration of synovial fluid for evaluation and culture, along with antimicrobial susceptibility testing to prescribe effective treatment such as antibiotics like oxacillin, cefazolin, or third-generation cephalosporins.