Final answer:
The bacterium most commonly responsible for both septic arthritis and osteomyelitis is Staphylococcus aureus. Diagnosis and treatment include imaging, culture, and antibiotics like nafcillin, oxacillin, or vancomycin for resistant cases.
Step-by-step explanation:
The bacterium that is most commonly associated with causing both septic arthritis and osteomyelitis is Staphylococcus aureus (S. aureus). Osteomyelitis is an infection of the bone that can be acute or chronic and may be caused by different microorganisms, depending on the location and individual's age. Aside from S. aureus, other bacteria such as Mycobacterium tuberculosis, Pseudomonas aeruginosa, and species in the Enterobacteriaceae family can lead to osteomyelitis.
Symptoms of osteomyelitis include fever, pain, and swelling. Diagnosis generally involves imaging studies and culturing bacteria from blood or bone. Treatment often includes antibiotics such as nafcillin, oxacillin, cephalosporin for acute cases, and ampicillin or piperacillin/tazobactam for chronic infections. Vancomycin may be necessary when dealing with antibiotic-resistant infections.