Organisms associated with underlying disorders in septic arthritis
| RA | S. aureus (frequently polyarticular) |
| Immunocompromised/alcoholics | S. aureus, Streptococci , Gram-negatives, Listeria |
| Malignancies/Diabetics | S. aureus, group B Streptococci |
| Drug abuse | Pseudomonas aeruginosa S. aureus |
| Dog/cat bites | Pasteurella multocida , Capnocytophaga , anaerobes |
| Human bites | Eikenella , anaerobes |
| Hemoglobinopathies | Streptococcus pneumoniae Salmonella spp (osteomyelitis) |
| Hemochromatosis | Vibrio vulnificus (oyster-eating) Yersinia species (esp prosthetic joints) |
| Postpartum women | Mycoplasma (also after genitourinary procedures) |
| Hypogammaglobulinemia | Mycoplasma (can involve >1 joint), others |
| Raw milk/dairy products | Brucella spp.—often involves sacroiliac joints |
| Systemic lupus erythematosus (SLE)/asplenia | Encapsulated organisms ( Neisseria, Salmonella) |
