According to Uworld:
1.) Arthrocentesis (find out what u are dealing with)
+100,000 WBC
+90% Neutrophils
-purlent
-these labs are diagnostic for septic arthritis
2.) Culture bugs
3.) Empiric Tx
4.) Specific treatment ie. emergency surgical drain, specific Antibiotic for bug found.
*You can not give empiric antibiotics before arthocentesis as it may affect the results when you try to culture the specific bug.