accuracy; alpha-defensin; area under the curve (AUC); c-reactive protein (CRP); cultures; diagnosis; erythrocyte sedimentation rate (ESR); gram stain; host factors; immunocompromised state; inflammatory arthritis; interleukins (Ils); laboratory testing; negative cultures; negative predictive value; polymorphonuclear neutrophils (PMN) percentage; positive predictive value; prior antibiotic use; procalcitonin (PCT); sensitivity; serum D-dimer; serum biomarkers; specificity; synovial biomarkers; thresholds; type of organism; white blood cell count; α-defensin