1151 The Accuracy and Diagnostic Value of Gram Staining from Joint Aspirates in Suspected Joint Infection

Abstract Aim Septic arthritis is a debilitating pathology. Joint aspirate gram stain often performed followed by definitive culture. We review the accuracy of staining for suspected septic arthritis, and investigate factors associated with cultures positive bacterial growth. Method reviewed all theatre joint aspirates at Major Trauma Centre from 2015-2021 arthritis. Information collected included aspirate-site, culture results delay, patient demographics, orthopaedic/rheumatological history affected joint, various comorbidities. Outcomes sensitivity specificity stain. Factors that predisposed patients to false-negative stains were calculated via multivariate binary logistic regression. Results A total 408 included, which 37 did not receive initial staining. Gram results’ delay on average 1.1 5.4 days respectively. Logistic regression revealed prosthetic (p = 0.007), past infections 0.006), (p<0.001), hypertension currently smoking 0.019) positively cultures, 0.004) significantly false negative results. Patients antibiotics time higher risk (OR 5.538, 95% CI [2.802-10.948], p<0.001). Conclusions Whilst fast, it has poor sensitivity. recommend caution when lending any weight result. Moreover, if comorbidities highlighted are present or aspirate, hyper-vigilance should be exercised stratifying clinical hallmarks infection.