458. Diagnostic Accuracy and Management of Suspected Moderate to Severe Cellulitis Referred to an Infectious Diseases Outpatient Parenteral Antibiotic Clinic: A Prospective Cross-Sectional Study

Abstract Background Moderate to severe cellulitis is a common reason for presentation to the emergency department and administration of intravenous antibiotics. Misdiagnosis of cellulitis occurs frequently as the disease can masquerade as a wide variety of noninfectious and infectious problems. There are currently no studies evaluating the impact of infectious diseases physicians on the diagnostic accuracy and management of cellulitis referred to an outpatient parenteral antibiotic clinic from the emergency department. The objective of this study was to quantify the prevalence of misdiagnosed moderate to severe cellulitis through an evaluation by an infectious diseases specialist, characterize the alternative diagnoses, and assess variables associated with misdiagnosis. Methods A prospective cross-sectional study of adults referred from emergency departments with presumed moderate to severe cellulitis to an outpatient parenteral antibiotic clinic staffed by infectious diseases specialists. Results 301 consecutive patients with presumed cellulitis were evaluated over a 6-month period. A concurring diagnosis of cellulitis was found in 170 patients (56.5%), for a misdiagnosis rate of 43.5% (131/301). Table 1 summarizes the alternative diagnoses. Infectious conditions other than cellulitis were the most common (63/301; 20.9%), with abscess being present in 23 (7.6%) of patients. Fifty-two of 301 (17.3%) of the diagnoses were noninfectious and 16/301 (5.3%) patients had a dual diagnosis where minor cellulitis was present, but secondary to another, predomintating condition. The presence of stasis dermatitis (OR 6.62, P = 0.013) and a history of physical trauma (OR 1.76, P = 0.046) were associated with a misdiagnosis. 31.9% (107/335) of antibiotic regimens prescribed by emergency physicians were inappropriate or sub-optimal compared with 7.9% (22/280) of those ordered by infectious disease doctors. Conclusion Moderate to severe cellulitis was incorrectly diagnosed in nearly half of the patients referred for intravenous antibiotics and resulted in a high rate of unstewardly antimicrobial use. Infectious diseases physicians at an outpatient antibiotic clinic improved the diagnostic accuracy and management of this complicated condition. Disclosures All authors: No reported disclosures.