94 - Appropriate Urine Legionella Antigen Testing: A Step Towards Diagnostic Stewardship.

Background: Pneumonia is a leading cause of sepsis and hospitalization. Infectious Diseases Society of America and American Thoracic Society (IDSA/ATS) published 2019 practice guidelines for community-acquired pneumonia (CAP), recommending urinary antigen testing (UAT) for Legionella pneumophila (LP) only in patients with severe pneumonia or having epidemiological risk factors. In the last 20 years, there has been no Legionella outbreak in Nebraska. Currently, the urine antigen test is considered based on the discretion of the ordering provider. However, this usually results in over-utilization of the test and associated financial burden.

Methods: Retrospective chart review of patients admitted to Bergan Mercy Medical Center, Creighton University, Omaha with the admission diagnosis of community-acquired pneumonia in the year 2019, by using electronic medical records. The charts were reviewed for baseline characteristics, admission diagnoses, and clinical outcomes. The project was submitted to and reviewed by the institutional review board.

Results: From January to December 2019, 4738 patients were admitted to the general medical floors with the diagnosis of community-acquired pneumonia. Among those patients, 826 patients (17.43%) had urine Legionella antigen tests done, only 11 (0.23%) were tested positive. Moreover, 140 patients (2.95%) had urine Legionella antigen tests in the absence of a documented diagnosis of community-acquired pneumonia. Patients admitted to intensive care units were not included in the study as guidelines do not restrict from ordering urine Legionella tests in patients with severe sepsis secondary to community-acquired pneumonia.

Conclusion: A diagnostic stewardship approach should be considered for urine Legionella antigen testing.  Moreover, such a retrospective review provides an opportunity for quality improvement initiatives at the academic medical facilities with lower Legionella outbreaks.