815Diagnosis of Pulmonary Nocardiosis

Background. Pulmonary nocardiosis (PN) is an uncommon infection often seen in immunocompromised patients. Definitive diagnosis depends on identification of the organism by culture in a patient with a clinical presentation suggestive of PN. As Nocardia can grow slowly and other infections can present similarly in the immunocompromised patient, we sought to find the performance of respiratory sampling in making diagnosis. Methods. Microbiologic data from1993-2013 was reviewed in any expectorated sputum (ES), bronchoalveolar lavage (BAL), and tissue biopsy in PN cases. Results. 71 patients were analyzed. 45 had obtained ES. 34 underwent BAL +/transbronchial biopsy (TBBx), 14 had percutaneous biopsy (PBx) and 5 had both BAL and PBx. 82% (37/45) had a diagnosis with positive culture in ES and 32% (12/37) suspected on the basis of organism morphology on smear (Gram stain, fungal or acid fast bacilli (AFB) stain). Of 37 positive cultures, 5/37 were positive on bacterial, 12/37 on fungal, 30/37 on AFB and 4/37 in multiple culture methods. Of 34 with BAL, 20% (7/34) had a suspected diagnosis by direct staining morphology, with a definitive diagnosis by culture in 82% (28/34); 10/28 positive on bacterial, 25/28 on fungal, 4/28 on AFB and 5/28 legionella cultures. TBBx had an overall sensitivity of 43% (6/14) by culture but secured a definitive diagnosis in an additional 2 patients. PBx made a diagnosis in 92% (12/13) of patients by positive tissue culture; 46% (6/13) had an organism with consistent morphology on direct staining and 9/13, 12/13 and 3/13 in positive bacterial, fungal and AFB cultures respectively. Acute inflammation was seen in 12/34, 3/14 and 13/13 patients in pathology of BAL, TBBx and PBx. Conclusion. Although an uncommon infection, PN should be suspected in the immunocompromised patient with pneumonia. If the suspicion is high, aggressive diagnostic assessment with bronchoscopy and/or percutaneous biopsy is warranted for adequate exclusion of the disease. Fungal and AFB culture of respiratory samples significantly increases the sensitivity of diagnosing this bacterial infection. Given the frequent delay in definitive diagnosis, development of sensitive and rapid molecular diagnostic tests is needed. Disclosures. All authors: No reported disclosures.