400. The Frequency and Clinical Characteristics of Positive Galactomannan Assay Results in Patients With Mucormycosis

BACKGROUND: Discrepancies between histomorphologic finding and indirect test results such as galactomannan (GM) assay make diagnosis of invasive fungal infection difficult. We investigated the frequency and clinical characterisitics of positive GM assay results in patients with mucormycosis. METHODS: Patients who met the modified criteria for proven or probable mucormycosis and had serum and/or bronchoalveolar lavage (BAL) fluid GM assay result were enrolled at a tertiary hospital from July 2009 to October 2017. Proven mucormycosis was defined as histologic evidence of tissue invasion of hyphae with positive mucormycosis immunohistochemistry (IHC) test result and the recovery of agents of mucormycosis (Rhizopus spp., Cunninghamella spp., Apophysomyces spp., Saksenaea spp., Absidia spp., Mucor spp.) by culture from sterile specimens. Probable mucormycosis was defined as histologic evidence of tissue invasion of hyphae with positive mucormycosis IHC test result with or without recovery of agents of mucormycosis by culture from nonsterile specimens. RESULTS: Among 50 patients of proven or probable mucormycosis, 20 (40%) patients were positive for serum and/or BAL fluid GM assay results; 13 of 20 (65.0%) were positive in serum, nine of 12 (75.0%) were positive in BAL fluid, and two of 12 (16.7%) were positive in both. There were more patients with gastrointestinal infections (4 of 20 [20%] vs. 0 of 30 [0%], P = 0.021) and diagnosed as histomorphologically aspergillosis (6 of 20 [30%] vs. 1 of 30 [3%], P = 0.012) in GM positive group than GM negative group. CONCLUSION: These results suggest that positive GM assay results are not uncommon in mucormycosis. GM assay results from the patients with mucormycosis appear to be related with gastrointestinal infections and histomorphologic diagnosis of aspergillosis. Further studies are needed on the mechanism of positive GM results in patients with mucormycosis and possible coinfection with other fungi such as Aspergillus species in these patients. DISCLOSURES: S. H. Kim, the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI): Investigator, Grant recipient