1714. Testing a Novel Clinical Surveillance Case Definition for Invasive Mold Infections

Abstract Background Invasive mold infections (IMI) such as aspergillosis and mucormycosis are often fatal among immunosuppressed patients and have caused high-profile outbreaks. Surveillance for IMI is challenging because distinguishing a case from colonization or contamination is complex. The established case definition, Mycoses Study Group (MSG) criteria, lacks sensitivity. Because the need for surveillance remains, we designed a pilot IMI surveillance system within the Georgia Emerging Infections Program. Here, we describe cases identified through this system, using both the MSG criteria and a novel, more sensitive clinical case definition. Methods To identify potential IMI cases, we captured fungal cultures positive for mold, histopathology specimens with evidence of fungal tissue invasion, and positive galactomannan results within a 60-day window at three large hospitals in Atlanta during March 2017–2018. We excluded dimorphic fungi and hair and nail specimens. Of 194 potential cases, we selected 24 for complete medical chart review. Two physicians classified cases as proven, probable, or non-case according to MSG criteria. Cases that partially met MSG probable criteria and included antifungal treatment were classified as clinical cases; definitions were mutually exclusive (Figure 1). Results Of 24 potential IMI cases, 16 (66%) met an IMI case definition, including 5 proven, 2 probable and 9 clinical cases. Inter-rater agreement was 92%., Most (5/7) MSG cases involved Aspergillus and were more likely to have cancer, a transplant, or other immunosuppression compared with clinical cases (Figure 2 and 3). Clinical cases included conditions not specified in MSG criteria, including burns (1), wounds (1) or eye (4) infections. MSG and clinical cases more often had antifungal treatment (16/16 vs. 1/8) or died (4/16 vs. 0/8) compared with non-cases. Conclusion In this preliminary analysis of potential IMI cases, most represented true invasive infections, indicating effective exclusion of most colonization. Most of the 16 cases were classified as clinical, however, and would have been missed in a system relying on the MSG criteria alone. Results suggest that a less-specific clinical case definition incorporating antifungal treatment may improve the sensitivity and utility of IMI surveillance. Disclosures All authors: No reported disclosures.