P-1039. Plasma Cathelicidin (LL37) Levels Are not Associated with Candida Gut Colonization in Critically Ill Patients

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Abstract Background In the intensive care unit (ICU), Candida spp. gut colonization is a risk factor for Candida bloodstream infection; however, the specific risk factors for Candida gut colonization remain unknown. Impaired anti-microbial immune responses may predispose to Candida gut colonization. LL37, an antimicrobial peptide (AMP) from the cathelicidin family, plays an important role in the immune response to pathogens, including Candida. The purpose of this study was to determine whether plasma LL37 levels are associated with Candida gut colonization in the ICU. Figure 1. Plasma LL-37 levels comparing patients with (Candida=1) and without (Candida=0) Candida gut colonization. Methods We examined a sample of patients enrolled in DYNAMITE (a prospective cohort study of ICU patients at a tertiary care hospital) who provided stool samples. Clinical data was collected by chart review. The first stool sample collected after enrollment was diluted in saline and plated on selective media for Candida spp.; species was identified from positive samples via matrix-assisted laser desorption/time-of-flight. Plasma samples were analyzed for LL37 levels via enzyme-linked immunosorbent assay. LL37 levels were normalized with a four-parameter logistic curve. We compared plasma LL37 levels between patients with and without Candida gut colonization, as well as different colonizing Candida species, using an unpaired t-test in R. Figure 2. Plasma LL-37 levels comparing patients with different Candida species causing gut colonization (0=no Candida gut colonization; 1=C. albicans; 2=C. glabrata; 3=C. parapsilosis; 4=C. albicans/C. glabrata co-colonization). Results Of 31 patients included, 14 (48%) had Candida gut colonization (6 [19%] C. albicans; 5 [16%] C. glabrata; 2 [6%] C. glabrata and C. albicans; 1 [3%] C. parapsilosis). Mean age was 60±16 years; 22 (71%) patients were white; 16 (52%) were women; and 10 (32%) were in shock on ICU admission. There was no statistically significant difference in plasma LL37 between patients with and without Candida gut colonization (mean 44.9± 22.6 ng/mL vs. mean 42.0 ±18.8 ng/mL, respectively, p=0.71) (Figure 1). LL37 levels also did not differ according to colonizing Candida species (Figure 2). Conclusion In this pilot study, plasma LL37 was not found to be associated with Candida gut colonization among ICU patients. These findings suggest that systemic levels may not reflect tissue (intestinal) immune responses. Understanding the role of LL37 and other AMPs in Candida colonization may inspire alternative approaches to reduce Candida colonization and resultant Candida bloodstream infections in the ICU. Disclosures All Authors: No reported disclosures

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