2238. Evaluation of Adjuvant Interferon-Gamma-Level Assessment to Improve the Performance of Procalcitonin Testing in Hospitalized Bacteremic Patients

BACKGROUND: Although procalcitonin-guided antimicrobial stewardship has had proven utility in emergency and ICU settings, it is still not widely adopted outside these areas. One limitation to a more universal uptake has been the unreliable performance in discriminating bacterial infected from uninfected individuals. Viral infections have been noted to suppress procalcitonin (PCT) levels through Interferon-gamma (IFN-G)-mediated inhibition of procalcitonin release from parenchymal cells. Unfortunately, clinical application algorithms do not assess INF-G levels at the time evaluation thus treating providers are unable to distinguish a true-negative test from a false-negative test resulting from INF-G-mediated procalcitonin suppression This undermines the performance of PCT, particularly in patients with bacterial and viral co-infections. We hypothesized that adjuvant interferon gamma testing could improve the performance of PCT. To test this hypothesis we prospectively enrolled bacteremic hospitalized patients along with culture-negative controls and then assessed the performance of PCT with adjuvant IFN-G testing. METHODS: 69 hospitalized patients with bacteremia and 32 culture-negative controls were enrolled. Demographic and clinical parameters were compared between groups alongside INFG and PCT levels Parametric and non-parametric statistical tests were performed where appropriate. Test performance was evaluated by constructing receiver operator curves (ROCs) for PCT, INF-G, and a combination of PCT+INF-G. RESULTS: Of 101 patients enrolled, the mean age was 49.46 ± 13.6 years with 47% being female. The following were comparative statistics between the culture-positive vs. culture-negative group: mean age 52.1 ± 15.7 vs. 46.4 ± 14.2 years, P = 0.56; WBC 11.9 ± 9.5 vs. 9.5±5.1, P = 0.170; ANC 8,466 ± 5,686 vs. 8,189 ± 4,769, P = 0.907; eGFR 73.2 ± 23 vs. 74.5 ± 26.1, P = 0.644; PCT 2.79 ± 5.87 vs. 0.71 ± 1.79, P = 0.03. Of these 57 patients had INF-G and PCT values available and their corresponding ROCs are shown in figure. CONCLUSION: Our interim results indicate adjuvant INF-G testing may not improve the performance of procalcitonin in hospitalized bacteremic patients. The additional samples are being analyzed to confirm these findings. [Image: see text] DISCLOSURES: All authors: No reported disclosures.