2126. Comparison of Time to Appropriate Antibiotic Between Using Microarray Assay and Mass Spectrometry Technique for Identification of Positive Blood Cultures

Background Microarray-based, multiplexed, automated molecular method is a rapid diagnosis of bloodstream infections by directly identify bacterial pathogens and antibiotic resistance by detection resistance genes from positive blood culture. Previous studies showed significantly reduce time to organism identification from positive blood culture and antibiotic resistance gene with 97.1% sensitivity and 100% specificity. This study aimed to evaluate time to appropriate antibiotic between using Microarray Assay and Mass Spectrometry technique for bacterial identification. Methods one hundred and forty-five patients with bloodstream infection in medical ward were enrolled between 1 June 2018 and 31 January 2019. There were 2 study periods (pre-intervention and post-intervention), using MALDI-TOF combined with the conventional microbiological method as the current standard diagnostic method in pre-intervention group (N = 70) and microarray technique was used add-on to post-intervention group (N = 75). Antibiotic therapy was adjusted by infectious disease team in both periods of study. Results There were significantly faster bacterial identification and detection of antibiotic resistance (39.34 hours vs. 5 hours, P = 0.0001) as well as time to adjust specific antibiotic therapy (75 hours vs. 27.65 hours, P = 0.0001) resulted in earlier appropriate antibiotic therapy (31 hours vs. 0 hours, P = 0.005) and decrease unnecessary of antibiotic adjustment (51.4% vs. 37.3%). However, all-cause mortality within 2 weeks was not significantly reduced (11.4% vs. 14.7%), no differences cost of antibiotic therapy and length of hospital stay (13 days vs. 17 days). Conclusion Microarray technique has rapid turnaround time to bacterial identification and detection of some resistant genes. A combination of this technique and clinical judgement encourage earlier appropriateness antibiotic therapy and may be helpful in antibiotic stewardship program. Disclosures All authors: No reported disclosures.