Background Urinary tract infections (UTIs) are one of the most common infections, associated with 10.5 million outpatient visits annually. Fast and accurate identification (ID) of bacteria causing a UTI would allow for immediate targeted therapy, as opposed to conventional methods which take one to three days. The Accelerate Pheno® system (ACC, Accelerate Diagnostics Inc., Tucson, AZ, USA) provides microbial ID and susceptibility (AST) from positive blood cultures. Our objective was to determine ACC’s potential to quickly ID bacterial pathogens directly from urine. Methods Remnant urine samples with >100K colony forming units (CFU)/mL of gram-negative bacteria as determined by quantitative plating were obtained from the clinical lab. 1.5ml of urine was dispensed into a capsule and loaded onto the Accelerate PhenoPrep™ module. This module automatically performs wash steps to separate bacteria from human cells and other debris. The processed sample was loaded onto ACC for analysis using a custom designed assay which detects the presence of bacteria and employs an Enterobacteriaceae family specific FISH probe. The results were compared to standard of care ID results. Results There were 10 E. coli and 1 C. koseri among the eleven samples tested. Baseline concentration of samples immediately prior to testing ranged from 2.5 x 106 to 1.08 x 1010 CFU/mL (average 4.19 x 109). After specimen processing, average concentration was 2.14 x 109 CFU/mL and average recovery was 42.83%. ACC detected bacteria and identified it as Enterobacteriaceae in 11/11 samples (100%). Average sample prep time was 55 min. Average time to Enterobacteriaceae ID was 8.6 hrs. Average total time to ID, including specimen processing, was 9.5 hrs. Table 1: Results of Direct from Urine Testing Conclusion ACC identified Enterobacteriaceae directly from remnant urine specimens in an average of 9.5 hours, approximately 24 to 48 hours faster than conventional methods. ACC was able to be adapted for use in urine samples. Future directions include improving the assay to identify bacteria to the species level and adding AST testing. This shows promise in providing fast actionable UTI diagnosis, allowing for tailored antibiotic therapy. *This information concerns a use that has not been approved or cleared by the Food and Drug Administration. Disclosures Martin Fuchs, BSEE, MSEE, Accelerate Diagnostics (Employee) Steve Metzger, BA, Accelerate Diagnostics (Employee)
BackgroundDetection of bacteremia directly from blood may improve time to clinical diagnosis and initiation of appropriate antibiotic therapy for hospitalized patients. Administration of empiric antibiotic therapy, whether prior to standard of care (SOC) or research study blood collection, adds to challenges in bacterial recovery. Strategies to improve detection were explored in this pilot study to inform future clinical trial design (CTD) on Enterobacteriaceae (ENT) detection directly from blood. One of the objectives was to assess effects of prior antibiotic administration on novel assay performance.MethodsConfirmed ENT bacteremic (Protocol A (P-A), n = 26), and suspected bacteremic (Protocol B (P-B), n = 25) participants were enrolled into one of two IRB approved protocols after obtaining informed consent. Fresh whole blood (20 mL) was collected within 12 hours of SOC blood culture positivity (P-A) or 20 hours of SOC blood culture collection (P-B), and divided: 10 mL inoculated into a lytic media collection vessel (P-A and B); and 10 mL into a BD BACTEC™ Bottle (P-A) as a control, or an Isolator™ lysis centrifugation tube (P-B) for quantification. For collection vessels, a 3-hour amplification step in lytic growth medium followed by cleanup and concentration steps was employed. Processed samples were tested using an investigational assay for universal bacterial detection on the Accelerate Pheno™ system. Results were analyzed manually and with proprietary software. Descriptive statistics were performed to inform future CTD.ResultsEmpiric antibiotic therapy was initiated prior to blood collection in 89% (P-A) and 36% (P-B) of participants. Improved detection sensitivity was achieved in P-B over P-A, when a study sample was obtained prior to empiric antibiotic therapy initiation (Table 1). ConclusionPrior antibiotic administration and low bacterial load in clinical samples affects ability to detect ENT directly from blood. Multiple factors are critical to address in future CTD to increase sensitivity of detecting ENT directly from blood including: (1) Targeting study samples prior to antibiotic therapy initiation and (2) Using enzymatic methods to neutralize antibiotics present in the blood.Disclosures M. Fuchs, Accelerate Diagnostics, Inc.: Employee, Salary. S. Kim, Accelerate Diagnostics, Inc.: Employee, Salary. S. Metzger, NIH: Grant Investigator, Grant recipient. Accelerate Diagnostics, Inc.: Employee, Salary.
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