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1758. Impact of Accelerate Pheno™ Rapid Blood Culture Detection System on Laboratory and Clinical Outcomes in Bacteremic Patients

Abstract Background Molecular-based automated systems for the rapid diagnosis of bacterial infections have potential to improve patient care. The Accelerate Pheno™ blood culture detection system (ACCEL) is an FDA approved platform that allows for identification (ID) and antimicrobial susceptibility testing (AST) 8 hours following growth in routine culture. Methods This is a single-center retrospective chart review of bacteremic adult inpatients before and after implementation of ACCEL. Laboratory and clinical data were collected February–March 2018 (intervention) and compared with a January–April 2017 historical cohort (standard of care). Standard of care ID and AST were performed using VITEK® MS (MALDI-TOF MS) and VITEK®2, respectively. An active antimicrobial stewardship program was in place during both study periods. Patients with polymicrobial cultures, off-panel isolates, previous positive culture, or who were discharged prior to final AST report were excluded. Primary outcome was length of stay (LOS). Secondary outcomes were inpatient antibiotic duration of therapy (DOT) and time to optimal therapy (TTOT). Nonparametric unadjusted analyses were performed due to non-normal distributions. Statistics were performed using SAS 9.4. Results Of the 143 positive cultures performed on ACCEL during intervention, 118 (83%) were identified as on-panel organisms. Seventy-five (64%) of these 118 cultures and 79 (70%) of 113 reviewed standard of care cultures met inclusion criteria. Patient comorbidities (P = NS), MEWS severity score (P = 0.10), source of bacteremia (P = NS), and pathogen detected (P = 0.30) were similar between cohorts. Time from collection to ID (28.2 ± 12.7 hours vs. 53.8 ± 20.9 hours; P < 0.001) and AST (31.9 ± 11 hours vs. 71.8 ± 20 hours; P < 0.001) were shorter in the intervention arm. Clinical Outcomes Standard of Care (Mean ± SD) N = 79 Intervention (Mean ± SD), N = 75 P-value LOS (days) 12.1 (11.9) 9.1 (7.6) 0.03 TTOT (hours) 73.5 (50.2) 37.5 (32.7) <0.001 Total antibiotic DOT (days) 9.0 (7.5) 7.0 (4.6) 0.05 Meropenem DOT (days) 6.6 (3.7) 3.7 (2.1) 0.03 Conclusion Compared with standard of care, ACCEL shortens laboratory turn-around-time and improves clinical outcomes. The use of this system has resulted in decreased mean antibiotic DOT, TTOT, and LOS. Further studies are needed to verify these findings. Disclosures All authors: No reported disclosures.


Conclusion.
Compared with standard of care, ACCEL shortens laboratory turnaround-time and improves clinical outcomes. The use of this system has resulted in decreased mean antibiotic DOT, TTOT, and LOS. Further studies are needed to verify these findings.
Disclosures. All authors: No reported disclosures. Background. FoodNet conducts active laboratory-based surveillance for 9 pathogens transmitted commonly through food, including Shiga toxin-producing E. coli (STEC). Adoption of CIDTs has allowed for rapid identification of Shiga toxin or Shiga toxin genes, but incorporating multiple test results with differing sensitivity and specificity complicates treatment decisions and public health surveillance. Between 2007 and 2017, FoodNet reported increases in the use of CIDTs and decreases in rates of confirmation by culture.

High Proportion of Discordant Results in
Methods. We examined STEC cases reported to FoodNet during 2012−2017 with a positive immunoassay (IA) or polymerase chain reaction (PCR) test performed at a clinical laboratory, followed by positive or negative test at a state public health laboratory. Three test type combinations were assessed (IA/IA, PCR/PCR, and IA/PCR) by state, symptoms, test discordance, and culture (cx) result.
Conclusion. Almost a quarter of results were discordant, with marked variation by state, and most of these infections could not be confirmed by culture at the public health laboratory. Discordant results can pose problems for patient management. Including or excluding patients with discordant results also affects our ability to measure trends. Sensitivity and specificity of test types, test targets, and specimen transport must be considered when interpreting test results.
Disclosures. All authors: No reported disclosures. Background. The sensitivity of current antibody detection assays against Borrelia burgdorferi in the early stage of Lyme disease is very low. In children especially, who commonly have febrile viral illnesses, manifestations of early Lyme disease can be misdiagnosed. We previously demonstrated that IFNγ secretion could be detected in whole blood collected from Lyme disease patients at first clinical presentation following overnight incubation of the blood with peptides derived from B. burgdorferi. In the present study, we further evaluated the utility of IFNγ release for the laboratory diagnosis of Lyme disease in children with varying stages of the illness.

Interferon Gamma Release Assay for Diagnosis of Lyme disease
Methods. Children ages 2-18 years with no prior history of Lyme disease and with manifestations of Lyme disease at any stage were enrolled in the study. Sick and healthy controls were enrolled for comparison. We collected history and physical examination data and blood samples at the time of enrollment, at 1 month, and at 6 months. Standard 2-tier testing with ELISA (whole cell sonicate [WCS] and C6) and western blot were run in parallel to the IFNγ release assay for all blood samples. Sensitivity and specificity of the study assay were determined for presentation at all stages of Lyme disease. Clinical data were summarized.
Results. Blood samples from 22 patients with Lyme disease and 7 controls (4 sick, 3 healthy) were obtained at the first visit. The IFNγ release assay detected early and early disseminated Lyme disease with 78% sensitivity compared with 59% sensitivity of 2-tier testing in our study. For patients presenting with a single erythema migrans (EM) lesion, the IFNγ release assay detected Lyme disease with 63% sensitivity compared with 14% sensitivity with 2-tier testing. The IFNγ release assay had only 25% sensitivity for detecting late disease. A single control patient was positive for both the IFNγ release assay and 2-tier serology.

Conclusion.
A novel IFNγ release assay demonstrated significantly increased sensitivity when compared with 2-tier testing in the laboratory diagnosis of Lyme disease in patients presenting with a single EM lesion. Future study is needed to determine its utility in detecting early Lyme disease in patients with nonspecific febrile illness in the absence of erythema migrans.