T2 Biosystems Research Articles

314. Ceftazidime-Avibactam Versus Meropenem-Vaborbactam for the Treatment of Carbapenem-Resistant Enterobacterales Infections

Abstract Background Infections due to carbapenem-resistant Enterobacterales (CRE) are increasing in the United States, most commonly the result of Klebsiella pneumoniae carbapenemase (KPC) production. Both ceftazidime-avibactam (CZA) and meropenem-vaborbactam (MVB) are preferred treatment options for CRE infections but comparative effectiveness data to assist clinicians with preferentially selecting between these agents are limited. Baseline characteristics of 118 patients treated with ceftazidime-avibactam or meropenem-vaborbactam for carbapenem-resistant Enterobacterales Methods We conducted an observational study of patients with CRE infections between 2018–2023 who received ≥ 3 days of CZA or MVB across five Maryland hospitals. Susceptibility to the administered agent (i.e., CZA or MVB) was required for eligibility. Inverse probability weighting (IPW) using propensity scores was used to assess the primary outcome of 30-day mortality. Development of resistance (i.e., ≥ 4-fold increase in MIC of the agent used to treat the index infection) within 90 days assessed by broth microdilution was a secondary outcome. Baseline characteristics of 75 patients treated with ceftazidime-avibactam or meropenem-vaborbactam for carbapenem-resistance Enterobacterales that harbored KPC genes Results In the entire cohort there were 95 and 23 patients in the CZA and MVB groups, respectively. Balance was achieved across all variables in the IPW cohort (Table 1). 30-day mortality was similar between the antibiotic groups comparing CZA to MVB (aOR 0.997, 95% CI 0.86–1.63, p=0.97) and in the subgroup of 75 patients with isolates with an identified blaKPC gene present who underwent IPW with good balance achieved (Table 2) (aOR 1.02, 95% CI 0.85–1.21, p=0.87). Conclusion In a cohort of patients with CRE infections treated with either CZA or MVB, 30-day mortality was similar. The frequency of subsequent emergence of resistance is currently being investigated. Disclosures Sara M. Karaba, MD, PhD, MHS, Entasis: Advisor/Consultant Patricia J. Simner, PhD, Affinity Biosensors: Grant/Research Support|BD Diagnostics: Grant/Research Support|bioMérieux: Grant/Research Support|Entasis: Personal fees|GeneCapture: Personal Fees|Merck: Personal fees|OpGen Inc: Grant/Research Support|Qiagen: Grant/Research Support|Shionogi: Personal fees|T2 Biosystems: Grant/Research Support

P-1800. Antimicrobial Stewardship Compliance with Accreditation Requirements within a Hospital Pharmacy Organization

Abstract Background Between 2022 and 2023 the Center for Medicare and Medicaid Services and The Joint Commission updated requirements and/or guidance related to antibiotic stewardship programs (ASPs). In June 2023, an antimicrobial stewardship gap analysis survey was required within all Cardinal Health pharmacy managed facilities to assess for compliance with accreditation requirements and identify areas for improvement. Methods This was a 55 question multi-site survey assessing compliance with accreditation requirements for hospital ASPs. Participants responded to questions as yes, no, or not applicable. Compliance was defined as a “yes” or “not applicable” response. A chi-square was used to assess responses between hospital types and average daily census (ADC). Results 122 hospitals completed the survey (41 hospitals, 17 critical access, 27 long-term acute care (LTAC), 29 rehabilitation, 8 LTAC/rehabilitation). Most facilities had an ADC of < 50 (< 26: 46, 26-50: 44, 51-100: 17, 101-200: 7, 201-500: 8). The mean (+ STD) compliance within all hospitals was 81.7% (+ 5.1%). A significant difference in compliance with accreditation requirements was found based on hospital type (p< 0.001) and ADC (p< 0.001). Rehabilitation and LTAC hospitals had the highest compliance rates of 89% and 83%, respectively. When assessed by ADC, the lowest compliance rates were found in hospitals with less than 26 beds (78.8%). The top five needs with < 75% compliance included documentation of program outcomes, documentation of evidence-based use of antibiotics in all departments and services of the hospital, reporting progress towards antibiotic stewardship goals and initiatives to hospital leadership, evaluating adherence to an evidence-based guideline, and providing competency-based education to hospital staff. Conclusion This standardized survey identified ASP gaps based on accreditation requirements and identified key areas for improvement. Interestingly, LTACs and rehabilitation hospitals had the highest compliance rates of all facility types; however, the largest post-acute system within the pharmacy managed hospitals, which accounted for 84.4% of all LTAC and rehabilitation hospitals, has a system-level antimicrobial stewardship committee as well as a dedicated infectious diseases pharmacist. Disclosures Katherine M. Shea, PharmD, BCIDP, T2 Biosystems: Advisor/Consultant

P-1780. Compliance Assessment of Antimicrobial Stewardship Program Activities within a Long Term Acute Care (LTAC) System

Abstract Background Long Term Acute Care (LTAC) hospitals encounter a unique challenge in that despite fewer resources, they are required to comply with CMS and TJC antibiotic stewardship programs (ASPs) Conditions of Participation for hospitals. In June 2023, completion of an antimicrobial stewardship gap analysis survey was required throughout a national LTAC system to assess compliance and identify areas for improvement. Methods This was a 173 question, multi-site survey consisting of four phases with questions about implementation of progressively more difficult ASP interventions; regulatory (n=55 questions), basic (n=45 questions), intermediate (n=41 questions), and advanced (n=32 questions) interventions. Compliance was defined as a “yes” or a “not-applicable” response. A chi-square test was used to assess responses between different phases and average monthly acute patient days (APD). Results All 26 LTAC hospitals in the system completed the survey. The average compliance within all hospitals was 84% for phase one, 86% for phase two, 73% for phase three, and 62% for phase four. There was a significant difference in compliance between the phases (p< 0.0001) and based on APD per facility (Table 1, p< 0.0001). When assessing compliance with individual questions, a total of 13 questions (7.5%) had low compliance (less than 50%), which were flagged as particular areas for opportunity. Low compliance questions were grouped based on CDC Core Elements, six of which pertained to Action, three to Tracking, two to Education, and one each to Reporting and Hospital Leadership Commitment. As expected, the majority (n=8) of low compliance questions were in phase four. Conclusion This standardized survey was used as a tool to ensure regulatory compliance and identify additional opportunities for ASP advancement in a system of LTACs. Overall, we report high rates of compliance, especially in the regulatory phase 1, likely due to support from a System ASP and dedicated ID pharmacist. Our evaluation suggests that smaller or less busy facilities with fewer average monthly APDs may have more resources to ensure compliance with ASP initiatives. It is important to recognize that some phase 4 advanced ASP interventions may not be feasible in the LTAC setting. Disclosures Katherine M. Shea, PharmD, BCIDP, T2 Biosystems: Advisor/Consultant

303. The A-Stop Study: Rapid Tests for Candida Infection in Non-neutropenic Critically-ill Patients - A Multicentre Diagnostic Test Accuracy Study

Abstract Background Among critically-ill patients, antifungal therapy is usually driven by risk rather than a confirmed diagnosis. This leads to overtreatment, due to both low confidence in culture-based diagnostics and the time-critical nature of antifungal treatment. Such overtreatment undermines antimicrobial stewardship which could be improved if rapid, non-culture, tests reliably exclude disease. Methods This was a prospective multicentre diagnostic test accuracy study of three rapid tests for Candida infection: beta-D-glucan (BDG), Associates of Cape Cod, and two PCR-based tests (Fungiplex Candida, Bruker Corporation; & T2Candida, T2 Biosystems). In brief, patients were eligible for recruitment within 24hr of being started empirically on antifungal therapy for suspected Candida infection if they were not neutropenic. In the primary analysis, diagnostic accuracy metrics were derived by comparing index test results to the EORTC/MSGERC definition of proven Candida disease for patients in intensive care units (ICU). In a secondary analysis, the tests were compared with a constructed reference standard for proven + probable Candida disease. Since the purpose of these tests was to rule-out disease, sensitivity and negative predictive value (NPV) were the focus. Results Of 4005 patients screened for eligibility, 1251 participants were recruited from 57 UK ICUs between 2018-2023. Of these, 1223 were evaluable against the definition of proven disease and 54 met that definition. In total, 1215, 1217, and 507 participants had an evaluable BDG, Fungiplex, and T2Candida test, respectively. For proven disease, the most sensitive test was BDG (69%), followed by T2Candida (44%) and Fungiplex (28%); the NPV of each of these three tests was 97%. The sensitivity was predictably lower for the proven + probable disease group (N=124), ranging from 18%-58%, yet NPV remained above 90% for all three tests. Conclusion There is an opportunity to reduce unnecessary antifungal prescribing in this patient group. Each of the tests evaluated had lower sensitivity than previously reported but, because of low disease prevalence, they had high NPV. Modelling the effects of using the tests to stop empiric treatment may further guide how best to apply the tests in practice. Disclosures All Authors: No reported disclosures

T2Bacteria panel used simultaneously with blood cultures helps to determine the etiology ofbloodstream infections.

Bloodstream infections (BSI) result in significant morbidity and mortality rates, and delayed administration of appropriate antimicrobial treatment is a major predictor of poor outcomes. T2 magnetic resonance (T2MR®) (T2 Biosystems®, Lexington, MA, USA) is an innovative technology that can rapidly identify pathogens from a sample of whole blood in a remarkably short time frame of 3-5 h. We are evaluating if the T2Bacteria Panel (T2BP) contributes to the etiological diagnosis of bloodstream infections when combined with standard blood cultures (BC). The study was performed between December 2018 and March 2019, and a total of 28 patients with suspected BSI were included. The most notable finding of our study was that the addition of T2BP to BC in a diagnostic workflow led to a statistically significant higher rate of T2BP-targeted bacteria identification in patients with suspected BSI (46.4% versus 7.1%, P = 0.001) when compared to BC alone. Considering the measures of diagnostic accuracy, T2BP showed 100.00% sensitivity, 88.24% specificity, 100% negative predictive value (NPV), and 84.62% positive predictive value (PPV). Our findings give valuable insights for microbiologists and clinicians into this molecular method and its advantages in routine diagnostics of BSI.

621. Evaluation of a Multiplex Endpoint PCR for the Detection of 21 Fungi Commonly Causing Fungal Pneumonia Using Barcoded Magnetic Bead Technology

Abstract Background Fungal pneumonia caused by Aspergillus, Mucorales, and other fungi are potentially life-threatening and often are difficult to diagnose due to similar clinical presentations and poor sensitivity by culture. The BioCode MDx-3000 from Applied BioCode uses Barcoded Magnetic Bead (BMB) technology to digitally detect 21 fungi in a multiplex PCR. We evaluated the BioCode assay using clinically simulated samples and retrospective frozen bronchoalveolar lavage samples. Methods For limit of detection (LOD), 10-20 replicates of each organism were run at 1E4-10 spores/mL. Reproducibility was performed by running three replicates of each target (1E3 spores/mL) within one run, three separate times. Specificity was determined by testing for 37 fungal analytes not targeted by the panel. Matrix specific inhibition was also tested by spiking each organism in the following matrices: whole blood, plasma, serum and BAL. 90 retrospective BAL samples from patients with fungal culture results were run to assess clinical performance. Results LOD of 21 fungal organisms ranging from 19.83 – 271.76 spores/ml. Detection rate was 100% (36/36) in all samples mixed with two fungi; 95% (20/21) in all samples mixed with three fungi. No detection or cross-reactivity was observed in samples containing any of the 37 non-targeted fungi. All replicates were detected in Inter- and intra- reproducibility experiments. No difference or inhibition was observed in detection of targeted fungi spiked in different matrices. Testing retrospective BAL samples showed an overall positive concordance of 61.4% and negative concordance of 98.1%. In 23 BALs positive by both calcofluor white stain (hypha elements) and culture, the BioCode assay correctly detected fungal targets in 78% (18/23) of the samples. Additionally, the assay produced positive detection in 25% of BALs that were culture negative. Limit of Detection and Concordance Limit of detection for the 21 fungal targets. Concordance for each target in retrospective BALs compared to culture. N/A indicates not tested. Conclusion The BioCode assay showed an overall good analytical sensitivity and specificity. Analysis of retrospective BAL samples demonstrated the assay showing good concordance with the culture results. Further studies are warranted to determine the assay’s clinical sensitivity and specificity in aid in diagnosis of fungal pneumonia. Disclosures Kristen Haag, BS, Applied BioCode, Inc.: I am an employee of Applied BioCode|Applied BioCode, Inc.: Stocks/Bonds Michael Aye, PhD, Applied BioCode: Stocks/Bonds Martín Cardona, BS, Applied BioCode, Inc.: I am an employee of Applied BioCode. Sean Zhang, PhD, Applied BioCode: Grant/Research Support|IMMY Diagnostics: Grant/Research Support|KARIUS: Advisor/Consultant|Pearl Diagnostics: Grant/Research Support|Scanogen: Grant/Research Support|T2 Biosystems: Advisor/Consultant|Vela Diagnostics: Grant/Research Support

810. Predictors of 30-Day Mortality Among Critically Ill Patients with Candidemia Identified by T2Candida Panel

Abstract Background Candidemia is associated with mortality rates exceeding 40%. However, prior studies indicate mortality may be reduced when antifungal therapy is initiated within 12 hours. The T2Candida Panel is a diagnostic assay that detects Candida species directly from a whole blood specimen within 3-5 hours (T2 Biosystems, Lexington, MA). The objective of this study is to identify predictors of 30-day mortality in patients with candidemia identified by T2Candida Panel. Methods This is a retrospective, multicenter study of critically ill patients with candidemia identified by T2Candida Panel from January 2016 - December 2022. Critically ill patients were defined as those who developed candidemia during an intensive care unit (ICU) stay or within 72 hours of ICU admission or discharge. T2Candida sites were chosen across the United States based on T2Candida utilization. Exclusion criteria were patients < 18 years of age, those with prophylactic indications for antifungal therapy, prisoners and pregnant patients. Multivariate logistic regression was conducted to identify factors associated with 30-day mortality measured from the T2Candida draw time. Results There were 171 ICU patients from seven institutions with candidemia identified by T2Candida panel. The mean (standard deviation [SD]) age was 59.7 (14.8) years and 52.1% were male. Mean (SD) APACHE II and Charlson Comorbidity Index scores were 20.6 (7.1) and 4.9 (2.8), respectively. Empiric antifungal therapy was administered to 36.8% of patients and the majority received infectious diseases (ID) consult (92.4%). Echinocandins were the most common agents used for empiric (72.7%) and definitive therapy (62.6%). Overall, 30-day mortality occurred in 36.0% and was not associated with antifungal de-escalation. Administration of empiric therapy (aOR 0.457, 95% CI 0.199-1.054) and ID consult (aOR 0.225, 95% CI 0.056-0.913) were associated with reduced odds of 30-day mortality. Conclusion Empiric antifungal administration and ID consult were independently associated with reduced odds of 30-day mortality in patients with candidemia identified by T2Candida Panel. Future studies are needed to evaluate the impact of the T2Candida panel on antifungal stewardship. Disclosures Ryan K. Shields, PharmD, MS, Allergan: Advisor/Consultant|Cidara: Advisor/Consultant|Entasis: Advisor/Consultant|GSK: Advisor/Consultant|Melinta: Advisor/Consultant|Melinta: Grant/Research Support|Menarini: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Advisor/Consultant|Roche: Grant/Research Support|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|Utility: Advisor/Consultant|Venatorx: Advisor/Consultant|Venatorx: Grant/Research Support Michael J. Rybak, PharmD, PhD, MPH, Abbvie, Merck, Paratek, Shionogi, Entasis, La Jolla, T2 Biosystems: Advisor/Consultant

2110. Enhancing Antibiotic Efficacy Against Enterococcal faecium with Bacteriophage and Antimicrobial Peptides

Abstract Background The urgency to find new alternatives has increased as multidrug-resistant organisms enhance their defense mechanisms. In recent years, there has been a renewed interest in bacteriophages as potential alternatives or adjuncts to antibiotic therapy. However, there is limited information on the impact of bacteriophages with the innate immune system. Cathelicidin LL-37, a cationic peptide with antimicrobial properties, functions in coordination with the immune system to eradicate pathogens. We aim to evaluate how the survival of daptomycin (DAP) and ampicillin (AMP) resistant or non-susceptible Enterococcus faecium isolates are impacted by the interaction between bacteriophage, LL-37, and the addition of DAP/AMP. Methods Two E. faecium clinical isolates were utilized: R497 and HOU503. Bacteriophages provided by the Naval Medical Research Command, NV- 503-01 and NV-497 were quantified and propagated to approximately 108 PFU/mL. LL-37 was prepared at a final concentration of 640μM and diluted in RPMI intentionally to a suboptimal concentration of 0.5μM to adjust for a 70-80% survival rate. This was done to detect a synergistic interaction more easily with the addition of phage. Samples were incubated at 37 °C and plated in triplicate on brain heart infusion agar at 2h. After 24h of incubation, colonies were counted for and analyzed. Data was expressed as a mean percent survival with standard deviation. ANOVA with Tukey's HSD post-hoc test was used to determine the variations between each combination used. Results The targeted bacterial survival rate against E. faecium isolates was attained by LL-37 at a concentration of 0.5μM. However, when R497 and HOU503 was combined with LL-37, bacteriophage, and DAP/AMP the percentage of bacterial survival was significantly (P< 0.05) lower than that of the growth control, LL-37, AMP/DAP, and bacteriophage alone. Conclusion By conducting bacterial survival assays, we observed a notable enhancement in the elimination of multi-drug resistant E. faecium when LL-37, bacteriophage, and DAP/AMP were added. Examining this interaction over longer periods, both with and without varying antimicrobials, will yield more understanding regarding the potential involvement of bacteriophage in the innate immune system's response to fighting infections. Disclosures Michael J. Rybak, PharmD, PhD, MPH, Abbvie, Merck, Paratek, Shionogi, Entasis, La Jolla, T2 Biosystems: Advisor/Consultant

2779. Early Administration of Ceftazidime-Avibactam for Carbapenem-Resistant Enterobacterales Is Associated with Improved Clinical Success

Abstract Background Carbapenem-resistant Enterobacterales (CRE) are a significant public health threat. Ceftazidime-avibactam (CZA) retains activity against most carbapenemase-producing CRE and demonstrates favorable health outcomes compared to historically best available therapy. While early initiation of effective therapy is critical in serious infections, the impact of time to CZA initiation on CRE infection-related outcomes has yet to be assessed. Aim: to evaluate clinical outcomes of patients with CRE infections receiving early vs. late CZA as the first active β-lactam. Methods Multicenter, retrospective cohort of hospitalized adult patients from 2019-2022 with culture-positive CRE and infectious symptoms receiving early vs. late CZA as the first active β-lactam. Early and late CZA were defined as CZA administration within or after 48 hours of index culture collection, respectively. Primary outcome was a composite of clinical success defined as i) the absence of all-cause mortality or microbiological recurrence requiring therapy within 30 days from the end of CZA therapy and ii) continued infectious symptoms during CZA therapy. Results In total, 174 patients were included (≤48 hours n=52, >48 hours n=122). Median (IQR) age was 61 (53, 73) years and 56.3% were male. ICU admission rates were similar between early vs. late CZA (73.1% vs. 72.1%; P=0.921). Most common infection sources were respiratory (59.8%) and skin and skin structure (9.2%). Klebsiella pneumoniae was the most common CRE isolated (66%). The overall median (IQR) of CZA MIC was 2 (1,4). and there was no difference in the receipt of package insert CZA doses in the first 48 hours of CZA therapy between the early vs. late groups, respectively (1.9% vs. 5.2%; P=0.311). In total, 40/52 (76.9%) early and 68/122 (55.7%) late CZA patients met the clinical endpoint of clinical success (P< 0.001). The early and late CZA groups demonstrated similar ICU length of stay (LOS) (26 [9, 46] vs. 22 [12, 40]; P=0.431, respectively). Table 1. Baseline and Clinical Characteristics Conclusion In hospitalized adult patients with CRE infections, CZA administration within 48 hours of culture collection was associated with a higher rate of clinical success compared to CZA administered after 48 hours. Further studies in a larger patient cohort are warranted to verify these results. Disclosures Wesley D. Kufel, Pharm.D., BCPS, BCIDP, AAHIVP, Merck: Grant/Research Support Bryan White, PharmD, BCPS, BCIDP, Gilead Sciences: Advisor/Consultant Michael J. Rybak, PharmD, PhD, MPH, Abbvie, Merck, Paratek, Shionogi, Entasis, La Jolla, T2 Biosystems: Advisor/Consultant

2118. Comparative Analysis of Cefiderocol Mono- and Combination Therapy for Multi-Drug Resistant Gram-negative Infections

Abstract Background Multi-drug resistant gram-negative infections are a growing concern, necessitating the development of novel treatments. Cefiderocol (CFDC) is a new siderophore cephalosporin that targets the iron transport mechanism used by many gram-negative pathogens. We aimed to compare the clinical outcomes of CFDC monotherapy and combination therapy in various infection types. Methods We performed a retrospective cohort analysis at 5 academic medical centers from May 2022 to April 2023. Patients were included if they were ≥18 years old and received CFDC for ≥48 hours, excluding subsequent courses not separated by ≥90 days. The primary objective was composite clinical success (30-day survival, absence of 30-day infection recurrence and resolution of signs and symptoms), with secondary objectives including individual components of clinical success, on-treatment resistance, 30-day readmission, and adverse reactions. Descriptive statistics and logistic regression were used. Results We analyzed 70 patients, with 35 in each treatment group. The cohort was predominantly male (64.3%), had a mean age of 55.5 years (17.6), and 67% were admitted to the Intensive Care Unit. The mean (SD) APACHE II scores were 12.8 (7.5) for monotherapy and 14.9 (6.7) for combination therapy (p=0.22), while the mean (SD) Charlson comorbidity scores were 5.0 (3.6) and 4.5 (3.5) for the respective groups (p=0.61). The most common infection source was respiratory tract (54.3%), with Pseudomonas aeruginosa (55.7%) and Acinetobacter baumannii (25.7%) as the most frequently isolated pathogens. The median (IQR) CFDC mean inhibitory concentration (MIC) was 0.5 µg/mL (0.25-1.0). The 30-day mortality rates for the monotherapy and combination groups were 20% and 28.6%, respectively. There was no significant difference in composite clinical success between the groups (p=0.59). Conclusion Our preliminary data suggest that there is no difference in clinical success between CFDC monotherapy and combination therapy with another antibiotic. Further studies are needed to confirm these findings and evaluate the optimal use of CFDC in a variety of clinical settings. Disclosures Michael J. Rybak, PharmD, PhD, MPH, Abbvie, Merck, Paratek, Shionogi, Entasis, La Jolla, T2 Biosystems: Advisor/Consultant

T2Candida assay: diagnostic performance and impact on antifungal prescribing.

To assess the performance of T2Candida for the diagnosis of invasive candidiasis (IC) against gold standards of candidaemia or consensus IC definitions, and to evaluate the impact of T2Candida on antifungal drug prescribing. A retrospective review was undertaken of all T2Candida (T2MR technology, T2 Biosystems) performed from October 2020 to February 2022. T2Candida performance was evaluated against confirmed candidaemia or against proven/probable IC within 48 hours of T2Candida, and its impact on antifungal drug prescriptions. T2Candida was performed in 61 patients, with 6 (9.8%) positive results. Diagnostic performance of T2Candida against candidaemia had a specificity of 85.7% and negative predictive value (NPV) of 96.8%. When comparing T2Candida results with consensus definitions of IC, the specificity and NPV of T2Candida was respectively 90% (54/60) and 98.2% (54/55) for proven IC, and 91.4% (53/58) and 96.4% (53/55) for proven/probable IC. Antifungals were initiated in three of six patients (50%) with a positive T2Candida result. Thirty-three patients were receiving empirical antifungals at the time of T2Candida testing, and a negative result prompted cessation of antifungals in 11 (33%) patients, compared with 6 (25%) antifungal prescriptions stopped following negative beta-d-glucan (BDG) testing in a control population (n = 24). T2Candida shows high specificity and NPV compared with evidence of Candida bloodstream infection or consensus definitions for invasive Candida infection, and may play an adjunctive role as a stewardship tool to limit unnecessary antifungal prescriptions.

198. The correlation of the genetic antibiotic resistance markers to antibiotic susceptibility testing (AST)

Abstract Background Antibiotic resistant infections are a risk for increased patient mortality due to long time-to-results for current diagnostic methods. Results from a ∼1,500 patient trial demonstrated bacterial blood culture required 51 hours on average for a positive result. Current antibiotic susceptibility testing (AST) requires two additional days for phenotypic results. Studies show delays in effective treatment increases mortality rates by 7.6% every hour. The CDC classifies carbapenem-resistant Enterobacterales (13,000 annual deaths) as urgent threats, and vancomycin-resistant Enterococci and methicillin-resistant S. aureus (∼15,000 annual deaths combined) as serious threats. Identifying resistance markers direct from patient samples may aid clinical decisions, reduce antibiotic use, reduce time to effective therapy, and improve patient outcomes Methods 200 antibiotic resistant bacterial strains were genotyped for 13 clinically-relevant resistance genes and screened for antibiotic resistance phenotypes. Results identified correlations between resistance markers and phenotypic resistance and potential aid for clinical treatment. Results High resistance to vancomycin and piperacillin-tazobactam, first-line antibiotics, were seen in 48 Gram-positive and 69 Gram-negative strains. Presence of Gram-positive markers vanA or vanB correlated to 100% (28/28) vancomycin resistance and 88% (25/28) ampicillin resistance. In 85 sequenced Gram-negative strains, 35 harbored metallo-β-lactamase (blaIMP,blaNDM,blaVIM), 35 contained extended spectrum β-lactamase (blaCTX-M-14,blaCTX-M-15), 21 contained AmpC β-lactamase (blaDHA,blaCMY), and 34 contained carbapenenase (blaKPC,blaOXA48). These markers correlated to 100% resistance to ampicillin, cefazolin, and cefuroxime in all strains. Conclusion Together, these data suggest that molecular diagnostics that identify genetic markers may provide clinicians with needed information during a window when therapeutic intervention can improve patient outcomes. Disclosures Caitlin Morrison, B.S., T2 Biosystems: Stocks/Bonds Janis Pham, B.S., T2 Biosystems: Stocks/Bonds Alicyn Pearson, PhD, T2 Biosystems: Stocks/Bonds John King, B.S., T2 Biosystems: Stocks/Bonds Heather S. Lapp Noucas, MSc, T2 Biosystems: Stocks/Bonds Robert Shivers, PhD, T2 Biosystems: US20200291488A1|T2 Biosystems: Stocks/Bonds Roger Smith, Ph.D., T2 Biosystems, Inc: US20180188195A1, EP3849938A1,WO2020257691A1, WO2020252084A1|T2 Biosystems, Inc: Stocks/Bonds.

324. Detection of Antibiotic Resistance Genes and Associated Genera Direct from Blood Samples by Multiplex PCR and Next Generation Sequencing

Abstract Background While blood culture and genotypic or phenotypic testing is standard procedure for identification of sepsis pathogens and resistance, blood culture negative sepsis occurs in 40-60% of patients. A culture independent diagnostic can identify pathogens that do not grow in culture and may provide a more sensitive indicator to blood stream infections. Here we discuss an assay that combines multiplex PCR with next generation sequencing (NGS) to detect resistance genes and pathogenic genera directly from whole blood. These genes include mecA, mecC, vanA, vanB, blaKPC, blaOXA-48 family, blaNDM, blaVIM, blaIMP, blaCMY-2, blaDHA, and blaCTX-M-14 and blaCTX-M-15 groups. Methods K2EDTA whole blood samples were spiked with low titers of antimicrobial resistant bacterial isolates. Sample processing involved chemical lysis of red blood cells, concentration and mechanical lysis of pathogen cells, and multiplex amplification of resistance genes and 16S rRNA gene. A synthetic DNA oligo was added at a fixed concentration as a read control. Samples were sequenced on Illumina platforms. NGS data was analyzed using a bioinformatics pipeline to process and match sequences to curated databases with BLAST. The number of reads per sequence was normalized by the number of reads for the read control, resulting in a read-control-normalized (RCN) value that could be used to establish positivity cutoffs. Results Resistance genes in bacterial pathogen spiked samples were identified at titers ≤ 10 CFU/mL. Owing to a unique dual indexing strategy, cross-reactivity was absent or low enough that cutoffs could be set using RCN values without reducing sensitivity. The expected genus was also detected at ≤ 10 CFU/mL for all samples; however, genera that may be representative of reagent or environmental contamination were observed at levels higher than a universal RCN cutoff in some samples. Conclusion We have shown that this NGS assay can detect 13 antimicrobial resistance genes with high sensitivity and specificity direct from blood. Bacterial genera associated with these genes were detected by this assay. As there is a risk of detection of contaminating species with a 16S target, further research into low DNA reagents or environmental controls may be required. Disclosures Daniel Gamero, BS, T2 Biosystems, inc: WO2018213641A8, EP3861013A1, WO2020055887A1, WO2020252084A1, WO2020257691A1|T2 Biosystems, inc: Stocks/Bonds Kelly Dabrowski, M.S., T2 Biosystems, Inc: Stocks/Bonds Analisa DeVito, B.S., T2 Biosystems, Inc: Stocks/Bonds Roger Smith, Ph.D., T2 Biosystems, Inc: US20180188195A1, EP3849938A1,WO2020257691A1, WO2020252084A1|T2 Biosystems, Inc: Stocks/Bonds Jessica L. Snyder, Ph.D., T2 Biosystems, Inc: CA3062882A1,US20180171388A1,WO2017180745A1 , EP3861013A1 , AU2020296183A1, WO2020055887A1, WO2020252084A1|T2 Biosystems, Inc: Stocks/Bonds.

1430. Eravacycline associated hypofibrinogenemia during treatment of M.abscessus

Abstract Background Eravacycline, a novel synthetic fluorocycline, is structurally similar to tigecycline. Cases of tigecycline associated hyperfibrinogenemia have been reported in the literature, however the mechanism is not currently well described. At this time it is unknown if this is a class effect. Methods Two cases of patients on eravacycline for treatment of Mycobacterium abscessus (M.abscessus) who received regular fibrinogen monitoring are described. Results Patient 1 received a kidney transplant (2010) and was admitted for acute hypoxic respiratory failure secondary to COVID-19. Their course was complicated by multiple infections including disseminated M.abscessus with positive cultures from the lung and blood. Eravacycline 1 mg/kg BID (80 mg) was started on D1 and continued through D24. Fibrinogen levels on D1 was 448 mg/dl and on D23 were 120 mg/dl. Eravacycline was stopped and fibrinogen returned to normal range (228 mg/dl) in 5 days. Eravacycline was re-trialed at 80 mg BID and fibrinogen level on D1 was 310 mg/dl and 147 mg/dl on D8. No repeat fibrinogen levels were obtained. Patient 2 was a lung transplant recipient (2019) admitted for treatment of M.abscessus skin and soft tissue infection. The patient was started on eravacycline 1 mg/kg BID (90 mg) due to concerns of hypofibrinogenemia from tigecycline. On D1 of eravacycline fibrinogen was 167 mg/dl , on D19 of therapy fibrinogen was 64 mg/dl and eravacycline was stopped. Fibrinogen level returned to normal 3 days after eravacycline discontinuation (212 mg/dl). Conclusion Similar to tigecycline, we observed eravacycline related hypofibrinogenemia. Time to onset was variable in the two cases presented. Hypofibrinogenemia was readily reversible, within 3-5 days, with drug withdrawal and reproducible in one patient with re-challenge of eravacycline. Further analysis into eravacycline related hypofibrinogenemia and its impact on coagulation outcomes are warranted based on these reports. Disclosures David van Duin, MD, PhD, Achaogen: Advisor/Consultant|Allergan: Advisor/Consultant|Astellas: Advisor/Consultant|MedImmune: Advisor/Consultant|Melinta: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|NeuMedicine: Advisor/Consultant|Pfizer: Advisor/Consultant|Qpex: Advisor/Consultant|Roche: Advisor/Consultant|Sanofi-Pasteur: Advisor/Consultant|Shionogi: Advisor/Consultant|Shionogi: Grant/Research Support|T2 Biosystems: Advisor/Consultant|Tetraphase: Advisor/Consultant.

The silent and dangerous inequity around access to COVID-19 testing: A call to action.

The silent and dangerous inequity around access to COVID-19 testing: A call to action.

966. ID Fellows Cup: Leveraging Gamification and Social Media to Enhance Clinical Infectious Diseases Education

BackgroundWe hypothesized that we could leverage social media to recruit learners to a gamification-infused ID knowledge competition, and entice them to explore additional online educational resources.MethodsWe created the ID Fellows Cup, a knowledge-based trivia competition, to engage Infectious Diseases fellows. The game was crafted via Kaizen-Education, a software platform developed at the University of Alabama at Birmingham, that uses gamification to engage learners. Multiple choice questions including figures and/or text are presented to learners, followed by detailed teaching explanations. 60 questions emphasizing high-yield concepts were delivered over 4 weeks. Questions were written by fellows and reviewed by faculty at three programs. Elements of gamification (virtual rewards, leaderboards, etc.) were included to enhance engagement. Recruitment strategies included Twitter, program director emails, and peer-to-peer. We measured game statistics and participation. Learners were invited to complete a post-game survey about their experience. ResultsTable 1 shows our game statistics with broad geographic reach including 42 programs. Most fellows matriculated in 2019 or 2020; the number of US ID fellows equaled 17% of those completing ID in-training exam. Recruitment sources included 44% co-fellow, 42% Twitter, and 15% Program Director. Through 20 days with questions, we had 155 daily average users. Overall, fellows answered 11,419 total questions, representing 89% of all released questions. Of 103 responses to post-game survey (table 2) 97% would participate again and all felt the game was a good use of their time. Over 80% of participants reported some engagement with linked resources included in the answer explanations. In general, 78% felt engagement with online resources increased subsequent to participating in the game, including learning about at least one new online resource. ConclusionWe leveraged social media and gamification to effectively engage, and stimulate ID learners to explore additional online educational resources. Technology enriched learning, helps supplement and globalize ID education, making it as diverse and engaging as our field. Disclosures Todd P. McCarty, MD, Cidara (Grant/Research Support)GenMark (Grant/Research Support, Other Financial or Material Support, Honoraria for Research Presentation)T2 Biosystems (Consultant) Prathit A. Kulkarni, M.D., Vessel Health, Inc. (Grant/Research Support)

214. Prospective Evaluation of the GenMark Dx ePlex® Blood Culture Identification Gram Negative Panel

BackgroundThe ePlex BCID Gram-Negative (GN) panel utilizes electrowetting technology to detect the most common causes of GN bacteremia (21 targets) and 6 antimicrobial resistance genes from positive blood culture bottles. Rapid detection of extended spectrum β-lactamases (ESBL; CTX-M), carbapenemases (KPC, NDM, IMP, VIM, OXA 23/48), and highly resistant bacteria such as Stenotrophomonas maltophilia enables early optimization of antimicrobial therapy.MethodsIn this prospective study, we evaluated the performance of the BCID-GN panel compared to traditional standard of care culture and susceptibility testing with organism identification using the BioMerieux Vitek MS Matrix Assisted Laser Desorption Ionization (MALDI) Time of Flight mass spectrometry. Samples submitted for standard of care testing in Biomerieux BacT/Alert resin FA/FN blood culture bottles on the BacT/Alert VIRTUO automated blood culture system with GN bacteria on direct exam (n=108) were included. ResultsAll but two GN bacteria identified by MALDI were represented on the BCID-GN Panel (106/108, 98.1%) and most tests (107/108, 99.1%) yielded valid results. Discordant analyses revealed a positive percent agreement (PPA) of 102/105 (97.2%) with 3 false negatives (2 pan-susceptible Enterobacterales, 1 ESBL E.coli) and a negative percent agreement (NPA) of 105/105 (100%). Consistent with alternative resistance mechanisms, only 8/12 (66.7%) of Enterobacterales with resistance to 3rd generation cephalosporins harbored the CTX-M gene. In contrast, 8/8 (100%) of isolates from samples harboring the CTX-M gene were resistant to 3rd generation cephalosporins. ConclusionDetection of 1 S. maltophilia, 1 Acinetobacter baumannii expressing OXA 23/48, and 8 Enterobacterales expressing CTX-M represent opportunities for early optimization of antimicrobial therapy in 10/108 (9.3%) of samples. The BCID-GN Panel provides rapid accurate detection of resistant gram negative bacteria enabling high quality data driven optimization of antimicrobial therapy. Disclosures Todd P. McCarty, MD, Cidara (Grant/Research Support)GenMark (Grant/Research Support, Other Financial or Material Support, Honoraria for Research Presentation)T2 Biosystems (Consultant) Sixto M. Leal, Jr., MD, PhD, Abnova (Grant/Research Support)AltImmune (Grant/Research Support)Amplyx Pharmaceuticals (Grant/Research Support)Astellas Pharmaceuticals (Grant/Research Support)CNINE Dx (Grant/Research Support)GenMark Diagnostics (Grant/Research Support, Other Financial or Material Support, Honoraria- Research Presentation)IHMA (Grant/Research Support)IMMY Dx (Grant/Research Support)JMI/Sentry (Grant/Research Support)mFluiDx Dx (Grant/Research Support)SpeeDx Dx (Grant/Research Support)Tetraphase Pharmaceuticals (Grant/Research Support)

310. Cryptococcal Infection Following COVID-19 infection in Solid Organ Transplant Recipients: A Case Series

BackgroundFungal infections have been identified with or following SARS-CoV-2 infection, most commonly COVID associated pulmonary aspergillosis. Cryptococcus species are ubiquitous in the environment and the third most common invasive fungal infection following Solid Organ Transplant (SOT). We describe four cases of concurrent or subsequent cryptococcal infection within 90 days following COVID-19 infection.MethodsWe conducted a retrospective study of patients presenting with proven cryptococcosis either concurrently or within 90 days following COVID-19 diagnosis. Cases were identified March 2020 through May 2021. All were seen at the University of Alabama in Birmingham, a regional referral and comprehensive transplant center. Exemption for this review was approved by our IRB.ResultsFour cases were identified, all were SOT recipients. Case details are provided in Table 1. No patients required ICU level care at any point. COVID-19 treatment included 10 days of increased steroids for 3 patients, remdesivir for 2, and 1 received no treatment for COVID-19. In contrast to the typical time-course for cryptococcal infection post-SOT (median time approx. 500 days post-transplant), three patients were greater than 2 years post-transplant and were without rejection or recent changes in immunosuppression. Patient 1 was less than 6 months post liver-kidney transplant and was diagnosed at time of admission with concurrent COVID-19 and cryptococcal pneumonia. Infection was disseminated in the other 3 cases including positive blood cultures in 2 patients and cryptococcal meningitis (CM) in 2 patients. CM cases presented later following COVID-19 and had the longest delay between symptom onset (headache, neurologic symptoms) and CM diagnosis. One patient had CM 8 years prior, but had done extremely well off fluconazole for over 6 years prior to this recurrence. All patients are doing well at most recent follow-up evaluations.Table 1. Summary of Cases ConclusionWe describe the first case series with a temporal association between SARS-CoV-2 infection and cryptococcosis. All cases were immunocompromised due to SOT. Some symptoms were attributed to post-COVID syndrome leading to significant delays in diagnosis for those patietns, highlighting the importance of considering this association for at-risk patients.Disclosures Todd P. McCarty, MD, Cidara (Grant/Research Support)GenMark (Grant/Research Support, Other Financial or Material Support, Honoraria for Research Presentation)T2 Biosystems (Consultant)

1027. Earlier Is Better: Progress Toward Decreased Time to Optimal Therapy and Improved Antibiotic Stewardship for Gram-positive Bloodstream Infections Through Use of GenMark Dx ePlex system

BackgroundThe ePlex BCID Gram-Positive (GP) panel utilizes electrowetting technology to detect the most common causes of GP bacteremia (20 targets) and 4 antimicrobial resistance (AMR) genes in positive blood culture (BC) bottles. Rapid detection of intrinsic vancomycin resistance and acquired resistance genes (mecA, mecC, vanA, vanB) enables early optimization of antimicrobial therapy whereas early detection of common contaminants is expected to decrease unnecessary antibiotic utilization and hospitalizations.MethodsIn this prospective study, aliquots of BC bottles with GP bacteria detected on Gram stain (GS) (n=101) received standard of care (SOC) culture and antimicrobial susceptibility testing (AST). Additionally, samples were evaluated with the BCID-GP panel but only SOC results were reported in the EMR and available to inform clinical decisions. Patients were excluded if the sample was a subsequent culture in a persistent episode of bacteremia (n=17) or if the assay failed (n=4). Chart review was performed to evaluate the expected impact of the BCID-GP panel on the time to organism identification, AST results, and optimization of antimicrobial therapy. ResultsA total of 80 patients were included in the final analysis (Table 1). S. epidermidis was the most common bacteria identified, followed by S. aureus, and other coagulase-negative staphylococci. Thirty-nine patients with staphylococci (48.8%) had the mecA gene detected and 2 patients with E. faecium had the vanA gene detected. The BCID-GP panel saved a mean of 24.4 hours (h) to identification and 48.3h to susceptibility testing compared to standard methods across all patients. In 38 patients (47.5%), the BCID-GP panel result could have enabled an earlier change in antibiotic therapy. Table 2 highlights opportunities to optimize antimicrobial therapy 53.4h earlier for 16 (20%) patients with organisms expressing AMR genes, 29.2h earlier for 8 (10%) patients infected with organisms, such as streptococci, with very low resistance rates, and to stop antimicrobial therapy 42.9h earlier for 14 (17.5%) patients with contaminated blood cultures. ConclusionThe BCID-GP panel could have enabled earlier optimization or stopping of antibiotics in many patients with significant time savings compared to standard laboratory methods. Disclosures Todd P. McCarty, MD, Cidara (Grant/Research Support)GenMark (Grant/Research Support, Other Financial or Material Support, Honoraria for Research Presentation)T2 Biosystems (Consultant) Sixto M. Leal, Jr., MD, PhD, Abnova (Grant/Research Support)AltImmune (Grant/Research Support)Amplyx Pharmaceuticals (Grant/Research Support)Astellas Pharmaceuticals (Grant/Research Support)CNINE Dx (Grant/Research Support)GenMark Diagnostics (Grant/Research Support, Other Financial or Material Support, Honoraria- Research Presentation)IHMA (Grant/Research Support)IMMY Dx (Grant/Research Support)JMI/Sentry (Grant/Research Support)mFluiDx Dx (Grant/Research Support)SpeeDx Dx (Grant/Research Support)Tetraphase Pharmaceuticals (Grant/Research Support)

200. Prospective Evaluation of the GenMark Dx ePlex® Blood Culture Identification Gram Positive Panel

BackgroundThe ePlex BCID Gram-Positive (GP) panel utilizes electrowetting technology to detect the most common causes of GP bacteremia (20 targets) and 4 antimicrobial resistance genes in positive blood culture bottles. Rapid detection of intrinsic vancomycin resistance and acquired resistance genes (mecA, mecC, vanA, vanB) enables early optimization of antimicrobial therapy whereas early detection of common contaminants decreases unnecessary antibiotic utilization and hospitalizations. MethodsIn this prospective study, we evaluated the performance of the BCID-GP panel compared to traditional standard of care culture and susceptibility testing with organism identification using the BioMerieux Vitek MS Matrix Assisted Laser Desorption Ionization (MALDI) Time of Flight mass spectrometry. Samples submitted for standard of care testing in Biomerieux BacT/Alert resin FA/FN blood culture bottles on the BacT/Alert VIRTUO automated blood culture system with GP bacteria on direct exam (n=100) were included. ResultsAll GP bacteria were represented on the BCID-GP panel, most tests 97/100 (97%) yielded valid results, 53 common skin contaminants (50 coagulase negative staphylococci (CNS), 2 Bacillus, 1 Corynebacterium) were identified, and 7/7 coinfections with Gram negative (GN) bacteria were detected by the Pan GN target and identified by the BCID-GN panel. Discordant analyses revealed a positive percent agreement (PPA) of 96/97 (99%) with 1 false negative CNS and a negative percent agreement (NPA) of 92/97 (94.8%) with 5 false positives for either S. epidermidis or Corynebacterium. Detection of vanA yielded a PPA of 4/4 and NPA of 9/9. mecA gene detection exhibited a PPA of 14/14 and NPA of 14/14 for S. aureus and a PPA of 31/32 (97%) and NPA of 16/16 for coagulase negative staphylococci with 1 false negative methicillin resistant S. epidermidis. ConclusionDetection of acquired vancomycin resistance (n=4) and absence of mecA gene detection in Staphylococcus species (n=30) represent opportunities for early optimization of antimicrobial therapy in 34/100 (34%) of samples. The BCID-GP panel provides rapid accurate detection of resistant isolates and common contaminants enabling high quality data driven optimization of antimicrobial therapy. Disclosures Todd P. McCarty, MD, Cidara (Grant/Research Support)GenMark (Grant/Research Support, Other Financial or Material Support, Honoraria for Research Presentation)T2 Biosystems (Consultant) Sixto M. Leal, Jr., MD, PhD, Abnova (Grant/Research Support)AltImmune (Grant/Research Support)Amplyx Pharmaceuticals (Grant/Research Support)Astellas Pharmaceuticals (Grant/Research Support)CNINE Dx (Grant/Research Support)GenMark Diagnostics (Grant/Research Support, Other Financial or Material Support, Honoraria- Research Presentation)IHMA (Grant/Research Support)IMMY Dx (Grant/Research Support)JMI/Sentry (Grant/Research Support)mFluiDx Dx (Grant/Research Support)SpeeDx Dx (Grant/Research Support)Tetraphase Pharmaceuticals (Grant/Research Support)