bluuebunny/crossref_metadata_2025 huggingface dataset:
628. The Role of the Advanced Practice Provider in Infectious Disease: Opportunities for Growth
Authors: Yoke Leah H , Yoke Leah H , Beieler Alison M , Beieler Alison M , Liu Catherine , Pergam Steven A , Wald Anna , Wald Anna , Dhanireddy Shireesha , Dhanireddy Shireesha
Published: January 2021

Background

Advanced Practice Providers (APPs), including nurse practitioners and physician assistants, provide high quality medical care in multiple specialties by extending the physician workforce. However, within the Infectious Disease (ID) specialty, their demographics, areas of practice, and experience are not well described. To better understand this key group, we examined APP years of experience in ID, primary practice settings, and perceived practice barriers from the APP perspective.

Methods

We created a survey using REDCap which was distributed between 12/1/2019-1/31/2020 to APPs practicing in ID by social media, direct emails to key stakeholders, and online Infectious Disease Society of America (IDSA) community forums.

Results

Ninety-three APPs responded to the posted survey from across the US (figure 1). Most respondents (45 [49%]) had between 2-9 years of overall experience as an APP, while 14 (15%) between 10-15 years, and 24 (26%) had >16 years of experience. Experience specifically as an ID APP varied, with the majority (56%) having 2-9 years of experience and 25% reporting >16 years of experience as an APP. Although over half of the respondents worked in an outpatient adult ID clinic, they also practiced in diverse settings and within multiple ID sub-specialties (figure 2). The other most common areas of practice included inpatient adult ID, HIV care, and outpatient parental antimicrobial therapy programs. Limited formalized ID education and misconceptions about APP scope of practice were perceived barriers to practicing in ID (figure 3). Lack of recognition as a peer amongst physician colleagues was also identified as a practice barrier.

Advanced Practice Provider Survey Response by Region

Advanced Practice Provider ID Practice Areas

Perceived Advanced Practice Provider Barriers

Conclusion

Our survey results demonstrate that the APP ID workforce is an experienced provider group, both in terms of total years as an APP and years exclusively in ID, working in a large variety of ID settings in a number of geographic locations. Creation of specific and directed ID educational opportunities, along with collaborating physician support and inclusion, are identified as significant areas of improvement. The establishment of APP-specific training programs and educational courses will create more opportunities for APPs and further expand the ID workforce.

Disclosures

Steven A. Pergam, MD, MPH, Chimerix, Inc (Scientific Research Study Investigator)Global Life Technologies, Inc. (Research Grant or Support)Merck & Co. (Scientific Research Study Investigator)Sanofi-Aventis (Other Financial or Material Support, Participate in clinical trial sponsored by NIAID (U01-AI132004); vaccines for this trial are provided by Sanofi-Aventis)
629. Understanding the Effects of Social Determinants of Health on Outcome When Discharging Veterans on Parenteral Antibiotic Therapy
Authors: Guenther Erin , Sherman Katherine , Shah Haroon , Dysart Claire , Gundacker Nathan
Published: January 2021

Background

Social determinants of health are conditions in which people live, including aspects of both social environments and physical environments, and how these conditions affect their health. Examples of social determinants include access to health care, social support, culture, etc. These factors are often considered when discharging a patient on IV antibiotics. The purpose of this study was to determine if social determinants of health are related to outcomes for veterans discharged from the Zablocki VA on outpatient parenteral antibiotic therapy (OPAT).

Methods

This retrospective chart review evaluated veterans discharged home from the Zablocki VA on OPAT between the years of 2013 and 2017. Variables of social determinants of health included: race/ethnicity, co-habitants, mental health diagnosis, employment, use of illicit drugs, use of tobacco, and use of alcohol. The primary outcome analyzed was completion of therapy with or without complication. Complication is defined as antibiotic change/dose adjustment, PICC line complication, or additional clinic/hospital visit.

Results

Overall, 294 veterans’ charts were reviewed. Of these patients, 188 (63.95%) had no complication and 106 (36.05%) had a complication. Univariate analyses of social determinants are summarized in Table 1. Tobacco use was the only factor significantly associated with OPAT complication (p= 0.008).

Table 1.

Conclusion

This analysis suggests that many social determinants thought to potentially impact OPAT outcomes, such as race/ethnicity, co-inhabitants, mental health diagnosis, employment status, and use of illicit drugs or alcohol were not significant contributions to OPAT complications in the Milwaukee VA population; although, veterans who were current smokers were more likely to have an OPAT complication. These results may speak to the VA’s integral social support provided to veterans upon discharge, and perhaps, the above social determinants should not be as heavily considered when deciding if a veteran can perform OPAT. However, it is important to consider that these results may reflect the careful selection of Milwaukee veterans discharged on OPAT, as questionable cases can be treated as an inpatient.

Disclosures

All Authors: No reported disclosures
631. Preliminary safety and pharmacokinetic profile of VIR-2482: a monoclonal antibody for the prevention of influenza A illness
Authors: Sager Jennifer , Hong David K , Bonavia Aurelio , Connolly Lynn , Cebrik Deborah , Fanget Marie Christine , Mogalian Erik , Griffin Paul
Published: January 2021

Background

VIR-2482 is a fully human immunoglobulin G1(IgG) monoclonal antibody (mAb) directed against a highly-conserved epitope in the influenza A hemagglutinin stem region and is in clinical development for the prevention of influenza A illness. The Fc region of VIR-2482 has been modified to provide an extended half-life.

Methods

This is a randomized, placebo-controlled, Phase 1/2 study of VIR-2482 administered intramuscularly (IM) to healthy adult volunteers aged 18-64 years old who have not received a current influenza vaccine. The Phase 1 portion of the study will evaluate the safety, tolerability, pharmacokinetic (PK), and immunogenicity profile of VIR-2482 following single (Part A) or multiple doses (Part B). The Phase 2 study will evaluate the efficacy of VIR-2482 in the prevention of influenza A illness as well as safety, tolerability, and PK. Part A is ongoing and consists of four single dose cohorts (N=25/cohort) randomized (4:1) to a single dose of VIR-2482 or placebo at 60, 300, 1200, or 1800 mg. Safety, tolerability, PK and immunogenicity will be evaluated for at least 52 weeks post-dose.

Results

In Part A, all 100 subjects received a single dose of VIR-2482 (N=80) or placebo (N=20). Preliminary blinded safety data for all cohorts and PK data for the 300 and 1200 mg cohorts are reported here. Dosing was well tolerated; 6% (6/100) of subjects experienced mild injection site reactions, which generally resolved within 48 hrs. Through 12 weeks post-dosing, the majority (124/126; 98.4%) of adverse events (AEs) were mild to moderate in nature, no serious AEs were reported, and no subjects discontinued due to an AE. Based on available data, exposure (Cmax and AUC) between 300 and 1200 mg of VIR-2482 increased in a dose proportional manner. The PK profile of VIR-2482 is consistent with a half-life extended IgG.

Conclusion

Based on available data, VIR-2482 has been well tolerated following single IM doses of up to 1800 mg in healthy subjects. The preliminary PK profile of VIR-2482 enables once per season dosing. Overall, these data support initiation of a Phase 2 study to evaluate efficacy of VIR-2482 for the prevention of influenza A illness.

Disclosures

Jennifer Sager, PharmD, Vir Biotechnology (Employee) David K. Hong, MD, Vir Biotechnology (Employee) Aurelio Bonavia, PhD, Vir Biotechnology (Employee) Lynn Connolly, MD, PhD, Vir Biotechnology (Employee) Deborah Cebrik, PhD, Vir Biotechnology (Independent Contractor) Marie Christine Fanget, MS, Vir Biotechnology (Employee) Erik Mogalian, PharmD, PhD, Vir Biotechnology (Employee)
642. Trends and cost burden of Legionella urine antigen test
Authors: Ordaz Victor-mauricio , Lewis Hallye M , Bathina Pradeep
Published: January 2021

Background

Legionella urine antigen (LUAg) testing is used to identify the pathogen Legionella pneumophila serotype 1 which accounts for 50 to 70% of Legionella pneumonia and has 80% sensitivity and 95% specificity. The 2019 ATS/IDSA CAP guidelines recommend against routinely testing urine for LUAg except when indicated by epidemiological factors or severe cases of CAP; however, the recommendation is based on a low quality of evidence. In 2014 & 2015 there were 32 and 39 cases, respectively in the state of Mississippi. The purpose of this study was to evaluate the trends of ordering LUAg, positive results and estimate the cost burden at the University of Mississippi Medical Center (UMMC).

Methods

We performed a retrospective study of all patients who received the LUAg test at UMMC from January 3, 2013 to December 31, 2019. Patient Cohort Explorer was used to obtain de-identified patient data from EPIC. We obtained the number of encounters and patients on whom the LUAg test was performed during their inpatient hospitalization. Coding and billing offices provided the cost per LUAg test.

Results

LUAg test was ordered 2,642 times on 2350 patients between 2013 and 2019. 22 LUAg test results were positive in 21 patients. 2,627 tests were done on patients admitted in the hospital. Of the 1,181 tests ordered in female patients, 11 were positive and of the 1461 tests done in male patients, 11 were positive. The minimum age for ordered test was under 1 year while the oldest patient is 89 years old with a median age of 57 years. The youngest patient to be positive is 21 and the oldest patient was 72 years. 1,471 tests were done in African American patients and 1084 tests in Caucasian patients. At the end of study period 1901 were alive and 741 deceased. The median length of stay for the patient receiving the test was 7 days with 1726 patients discharged within 10 days. 174, 255, 301, 433, 467, 395, 613 tests were ordered respectively from 2013 to 2019. At self pay cost of $132.82 in 2019 USD, the total cost of 2642 tests was $350,910.44. About $15,950.47 was spent for each positive LUAg test during the study period.

Conclusion

Incidence of pneumonia from Legionella in Mississippi is low. Based on our study, we recommend to follow the current ATS/IDSA guidelines and order the test in select patients as recommended, in efforts to reduce diagnostic costs.

Disclosures

All Authors: No reported disclosures
643. Trends, outcomes and cost analysis of Streptococcus urinary antigen testing
Authors: Bathina Pradeep , Lewis Hallye M , Ordaz Victor-mauricio
Published: January 2021

Background

Streptococcus pneumoniae urinary antigen (SUAg) testing detects the capsular polysaccharide of S. pneumoniae; which has a sensitivity and specificity of about 75% and 95%, respectively. IDSA/ATS guidelines recommend empirically covering those who present with community acquired pneumonia (CAP) for common pathogens including S. pneumoniae. These guidelines also recommend against routinely performing SUAg testing in adults with CAP unless the presentation is severe. However, the guidelines acknowledge that this a conditional recommendation based on a low quality of evidence. This study aims to investigate the utility of testing patients with pneumonia for S. pneumoniae and the economic burden.

Methods

We performed a retrospective study of all patients who received the SUAg test at University of Mississippi Medical Center (UMMC) from January 3, 2013 to December 31, 2019. Patient Cohort Explorer was used to obtain de-identified patient data from EPIC. We obtained the number of encounters and patients on whom the SUAg test was performed. Coding and billing offices provided the self pay cost of $101.37 per SUAg test in 2019 USD.

Results

The SUAg was ordered 2,507 times with 105 (4.18%) total positives results. Age range was 1 to 89 years with a median age of 57 years for ordering the test. 136, 256, 314, 419, 433, 382, 566 SUAg tests were ordered respectively from 2013 to 2019. 59% of the positive results were in female patients while 54% percent of the negative results were in male patients. Current every day smokers were more likely to test positive (29% versus 18% negative). Median length of stay was longer for a negative test (6 days versus 5 days). 16% of the patients with a positive result expired compared to 10.5% with a negative result.

Over the study period, 2,507 tests cost an estimated $254,134.59 using the 2019 pricing. Therefore, approximately $2420.32 was spent in testing to identify each positive result.

Conclusion

With low positive rate and Streptococci pneumonia that is already covered with empirical antibiotics, we recommend following the current ATS/IDSA guidelines and order the test in select patients as recommended, in efforts to reduce diagnostic burden and health care costs. However a positive result showed a decreased length of stay and higher mortality.

Disclosures

All Authors: No reported disclosures
646. Adapting the modified Carbapenem Inactivation Method to assess for possible beta-lactamase mediated resistance in Piperacillin-Tazobactam resistant/ Ceftriaxone susceptible Escherichia. coli and Klebsiella pneumoniae
Authors: Lawandi Alexander , De L’Etoile-Morel Samuel , Leite Gleice C , Lee Todd C
Published: January 2021

Background

A cluster of piperacillin-tazobactam resistant/ceftriaxone susceptible Escherichia coli and Klebsiella pneumonaie bacteremias were noted at our institution. A review of the literature suggested this resistance phenotype was mediated by a beta-lactamase. We sought to further corroborate this phenotypically.

Methods

We adapted the “carbapenem inactivation method” utilizing piperacillin-tazobactam and ceftriaxone discs on all E. coli and K. pneumoniae isolated from blood and demonstrating piperacillin-tazobactam resistance but with ceftriaxone susceptibility. We utilized pan-susceptible and carbapenem resistance Enterobacteriaceae reference strains as well as third generation cephalosporin resistant, piperacillin-tazobactam susceptible isolates as controls.

Results

96% of the piperacillin-tazobactam resistant, ceftriaxone susceptible strains demonstrated the capacity to degrade the piperacillin-tazobactam discs while 100% spared the ceftriaxone discs. 75% of the piperacillin-tazobactam susceptible, ceftriaxone resistant control strains spared the piperacillin-tazobactam discs while degrading the ceftriaxone discs.

Conclusion

The resistance phenotype observed is due to beta-lactamase production and the modified carbapenem inactivation method can be adapted to probe for other beta-lactamases. Further study is required to definitively identify which beta-lactamase is responsible.

Disclosures

All Authors: No reported disclosures
649. Clinical Implementation of a Rapid Susceptibility Testing Procedure, Directly From a Positive Blood Culture Using the Vitek®2 System on Gram Negative Rods
Authors: Henry Charma , Evans Dustin , Navas Daniel , Barker Arleen , Somyos Chonnapat , Rodriguez Melissa , Rahimzadeh Nahid , Silva Victoria , Carr Amy , Charles Angela , Alexander Jose
Published: January 2021

Background

The national average of identification and susceptibility for organisms isolated from positive blood culture to final susceptibility based on growth on solid media is 48 hours. The goal of this research was to prove that the Vitek®2 (bioMérieux, Inc.) system can provide an accurate and reliable susceptibility result directly from positive blood culture for Gram negative rods and reduce the turnaround time (TAT) from positive blood culture to the final susceptibility.

Methods

An FDA-modified validation procedure was performed on positive blood cultures directly from the bottle to the VITEK®2 System for susceptibility testing. The protocol tested and validated an aliquot of 50uL of blood directly from the positive bottle into 10 mL of saline (1:200). The solution was vortexed and 3mL were placed in the VITEK®2 test tube. This protocol was intended only for Gram negative rods using the AST-GN70, AST-GN81 & AST-GN801 cards. This protocol followed the CLSI M52 and M100 guidelines.

Results

515 organisms from clinical blood culture samples from July 2018 to October 2019 were evaluated. Organisms included, but were not limited to: E. coli, K. pneumoniae, Enterobacter spp., and P. aeruginosa, Proteus spp., Salmonella spp., Acinetobacter spp., and S. maltophilia. There were 5,201 drug/bug combinations. AdventHealth Orlando achieved an essential agreement of 99.32% (n=5,166), minor error 0.74% (n=39) major error 0.02% (n=1) and very major error 0.49% (n=2). A 100% agreement was achieved on detection of ESBL, CRE, and MDR organisms.

Conclusion

Rapid direct blood culture protocol using the VITEK®2 System and the AST-GN cards is accurate, reliable and can be performed with less than 1 minute hands-on time. The protocol can be implemented in any laboratory at no additional costs or modification where the current VITEK®2 AST-GN panels are in use. This protocol was clinically implemented at AdventHealth Orlando on July 15, 2019. Compared with the national average of 72 hours, the TAT obtained during this study was 23 hours from positive blood culture to final susceptibility, a significant reduction of 25 hours. The authors encourage bioMérieux Inc. to evaluate and explore the opportunity to expand the use of the VITEK®2 system for this application with the appropriate clinical trial.

Disclosures

All Authors: No reported disclosures
651. Comparative Analysis Between Bacterial And Fungal Malignant Otitis Externa
Authors: Hammami Fatma , Koubaa Makram , Chakroun Amal , Smaoui Fatma , Rekik Khaoula , Elleuch Emna , Marrakchi Chakib , Jemaa Mounir Ben
Published: January 2021

Background

Malignant otitis externa is a fatal infection of the external ear and temporal bone. Pseudomonas aeruginosa is the most common causative organism, while fungi are a rare cause of malignant otitis externa. We aimed to compare the clinical, therapeutic and evolutionary features between bacterial and fungal malignant otitis externa.

Methods

We conducted a retrospective study including all patients hospitalized for malignant otitis externa in the infectious diseases department between 2000 and 2018.

Results

Overall, we encountered 82 cases of malignant otitis externa, among which there were 54 cases (65.9%) of bacterial malignant otitis externa (BMO) and 28 cases (34.1%) of fungal malignant otitis externa (FMO). The males were predominant among BMO cases (57.4% vs 50%; p=0.5). Patients with FMO were significantly older (70±9 years vs 61±10 years; p< 0.001) and had medical history of diabetes mellitus more frequently (96.4% vs 77.8%; p=0.03). The use of topical corticosteroids was significantly more reported among FMO cases (28.6% vs 5.6%; p=0.006). Otalgia (96.4% vs 81.5%), otorrhea (75% vs 66.7%) and cephalalgia (46.4% vs 42.6%) were the revealing symptoms among FMO and BMO, respectively, with no significant difference. Tenderness to palpation of the mastoid bone (64.3% vs 38.9%; p=0.02) and stenosis of the external auditory canal (92.9% vs 72.2%; p=0.02) were significantly more frequent among FMO cases. Complications were significantly more frequent among FMO cases (42.9% vs 9.3%; p< 0.001). Treatment duration was significantly longer among FMO cases (70[40-90] days vs 45[34-75] days; p=0.03).

Conclusion

Our study showed that FMO affected more frequently the elderly and diabetic patients, when compared with BMO. Regardless of the causative agent, the clinical presentation was similar. However, the outcome was poor among FMO cases with the occurrence of complications, requiring a longer duration of treatment.

Disclosures

All Authors: No reported disclosures
652. Comparison of fosfomycin (FOF) activity and prevalence of subpopulations between Escherichia coli (EC) and Klebsiella pneumoniae (KP) during susceptibility testing
Authors: Anderson Jadyn C , Krueger Amanda R , Smith Elizabeth C , Bixby Morgan L , Brigman Hunter V , Hirsch Elizabeth B
Published: January 2021

Background

In the United States, interpretive criteria for FOF are established only for EC, yet those criteria are often extrapolated to KP. Recent studies have highlighted both inferior clinical outcomes after FOF treatment and difficulties in interpretation of inner colony subpopulations, the presence of which may affect clinical efficacy. We sought to compare FOF activity against EC and KP and to determine the prevalence of inner colony subpopulations following disk diffusion (DD) testing of the two species.

Methods

A convenience collection of 73 KP and 42 EC isolates from 3 U.S. institutions were included. Minimal inhibitory concentration (MIC) testing was performed in duplicate on separate days using agar dilution (AD) and DD as recommended by the Clinical and Laboratory Standards Institute guidelines, with application of EC susceptibility (≤ 64mg/L) breakpoints. The frequency and counts of inner colonies observed during DD testing was calculated, and colonies were subcultured for use in future studies.

Results

MIC50/90 values were 1/16 mg/L and 32/256 mg/L for EC and KP respectively. All EC isolates were considered susceptible and therefore categorical agreement was 100%. The majority of KP isolates were considered susceptible (83.6% with AD and 86.3% with DD) and categorical agreement between the methods was 84.9%. Inner colonies were observed during DD testing in 88.1% of EC isolates and 80.8% of KP isolates during at least one replicate, with 47.6% of EC isolates and 39.7% of KP isolates showing inner colony growth during both DD test replicates. More than 10 inner colonies were observed in 50% of EC isolates compared to 12.3% of KP isolates.

Conclusion

KP isolates demonstrated considerably higher FOF MIC values compared to EC, as evidenced by MIC50/90 values 4-5 dilutions higher than those for EC. The categorical agreement rate was higher among EC than KP, highlighting concerns regarding the practice of extrapolating FOF susceptibility breakpoints for EC to KP. The high frequency of inner colonies observed in DD for both species necessitates further studies to determine best practices for interpreting their relevance, fitness, and resistance in order to identify potential impacts to clinical efficacy of FOF.

Disclosures

Elizabeth B. Hirsch, PharmD, Merck (Grant/Research Support)Nabriva Therapeutics (Advisor or Review Panel member)
654. Core Antibiotic-Induced Transcriptional Signatures Reflect Susceptibility to All Members of an Antibiotic Class
Authors: Martinsen Melanie A , Bhattacharyya Roby P
Published: January 2021

Background

Current growth-based antibiotic susceptibility testing (AST) is too slow to guide key clinical decisions. We previously demonstrated a combined Genotypic and Phenotypic AST assay using RNA detection (GoPhAST-R) that can provide AST in < 4h directly from blood culture, 24-36h faster than standard growth-based methods. GoPhAST-R quantifies specific mRNA expression signatures using the multiplexed hybridization RNA-detection platform, NanoString. After brief antibiotic exposure, susceptible cells become stressed, eliciting transcriptional changes that distinguish them from unharmed resistant cells. Here, we assess the generalizability of transcriptional signatures of susceptibility within an antibiotic class.

Methods

For Escherichia coli and Klebsiella pneumoniae, we assessed the ability of the top ten antibiotic-responsive genes previously identified for ciprofloxacin, gentamicin, and meropenem to predict susceptibility to two other fluoroquinolones (FQ), two other aminoglycosides (AG), and six other beta-lactams (BL), respectively, across 6-8 clinical isolates for each drug for a total of 184 pathogen-drug pairs. After standardized antibiotic exposure (60m for FQs and AGs, 120m for BLs, each at its CLSI breakpoint MIC), samples were mechanically lysed and used as input for NanoString assays as previously described (Bhattacharyya, Nat Med 2019).

Results

In both species, the top ten genes identified for AST of ciprofloxacin, gentamicin, and meropenem showed similar normalized fold-induction upon treatment with three FQs, three AGs, and seven BLs, respectively, allowing robust distinction of susceptible and resistant isolates (Fig 1).

Figure 1

Conclusion

We show that a shared set of genes optimized for AST of one antibiotic can predict susceptibility to all members of that drug class, consistent with a conserved core transcriptional response related to mechanism of action. We demonstrate this phenomenon for two common pathogens with propensity for multidrug resistance treated with multiple members of three major antibiotic classes in common clinical use. This unified set of genes for susceptibility prediction would streamline GoPhAST-R implementation, in turn facilitating efficient deployment of antibiotics and reducing unnecessary broad-spectrum use.

Disclosures

All Authors: No reported disclosures
657. Diagnostic Utility of Dedicated Fungal Blood Cultures for Diagnosis of Candidemia
Authors: Yang Bryant , Garner Omai , Ou Richard , Stanzione Nicholas
Published: January 2021

Background

Blood culture techniques have improved to the point where they are considered sensitive enough for detection of Candida. Expert guidelines clarifying the utility of use of dedicated fungal isolator cultures are lacking, and we wondered what utility, if any, they add for the diagnosis of candidemia.

Methods

All patients with cultures between March 2016-February 2020 positive for Candida were examined via manual chart review, noting time to positivity and time of initiation of antifungal therapy.

Results

We focused on cases of candidemia where a fungal culture was ordered and turned positive (59 out of the total 181 cases of candidemia). We eliminated an additional 10 cases where fungal cultures were sent while already on antifungal therapy or in patients already known to be fungemic, given our interest in de novo diagnoses. Another case was removed due to lack of clinical details, as the patient was discharged prior to culture results and managed at a different medical facility.

There were 14 cases with discordant growth (fungal culture positive, bacterial culture negative). One patient passed away prior to culture results, but in the remaining 13 cases, the fungal culture changed clinical management, in most cases by prompting initiation of antifungal therapy.

The remaining 36 cases involved with concordant growth between bacterial and fungal cultures. In 11 of those cases, the fungal culture isolated yeast 12 or more hours faster than its paired bacterial culture (average 40.7 +/- 26.6 hours). In 7 of these cases, the fungal culture changed management – in the remaining cases, the patient was already on empiric therapy.

Among all cultures sent in patients not receiving antifungals that isolated Candida, the overall time to positivity for fungal cultures was 37.2 +/- 13 hours, while bacterial cultures took 54 +/- 26.4 hours.

Fungal Culture Results

Conclusion

Fungal cultures changed management in 20/59 cases of candidemia (34%) either by making the diagnosis faster than a bacterial culture or making it outright. Given the morbidity and mortality associated with candidemia, rapid diagnosis is critically important. More specific guidelines optimizing how to best utilize fungal cultures to help standardize practice among clinicians will be critical going forward.

Disclosures

Omai Garner, PhD, D(ABMM), Beckman Coulter (Scientific Research Study Investigator)
660. Evaluation of Qvella’s FAST-Prep™ Liquid Colony™ for Early Antimicrobial Sensitivity Testing of Positive Blood Culture by Disk Diffusion Method
Authors: Novak-Weekley Susan M , Khine Aye Aye , Alavie Tino , Fernandez Namidha , Pandey Laxman , Talebpour Abdossamad
Published: January 2021

Background

Conventional antimicrobial susceptibility testing (AST) of microorganisms from positive blood cultures (PBC) can take ≥ 2 days. In order to improve the turnaround time for AST on a PBC, CLSI and EUCAST have made efforts to standardize procedures for disk diffusion (DD) direct from a PBC. Qvella Corporation (Richmond Hill, ON, Canada) has recently developed FAST-Prep, an automated centrifugal sample preparation system that rapidly delivers a Liquid Colony consisting of a purified, concentrated, viable cell suspension directly from a PBC. This study was performed to investigate the feasibility of DD AST off of a PBC using a FAST-Prep Liquid Colony.

Methods

Contrived PBC samples were prepared by spiking 6 species of Gram-positive and 4 species of Gram-negative bacteria (3-5 strains per species) into FA® Plus bottles and incubating in the BACT/ALERT® VIRTUO® System (bioMerieux, Durham, NC). After positivity, 3 mL of PBC was added to the FAST-Prep cartridge. After 20 minutes of processing in the FAST-Prep instrument, the Liquid Colony was removed from the cartridge and a 0.5 McFarland sample was prepared for DD AST. In parallel, the DD AST from a PBC was performed using 4 drops of PBC (CLSI direct method). Both methods were compared to conventional colony-based DD AST. After 16-18 hours of incubation zone diameters and S/I/R interpretations were determined. Categorical agreement (CA) and errors for both DD AST methods were calculated. In addition, colony plate counting was performed on 0.5 McFarland suspensions of Liquid Colony and the plate colony to determine biomass recovery and sample purity.

Results

CA for a FAST-Prep DD AST for Gram-positive and Gram-negative bacteria was 95.6% and 98.6%, respectively, compared to CA for CLSI DD AST of 77.2% and 81.9%, respectively. Biomass in the Liquid Colony was 7.2x108 and 1.2x109 CFU for Gram-positive and Gram-negative bacteria, respectively. Cell concentration in the 0.5 McFarland suspension of the Liquid Colony was 3.7x107 and 5.9x107 CFU/mL for Gram-positive and Gram-negative bacteria, respectively, which was similar to the concentration for the reference colony suspension.

Conclusion

The results support the potential role of FAST-Prep in providing a Liquid Colony for use in rapid AST.

Disclosures

Susan M. Novak-Weekley, PhD, D(ABMM), Qvella (Employee, Shareholder) Aye Aye Khine, PhD, Qvella (Employee, Shareholder) Tino Alavie, PhD, Qvella (Employee) Namidha Fernandez, MS, Qvella (Employee) Laxman Pandey, MS, Qvella (Employee) Abdossamad Talebpour, PhD, Qvella (Employee, Shareholder)
661. Futility of Bacterial Bone Marrow Cultures: Experience over a 19 Year Period
Authors: Kline Ahnika , Porterfield Harry , Zelazny A
Published: January 2021

Background

Bone marrow biopsies are often performed on patients with unclear diagnoses and cultures may be ordered for both routine bacterial, mycobacterial and fungal pathogens. They are performed in semi-sterile conditions and involve needle penetration through the skin, posing an increased risk of skin contamination. These cultures also require a substantial amount of laboratory personnel time.

Methods

Cultures collected from 2001-2020 were surveyed in the lab electronic record. We assessed the culture type (fungal, bacterial, mycobacterial), and the presence of pathogens and contaminants. An organism was deemed a contaminant if it was consistent with skin flora or listed as a contaminant in the report given to the physician. Organisms for which the role in bone marrow disease is unclear were included as possible pathogens. For questionable non-contaminant organisms, clinical significance was determined based on if patient was treated for the organism. For all bone marrow cultures, growth of the same organism within 1 month of the bone marrow specimen was surveyed to determine whether the organism would have been found by alternative methods.

Results

Of 483 bacterial bone marrow cultures, there were 110 (23%) positives, of which 76 (69%) were deemed contaminants. Twenty (18%) of the 76 contaminants grew in the routine bacterial culture. However, 49 (65%) contaminants grew in the AFB culture, of which 10 also grew in the bacterial culture. For the 34 non-contaminant organisms, 26 were determined to be clinically significant. Nineteen of the 26 had a matching culture (usually blood) growing the organism within 1 month. The majority of pathogens were mycobacteria (18 of the 34). Fungal organisms represented 5 cultures and 11 were bacterial. Of the 11 bacterial organisms, 1 was a Helicobacter species (grown in special media), and 4 had a matching positive blood culture. Only 4 (1% of 483) bacterial non-contaminants grew in the routine bacterial culture. Given an unknown number of true negatives, we can only conclude a positive predictive value (PPV) of 0.16 for routine bacterial cultures. Including AFB and fungal cultures, the PPV increased to 0.30.

Conclusion

Our findings indicate that routine bacterial bone marrow culture is unlikely to yield a novel result and is likely a poor use of lab resources.

Disclosures

All Authors: No reported disclosures
666. Microbial Cell-Free DNA Sequencing for Evaluation of Response to Antibiotic Therapy in Patients with Relapsed or Refractory Leukemia
Authors: Wolf Joshua , Goggin Kathryn , griffen Amanda , Kohler Christina , Allison Kim J , Inaba Yuki , Ahmed Asim A , Hollemon Desiree D , Brenner Abigail , Maron Gabriela , Maron Gabriela , Sun Yilun , Tang Li , Gawad Charles , Margolis Ellie
Published: January 2021

Background

In patients with bloodstream infection (BSI), true eradication of infection takes longer than blood culture clearance. Therefore, optimal treatment duration, especially in immunocompromised hosts, is unknown. A sensitive test of microbiological response to treatment could improve care by indicating a time for safe antibiotic discontinuation. Microbial cell-free DNA sequencing (mcfDNA-seq) is a sensitive predictor of BSI, and we hypothesize that it might also be useful to measure response to treatment.

Methods

Eligible participants were < 25 years of age being treated for leukemia. Remnant plasma samples were collected as part of a prospective study (PREDSEQ), and underwent mcfDNA-seq by Karius Inc. in a CLIA/CAP-accredited laboratory. Pathogen DNA was reported in molecules per microliter (MPM). Testing was batched and blinded. Available samples from Day 1 through Day 7 after onset of bacterial BSI were included. We evaluated decay of the BSI pathogen DNA after initiation of effective antibiotic therapy, from the peak to last available sample, and compared episodes with slow (< 0.5 log10 MPM/day) vs. rapid DNA decay.

Results

There were 13 evaluable BSI episodes in 9 participants; 7 had slow DNA decay. Persistence of bacteremia or fever ≥1 day after initiation of effective antibiotics occurred in 9/13 episodes (7/7 slow decay and 2/6 rapid decay; P = 0.02). Slow decay persisted beyond resolution of bacteremia and fever in 3/7 of these cases.

Figure 1. Pathogen DNA Concentration by mcfDNA-seq During Antibiotic Treatment of Bacteremia; Dashed line, blood culture positive; Red circle, last fever

Conclusion

In this small convenience sample of patients with leukemia, slow mcfDNA-seq DNA decay correlated with persistent fever or bacteremia. Post-BSI mcfDNA-seq monitoring should be investigated with the goal of decreasing inappropriate antibiotic therapy and preventing treatment failure.

Disclosures

Joshua Wolf, MBBS, PhD, FRACP, Karius inc (Grant/Research Support) Asim A. Ahmed, MD, Karius (Employee) Desiree D. Hollemon, MSN, MPH, Karius inc (Employee) Charles Gawad, MD PhD, Karius inc (Grant/Research Support)
668. Rapid Identification and Antimicrobial Susceptibility Testing of Gram-Negative Rod Bacteremia: Impact on Duration of Hospital Admission
Authors: Rogers Ralph , Tansarli Giannoula , Parente Diane , Brotherton Amy , Shah Rajeev , Cunha Cheston , Bobenchik April , Chapin Kimberle
Published: January 2021

Background

There are many emerging diagnostic technologies that provide rapid identification (ID) and antimicrobial susceptibility testing (AST) of blood cultures after initial microbial growth is detected. The clinical utility of having these results sooner than standard of care (SOC) ID/AST testing is less clear; one potential advantage would be shorter hospital admissions for those patients with less severe infections whose discharge planning is delayed while waiting for ID/AST results.

Methods

The Accelerate Pheno™ rapid ID/AST system (AP) was implemented in the clinical microbiology lab at two hospitals within our academic hospital system to run in parallel with our SOC ID/AST diagnostics for all blood cultures with Gram-negative rod (GNR) bacterial growth on initial Gram stain. Results of both diagnostic assays were uploaded to the medical record when available; our antimicrobial stewardship (AS) team discussed the AP results with clinical care teams during working hours. Length of stay (LOS) data was compared between a cohort with GNR bacteremia before and after the implementation of AP testing with AS review.

Results

There were 207 patients with GNR bacteremia admitted to the hospital during the first six months after implementation of AP testing with AS review (12/2019 – 05/2020). A historical cohort of 96 patients with GNR bacteremia (admitted 01/2018 – 08/2018) with SOC testing without AS review was used for comparison. Median LOS was 5.28 and 5.84 days for the AP and SOC cohorts, respectively; the distribution in the two groups differed significantly (Mann-Whitney U = 8728.5, p = 0.0446). There was also an increase in the percent of admissions shorter than 2 days between the AP and SOC cohorts (12.5% v. 5.2%, p = 0.024) [Figure1].

Figure 1

Conclusion

The use of a rapid ID/AST diagnostic technology with AS review may lead to shorter hospitalizations in select patient populations.

Disclosures

Kimberle Chapin, MD, genmark (Scientific Research Study Investigator)
671. Same Day Identification of Enterobacteriaceae Directly from Urine Samples
Authors: Kon Shelley E , Giddins Sara , Yushkevich Irina , Fuchs Martin , Irwin Amy , Metzger Steve , Price Connie S
Published: January 2021

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)
673. Updated CLSI Ciprofloxacin Breakpoints from a Multicenter Assessment for Enterobacterales, Salmonella spp. and Pseudomonas aeruginosa Using MicroScan Dried Gram Negative MIC Panels
Authors: Traczewski Maria M , Beasley Denise , Harrington Amanda , DesJarlais Sharon , Garner Omai , Hastey Christine , Brookman Regina , Lockett Zabrina , Chau Jennifer
Published: January 2021

Background

Updated US FDA/CLSI ciprofloxacin breakpoints were evaluated against data from a multicenter clinical study with Enterobacterales, Salmonella spp. and P. aeruginosa on a MicroScan Dried Gram-negative MIC (MSDGN) Panel. MIC results were compared to results obtained with frozen broth microdilution panels prepared according to CLSI methodology.

Methods

MSDGN panels were evaluated at three clinical sites by comparing MIC values obtained using the MSDGN panels to MICs utilizing a CLSI broth microdilution reference panel. Data from the combined phases of efficacy and challenge included 803 Enterobacterales, Salmonella spp. and P. aeruginosa clinical isolates tested using the turbidity and Prompt® methods of inoculation. To demonstrate reproducibility, a subset of 12 organisms were tested on MSDGN panels at each site during reproducibility. MSDGN panels were incubated at 35 ± 1ºC and read on the WalkAway System, the autoSCAN-4 instrument, and visually. Read times for the MSDGN panels were at 16-20 hours. Frozen reference panels were prepared and read according to CLSI methodology. FDA and CLSI breakpoints (µg/mL) used for interpretation of MIC results were: Enterobacterales ≤ 0.25 S, 0.5 I, ≥ 1 R; Salmonella spp. ≤ 0.06 S, 0.12-0.5 I, ≥ 1 R; P. aeruginosa ≤ 0.5 S, 1 I, ≥ 2 R.

Results

Essential and categorical agreement was calculated compared to frozen reference panel results. Results for isolates tested during efficacy and challenge with Prompt inoculation and manual read are as follows:

Conclusion

Ciprofloxacin MIC results for Enterobacterales, Salmonella spp., and P. aeruginosa obtained with the MSDGN panel correlate well with MICs obtained using frozen reference panels using updated FDA/CLSI interpretive criteria in this multicenter study.

* PROMPT® is a registered trademark of 3M Company, St. Paul, MN USA.

BEC, the stylized logo and the BEC product and service marks mentioned herein are trademarks or registered trademarks of Beckman Coulter, Inc. in the US and other countries.

Disclosures

Maria M. Traczewski, BS MT (ASCP), Beckman Coulter (Scientific Research Study Investigator) Denise Beasley, BS, Beckman Coulter (Other Financial or Material Support, Research personnel) Amanda Harrington, PhD, Beckman Coulter (Scientific Research Study Investigator) Sharon DesJarlais, BS, Beckman Coulter (Other Financial or Material Support, Research personnel) Omai Garner, PhD, D(ABMM), Beckman Coulter (Scientific Research Study Investigator) Christine Hastey, PhD, Beckman Coulter (Employee) Regina Brookman, BS, Beckman Coulter (Employee) Zabrina Lockett, MS, Beckman Coulter (Employee) Jennifer Chau, PhD, Beckman Coulter (Employee)
675. Evaluation of PLST for Clostridioides difficile Sequence-based Strain Typing
Authors: Edlind Tom , Redding Laurel
Published: January 2021

Background

Clostridioides difficile is a leading cause of healthcare-associated infection (HAI), most often following antibiotic therapy. The source of these infections may be endogenous or nosocomial; effective intervention requires distinquishing between these, which in turn requires strain typing. Numerous methods have been developed for C. difficile typing, ranging from length-based ribotyping and MLVA to whole genome sequencing. However, none are routinely used in clinical settings due to low resolution, high cost, technical complexity, or requirement for cultured isolates. The application of polymorphic locus sequence typing (PLST) to epidemiological analysis of HAI and foodborne infections has recently been described; here this approach is extended to C. difficile.

Methods

Tandem repeats were bioinformatically identified in the genome sequence of ribotype 027 strain R20291. These were screened by BLASTN of GenBank databases for the most polymorphic locus, which identified CdMT1 (Mbp 3.149). DNA was purified from colonies or environmental (Banana Broth) cultures; bead-beating and PCR inhibitor removal steps were required for consistent results.

Results

CdMT1 encompassed MLVA repeat C6cd which, based on length alone, yielded the highest diversity index (DI) of 0.96. In contrast, CdMT1 sequence analysis yielded DI of >0.99. Comparison to ribotype further illustrated high level resolution; e.g., 9 ribotype 027 strains were resolved into 8 CdMT1 alleles. For initial laboratory evalulation, veterinary C. difficile isolates (44 canine, 4 bovine) were CdMT1 typed. Bioinformatic analysis of the 48 sequences resolved 24 CdMT1 alleles, including 8 clusters of 2 to 6 canine strains. Six of these clusters represented isolates from individual puppies in the same litter, or from different litters but the same household, while the bovine isolates formed a phylogenetically distinct group. Using the same DNA purification protocol, CdMT1 typing demonstrated compatibility with C. difficile-spiked stool samples and Banana Broth environmental cultures.

Conclusion

CdMT1 typing represents a potentially useful tool for outbreak detection and investigation in healthcare facilities, particularly in light of its compatibility with both stool and environmental samples.

Disclosures

Tom Edlind, PhD, MicrobiType LLC (Employee, Scientific Research Study Investigator)