bluuebunny/crossref_metadata_2025 huggingface dataset:
1229. Volatile Biomarkers of Influenza Infection in the Breath
Authors: Danaher Patrick , Phillips Michael , Schmitt Peter , Richard Stephanie , Millar Gene , White Brian , Okulicz Jason , Coles Christian L , Burgess Timothy
Published: January 2021

Background

Annual influenza epidemics cause significant morbidity and mortality. New, emerging strains threaten to cause catastrophic pandemics. Assay of exhaled breath for volatile organic compounds (VOCs) via gas chromatography-mass spectroscopy (GC-MS) is an emerging diagnostic modality ideally suited to fill the gap in influenza diagnostics.

Methods

Patients with influenza like illness (ILI) presenting to the Troop Medical Clinic on JBSA Fort Sam Houston, TX, from 3/2017 to 3/2019 submitted a 2-minute breath sample in addition to a nasopharyngeal swab collected for polymerase chain reaction (PCR) assay for influenza virus. ILI was defined as temperature > 100.40F AND respiratory symptoms like cough, sputum production, chest pain and/or sore throat. Breath VOCs were assayed with GC-MS and data were analyzed in order to identify the significant breath VOC biomarkers that discriminated between ILI patients with and without a PCR assay positive for influenza with greater than random accuracy.

Results

Demographic, clinical, PCR and breath data were available for 237 episodes of ILI. PCR was positive for influenza for 32 episodes (30 influenza A and 2 B). The median age of participants was 21 (IQR 19, 23) and 69% were male. There were no differences in age, gender, education, race, or smoking, between the influenza positive and negative groups. Likewise, there was no difference in days of limited activity or missed work, or symptoms at presentation between the groups. The algorithm achieved near maximal predictive accuracy of 78% with four biomarkers (74% sensitivity and 70% specificity). Based on their mass spectra, these biomarker VOCs were tentatively identified as 2-amino-1-propanol, 2-butanamine, n-nitro, 3-methyl-hexanal, and heptane, which are consistent with products of oxidative stress.

Figure. Accuracy, Sensitivity, and Specificity of Influenza Breath Test. Receiver operating characteristic (ROC) of the breath test (sensitivity versus 1-specificity). The accuracy of the breath test was 78%. With a cutoff point at the “shoulder” of the ROC curve, the test had 74% sensitivity and 70% specificity.

Conclusion

Our findings bolster available benchtop and clinical data suggesting that breath testing may be a useful diagnostic modality for influenza infection. The next step will be to study the predictive algorithm developed in this protocol in a blinded validation cohort. If the predictive algorithm performs well in a validation study, adaptation for its use in a portable, tabletop GC would be warranted to allow for a rapid, accurate, universal point-of-care influenza diagnostic test.

Disclosures

Michael Phillips, MD, Menssana Research, Inc (Grant/Research Support)
1233. Identification of Novel Inhibitors of Clostridioides difficile Enoyl-Reductase II (FabK) by High-Throughput Virtual and Experimental Screening
Authors: Wahrmund Rebecca D , Avad Kristiana A , Reeve Stephanie M , Jones Jesse A , La Thao , Lee Richard E , Hevener Kirk E
Published: January 2021

Background

Clostridioides difficile is one of only three bacteria categorized as an ‘urgent’ drug-resistant threat by the CDC. This pathogen is responsible for nearly 500,000 hospital-acquired infections and 29,000 deaths per year at a cost of nearly $4.8 billion. There is a critical need for the identification of novel, anti-difficile agents with narrow-spectrum activity that can spare the human microbiome. We previously reported the essentiality of the FAS-II enzyme, enoyl-ACP reductase (FabK) in C. difficile, and the narrow-spectrum activity of a series of phenylimidazole inhibitors. We present here experimental and virtual compound screening studies that identified novel FabK inhibitors with sub-micromolar activity and follow-up SAR and structural studies.

Methods

Using a novel luminescence assay, 20K diverse compounds from the St. Jude drug-like and lead-like libraries were screened. In parallel, a ligand-based virtual screen was performed against 2.4 million lead- and drug-like compounds from commercial libraries. Hit compounds were confirmed using an orthogonal fluorescence-intensity assay and SAR studies were performed by testing commercially available hit analogs. The most potent inhibitor was advanced into co-crystallography structural studies.

Results

The compound screening campaigns resulted in the identification of several confirmed hit compounds with low to sub-micromolar activity and novel scaffolds relative to the known phenylimidazole inhibitors. Importantly, the first confirmed nanomolar inhibitor of C. difficile FabK was identified and validated with an IC50 of 0.35 μM. SAR studies of the hits along with a high-resolution co-crystal structure have allowed new insights into the key binding determinants and structural requirements for activity as well as the structural requirements for species specificity.

Conclusion

The C. difficile FabK enzyme offers a promising narrow-spectrum drug target that can potentially spare the human microbiome. The known activity of the phenylimidazole inhibitor series supports the druggability of this target. The newly discovered inhibitor class presented here further demonstrates the potential of FabK inhibition and will facilitate the development of clinically relevant, narrow-spectrum anti-difficile agents.

Disclosures

All Authors: No reported disclosures
1234. Increasing private sector investment in neglected tropical disease (NTD) research and development: a mixed methods study
Authors: Barofsky Jeremy , Xu Jacqueline , Schneider Jake , Manne-Goehler Jennifer
Published: January 2021

Background

This study explores the drug development environment for Human African Trypanosomiasis and Chagas disease and investigates ways to stimulate greater investment in the small molecule drug pipeline for NTDs.

Methods

We conducted qualitative case studies of successful public-private partnerships (PPPs) that have supported the research pipeline for treatment of HAT (Fexinidazole & Acoziborole) & Chagas disease (Benznidazole). We conducted semi-structured interviews with 21 key informants. We then performed an economic modeling analysis to evaluate the development costs compared to estimates of potential revenue in order to identify expected private investment returns, inclusive of the contribution of the Priority Review Voucher (PRV) program. We also investigate under what circumstances one can expect positive returns if R&D for NTDs was executed by a private biopharmaceutical firm. We calculate the net present value of R&D costs both for an average NTD drug and use the specific features of these three candidates to estimate the private ROI that would have prevailed for each drug had they been developed by a for-profit entity.

Results

The major themes that emerged from the case studies were: (1) the importance of pre-existing philanthropic efforts for a given disease, (2) the desire to align the social goals of the company with its actions, (3) the vital role of PPPs in coordinating development and reducing private-sector risk & (4) the limited role that the PRV played in motivating these activities. Overall, the current NTD R&D landscape is driven by PPPs. The modeling analysis shows why: although the PRV is an important incentive for drug development, it is not sufficient to generate a positive private return for novel drug development when adjusting for capitalized costs and failure risk. However, for a pre-existing, unapproved drug such as Benzinadozole, returns are positive in the current environment (Table 1). We find that both a restricted PRV supply & better estimates of approval probabilities would generate positive returns (Fig 1 + 2).

Table 1: Return on investment by small molecule drug

Figure 1. Return on Investment Sensitivity Analysis for Fexinidazole (Source: Authors’ calculations)

Figure 2. Return on Investment Sensitivity Analysis for Acoziborole (Source: Authors’ calculations)

Conclusion

We find support for NTD drug development within the private sector, but no novel R&D without nonprofit stewardship. Our findings intend to foster PPPs that stimulate this pipeline from very low current levels.

Disclosures

All Authors: No reported disclosures
1237. Robust Adjuvant Activity and Dose-sparing Potential of the Novel Semisynthetic Saponin Adjuvant TQL1055 for Seasonal and Pandemic Influenza
Authors: Buzz Chloe , Farris Eric , Bennett Sean R , Frenchick Pat , Martin Tyler
Published: January 2021

Background

Vaccination against both seasonal and pandemic influenza requires effective adjuvants to maximize the utility of limited antigen and to enhance immunogenicity in hyporesponsive at-risk populations. First-generation natural saponins are potent immuno-enhancers but are reactogenic and have supply constraints. As part of a NIH-funded project, the novel semisynthetic saponin TQL1055 was evaluated for its potential to augment the immunogenicity of influenza antigens.

Figure 1: TQL1055 Enhances the Antibody Response to a Recombinant Antigen Influenza Vaccine (Flublok®) and Exhibits Antigen Dose-Sparing Effects

Figure 2: TQL1055 Exhibits Improved Systemic Tolerability Over QS-21.

Methods

Groups of 10 C57BL/6J mice were immunized subcutaneously (SC) with Flublok® (H3N2 antigen) alone at either a 4.5 mcg or 1.1 mcg dose, or at a 1.1 mcg dose in combination with 10, 30 or 100 mcg TQL1055 on Days 0 and 21. Sera were analyzed at days 0, 21 and 42 by ELISA for H3N2-specific IgG. Body weights were measured serially.

Results

A 2-dose series of 1.1 mcg Flublok with TQL1055 elicited anti-H3N2 antibodies in all mice. This effect was TQL1055 dose-dependent, with GMTs of 2178 in the 10 mcg group, 13674 in the 30 mcg group and 48959 in the 100 mcg group. The GMT in all TQL1055 groups was higher than the GMT of 176 in the group receiving 4.5 mcg of Flublok alone. Mice receiving TQL1055 gained weight steadily after immunization, compared with a maximum weight loss of >10% in mice receiving 20 mcg of QS-21.

Conclusion

TQL1055 exhibits robust adjuvant activity for influenza antigens, demonstrating a dose-sparing effect and improved systemic tolerability compared with QS-21. Taken together, these finding support further evaluation of its potential as an adjuvant for influenza vaccines.

Disclosures

Chloe Buzz, BS, Adjuvance Technologies (Employee) Eric Farris, PhD, Adjuvance Technologies (Employee) Sean R. Bennett, MD PhD, Adjuvance Technologies (Employee) Pat Frenchick, PhD, Adjuvance Technologies (Consultant) Tyler Martin, MD, Adjuvance Technologies (Employee, Shareholder)
1240. Persistence of Circulating Antibody Through 12 Months Following Vaccination With a 20-Valent Pneumococcal Conjugate Vaccine in Adults 60–64 Years of Age
Authors: Hurley Donald , Griffin Carl , Young Jr. Mariano , Scott Daniel , Pride Michael W , Scully Ingrid L , Ginis John , Peng Yahong , Jansen Kathrin U , Gruber William C , Watson Wendy
Published: January 2021

Background

While widespread use of pneumococcal conjugate vaccines (PCVs) has reduced disease burden, expanding serotype coverage remains an unmet need in disease prevention. The 20-valent PCV (PCV20) contains capsular polysaccharide conjugates from serotypes included in the 13-valent PCV (PCV13; Prevnar 13®) as well as 7 additional serotypes. In a phase 2 study of PCV20 in adults 60–64 years of age, robust immune responses were observed at 1 month after vaccination; antibody persistence up to 12 months after vaccination from that study is described herein.

Methods

In this randomized, active-controlled, double-blind study (ClinicalTrials.gov NCT03313037), adults aged 60–64 years received a single PCV20 dose followed 1 month later by saline placebo or PCV13 followed 1 month later by 23-valent pneumococcal polysaccharide vaccine (PPSV23), which provided benchmarks for all PCV20 serotypes. Immunogenicity was assessed at baseline and at 1 and 12 months after vaccination as serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) and immunoglobulin G (IgG) geometric mean concentrations (GMCs). OPA and IgG geometric mean fold rises (GMFRs) from baseline to 12 months after vaccination were assessed.

Results

In the PCV20 group, OPA GMTs (n=185–200 at Month 12) for all PCV20 serotypes increased substantially from baseline to 1 month after vaccination and then declined by Month 12 but remained elevated above baseline. OPA GMFRs from baseline to Month 12 after PCV20 vaccination were 1.9–15.0 for the serotypes in common with PCV13 and 5.6–15.6 for the 7 additional serotypes. Similar results were observed for IgG concentrations, with GMFRs of 2.4–9.4 for the PCV13 serotypes and 3.0–15.5 for the 7 additional serotypes. At Month 12, 11 months after PPSV23 vaccination (n=162–195), OPA GMFRs were 5.3–11.5 for the 7 additional serotypes; IgG GMFRs were 5.0–10.4. Benchmarking to PCV13 serotypes in the control group was not appropriate as these subjects received both PCV13 and PPSV23, which overlap in polysaccharide composition for 12 serotypes.

Conclusion

Immune responses induced by PCV20 persisted at 12 months after vaccination in adults 60–64 years of age, further supporting the potential of PCV20 to expand serotype protection against adult pneumococcal disease.

Disclosures

Mariano Young Jr., MD, Pfizer Inc (Employee, Shareholder) Daniel Scott, MD, Pfizer (Employee, Shareholder) Michael W. Pride, PhD, Pfizer (Employee, Shareholder) Ingrid L. Scully, PhD, Pfizer Inc (Employee, Shareholder) John Ginis, BS, Pfizer Inc (Employee, Shareholder) Yahong Peng, PhD, Pfizer (Employee, Shareholder) Kathrin U. Jansen, PhD, Pfizer (Employee, Shareholder) William C. Gruber, MD, Pfizer (Employee, Shareholder) Wendy Watson, MD, Pfizer (Employee, Shareholder)
1249. Genetic Evidence That Gepotidacin Shows Well-balanced Dual Targeting against DNA Gyrase And Topoisomerase IV in Neisseria gonorrhoeae
Authors: Chan Pan , Ingraham Karen , Min Sharon , Scangarella-Oman Nicole , Rittenhouse Steve , Huang Jianzhong
Published: January 2021

Background

Gepotidacin (GEP) is a novel triazaacenaphthylene bacterial type II topoisomerase inhibitor targeting both bacterial DNA gyrase and topoisomerase IV by a different mechanism from fluoroquinolone antibiotics. Although in vitro frequency of resistance to GEP in Neisseria gonorrhoeae (NG) is low, during a phase 2 trial, clinical resistance to gepotidacin in NG emerged in a subset of fluoroquinolone-resistant NG isolates that contained a pre-existing ParC D86N mutation by introduction of a new GyrA A92T mutation. The objective of this study was to evaluate the role of GyrA A92T & Parc D86N mutations in resistance to GEP.

Methods

We utilized the high frequency of natural transformation to introduce GyrA A92T and ParC D86N mutations, individually and in combination, into NG isolates either with GyrA S91F D95G mutations or with wild type (WT) GyrA by selection on ciprofloxacin (CIP) or GEP to generate isogenic strains for susceptibility evaluation.

Results

Results are summarized in enclosed table. Overall, GyrA A92T and ParC D86N mutations alone did not confer a significant (>4-fold) increase in GEP MIC; whereas together they gave >16-fold increases in GEP MIC. Importantly, quinolone target mutations (GyrA S91F D95G and ParC D86N) together showed no significant effect on the GEP MIC; while they gave >1000-fold increase in CIP MIC. As expected, GyrA A92T and ParC D86N mutations alone or together in WT GyrA background had no significant effect on CIP susceptibility.

Susceptibility of isogenic NG strains to gepotidacin and ciprofloxacin

Conclusion

Our results indicated that unlike fluoroquinolones that primarily target DNA gyrase in NG, there is no obvious primary target for GEP, supporting well-balanced dual targeting of DNA gyrase and topoisomerase IV by GEP in NG. Though, the pre-existing ParC D86N mutation is a potential risk marker for clinical resistance development, as this mutation compromises dual targeting of GEP, our studies provide mechanistic insight for appropriate clinical dose selection to potentially suppress further resistance development in this subset of clinical isolates.

Disclosures

Pan Chan, PhD, GlaxoSmithKline (Employee, Shareholder) Karen Ingraham, MS, GlaxoSmithKline (Employee, Shareholder) Sharon Min, MS, GlaxoSmithKline (Employee, Shareholder) Nicole Scangarella-Oman, MS, GlaxoSmithKline plc. (Employee, Shareholder) Steve Rittenhouse, PhD, GlaxoSmithKline (Employee, Shareholder) Jianzhong Huang, PhD, GlaxoSmithKline (Employee, Shareholder)
1252. In Vitro Activity of Cefiderocol Against Metallo-β-Lactamase-Producing Gram-Negative Bacteria Collected in North America and Europe Between 2014 and 2017: SIDERO-WT-2014–2016 Studies
Authors: Takemura Miki , Kazmierczak Krystyna , Hackel Meredith , Sahm Daniel F , Echols Roger , Yamano Yoshinori
Published: January 2021

Background

Metallo-β-lactamases (MBLs; eg, NDM, VIM, and IMP) can inactivate most commonly-used β-lactam antibiotics, including carbapenems. Infections caused by MBL producers are difficult to treat due to their resistance to many antibiotics. Cefiderocol (CFDC) is a siderophore cephalosporin antibiotic approved in the USA in 2019, with potent activity against carbapenem-resistant Gram-negative bacteria (GNB), including both serine- and metallo-carbapenemase positive strains. We evaluated the in vitro activity of CFDC and comparator agents against MBL-producing strains of GNB from North America and Europe in 3 years’ of consecutive surveillance studies (SIDERO-WT-2014–2016).

Methods

Susceptibility testing for CFDC, ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), meropenem (MEM), cefepime (FEP), ciprofloxacin (CIP), and colistin (CST) was performed by broth microdilution according to CLSI guidance. CFDC was tested in iron-depleted medium. A total of 275 MBL-producing strains, consisting of 120 Enterobacterales (45 NDM; 75 VIM), 5 NDM-producing Acinetobacter baumannii, and 150 Pseudomonas aeruginosa (134 VIM; 16 IMP), identified among 4985 (654 Enterobacterales and 4331 non-fermenters) MEM non-susceptible (based on CLSI breakpoints) strains were used for the current analysis.

Results

The minimum inhibitory concentration (MIC) range and MIC90 for CFDC and comparators for each MBL-producing organism group are shown in the Table. Against NDM-producing Enterobacterales, of which 42% and 33% were isolated in Turkey and Russia, respectively, CFDC inhibited the growth of 84% of isolates tested at ≤4 µg/mL. CFDC MIC90 was 4 μg/mL for VIM-producing Enterobacterales (41% and 31% isolated in Greece and Italy, respectively), 1 μg/mL for VIM-producing P. aeruginosa (50% isolated in Russia), and 4 μg/mL for IMP-producing P. aeruginosa (88% isolated in Czech Republic). Other comparators (except for CST) were not active against these MBL producers.

Table. MIC range and MIC90 (μg/mL) for CFDC and comparators of MBL-producing organisms

Conclusion

CFDC inhibited the growth of 100% of MBL-positive GNB at ≤8 mg/mL and showed MIC90 of 4 μg/mL against all 275 MBL producers, indicating that CFDC has high potential for treating infections caused by these difficult-to-treat strains.

Disclosures

Miki Takemura, MSc, Shionogi & Co., Ltd. (Employee) Krystyna Kazmierczak, PhD, Shionogi & Co., Ltd. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor) Roger Echols, MD, Shionogi Inc. (Consultant) Yoshinori Yamano, PhD, Shionogi & Co., Ltd. (Employee)
1254. In vitro activity of sulbactam-durlobactam against recent global clinical Acinetobacter baumannii-calcoaceticus complex isolates
Authors: McLeod Sarah , Moussa Samir , Hackel Meredith , Miller Alita
Published: January 2021

Background

Acinetobacter baumannii-calcoaceticus complex (ABC) causes severe infections that are difficult to treat due to increasing resistance to antibacterial therapy. Sulbactam (SUL) has intrinsic antibacterial activity against ABC, but its clinical utility has been compromised by the prevalence of serine β-lactamases. Durlobactam (DUR, previously ETX2514) is a diazabicyclooctenone β-lactamase inhibitor with potent activity against Ambler classes A, C and D serine β-lactamases that effectively restores SUL activity against ABC isolates. SUL-DUR is an antibiotic designed to treat serious infections caused by Acinetobacter, including multidrug-resistant strains, which is currently in Phase 3 clinical testing. The potency of SUL-DUR against geographically diverse ABC isolates collected in 2018 was measured.

Methods

929 ABC isolates, including 698 A. baumannii, 13 A. calcoaceticus, 54 A. nosocomialis, and 164 A. pittii, were collected in 2018 from geographically diverse medical centers in the United States, Europe, Latin America, Israel and the Asia-Pacific region. Susceptibility testing was performed according to CLSI guidelines. Data analysis was performed using CLSI and EUCAST breakpoint criteria where available. Select isolates were subjected to whole genome sequencing with an Illumina MiSeq V2 instrument and analysis using CLCBio Genomics Workbench v6.5.

Results

In surveillance of 929 global isolates from 2018, the SUL-DUR MIC90 was 2 mg/L compared with 64 mg/L for SUL alone. This level of potency was consistent across species, regions, source of infection and subsets of resistance phenotypes. Fifty percent of the isolates were non-susceptible to carbapenems. Only 7 isolates (0.75%) had SUL-DUR MIC values >4 mg/L. Whole genome sequencing of these 7 isolates revealed that they either encoded the metallo-β-lactamase NDM-1, which DUR does not inhibit, or single amino acid substitutions near the active site of PBP3, the primary target of SUL.

Conclusion

SUL-DUR demonstrated potent antibacterial activity against recent, geographically diverse clinical isolates of ABC, including MDR isolates. These data support the potential utility of SUL-DUR for the treatment of antibiotic-resistant infections caused by ABC.

Disclosures

Sarah McLeod, PhD, Entasis Therapeutics (Employee) Samir Moussa, PhD, Entasis Therapeutics (Employee) Alita Miller, PhD, Entasis Therapeutics (Employee)
1256. In Vivo Activity and Structural Characterization of a New Generation γ-Lactam Siderophore Antibiotic Against Multidrug-Resistant Gram-Negative Bacteria and Acinetobacter spp
Authors: Goldberg Joel , Bethel Christopher , Hujer Andrea M , Marshall Steven , Taracila Magdalena A , Papp-Wallce Krisztina M , Kumar Vijay , van den Akker Focco , Plummer Mark , Bonomo Robert A
Published: January 2021

Background

Multidrug-resistant (MDR) A. baumannii presents a critical need for innovative antibacterial development. We have identified a new series of γ-lactam (oxopyrazole) antibiotics that target penicillin binding proteins (PBPs) and incorporate a siderophore moiety to facilitate periplasmic uptake. YU253911, an advanced iteration of this class shows potent in vitro activity against clinically relevant Gram-negative organisms including Acinetobacter spp.

Methods

Minimum inhibitory concentrations (MICs) for YU253911 were determined using broth microdilution against a 198-member panel of clinical isolates of Acinetobacter spp. Resistant strains were further evaluated for susceptibility to YU253911 in combination with sulbactam. The antibiotic’s target protein was evaluated by binding studies with Bocillin™, a fluorescent penicillin analogue, and modeled in the PBP active site. YU253911 was evaluated in vivo in a mouse soft tissue infection model.

Results

MIC testing for YU253911 revealed an MIC50 of 0.5 μg/mL and an MIC90 of 16 μg/mL, which compared favorably to all tested β-lactam antibiotics including penicillins, cephalosporins, monobactams and carbapenems (MIC50 = 2 to > 16 μg/mL). Combination with sulbactam augmented the activity of the agent. There was no apparent correlation between YU253911-resistance and the presence of specific β-lactamase genes, and incubation with representative β-lactamase proteins (KPC-2, OXA-23, OXA-24, PER-2, PDC-3, NDM-1, VIM-2, and IMP-1) showed negligible hydrolysis of the agent. YU253911 showed promising preclinical pharmacokinetics in mice with a 15 h half-life from intravenous administration and demonstrated a dose-dependent reduction in colony forming units from 50 and 100 mg/kg q6h dosing in a mouse thigh infection model using P. aeruginosa.

Conclusion

YU253911, a new generation γ-lactam antibiotic effective against MDR A. baumannii demonstrated promising in in vitro potency and favorable pharmacokinetics which correlated with in vivo efficacy.

Disclosures

Krisztina M. Papp-Wallce, PhD, Entasis (Grant/Research Support)Merck (Grant/Research Support)Venatorx (Grant/Research Support) Robert A. Bonomo, MD, Entasis, Merck, Venatorx (Research Grant or Support)
1257. A phase II Prospective Randomized Study to Assess Ceftolozane-Tazobactam in the Management of Febrile Neutropenia in Patients with Hematological Malignancies
Authors: Chaftari Anne-Marie , Hachem Ray Y , Malek Alexandre , Mulonovich Victor , Szvalb Ariel D , Jiang Ying , Ali Shahnoor , Deeba Rita , Chaftari Patrick , Raad Issam I , Raad Issam I
Published: January 2021

Background

Despite the implementation of successful antibiotic stewardship programs, antibiotic resistance continue to emerge particularly against gram-negative bacteria. With the increase use of antibiotics in high risk patients with hematological malignancies, the empiric therapy with standard antibiotic could be inappropriate. New antibiotics may be useful to cover potential resistant pathogens. We evaluated the role of a new cephalosporin /β-lactamase inhibitor ceftolozane-tazobactam (C/T) in comparison to standard of care (SOC) antibiotics in the empiric treatment of febrile neutropenic cancer patients with hematological malignancies.

Methods

We conducted a prospective randomized open label comparative study to evaluate the safety and efficacy of C/T vs SOC antibiotics consisting of cefepime, piperacillin-tazobactam or meropenem when used in combination with gram positive antibacterial agents. Between May 2018 and March 2020, we enrolled 88 febrile neutropenic patients with hematological malignancies who presented to our emergency center. Patients received at least 72 hours of intravenous study drugs and were followed through end of IV therapy and for up to 42 days.

Results

A total of 88 patients were analyzed of whom 42 received C/T and 46 SOC

antimicrobial agents. The rate of documented bloodstream infections was similar in both groups (CE-TZ 21% vs SOC 26%, p=0.61). Favorable clinical response at end of IV therapy was significantly better in the C/T arm compared to SOC therapy (88% vs 72%, p=0.039), at test of cure (21 days), and last follow-up (42 days). In patients with documented infections, the rate of microbiological eradication was similar in both groups. Drug-related adverse events that led to drug discontinuation was similar in both groups (7%). Similarly overall mortality was similar in both groups.

Conclusion

The empiric use of C/T to cover gram negative organisms in high risk febrile neutropenic patients with hematological malignancies is safe and associated with better clinical outcome than SOC antimicrobial agents. The emergence of resistant pathogens should be further evaluated.

Disclosures

Issam I. Raad, MD, Citius (Other Financial or Material Support, Ownership interest)Cook Medical (Grant/Research Support)Inventive Protocol (Other Financial or Material Support, Ownership interest)Novel Anti-Infective Technologies (Shareholder, Other Financial or Material Support, Ownership interest)
1259. Activity of eravacycline against staphylococci isolated from periprosthetic joint infections
Authors: Zhuchenko Georg , Schmidt-Malan Suzannah , Patel Robin , Patel Robin
Published: January 2021

Background

Perirosthetic joint infections (PJIs) are costly and difficult to treat. The most common causes of PJIs are Staphylococcus aureus and Staphylococcus epidermidis. Eravacycline is a newer tetracycline with promising activity against Gram-positive and negative bacteria which is approved for treatment of complicated intraabdominal infections. Here, the in vitro activity of eravacycline was assessed against bacteria associated with PJI.

Methods

185 staphylococcal isolates, including 38 methicillin-resistant S. aureus (MRSA), 64 methicillin-susceptible S. aureus (MSSA), 62 methicillin-resistant S. epidermidis (MRSE) and 21 methicillin-susceptible S. epidermidis (MSSE) strains were studied. Minimum inhibitory concentrations (MICs) were determined according to Clinical and Laboratory Standards Institute guidelines (range of 0.06-64 µg/ml tested). Results were analyzed using susceptible breakpoints from EUCAST (≤0.25 µg/ml) and the FDA (≤0.06 µg/ml). Minimum biofilm bactericidal concentrations (MBBCs) were determined using a modification of the Calgary biofilm method. Briefly, biofilms were formed on pegged lids in trypticase soy broth, after which the pegged lids were rinsed in phosphate buffered saline (PBS), transferred to a plate containing dilutions of eravacycline in cation-adjusted Mueller Hinton broth (CAMHB) and incubated for 20-24h. Finally, the pegged lids were again rinsed in PBS and transferred to a plate containing CAMHB and incubated for 24h. The MBBC was the lowest concentration with no visible growth.

Results

MIC50/90 (range) in µg/ml for MRSA, MSSA, MRSE, and MSSE were 0.125/0.125 (≤0.06-0.25), ≤0.06/0.125 (≤0.06-0.25). 0.125/1 (≤0.06-2), and 0.25/1 (≤0.06-1), respectively. Using the EUCAST susceptible breakpoint, 100% of isolates would be considered susceptible, whereas only 54% would be considered susceptible using the FDA breakpoint. MBBC50/90 (range) in µg/ml for MRSA and MSSA were both 8/16 (4-16); for MRSE and MSSE, the values were 4/16 (2-32) and 8/16 (2-32), respectively.

Conclusion

Our data suggest that the FDA susceptible breakpoint may need re-evaluation. Eravacycline has low anti-staphylococcal biofilm activity.

Disclosures

Robin Patel, MD, Accelerate Diagnostics (Grant/Research Support)CD Diagnostics (Grant/Research Support)Contrafect (Grant/Research Support)Curetis (Consultant)GenMark Diagnostics (Consultant)Heraeus Medical (Consultant)Hutchison Biofilm Medical Solutions (Grant/Research Support)Merck (Grant/Research Support)Next Gen Diagnostics (Consultant)PathoQuest (Consultant)Qvella (Consultant)Samsung (Other Financial or Material Support, Dr. Patel has a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued.)Selux Dx (Consultant)Shionogi (Grant/Research Support)Specific Technologies (Consultant)
1265. AT-527, an Oral Purine Nucleotide Prodrug Exhibiting Potent In Vitro Antiviral Activity Against Human Coronaviruses, Including SARS-CoV-2
Authors: Good Steven S , Moussa Adel , Zhou Xiao-Jian , Pietropaolo Keith , Sommadossi Jean-Pierre
Published: January 2021

Background

Coronaviruses (CoVs) are the causative pathogens of several human diseases, including seasonal respiratory infections (HCoV-229E and HCoV-OC43), Middle East respiratory syndrome (MERS-CoV), severe acute respiratory syndrome (SARS-CoV-1) and the novel CoV recently identified as the virus responsible for the current COVID-19 pandemic, SARS-CoV-2. AT-527 is currently in Phase 2 clinical trials and has demonstrated potent activity and a well-tolerated safety profile in HCV-infected subjects. Here we report the in vitro activity of AT-511, the free base form of AT-527, against SARS-CoV-2 and other CoVs.

Methods

BHK-21, Huh-7, RD and differentiated normal human bronchial epithelial (dNHBE) cell cultures were exposed to virus and serial dilutions of test compounds. Independent assessments of antiviral activity were obtained by determining effective concentrations of test compounds required to 1) prevent half-maximal (EC50) virus-induced cytopathic effect (CPE) using MTT or neutral red staining and 2) produce virus yield reductions (VYR) by 90% (EC90) using standard endpoint dilution CCID50 assays in Vero 76 cells. Half maximal cytotoxicity of test compounds was determined by dye (MTT or neutral red) staining in the absence of added virus or by microscopic inspection (dNHBE cells only).

Results

Table 1 presents the in vitro activities of AT-511 against several coronaviruses. Also included in these assays are the antiviral activities of potential COVID-19 oral treatments, including chloroquine, hydroxychloroquine and N4-hydroxycytidine.

Table 1. In Vitro Activity of AT-511 Against Various Human Coronaviruses

Conclusion

The data demonstrate the potent in vitro activity of AT-511 against several CoVs, with individual EC90 values ranging from 0.34 to 1.2 µM against HCoV-229E, HCoV-OC43, SARS-CoV-1 and SARS-CoV-2 and less activity against MERS-CoV (average EC90 = 36 µM). The potent in vitro antiviral activity of AT-511 against SARS-CoV-2 (EC90 = 0.55 µM), associated with the AT-527 safety profile in treated HCV patients, support the ongoing clinical evaluation of the safety and efficacy of AT-527 in COVID-19 patients.

Disclosures

Steven S. Good, MS, Atea Pharmaceuticals, Inc. (Employee) Adel Moussa, PhD, Atea Pharmaceuticals, Inc. (Employee) Xiao-Jian Zhou, PhD, Atea Pharmaceuticals, Inc. (Employee) Keith Pietropaolo, B.A., Atea Pharmaceuticals, Inc. (Employee) Jean-Pierre Sommadossi, PhD, Atea Pharmaceuticals, Inc. (Board Member)
100. Development and Implementation of a 2-Tier Testing Algorithm for Clostridioides difficile: An Evaluation of Outcomes on Patients with Indeterminate Results at 90 Days
Authors: Brown Johanna P , Puckett Stephanie
Published: January 2021

Background

There is no definitive gold standard for accurate diagnosis of Clostridioides difficile (C difficile) infection. There is ample evidence that relying on a molecular test such as Polymerase Chain Reaction (PCR) for diagnosis, can lead to over diagnosis and unnecessary treatment. Combined, multi-step algorithms have been proposed to improve specificity of testing. The challenge remains in interpreting discordant or indeterminate results. Additionally, the risk of hospitalization due to lack of treatment for indeterminate results remains unclear.

Methods

To improve C difficile testing, a new 2-tier algorithm was implemented in 2019 starting with PCR testing. An indeterminate result was defined as a sample with a positive PCR and a positive Glutamate Dehydrogenase (GDH)/negative toxin result or a positive PCR and a negative GDH/positive toxin result.

Indeterminate results were classified by episode severity and number. Patient records were reviewed by the Antimicrobial Stewardship (AS) physician and pharmacist to determine true infection versus colonization. Treatment was given as per recent IDSA Guidelines.

All patients with indeterminate results were followed for 90 days for development of infection or hospitalization due to C difficile.

Adults with stool samples submitted for testing between 6/1/2019 and 12/31/2019 were included. A total of 169 specimens were reviewed: 75 were positive, 72 were indeterminate (4 excluded from final analysis) and 22 were negative.

Results

Using a 2-tier testing algorithm, 68 (41%) of all results were indeterminate. Our AS classified 47 (69%) of those as infection and 21 (31%) as colonization.

Patients with indeterminate results who were treated had a low incidence (8.5%) of reinfection requiring hospitalization in the following 90 days. There were no hospitalizations in the untreated group.

Of patients with an indeterminate result who were treated, 42 (89%) were categorized as an initial episode of C difficile infection.

Conclusion

Clinical correlation of indeterminate results is critical to algorithm interpretation.

A combined approach with provider education, an electronic testing advisor, a 2-tier testing algorithm, daily monitoring and prescribing by the AS team resulted in favorable outcomes for patients with indeterminate results

Disclosures

All Authors: No reported disclosures
1266. Characterization of Shifts in Minimum Inhibitory Concentrations During Treatment with Cefiderocol or Comparators in the Phase 3 CREDIBLE-CR and APEKS-NP Studies
Authors: Takemura Miki , Yamano Yoshinori , Matsunaga Yuko , Ariyasu Mari , Echols Roger , Den Nagata Tsutae
Published: January 2021

Background

Cefiderocol (CFDC) is a novel siderophore cephalosporin developed to treat serious carbapenem-resistant (CR) Gram-negative (GN) infections.

Methods

In CREDIBLE-CR (NCT02714595), adults with serious infections caused by CR GN pathogens received CFDC 2 g, q8h, 3-h infusion, or best available therapy (BAT). In APEKS-NP (NCT03032380), adults with nosocomial pneumonia received CFDC or high-dose, extended-infusion meropenem (each 2 g, q8h, 3-h infusion). All treatments were given for 7‒14 days (extendable to 21 days). Biospecimens were collected before the first dose of study drug and at subsequent visits for assessments, and minimum inhibitory concentrations (MIC) to various antibiotics, including CFDC and carbapenems, were determined. Isolates with an increased MIC were evaluated by RT-PCR or whole genome sequencing (WGS) for CFDC resistance-related genes or mutations. Results for genetically related isolates with an elevated MIC during therapy are shown.

Results

On-therapy ≥4-fold CFDC MIC increase was found in 12 out of 106 (CREDIBLE-CR; Table 1) and 7 out of 159 (APEKS-NP; Table 2) isolates, respectively. For most isolates, CFDC MIC increased by 4–8-fold but remained ≤4 µg/mL. Specific mutations which could explain CFDC MIC increases were found in only 3 isolates. Mutations in iron-transport related genes were not identified. Mutation in CFDC target gene PBP-3 was identified in 1 A. baumannii isolate. Class-C enzyme mutation was observed in 2 isolates (CREDIBLE-CR: PDC-30 in P. aeruginosa; APEKS-NP: ACT-17 in E. cloacae), although the contribution to CFDC MIC increase has not been confirmed. In the BAT arm in CREDIBLE-CR, 6 out of 46 isolates had ≥4-fold MIC increase; all post-treatment isolates were resistant to BAT agents (Table 1), although WGS was not conducted for these isolates. In the meropenem arm in APEKS-NP, 5 out of 164 isolates had ≥4-fold MIC increase (Table 2).

Table 1. MIC changes in CREDIBLE-CR

Table 2. MIC changes in APEKS-NP

Conclusion

Among isolates with ≥4-fold MIC increase during CFDC treatment, actual CFDC MIC values remained relatively low for most isolates. Frequency of MIC increase in BAT or meropenem arms was similar to that of CFDC, but the magnitude was greater. Acquisition of contributory mechanism has not been identified except for the mutation in PBP 3 and some β-lactamases.

Disclosures

Miki Takemura, MSc, Shionogi & Co., Ltd. (Employee) Yoshinori Yamano, PhD, Shionogi & Co., Ltd. (Employee) Yuko Matsunaga, MD, Shionogi Inc. (Employee) Mari Ariyasu, BPharm, Shionogi & Co., Ltd. (Employee) Roger Echols, MD, Shionogi Inc. (Consultant) Tsutae Den Nagata, MD, Shionogi & Co., Ltd. (Employee)
1267. Comparative activity of omadacycline against extended-spectrum beta-lactamase positive and negative Escherichia coli and Klebsiella pneumoniae strains recovered from urine specimens
Authors: Stone Tyler J , Kilic Abdullah , Williamson John , Palavecino Elizabeth , Palavecino Elizabeth
Published: January 2021

Background

Omadacycline (OMC) is a novel tetracycline (TET) derivative antibiotic with activity against TET-resistant Enterobacterales. OMC is available in both oral and intravenous formulations and is has been studied as a treatment of uncomplicated urinary tract infection (UTI) and acute pyelonephritis. The purpose of this study was to evaluate OMC activity against extended-spectrum beta-lactamase (ESBL) positive and negative Enterobacterales strains recovered from urine specimens.

Methods

Urine samples from patients with suspected UTI were quantitatively plated onto blood agar and MacConkey agar plates in the microbiology lab of Wake Forest Baptist Medical Center. After overnight incubation, colonies were identified to the species level by MALDI-TOF system. Susceptibility testing was performed for isolates of E. coli and K. pneumoniae. OMC and TET susceptibility testing was performed by disk diffusion and gradient strip methodologies. Results were interpreted in accordance with the Clinical and Laboratory Standards Institute (CLSI) or Food and Drug Administration breakpoints. Isolates were tested in triplicate. ESBL screening and susceptibility testing to oral antibiotics commonly prescribed for UTI were performed by the MicroScan WalkAway System. Susceptibility rates and MIC50/90 were calculated and subsets of isolates were analyzed using descriptive statistics.

Results

A total of 204 isolates, including 102 E. coli and 102 K. pneumoniae, were tested. All but 1 isolate (99.5%) exhibited categorical agreement in results generated by the strip (Table 1) and disk (data not shown) methods and this was considered a minor error involving an intermediate result. OMC MIC90 for E. coli and K. pneumoniae were 6 µg/mL and >32 µg/mL, respectively. OMC displayed increased susceptibility rates compared to TET regardless of isolate species or ESBL positivity (Table 2).

Table 1. Omadacycline Minimum Inhibitory Concentrations (MICs, µg/mL)

Table 2. Susceptibilities of Oral Antibiotics Used to Treat UTI (% S)

Conclusion

OMC exhibits promising antimicrobial activity against TET-resistant and ESBL-positive E. coli and K. pneumoniae. OMC displays superior activity to ESBL positive E. coli when compared to ESBL positive K. pneumoniae. These data support the development of OMC as a much needed option in the treatment of UTI caused by resistant Enterobacterales.

Disclosures

Tyler J. Stone, PharmD, Paratek (Research Grant or Support) Abdullah Kilic, MD, Paratek (Grant/Research Support) John Williamson, PharmD, Paratek (Research Grant or Support) Elizabeth Palavecino, MD, Paratek (Grant/Research Support)Paratek (Grant/Research Support)
1269. Differences in Interpretative Breakpoints Between CLSI, FDA and EUCAST Impact Reporting of Susceptibility and Resistance to Cefiderocol
Authors: Yamano Yoshinori , Takemura Miki , Longshaw Christopher , Echols Roger
Published: January 2021

Background

Cefiderocol (CFDC) is a siderophore cephalosporin with broad coverage of aerobic Gram-negative (GN) bacteria. Provisional breakpoints (BP) were approved by CLSI in 2018, with FDA and EUCAST providing clinical BP in 2019 and 2020, respectively; however, BPs differ markedly between organizations, reflecting differences in labelling, PK/PD standards and availability of clinical study data during regulatory review. Here we compare susceptibility rates based on these different BPs.

Methods

Susceptibility rates for each bacterial species were determined using CFDC BP from each organization and the MICs of 28,629 GN clinical isolates from 3 consecutive years of SIDERO-WT surveillance studies (2014–17). The analysis used all isolates and sub-grouped isolates based on meropenem (MEM) susceptibility (CLSI BP) or carbapenemase production.

Results

Within the overall Enterobacterales group, ≥98.5% isolates were interpreted as susceptible to CFDC regardless of BP used. However, the proportion of susceptible differed significantly (82.5–98.6%) when applied to MEM-non-susceptible (NS) isolates. Similarly, against most carbapenemase producers, susceptibility ranged from 80 to 100%, however for NDM producers, only 51% of isolates were defined as susceptible by FDA or EUCAST BP vs 84% using the CLSI BP. Against Pseudomonas aeruginosa including MEM-NS isolates, susceptibility was ≥94% despite different BPs recommended by FDA (1 mg/L), EUCAST (2 mg/L) and CLSI (4 mg/L). This changed the proportion of IMP-producing isolates classified as susceptible from 100% (CLSI) and 81% (EUCAST) to only 19% (FDA). Against other non-fermenters, susceptibility was ≥91% irrespective of BP used.

Table 1. Susceptibility rates against Enterobacterales based on breakpoints from each organization

Table 2. Susceptibility rates against non-fermenters based on breakpoints from each organization

Conclusion

Differences in BPs between FDA, CLSI and EUCAST could impact on the reporting of susceptibility or resistance to CFDC, particularly for MEM-NS isolates. PK/PD model simulations support 100% fT >MIC up to an MIC of 4 mg/L, and in Phase 3 trials the mean trough concentration of unbound cefiderocol was >4 mg/L. The potential impact of these differences on clinical decision making are important as the greatest clinical utility for CDFC is expected to be in patients with carbapenem-resistant GN infections due to limited treatment options.

Disclosures

Yoshinori Yamano, PhD, Shionogi & Co., Ltd. (Employee) Miki Takemura, MSc, Shionogi & Co., Ltd. (Employee) Christopher Longshaw, PhD, Shionogi B.V. (Employee) Roger Echols, MD, Shionogi Inc. (Consultant)
1279. In Vitro Activity of Nacubactam (OP0595) Alone and in Combination with β-Lactams against β-Lactamase-Producing Enterobacterales Isolated in Japan
Authors: Nagira Yu , Yamada Keiko , Okade Hayato , Senju Nami , Tsutsumi Yuko , Tabata Yuji , Kato Kazuhiko
Published: January 2021

Background

Nacubactam (NAC) is a novel serine β-lactamase inhibitor in clinical development, and inhibits Ambler class A, class C, and some class D β-lactamases. In addition, it has penicillin-binding protein (PBP) 2-dependent antibacterial activity and an ‘enhancer’ effect when combined with β-lactams bound to PBP3. This study assessed the in vitro activity of NAC alone and in combination with β-lactams against IMP-type metallo-β-lactamase-producing and ESBL-producing Enterobacterales isolated in Japan.

Methods

The MICs for the clinical isolates in Japan were determined and time kill studies were performed. IMP and ESBL genes were detected by PCR. The MICs were determined by broth microdilution method following CLSI methodology. β-lactams and NAC were tested as a ratio of 1:1. Time kill profiles were also studied according to CLSI methodology.

Results

The MIC50/MIC90s of NAC alone against 112 IMP-producing Enterobacterales and 154 ESBL-producing Enterobacterales were 2/ >32 and 2/8 mg/L, respectively. Regarding the MICs of cefepime (FEP)/NAC and aztreonam (ATM)/NAC against IMP-producing isolates, the MIC90s were 2 and 1 mg/L and the MIC ranges were 0.06 - 32 and 0.06 - 4 mg/L, respectively. The MIC90s of FEP/NAC and ATM/NAC against ESBL-producing isolates were 0.5 and 1 mg/L. These MIC90s of β-lactam/NAC against IMP-producing and ESBL-producing isolates were significantly lower than those of β-lactam alone (>128 mg/L). The highest MIC of ATM/NAC against IMP-producing isolates was lower than that of FEP/NAC. In addition, bactericidal activities of β-lactam/NAC were observed at the lower concentration of β-lactam compared to that of β-lactam alone.

Conclusion

NAC in combination with β-lactams showed excellent in vitro activities against not only ESBL-producing Enterobacterales but also IMP-producing Enterobacterales isolated in Japan. ATM/NAC tended to show higher antimicrobial effect against IMP-producing isolates by the enzyme stability of ATM. These results support the complex activities of NAC which works as a β-lactamase inhibitor, an antibacterial agent and also an enhancer when combined with β-lactams. Furthermore, these will be useful for selecting a partner β-lactam for NAC.

Disclosures

Yu Nagira, MS, Meiji Seika Pharma Co., Ltd. (Employee) Keiko Yamada, BS, Meiji Seika Pharma Co., Ltd. (Employee) Hayato Okade, Ph.D, Meiji Seika Pharma Co., Ltd. (Employee) Nami Senju, BS, Meiji Seika Pharma Co., Ltd. (Employee) Yuko Tsutsumi, MS, Meiji Seika Pharma Co., Ltd. (Employee) Yuji Tabata, Ph.D, Meiji Seika Pharma Co., Ltd. (Employee)