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Background: Desirability of outcome ranking (DOOR) is an innovative approach to clinical trial design and analysis that uses an ordinal ranking system to incorporate the overall risks and benefits of a therapeutic intervention into a single measurement. Here we derived and evaluated a disease-specific DOOR endpoint for registrational trials for hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia (HABP/VABP)., Methods: Through comprehensive examination of data from nearly 4000 participants enrolled in six registrational trials for HABP/VABP submitted to the Food and Drug Administration (FDA) between 2005 and 2022, we derived and applied a HABP/VABP specific endpoint. We estimated the probability that a participant assigned to the study treatment arm would have a more favorable overall DOOR or component outcome than a participant assigned to comparator., Results: DOOR distributions between treatment arms were similar in all trials. DOOR probability estimates ranged from 48.3% to 52.9% and were not statistically different. There were no significant differences between treatment arms in the component analyses. Although infectious complications and serious adverse events occurred more frequently in ventilated participants compared to non-ventilated participants, the types of events were similar., Conclusions: Through a data-driven approach, we constructed and applied a potential DOOR endpoint for HABP/VABP trials. The inclusion of syndrome-specific events may help to better delineate and evaluate participant experiences and outcomes in future HABP/VABP trials and could help inform data collection and trial design., Competing Interests: Potential conflicts of interest. V. G. F. reports personal fees from Novartis, Debiopharm, Genentech, Achaogen, Affinium, Medicines Co., MedImmune, Bayer, Basilea, Affinergy, Janssen, Contrafect, Regeneron, Destiny, Amphliphi Biosciences, Integrated Biotherapeutics; C3J, Armata, Valanbio; Akagera, Aridis, Roche, grants from NIH, MedImmune, Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Merck; Medical Biosurfaces; Locus; Affinergy; Contrafect; Karius; Genentech, Regeneron, Deep Blue, Basilea, Janssen; Royalties from UpToDate, stock options from Valanbio and ArcBio, Honoraria from Infectious Diseases of America for his service as Associate Editor of Clinical Infectious Diseases, and a patent sepsis diagnostics pending. H. W. B. reports royalties to author from Sanford Guide; editorial consulting fees from Sanford Guide, Antimicrobial Agents and Chemotherapy/ASM, ID Clinics of North America/Elsevier; payment or honoraria for lectures, presentations, speakers’ bureaus, manuscript writing or educational events from Grand Rounds at Temple; IDWeek lecture travel support from Finland Award; role as PACCARB Voting Member (travel reimbursed) and on Board of Trustees, College of the Holy Cross (travel reimbursed). T. H. reports grants or contracts from Aceragen; consulting fees from Astellas Pharma US and Mitsubishi Tanabe Pharma; payment or honoraria for lectures, presentations, speakers’ bureaus, manuscript writing, or educational events from Cancer and Chemotherapy KK. S. R. E. reports NCI/NIH grant, NHLBI/NIH grant, CDC grant, and grants or contracts from Degruyter (Editor-in-Chief: Statistical Communications in Infectious Diseases); book royalties from Taylor & Francis; consulting fees from Genentech, AstraZeneca, Takeda, Microbiotix, Johnson & Johnson, Endologix, ChemoCentryx, Becton Dickenson, Atricure, Roivant, Neovasc, Nobel Pharma, Horizon, International Drug Development Institute, SVB Leerink, Medtronic, Regeneron, Wake Forest University, Recor, Janssen, IDDI; honorarium from Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), and payment or honorarium for travel from Liver Forum and Paris NASH Meeting; support for attending meetings and/or travel from FDA (honorarium); paid participation on a Data Safety Monitoring Board or Advisory Board for NIH, BARDA, Breast International Group, University of Pennsylvania, Washington University, Duke University, Roche, Pfizer, Takeda, Akouos, Apellis, Teva, Vir, DayOneBio, Alexion, Tracon, Rakuten, Abbvie, GSK, Eli Lilly, Nuvelution, Clover, FHI Clinical, Lung Biotech, SAB Biopharm, Advantagene, Candel, Novartis; unpaid Board member for American Statistical Association, Society for Clinical Trials, and Frontier Science Foundation. J. H. A. reports grant funding to institution for work unrelated to this from the Centers for Disease Control and Prevention (CDC); support for speaking at SHEA Spring Conference from SHEA. S. N. reports support for travel to meetings is supported by my employer, Johnson and Johnson; stocks in J&J, author's employer. T. H. reports grant from NIH to Antibacterial Resistance Leadership Group and grants or contracts from Karius for Adjudication committee; royalties or licenses from UpToDate; consulting fees from Aridis, Pfizer, Lysovant, Affinivax, Basilea, Concert Genetics; participation on Data and Safety Monitoring Board (DSMB) for Staphylococcus aureus Network Adaptive Platform (SNAP) trial and Spero and on Advisory Board for Basilea and Paul Scherrer Institut (PSI). S. B. D. reports grants or contracts to University of California San Francisco (UCSF) from Gilead, Pfizer, F2G, Regeneron, Chan Zuckerberg Biohub, and NIAID/NIH; consulting fees to author from Genentech and Janssen/J + J; support for travel to speak at IDWeek from Infectious Diseases Society of America (IDSA); patent US20100143379A1 for Mif agonists and antagonist and therapeutic uses thereof; leadership or fiduciary roles on IDSA Antibacterial Resistance Committee, CADPH HAI Advisory Committee, Antibacterial Resistance Leadership Group Innovations Group, Laboratory Center, Mentorship Committee, Gram Positive Committee, Immunosuppressed Host Group; payment for clinical events committee/adjudication committee participation from Shinogi, Basilea, Duke Clinical Research Institute. H. C. reports stock or stock options from Merck and Moderna; membership of DSMB for COVID antiviral RCT for Merck. D. C. reports grants or contracts from Duke University for COMET study (cancer) Patient Leadership Group, from UCSF for STORMing Cancer Patient Advocate Team, and from MD Anderson for PRECISION Patient Advisory Involvement Panel; consulting fees for ongoing projects from SimBioSys and MaxisHealth, from Health Literacy Media (HLM) for Patient Advisor for ongoing projects, and from Appelis Pharmaceuticals, Inc., for consulting/project ended in 12/2022 and from Kinnate Biopharma for consulting/project ended in 06/2022; honoraria and travel support from HMP Education; support for travel from Agile Falcon Strategic Group, DGE Events, and Informa; participation on DSMB for American Society for Clinical Oncology and on Patient Partner Council for Evidera; a role on Executive Group for Metastatic Breast Cancer Alliance and a role as committee member for Alliance for Clinical Trials in Oncology; receitp of manuscript writing support from IQVIA through Regeneron. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2024.)

Allergic bronchopulmonary aspergillosis and invasive fungal diseases represent distinct infectious entities that cause significant morbidity and mortality. Currently, administered inhaled antifungal therapies are unapproved, have suboptimal efficacy, and are associated with considerable adverse reactions. The emergence of resistant pathogens is also a growing concern. Inhaled antifungal development programs are challenged by inadequate nonclinical infection models, highly heterogenous patient populations, low prevalence rates of fungal diseases, difficulties defining clinical trial enrollment criteria, and lack of robust clinical trial endpoints. On 25 September 2020, the US Food and Drug Administration (FDA) convened a workshop with experts in pulmonary medicine and infectious diseases from academia, industry, and other governmental agencies. Key discussion topics included regulatory incentives to facilitate development of inhaled antifungal drugs and combination inhalational devices, limitations of existing nonclinical models and clinical trial designs, patient perspectives, and industry insights., Competing Interests: Potential conflicts of interest. L. B. is a full-time employee of Pulmocide. As an employee, he receives reimbursements for conference- and travel-related costs to attend scientific conferences. He also owns Pulmocide stock options. D. J. C. serves as a consultant to TFF Pharmaceuticals, which covers his travel to conferences/meetings. He also owns TFF Pharmaceuticals stock options. R. G. C. is an interim executive and consultant for companies developing and commercializing pharmaceutical, biologic, and medical device products. He is currently working with Pulmatrix (has antifungal product in development), Larimar Therapeutics (not in antifungal space), and Respira, Inc (not in antifungal space). D. W. D. and family hold Founder shares in F2G Ltd, a University of Manchester spin-out antifungal discovery company, and share options in TFF Pharmaceuticals. He acts or has recently acted as a consultant to Pulmatrix, Pulmocide, Biosergen, TFF Pharmaceuticals, Pfizer, Omega, Novacyt, Rostra Therapeutics, MucPharm, Mundipharma, and Cipla, and reports grants from Pfizer. He chairs a Data Review Committee for Pulmocide and as Phase 1 Medical Monitor for Biosergen. In the last 3 years, he has been paid for talks on behalf of BioRad, Basilea, and Pfizer. He is a longstanding member of the Infectious Diseases Society of America Aspergillosis Guidelines group, the European Society for Clinical Microbiology and Infectious Diseases Aspergillosis Guidelines group, and recently joined the One World Guideline for Aspergillosis. He also reports issued and licensed patents for assays for fungal infection. S. H. has received grants from Pulmocide, Synerxis, Takeda, Merck, Avir Pharma, Inc, and Astellas. He also reports receiving consulting fees from Takeda. K. A. M. is the founder and chief executive officer of MycoMed Technologies. She is a consultant for Cidara Therapeutics and receives license revenue from Pearl Diagnostics. She also reports leadership or fiduciary roles at Pearl Diagnostics and Sfunga Therapeutics, and ownership of stocks or stock options of Pearl Diagnostics, Sfunga Therapeutics, and Cidara Therapeutics. R. B. M. is currently a consultant to 4D Molecular Therapeutics, Aridis Pharmaceuticals, Zambon Company SpA, and Nob Hill Therapeutics. He receives authorship and editorial royalties from UpToDate. He is on the Board of Directors of Cystic Fibrosis Research Institute. S.N.’s contributions occurred entirely while she worked at the Food and Drug Administration. She is currently employed by Johnson & Johnson and, as an employee, her travel to conferences/meetings is covered; she also owns Johnson & Johnson stock or stock options. S. N. is an unpaid member of the Scientific Advisory Committee for Global Antibiotic Research and Development Partnership. T. J. W. reports support for the workshop from the Henry Schueler Foundation. He has received grants for experimental and clinical antimicrobial pharmacology and therapeutics to his institution from Amplyx, Astellas, Leadiant, Gilead, Merck, and Shionogi. He reports payment or honoraria for lectures, presentations, speakers’ bureaus, manuscript writing, or educational events from Astellas, Leadiant, Scynexis, Shionogi, Statera, and T2 Biosystems. T. J. W. also reports a leadership or fiduciary role in the Medical Mycological Society of the Americas. J. F. reports being a US government employee. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Bordetella bronchiseptica is a highly contagious respiratory bacterial veterinary pathogen. In this study the contribution of the transcriptional regulators BvgR, RisA, RisS, and the phosphorylation of RisA to global gene regulation, intracellular cyclic-di-GMP levels, motility, and biofilm formation were evaluated. Next Generation Sequencing (RNASeq) was used to differentiate the global gene regulation of both virulence-activated and virulence-repressed genes by each of these factors. The BvgAS system, along with BvgR, RisA, and the phosphorylation of RisA served in cyclic-di-GMP degradation. BvgR and unphosphorylated RisA were found to temporally regulate motility. Additionally, BvgR, RisA, and RisS were found to be required for biofilm formation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Nicholson, Waack, Fleming, Chen, Miller, Merkel and Stibitz.)

Background: Desirability of outcome ranking (DOOR) is a novel approach to clinical trial design that incorporates safety and efficacy assessments into an ordinal ranking system to evaluate overall outcomes of clinical trial participants. Here, we derived and applied a disease-specific DOOR endpoint to registrational trials for complicated intra-abdominal infection (cIAI)., Methods: Initially, we applied an a priori DOOR prototype to electronic patient-level data from 9 phase 3 noninferiority trials for cIAI submitted to the US Food and Drug Administration between 2005 and 2019. We derived a cIAI-specific DOOR endpoint based on clinically meaningful events that trial participants experienced. Next, we applied the cIAI-specific DOOR endpoint to the same datasets and, for each trial, estimated the probability that a participant assigned to the study treatment would have a more desirable DOOR or component outcome than if assigned to the comparator., Results: Three key findings informed the cIAI-specific DOOR endpoint: (1) a significant proportion of participants underwent additional surgical procedures related to their baseline infection; (2) infectious complications of cIAI were diverse; and (3) participants with worse outcomes experienced more infectious complications, more serious adverse events, and underwent more procedures. DOOR distributions between treatment arms were similar in all trials. DOOR probability estimates ranged from 47.4% to 50.3% and were not significantly different. Component analyses depicted risk-benefit assessments of study treatment versus comparator., Conclusions: We designed and evaluated a potential DOOR endpoint for cIAI trials to further characterize overall clinical experiences of participants. Similar data-driven approaches can be utilized to create other infectious disease-specific DOOR endpoints., Competing Interests: Potential conflicts of interest. H. W. B. declares consulting fees from Antimicrobial Agents and Chemotherapy, Sanford Guide, and ID Clinics of North America. H. C. reports grant funding from the NIH; participation in a data and safety monitoring board (DSMB) for Merck; and stock in Merck and Moderna. D. C. reports grant funding from Apellis Pharmaceuticals, CRUK Cancer Grand Challenges, Kinnate Biopharma, and Incyte; consulting fees from Health Literacy Media and MaxisIT Clinical Science; payment for expert panel session from Pfizer; participation on a patient advisory council and travel support for meetings from M2GEN; and participation in the American Society of Clinical Oncology TAPUR Study DSMB and Parexel patient advisory council. S. B. D. reports grant funding from NIH; grant funding for COVID-19–related clinical trials from Gilead and Regeneron; payments for clinical event adjudication committees from Basilea and Shinogi; and consulting fees from Genentech. S. E. reports grant funding from NIH, Degruyter, and Aceragen; royalties from Taylor & Francis; consulting fees from Genetech, AstraZeneca, Takeda, Microbiotix, Johnson & Johnson, Endologix, ChemoCentryx, Becton Dickinson, Atricure, Roivant, Neovasc, Nobel Pharma, Horizon, International Drug Development Institute, and SVB Leerink; payments for lectures from the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION); support for attending meetings from FDA, Deming Conference on Applied Statistics, Clinical Trial Transformation Initiative, Council for International Organization of Medical Sciences, International Chinese Statistical Association Applied Statistics Symposium, and Antimicrobial Resistance and Stewardship Conference; participation on DSMB for NIH, Breast International Group, University of Pennsylvania, Duke University, Roche, Pfizer, Takeda, Akouous, Appelis, Teva, Vir, DayOneBio, Alexion, Tracon, Rakuten, AbbVie, Nuvelution, Clover, FHI Clinical, Lung Biotech, SAB Biopharm, and Candel; and board membership for the American Statistical Association, Society for Clinical Trials, and Frontier Science Foundation. V. G. F. reports grant funding or contracts from NIH, MedImmune, Allergan, Pfizer, Advanced Liquid Logics, Theravance, Novartis, Merck, Medical Biosurfaces, Locus, Affinergy, Contrafect, Karius, Genetech, Regeneron, Deep Blue, Basilea, and Janssen; royalties from UpToDate; consulting fees from Novartis, Debiopharm, Genetech, Achaogen, Affinium, The Medicines Co., MedImmune, Bayer, Basilea, Affinergy, Janssen, Contrafect, Regeneron, Destiny, Amphliphi Biosciences, Integrated Biotherapeutics, C3J, Armata, Valanbio, Akagera, Aridis, Roche, and Pfizer; support from Contrafect to present phase 2 data at 2019 European Congress of Clinical Microbiology and Infectious Diseases; a patent for sepsis diagnostics; serving as Associate Editor of Clinical Infectious Diseases in 2017–2022; and stock options from ArcBio and Valanbio. T. H. reports consulting fees from Tanabe-Mitsubishi Pharma K.K; a contract from Aceragen; payment for lectures from Duke University and Johnson & Johnson K.K.; and payment for manuscript preparation from Cancer and Chemotherapy K.K. (Japanese Journal of Cancer and Chemotherapy). T. L. H. reports grant funding from NIH; royalties from UpToDate; consulting fees from Lysovant and Affinivax; and participation on DSMB for SNAP Trial Platform. J. H.-A. reports grant funding from NIH. S. N. is an employee of Johnson & Johnson. U. W. reports support from the American Society for Microbiology to attend ASM Microbe 2022 as a speaker. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2023.)

Pressing challenges in the treatment of invasive fungal infections (IFIs) include emerging and rare pathogens, resistant/refractory infections, and antifungal armamentarium limited by toxicity, drug-drug interactions, and lack of oral formulations. Development of new antifungal drugs is hampered by the limitations of the available diagnostics, clinical trial endpoints, prolonged trial duration, difficulties in patient recruitment, including subpopulations (eg, pediatrics), and heterogeneity of the IFIs. On 4 August 2020, the US Food and Drug Administration convened a workshop that included IFI experts from academia, industry, and other government agencies to discuss the IFI landscape, unmet need, and potential strategies to facilitate the development of antifungal drugs for treatment and prophylaxis. This article summarizes the key topics presented and discussed during the workshop, such as incentives and research support for drug developers, nonclinical development, clinical trial design challenges, lessons learned from industry, and potential collaborations to facilitate antifungal drug development., Competing Interests: Potential conflicts of interest. P. C. was employed at the Food and Drug Administration until 31 December 2020. S. N.'s contributions occurred entirely while she worked at the Food and Drug Administration. She is currently employed by Johnson & Johnson, and as an employee her travel to conferences/meetings is covered; she also owns Johnson & Johnson stock or stock options. D. A. is an employee and own shares of Scynexis. A. D. of DaneStat Consulting is a statistical consultant for the Pharmaceutical and Biotechnology Industry; he has acted as a consultant for Adaigo, AN2, Achaogen, Allecra, Amicrobe, Amplyx, Artizan, Bioscript, Bugworks, CARBX, Cidara, Closed Loop Medicine, Correvio, ContraFect, DaVolterra, Destiny, F2G, Entasis, Gates, Geom, GSK, Gyroscope, Humanigen, Kymab, Liverpool University, Melinta, Mironid, Modis, Nabriva, Orca, Pfizer, Phico, Pled, Quince, Roche, SFunga, Scynexis, Spero, Sinovent, SNIPR Biome, TenNor, Transcrip, VenatoRx, and Zavante (payments to DaneStat Consulting). He also reports as the independent statistician on data safety monitoring boards for a number of companies, including Aridis, ContraFect Midatech, Pfizer, Pled, Rare Thyroid, Sanofi, and Transcrip. M. R. H. reports support as a full-time employee of Amplyx Pharmaceuticals, a biotech company that was developing fosmanogepix, and received stock potions and a salary. T. S. is a full-time employee of and owns stock or stock options in Cidara Therapeutics. W. H. reports grants or contracts from F2G and Pfizer; personal consulting fees from F2G, Amplyx, Pfizer, Mundipharma, and Gilead (payments to DaneStat Consulting); participation on F2G's advisory board; a role as National Institutes of Health Research Specialty Co-lead for Infection; and a data sharing agreement with Astellas without any financial commitment. T. J. W. has received grants for experimental and clinical antimicrobial pharmacology and therapeutics to his institution from Allergan, Amplyx, Astellas, Lediant, Medicines Company, Merck, Scynexis, and Tetraphase; has served as consultant to Amplyx, Astellas, Allergan, ContraFect, Gilead, Leadiant, Medicines Company, Merck, Methylgene, Pfizer, and Scynexis; reports payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Astellas, Leadiant, Scynexis, Shinogi, Statera, and T2 Biosystems; and reports a leadership or fiduciary role in the Medical Mycological Society of the Americas. P. P. reports grants from Merck, Astellas, Scynexis, Cidara, and F2G and consulting fees from F2G and Cidara. L. K. reports support as a full-time employee of Astellas Pharma Global Development. J. H. R. is chief medical officer and director of F2G, operating partner and consultant for Advent Life Sciences, and expert in residence for Wellcome Trust. He sits on the scientific advisory boards of Bugworks Research, Basilea Pharmaceutica, Forge Therapeutics, Novo Holdings, and Roche Pharma Research & Early Development and is a shareholder in AstraZeneca Pharmaceuticals, F2G, Advent Life Sciences, Macrolide Pharmaceuticals, and Bugworks Research. He has also received consulting fees from Phico Therapeutics, ABAC Therapeutics, Polyphor, Heptares Therapeutics, Gangagen, Meiji Seika Pharma, Basilea Pharmaceutica International, Allecra Therapeutics, Forge Therapeutics, SinSa Labs, AtoxBio, Peptilogics, F. Hoffmann-LaRoche, Novo Holdings, Innocoll, Vedanta, Progenity, Nosopharm, Roivant Sciences, and Shionogi. K. A. M. is founder and chief executive officer of MycoMed Technologies and a consultant and advisory board member for Cidara Therapeutics and Sfunga Therapeutics. She has consulted for Amplyx Pharmaceuticals, Astellas Pharma, Advaxis, Chimerix, F2G, Genentech, Incyte, Merck & Co, OncoSec, RTI Surgical, Scynexis. and Vical. She receives authorship and editorial royalties from UpToDate and a grant from Merck, owns shares in Pearl Diagnostics and Sfunga Therapeutics, and is an employee of Sfunga Therapeutics. L. O. Z. has received research funding and/or personal honoraria for consulting or speaking from Pulmocide, Pfizer, Merck, Astellas, Cidara, Scynexis, F2G, Amplyx, Gilead, Therapeutics, Viracor, Octapharma, Biotoscana, Stendhal, Mayne, Takeda, RealTime Labs, and Viracor. L. O. Z. also reports honoraria from F2G, Pfizer, and Gilead; participation on a data safety monitoring board or advisory board for Octapharma, Cidara, F2G, and Pfizer; and leadership roles as president for the Mycoses Study Group and Education Consortium, president-elect for the Immunocompromised Host Society, senior editor for Journal of Antimicrobial Chemotherapy, and an associate editor for Clinical Infectious Diseases. J. F. reports being a US government employee. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2023.)

Background: An antibacterial drug's susceptibility test interpretive criteria (STIC) are determined by integrating clinical, microbiological and pharmacokinetic-pharmacodynamic (PK-PD) data. PTA analysis plays a pivotal or supportive role in STIC determination and is heavily dependent on the PK-PD target values determined from animal PK-PD studies. Therefore, variations in PK-PD target values may impact STIC determination. Factors contributing to variation in the PK-PD target values include the number of and MICs for bacterial isolates used in animal PK-PD studies., Objectives: To analyse the relationship between PK-PD target values and MICs, describe the variations in PK-PD target values of isolates and evaluate whether the proposed/target STICs were within the ranges of the MICs for isolates used in animal PK-PD studies., Methods: A database was compiled for this research by screening animal PK-PD study reports submitted to the FDA from 10 new drug applications (NDAs)., Results: A relationship evaluation between PK-PD target values and MICs for tested isolates for seven drugs (that used AUC/MIC ratio as the PK-PD index) showed that, generally, the AUC/MIC values decreased with an increase in MIC. These target values were highly variable, with the percentage coefficient of variation ranging between 1% and 132% for isolates having the same MIC. For 16/27 (59%) drug/bacteria combinations from all 10 drugs, the proposed/target STICs were higher than the highest MIC for bacteria isolates evaluated, while 6/27 (22.5%) were lower., Conclusions: This research suggests that careful considerations related to selection of bacterial isolates for animal PK-PD studies could strengthen the STIC determination process., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Streptococcus suis is a zoonotic bacterial swine pathogen causing substantial economic and health burdens to the pork industry. Mechanisms used by S. suis to colonize and cause disease remain unknown and vaccines and/or intervention strategies currently do not exist. Studies addressing virulence mechanisms used by S. suis have been complicated because different isolates can cause a spectrum of disease outcomes ranging from lethal systemic disease to asymptomatic carriage. The objectives of this study were to evaluate the virulence capacity of nine United States S. suis isolates following intranasal challenge in swine and then perform comparative genomic analyses to identify genomic attributes associated with swine-virulent phenotypes. No correlation was found between the capacity to cause disease in swine and the functional characteristics of genome size, serotype, sequence type (ST), or in vitro virulence-associated phenotypes. A search for orthologs found in highly virulent isolates and not found in non-virulent isolates revealed numerous predicted protein coding sequences specific to each category. While none of these predicted protein coding sequences have been previously characterized as potential virulence factors, this analysis does provide a reliable one-to-one assignment of specific genes of interest that could prove useful in future allelic replacement and/or functional genomic studies. Collectively, this report provides a framework for future allelic replacement and/or functional genomic studies investigating genetic characteristics underlying the spectrum of disease outcomes caused by S. suis isolates., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Nicholson, Waack, Anderson, Bayles, Zaia, Goertz, Eppinger, Hau, Brockmeier and Shore.)

The U.S. Food and Drug Administration (FDA) hosted a public workshop entitled "Advancing Animal Models for Antibacterial Drug Development" on 5 March 2020. The workshop mainly focused on models of pneumonia caused by Pseudomonas aeruginosa and Acinetobacter baumannii The program included discussions from academic investigators, industry, and U.S. government scientists. The potential use of mouse, rabbit, and pig models for antibacterial drug development was presented and discussed., (Copyright © 2020 American Society for Microbiology.)

Animal models of bacterial infection have been widely used to explore the in vivo activity of antibacterial drugs. These data are often submitted to the U.S. Food and Drug Administration to support human use in an investigational new drug application (IND). To better understand the range and scientific use of animal models in regulatory submissions, a database was created surveying recent pneumonia models submitted as part of IND application packages. The IND studies were compared to animal models of bacterial pneumonia published in the scientific literature over the same period of time. In this review, we analyze the key experimental design elements, such as animal species, immune status, pathogens selected, and route of administration, and study endpoints., (Copyright © 2020 American Society for Microbiology.)

Antibiotic-resistant Acinetobacter baumannii is increasingly recognized as a cause of difficult-to-treat nosocomial infections, including pneumonia, wound infections, and bacteremia. Previous studies have demonstrated that the metalloprotease CpaA contributes to virulence and prolongs clotting time when added to human plasma as measured by the activated partial thromboplastin time (aPTT) assay. Here, we show that CpaA interferes with the intrinsic coagulation pathway, also called the contact activation system, in human as well as murine plasma, but has no discernible effect on the extrinsic pathway. By utilizing a modified aPTT assay, we demonstrate that coagulation factor XII (fXII) is a target of CpaA. In addition, we map the cleavage by CpaA to two positions, 279-280 and 308-309, within the highly glycosylated proline-rich region of human fXII, and show that cleavage at the 308-309 site is responsible for inactivation of fXII. At both sites, cleavage occurs between proline and an O-linked glycosylated threonine, and deglycosylation of fXII prevents cleavage by CpaA. Consistent with this, mutant fXII (fXII-Thr309Lys) from patients with hereditary angioedema type III (HAEIII) is protected from CpaA inactivation. This raises the possibility that individuals with HAEIII who harbor this mutation may be partially protected from A. baumannii infection if CpaA contributes to human disease. By inactivating fXII, CpaA may attenuate important antimicrobial defense mechanisms such as intravascular thrombus formation, thus allowing A. baumannii to disseminate. IMPORTANCE Ventilator-associated pneumonia and catheter-related bacteremia are the most common and severe infections caused by Acinetobacter baumannii Besides the capsule, lipopolysaccharides, and the outer membrane porin OmpA, little is known about the contribution of secreted proteins to A. baumannii survival in vivo Here we focus on CpaA, a potentially recently acquired virulence factor that inhibits blood coagulation in vitro We identify coagulation factor XII as a target of CpaA, map the cleavage sites, and show that glycosylation is a prerequisite for CpaA-mediated inactivation of factor XII. We propose adding CpaA to a small, but growing list of bacterial proteases that are specific for highly glycosylated components of the host defense system., (Copyright © 2018 Waack et al.)

Streptococcus suis is a bacterial swine pathogen with a significant economic burden. It typically colonizes the tonsil and nasal cavity of swine causing a variety of symptoms ranging from asymptomatic carriage to lethal systemic disease. A key barrier toward the development of improved vaccines or interventions for S. suis infections is a gap in our understanding of the mechanisms contributing to persistence in the host, in which colonized pigs continue to shed and transmit S. suis. We hypothesized that exposure to sub-MICs of antibiotics commonly used by the swine industry would increase the biofilm capacity of S. suis strains. Using a 96-well plate MIC protocol, we experimentally determined the MIC for each of 12 antibiotics for a virulent strain of S. suis strain that consistently formed biofilms using a standard crystal violet assay. Using this static biofilm assay, we demonstrated that sub-MICs of bacitracin, carbadox, chlortetracycline, enrofloxacin, gentamicin, neomycin, sulfadimethoxine, tiamulin, and tylosin did not increase S. suis biofilms. In contrast, we demonstrated that sub-MICs of amoxicillin, lincomycin, and oxytetracycline increased overall biofilm formation under both static and flow conditions. The biofilm formation of 11 additional clinical isolates were measured using the relevant concentrations of amoxicillin, lincomycin, and oxytetracycline. Eight of the eleven strains increased the biofilm formation with lincomycin, seven with amoxicillin, and three with oxytetracycline. Collectively, our data demonstrate that exposure to sub-MICs of these commonly used antibiotics contributes to increased biofilm formation of S. suis , thereby potentially increasing survival and persistence within the respiratory tract of swine.

Staphylococcus aureus is part of the nasal microbiome of many humans and has become a significant public health burden due to infections with antibiotic-resistant strains, including methicillin-resistant S. aureus (MRSA) strains. Several lineages of S. aureus , including MRSA, are found in livestock species and can be acquired by humans through contact with animals. These livestock-associated MRSA (LA-MRSA) isolates raise public health concerns because of the potential for livestock to act as reservoirs for MRSA outside the hospital setting. In the United States, swine harbor a mixed population of LA-MRSA isolates, with the sequence type 398 (ST398), ST9, and ST5 lineages being detected. LA-MRSA ST5 isolates are particularly concerning to the public health community because, unlike the isolates in the ST398 and ST9 lineages, isolates in the ST5 lineage are a significant cause of human disease in both the hospital and community settings globally. The ability of swine-associated LA-MRSA ST5 isolates to adhere to human keratinocytes in vitro was investigated, and the adherence genes harbored by these isolates were evaluated and compared to those in clinical MRSA ST5 isolates from humans with no swine contact. The two subsets of isolates adhered equivalently to human keratinocytes in vitro and contained an indistinguishable complement of adherence genes that possessed a high degree of sequence identity. Collectively, our data indicate that, unlike LA-MRSA ST398 isolates, LA-MRSA ST5 isolates do not exhibit a reduced genotypic or phenotypic capacity to adhere to human keratinocytes. IMPORTANCE Our data indicate that swine-associated livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) ST5 isolates are as capable of adhering to human skin and have the same genetic potential to adhere as clinical MRSA ST5 isolates from humans. This suggests that humans in contact with livestock have the potential to become colonized with LA-MRSA ST5 isolates; however, the genes that contribute to the persistence of S. aureus on human skin were absent in LA-MRSA ST5 isolates. The data presented here are important evidence in evaluating the potential risks that LA-MRSA ST5 isolates pose to humans who come into contact with livestock., (Copyright © 2018 American Society for Microbiology.)

Nosocomial pathogens that develop multidrug resistance present an increasing problem for healthcare facilities. Due to its rapid rise in antibiotic resistance, Acinetobacter baumannii is one of the most concerning gram-negative species. A. baumannii typically infects immune compromised individuals resulting in a variety of outcomes, including pneumonia and bacteremia. Using a murine model for bacteremia, we have previously shown that the type II secretion system (T2SS) contributes to in vivo fitness of A. baumannii . Here, we provide support for a role of the T2SS in protecting A. baumannii from human complement as deletion of the T2SS gene gspD resulted in a 100-fold reduction in surviving cells when incubated with human serum. This effect was abrogated in the absence of Factor B, a component of the alternative pathway of complement activation, indicating that the T2SS protects A. baumannii against the alternative complement pathway. Because inactivation of the T2SS results in loss of secretion of multiple enzymes, reduced in vivo fitness, and increased sensitivity to human complement, the T2SS may be a suitable target for therapeutic intervention. Accordingly, we developed and optimized a whole-cell high-throughput screening (HTS) assay based on secreted lipase activity to identify small molecule inhibitors of the T2SS. We tested the reproducibility of our assay using a 6,400-compound library. With small variation within controls and a dynamic range between positive and negative controls, the assay had a z-factor of 0.65, establishing its suitability for HTS. Our screen identified the lipase inhibitors Orlistat and Ebelactone B demonstrating the specificity of the assay. To eliminate inhibitors of lipase activity and lipase expression, two counter assays were developed and optimized. By implementing these assays, all seven tricyclic antidepressants present in the library were found to be inhibitors of the lipase, highlighting the potential of identifying alternative targets for approved pharmaceuticals. Although no T2SS inhibitor was identified among the compounds that reduced lipase activity by ≥30%, our small proof-of-concept pilot study indicates that the HTS regimen is simple, reproducible, and specific and that it can be used to screen larger libraries for the identification of T2SS inhibitors that may be developed into novel A. baumannii therapeutics.

Unlabelled: Gram-negative bacteria express a number of sophisticated secretion systems to transport virulence factors across the cell envelope, including the type II secretion (T2S) system. Genes for the T2S components GspC through GspN and PilD are conserved among isolates of Acinetobacter baumannii, an increasingly common nosocomial pathogen that is developing multidrug resistance at an alarming rate. In contrast to most species, however, the T2S genes are dispersed throughout the genome rather than linked into one or two operons. Despite this unique genetic organization, we show here that the A. baumannii T2S system is functional. Deletion of gspD or gspE in A. baumannii ATCC 17978 results in loss of secretion of LipA, a lipase that breaks down long-chain fatty acids. Due to a lack of extracellular lipase, the gspD mutant, the gspE mutant, and a lipA deletion strain are incapable of growth on long-chain fatty acids as a sole source of carbon, while their growth characteristics are indistinguishable from those of the wild-type strain in nutrient-rich broth. Genetic inactivation of the T2S system and its substrate, LipA, also has a negative impact on in vivo fitness in a neutropenic murine model for bacteremia. Both the gspD and lipA mutants are outcompeted by the wild-type strain as judged by their reduced numbers in spleen and liver following intravenous coinoculation. Collectively, our findings suggest that the T2S system plays a hitherto-unrecognized role in in vivo survival of A. baumannii by transporting a lipase that may contribute to fatty acid metabolism., Importance: Infections by multidrug-resistant Acinetobacter baumannii are a growing health concern worldwide, underscoring the need for a better understanding of the molecular mechanisms by which this pathogen causes disease. In this study, we demonstrated that A. baumannii expresses a functional type II secretion (T2S) system that is responsible for secretion of LipA, an extracellular lipase required for utilization of exogenously added lipids. The T2S system and the secreted lipase support in vivo colonization and thus contribute to the pathogenic potential of A. baumannii., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)