The Antibacterial Resistance Leadership Group: Scientific Advancements and Future Directions.

In this overview, we describe important contributions from the Antibacterial Resistance Leadership Group (ARLG) to patient care, clinical trials design, and mentorship while outlining future priorities. The ARLG research agenda is focused on 3 key areas: gram-positive infections, gram-negative infections, and diagnostics. The ARLG has developed an innovative approach to clinical trials design, the desirability of outcome ranking (DOOR), which uses an ordinal measure of global outcome to assess both benefits and harms. DOOR was initially applied to observational studies to determine optimal dosing of vancomycin for methicillin-resistant Staphylcococcus aureus bacteremia and the efficacy of ceftazidime-avibactam versus colistin for the treatment of carbapenem-resistant Enterobacterales infection. DOOR is being successfully applied to the analysis of interventional trials and, in collaboration with the US Food and Drug Administration (FDA), for use in registrational trials. In the area of diagnostics, the ARLG developed Master Protocol for Evaluating Multiple Infection Diagnostics (MASTERMIND), an innovative design that allows simultaneous testing of multiple diagnostic platforms in a single study. This approach will be used to compare molecular assays for the identification of fluoroquinolone-resistant Neisseria gonorrhoeae (MASTER GC) and to compare rapid diagnostic tests for bloodstream infections. The ARLG has initiated a first-in-kind randomized, double-blind, placebo-controlled trial in participants with cystic fibrosis who are chronically colonized with Pseudomonas aeruginosa to assess the pharmacokinetics and antimicrobial activity of bacteriophage therapy. Finally, an engaged and highly trained workforce is critical for continued and future success against antimicrobial drug resistance. Thus, the ARLG has developed a robust mentoring program targeted to each stage of research training to attract and retain investigators in the field of antimicrobial resistance research.

Under the Hood: The Scientific Leadership, Clinical Operations, Statistical and Data Management, and Laboratory Centers of the Antibacterial Resistance Leadership Group.

Developing and implementing the scientific agenda of the Antibacterial Resistance Leadership Group (ARLG) by soliciting input and proposals, transforming concepts into clinical trials, conducting those trials, and translating trial data analyses into actionable information for infectious disease clinical practice is the collective role of the Scientific Leadership Center, Clinical Operations Center, Statistical and Data Management Center, and Laboratory Center of the ARLG. These activities include shepherding concept proposal applications through peer review; identifying, qualifying, training, and overseeing clinical trials sites; recommending, developing, performing, and evaluating laboratory assays in support of clinical trials; and designing and performing data collection and statistical analyses. This article describes key components involved in realizing the ARLG scientific agenda through the activities of the ARLG centers.

The Future Ain't What It Used to Be Out With the Old In With the Better: Antibacterial Resistance Leadership Group Innovations.

Clinical research networks conduct important studies that would not otherwise be performed by other entities. In the case of the Antibacterial Resistance Leadership Group (ARLG), such studies include diagnostic studies using master protocols, controlled phage intervention trials, and studies that evaluate treatment strategies or dynamic interventions, such as sequences of empiric and definitive therapies. However, the value of a clinical research network lies not only in the results from these important studies but in the creation of new approaches derived from collaborative thinking, carefully examining and defining the most important research questions for clinical practice, recognizing and addressing common but suboptimal approaches, and anticipating that the standard approaches of today may be insufficient for tomorrow. This results in the development and implementation of new methodologies and tools for the design, conduct, analyses, and reporting of research studies. These new methodologies directly impact the studies conducted within the network and have a broad and long-lasting impact on the field, enhancing the scientific value and efficiency of generations of research studies. This article describes innovations from the ARLG in diagnostic studies, observational studies, and clinical trials evaluating interventions for the prevention and treatment of antibiotic-resistant bacterial infections.

Antibacterial Resistance Leadership Group 2.0: Back to Business.

In December 2019, the Antibacterial Resistance Leadership Group (ARLG) was awarded funding for another 7-year cycle to support a clinical research network on antibacterial resistance. ARLG 2.0 has 3 overarching research priorities: infections caused by antibiotic-resistant (AR) gram-negative bacteria, infections caused by AR gram-positive bacteria, and diagnostic tests to optimize use of antibiotics. To support the next generation of AR researchers, the ARLG offers 3 mentoring opportunities: the ARLG Fellowship, Early Stage Investigator seed grants, and the Trialists in Training Program. The purpose of this article is to update the scientific community on the progress made in the original funding period and to encourage submission of clinical research that addresses 1 or more of the research priority areas of ARLG 2.0.

The Antibacterial Resistance Leadership Group: Progress Report and Work in Progress.

The Antibacterial Resistance Leadership Group (ARLG), with funding from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, was created in June 2013. Its mission is to develop, prioritize, and implement a clinical research agenda that addresses the public health threat of antibacterial resistance. This article reports on the progress that the ARLG has made to date in fulfilling its mission. Since inception, the ARLG has received and reviewed >70 study proposals, initiated >30 studies, executed >300 agreements, included data from >7000 subjects, published >45 manuscripts, and provided opportunities for 26 mentees. Despite this substantial progress, there remains significant work to be accomplished. This article also describes the considerable challenges that lie ahead.

Transforming Concepts Into Clinical Trials and Creating a Multisite Network: The Leadership and Operations Center of the Antibacterial Resistance Leadership Group.

The Leadership and Operations Center (LOC) is responsible for facilitating, coordinating, and implementing the Antibacterial Resistance Leadership Group (ARLG) scientific agenda by engaging thought leaders; soliciting research proposals; and developing the processes, tools, and infrastructure required to operationalize studies and create and sustain the ARLG network. These efforts are ongoing as new projects are developed and the network expands and grows to address the ever-changing priorities in antibacterial resistance. This article describes the innovations, accomplishments, and opportunities of the LOC since the inception of the ARLG in 2013.

Antibacterial resistance leadership group: open for business.

Funded by the National Institute of Allergy and Infectious Diseases, the Antibacterial Resistance Leadership Group (ARLG) is tasked with developing a clinical research agenda and conducting clinical studies to address the growing public health threat of antibacterial resistance. The ARLG has identified 4 high-priority areas of research: infections caused by gram-negative bacteria, infections caused by gram-positive bacteria, antimicrobial stewardship and infection prevention, and diagnostics. The ARLG will be accepting proposals from the scientific community for clinical research that addresses 1 or more of these high-priority areas. These studies should have the potential to transform medical practice and be unlikely to occur without ARLG support. The purpose of this article is to make interested parties aware of clinical research opportunities made available by ARLG and to encourage submission of clinical research proposals that address the problem of antibacterial resistance.

Male and female mice overexpressing the beta(2)-adrenergic receptor exhibit differences in ischemia/reperfusion injury: role of nitric oxide.

OBJECTIVE: Cardiac overexpression of beta(2)-adrenergic receptors (beta(2)ARs) in male mice (MTG4) results in increased contractility and increased ischemic injury. Considering recent clinical data indicating that premenopausal women are protected from cardiovascular injury, we assessed the consequences of beta(2)AR overexpression in females (FTG4). Since protection in females is mediated via estrogen, which activates endothelial and inducible nitric oxide synthases (eNOS and iNOS) we also examined the role of NOS in ischemia/reperfusion injury in male and female TG4 and wild-type (WT) mice. METHODS: Hearts from MTG4, FTG4, MWT and FWT mice were isolated and perfused in the Langendorff mode. Hearts were pretreated with either 1 micromol/l of the nonspecific NOS inhibitor, L-NAME, or 100 nmol/l of the specific iNOS inhibitor, 1400W. Control hearts received no treatment. All hearts were subjected to 20 min ischemia and 40 min reperfusion while 31P-NMR spectra were acquired. RESULTS: During ischemia, ATP and pH fell lower in MTG4 hearts than in FTG4 or WT hearts. Hearts from MTG4 mice exhibited increased ischemia/reperfusion injury as indicated by lower recoveries of postischemic contractile function, ATP and PCr than WT. Despite contractility being elevated in FTG4 hearts to the same level as MTG4 hearts, ischemia/reperfusion injury was not increased, as indicated by similar postischemic recoveries of contractile function, ATP and PCr in FTG4 hearts compared to WT. ATP and pH fell lower during ischemia in L-NAME-treated FTG4 hearts than in untreated FTG4 hearts, falling as low as untreated MTG4s. Recoveries of contractile function, ATP and PCr were as low in L-NAME-treated FTG4 hearts as in untreated MTG4 hearts and lower than untreated FTG4 hearts. In contrast, 1400W had no effect on FTG4 hearts. MTG4 hearts were unaffected by L-NAME or 1400W. CONCLUSIONS: beta(2)AR overexpression increased ischemia/reperfusion injury in males but not females, thus females were protected from the detrimental effects of beta(2)AR overexpression. Protection was abolished by treatment with L-NAME, but not 1400W, implying that protection was mediated by eNOS not iNOS.

No survival benefit with empirical vancomycin therapy for coagulase-negative staphylococcal bloodstream infections in infants.

BACKGROUND: Coagulase-negative Staphylococcus (CoNS) is the most common cause of bloodstream infections (BSI) in hospitalized infants. CoNS BSI is most reliably treated with vancomycin; however, concerns about side effects and promoting resistance often delay empirical vancomycin therapy until culture results become available. METHODS: All infants with CoNS BSI discharged from 348 neonatal intensive care units managed by the Pediatrix Medical Group from 1997 to 2012 were identified. Empirical vancomycin therapy was defined as vancomycin exposure on the day of the first positive blood culture. Delayed vancomycin therapy was defined as vancomycin exposure 1-3 days after the first positive blood culture. We used multivariable logistic regression with random effects for site to evaluate the association between the use of empirical vancomycin therapy versus delayed vancomycin therapy and 30-day mortality, controlling for gestational age, small-for-gestational age status, postnatal age on the day of the first positive culture, oxygen requirement, ventilator support and inotropic support on the day the first positive culture was obtained. RESULTS: A total of 4364 infants with CoNS BSI were identified; 2848 (65%) were treated with empirical vancomycin. The median postnatal age at first positive culture was 14 days (interquartile range: 9, 21). Unadjusted 30-day mortality was similar for infants treated with empirical vancomycin and infants treated with delayed vancomycin therapy [166/2848 (6%) vs. 69/1516 (4%); P = 0.08]. There was no significant difference in 30-day mortality on multivariable analysis [odds ratio: 1.14 (0.84, 1.56)]. The median duration of bacteremia was 1 day longer for infants with delayed vancomycin therapy [4 days (interquartile range: 2, 6) vs. 3 days (2, 5); P < 0.0001]. CONCLUSIONS: The median duration of bacteremia was 1 day longer in infants with CoNS BSI who received delayed vancomycin therapy. Despite this finding, empirical vancomycin therapy for CoNS BSI was not associated with improved mortality.

Is Na/Ca exchange during ischemia and reperfusion beneficial or detrimental?

Cytosolic calcium increases to approximately 3 micro M after 15 min of global ischemia. Manipulations that attenuate this increase in cytosolic Ca(2+) reduce myocyte death and dysfunction. The increase in cytosolic Ca(2+) during ischemia is dependent on an increase in intracellular Na(+), suggesting a role for Na/Ca exchange. Typical ischemic values for ionized intra- and extracellular Na(+), Ca(2+), and membrane potential are consistent with the Na/Ca exchanger operating near equilibrium during ischemia. Studies were undertaken using hearts from mice that overexpress the Na/Ca exchanger to determine if Na/Ca exchanger overexpression enhances or reduces ischemic injury. These studies suggest that overexpression of the Na/Ca exchanger enhances injury in males, but females are protected by a gender-related mechanism.

Ca(2+) loading and adrenergic stimulation reveal male/female differences in susceptibility to ischemia-reperfusion injury.

To compare ischemia-reperfusion injury in males versus females under hypercontractile conditions, perfused hearts from 129J mice pretreated with 3 mmol/l Ca(2+) or 10(-8) mol/l isoproterenol +/- 10(-6) mol/l N(omega)-nitro-L-arginine methyl ester (L-NAME) were subjected to 20 min of ischemia and 40 min of reperfusion while (31)P NMR spectra were acquired. Basal contractility increased equivalently in female versus male hearts with isoproterenol- or Ca(2+) treatment. Injury was equivalent in untreated male versus female hearts but was greater in isoproterenol or Ca(2+)-treated male than female hearts, as indicated by lower postischemic contractile function, ATP, and PCr. Endothelial nitric oxide (NO) synthase (eNOS) expression was higher in female than male hearts, neuronal NOS (nNOS) did not differ, and inducible NOS (iNOS) was undetectable. Ischemic NO production was higher in female than male hearts, and L-NAME increased injury in female isoproterenol-treated hearts. In summary, isoproterenol or high Ca(2+) pretreatment increased ischemia-reperfusion injury in males more than females. eNOS expression and NO production were higher in female than male hearts, and L-NAME blocked female protection. Females were therefore protected from the detrimental effects of adrenergic stimulation and Ca(2+) loading via a NOS-mediated mechanism.

Overexpression of A(3) adenosine receptors decreases heart rate, preserves energetics, and protects ischemic hearts.

To determine whether A(3) adenosine receptor (A(3)AR) signaling modulates myocardial function, energetics, and cardioprotection, hearts from wild-type and A(3)AR-overexpressor mice were subjected to 20-min ischemia and 40-min reperfusion while (31)P NMR spectra were acquired. Basal heart rate and left ventricular developed pressure (LVDP) were lower in A(3)AR-overexpressor hearts than wild-type hearts. Ischemic ATP depletion was delayed and postischemic recoveries of contractile function, ATP, and phosphocreatine were greater in A(3)AR-hearts. To determine the role of depressed heart rate and to confirm A(3)AR-specific signaling, hearts were paced at 480 beats/min with or without 60 nmol/l MRS-1220 (A(3)AR-specific inhibitor) and then subjected to ischemia-reperfusion. LVDP was similar in paced A(3)AR-overexpressor and paced wild-type hearts. Differences in ischemic ATP depletion and postischemic contractile and energetic dysfunction remained in paced A(3)AR-overexpressor hearts versus paced wild-type hearts but were abolished by MRS-1220. In summary, A(3)AR overexpression decreased basal heart rate and contractility, preserved ischemic ATP, and decreased postischemic dysfunction. Pacing abolished the decreased contractility but not the ATP preservation or cardioprotection. Therefore, A(3)AR overexpression results in cardioprotection via a specific A(3)AR effect, possibly involving preservation of ATP during ischemia.

Ablation of PLB exacerbates ischemic injury to a lesser extent in female than male mice: protective role of NO.

Recent studies suggest a role for phospholamban phosphorylation during ischemia and reperfusion. The role of phospholamban in ischemia was studied by subjecting hearts from male and female wild-type (MWT/FWT) and phospholamban-knockout (MKO/FKO) mice to 20 min of ischemia-40 min of reperfusion while (31)P NMR spectra were acquired. ATP and pH values fell lower during ischemia, and postischemic contractility was less, in MKO and FKO versus WT hearts. After shorter ischemia (15 min), recoveries of contraction, ATP, and pH were greater in FKO than MKO hearts. To examine the role of nitric oxide (NO) synthases (NOS) in the protection in FKO versus MKO hearts, we utilized 1 microM l-NAME, a NOS inhibitor, or 100 microM S-nitroso-N-acetylpenicillamine (SNAP), an NO donor. Recoveries of function, ATP, and pH were less in l-NAME-treated FKO than untreated FKO hearts and greater in SNAP-treated MKO than untreated MKO hearts. In conclusion, phospholamban ablation increased ischemic injury in both males and females; however, female hearts were less susceptible than male hearts. Protection in females was decreased by a NOS inhibitor and mimicked in males by an NO donor, implying that protection was NOS mediated.

Expression of activated PKC epsilon (PKC epsilon) protects the ischemic heart, without attenuating ischemic H(+) production.

PKC epsilon is a PKC isoform that translocates during preconditioning and may mediate cardioprotection. To investigate whether PKC epsilon activation is cardioprotective, Langendorff-perfused hearts from wild-type (WT) mice and from mice expressing constitutively active mutant PKC epsilon were subjected to 20 min ischemia and 40 min reperfusion while(31)P NMR spectra were acquired. Pre-ischemic glycogen levels were similar in WT and PKC epsilon hearts. During ischemia, ATP fell less in PKC epsilon than in WT hearts. Ischemic intracellular pH, however, was similar in WT and PKC epsilon hearts. During reperfusion, recovery of contractile function and ATP were greater in PKC epsilon than WT hearts. In conclusion, expression of activated PKC epsilon protected hearts from post-ischemic energetic and contractile dysfunction, consistent with the proposed cardioprotective role of PKC epsilon. Protection occurred in the PKC epsilon hearts without attenuation of ischemic H(+) production, implying that, at least in this ischemic model, reduced acidification during ischemia is not necessary for cardioprotection.