Effect of Meropenem-Vaborbactam vs Piperacillin-Tazobactam on Clinical Cure or Improvement and Microbial Eradication in Complicated Urinary Tract Infection: The TANGO I Randomized Clinical Trial.

Importance: Meropenem-vaborbactam is a combination carbapenem/beta-lactamase inhibitor and a potential treatment for severe drug-resistant gram-negative infections. Objective: To evaluate efficacy and adverse events of meropenem-vaborbactam in complicated urinary tract infection (UTI), including acute pyelonephritis. Design, Setting, and Participants: Phase 3, multicenter, multinational, randomized clinical trial (TANGO I) conducted November 2014 to April 2016 and enrolling patients (≥18 years) with complicated UTI, stratified by infection type and geographic region. Interventions: Eligible patients were randomized 1:1 to receive meropenem-vaborbactam (2g/2g over 3 hours; n = 274) or piperacillin-tazobactam (4g/0.5g over 30 minutes; n = 276) every 8 hours. After 15 or more doses, patients could be switched to oral levofloxacin if they met prespecified criteria for improvement, to complete 10 days of total treatment. Main Outcomes and Measures: Primary end point for FDA criteria was overall success (clinical cure or improvement and microbial eradication composite) at end of intravenous treatment in the microbiologic modified intent-to-treat (ITT) population. Primary end point for European Medicines Agency (EMA) criteria was microbial eradication at test-of-cure visit in the microbiologic modified ITT and microbiologic evaluable populations. Prespecified noninferiority margin was -15%. Because the protocol prespecified superiority testing in the event of noninferiority, 2-sided 95% CIs were calculated. Results: Among 550 patients randomized, 545 received study drug (mean age, 52.8 years; 361 [66.2%] women; 374 [68.6%] in the microbiologic modified ITT population; 347 [63.7%] in the microbiologic evaluable population; 508 [93.2%] completed the trial). For the FDA primary end point, overall success occurred in 189 of 192 (98.4%) with meropenem-vaborbactam vs 171 of 182 (94.0%) with piperacillin-tazobactam (difference, 4.5% [95% CI, 0.7% to 9.1%]; P < .001 for noninferiority). For the EMA primary end point, microbial eradication in the microbiologic modified ITT population occurred in 128 of 192 (66.7%) with meropenem-vaborbactam vs 105 of 182 (57.7%) with piperacillin-tazobactam (difference, 9.0% [95% CI, -0.9% to 18.7%]; P < .001 for noninferiority); microbial eradication in the microbiologic evaluable population occurred in 118 of 178 (66.3%) vs 102 of 169 (60.4%) (difference, 5.9% [95% CI, -4.2% to 16.0%]; P < .001 for noninferiority). Adverse events were reported in 106 of 272 (39.0%) with meropenem-vaborbactam vs 97 of 273 (35.5%) with piperacillin-tazobactam. Conclusions and Relevance: Among patients with complicated UTI, including acute pyelonephritis and growth of a baseline pathogen, meropenem-vaborbactam vs piperacillin-tazobactam resulted in a composite outcome of complete resolution or improvement of symptoms along with microbial eradication that met the noninferiority criterion. Further research is needed to understand the spectrum of patients in whom meropenem-vaborbactam offers a clinical advantage. Trial Registration: clinicaltrials.gov Identifier: NCT02166476.

Hierarchical expression of genes controlled by the Bacillus subtilis global regulatory protein CodY.

Global regulators that bind strategic metabolites allow bacteria to adapt rapidly to dynamic environments by coordinating the expression of many genes. We report an approach for determining gene regulation hierarchy using the regulon of the Bacillus subtilis global regulatory protein CodY as proof of principle. In theory, this approach can be used to measure the dynamics of any bacterial transcriptional regulatory network that is affected by interaction with a ligand. In B. subtilis, CodY controls dozens of genes, but the threshold activities of CodY required to regulate each gene are unknown. We hypothesized that targets of CodY are differentially regulated based on varying affinity for the protein's many binding sites. We used RNA sequencing to determine the transcription profiles of B. subtilis strains expressing mutant CodY proteins with different levels of residual activity. In parallel, we quantified intracellular metabolites connected to central metabolism. Strains producing CodY variants F71Y, R61K, and R61H retained varying degrees of partial activity relative to the WT protein, leading to gene-specific, differential alterations in transcript abundance for the 223 identified members of the CodY regulon. Using liquid chromatography coupled to MS, we detected significant increases in branched-chain amino acids and intermediates of arginine, proline, and glutamate metabolism, as well as decreases in pyruvate and glycerate as CodY activity decreased. We conclude that a spectrum of CodY activities leads to programmed regulation of gene expression and an apparent rerouting of carbon and nitrogen metabolism, suggesting that during changes in nutrient availability, CodY prioritizes the expression of specific pathways.

Effects of fluconazole on the metabolomic profile of Candida albicans.

BACKGROUND: Little is known about the effects of fluconazole on the metabolism of Candida albicans. We performed LC/MS-based metabolomic profiling of the response of C. albicans cells to increasing doses of fluconazole. METHODS: C. albicans cells were cultured to mid-logarithmic growth phase in liquid medium and then inoculated in replicate on to nitrocellulose filters under vacuum filtration. Organisms were cultured to mid-logarithmic growth phase and treated with 0-4 mg/L fluconazole. Following metabolic quenching at mid-logarithmic growth phase, intracellular metabolites were extracted and analysed by LC/MS. Changes in pool sizes of individual metabolites were verified by Student's t-test, adjusted for multiple hypothesis testing by Benjamini-Hochberg correction. Distribution of metabolites was analysed by the Kyoto Encyclopedia of Genes and Genomes metabolic pathways database. RESULTS: We reproducibly detected 64 metabolites whose identities were confirmed by comparison against a pure standard and a library of accurate mass-retention time pairs. These 64 metabolites were broadly representative of eukaryotic central metabolic pathways. Among them 12 had their mean abundance significantly altered in response to increasing fluconazole concentrations. Pool sizes of four intermediates of central carbon metabolism (α-ketoglutarate, glucose-6-phosphate, phenylpyruvate and ribose-5-phosphate) and mevalonate were increased by 0.5-1.5-fold (P ≤ 0.05). Five amino acids (glycine, proline, tryptophan, aminoisobutanoate and asparagine) and guanine were decreased by 0.5-0.75-fold (P ≤ 0.05). CONCLUSIONS: Fluconazole treatment of C. albicans resulted in increased central carbon and decreased amino acid synthesis intermediates, suggesting a rerouting of metabolic pathways. The function of these metabolomic changes remains to be elucidated; however, they may represent previously unrecognized mechanisms of metabolic injury induced by fluconazole against C. albicans.

In vitro interactions between farnesol and fluconazole, amphotericin B or micafungin against Candida albicans biofilms.

OBJECTIVES: Biofilm formation by Candida albicans poses an important therapeutic challenge in human diseases. Typically, conventional antifungal agents encounter difficulty in treating and fully eradicating biofilm-related infections. Novel therapeutic approaches are needed to treat recalcitrant Candida biofilms. Farnesol is a quorum-sensing molecule, which induces apoptosis, inhibits Ras protein pathways and profoundly affects the morphogenesis of C. albicans. We therefore investigated the interactions between farnesol and different classes of antifungal agents. METHODS: The combined antifungal effects of triazoles (fluconazole), polyenes (amphotericin B) and echinocandins (micafungin) with farnesol against C. albicans biofilms were assessed in vitro. Antifungal activity was determined by the XTT metabolic assay and confocal microscopy. The nature and the intensity of the interactions were assessed using the Loewe additivity model [fractional inhibitory concentration (FIC) index] and the Bliss independence (BI) model. RESULTS: Significant synergy was found between each of the three antifungal agents and farnesol, while antagonism was not observed for any of the combinations tested. The greatest synergistic effect was found with the farnesol/micafungin combination, for which the BI-based model showed the observed effects as being 39%-52% higher than expected if the drugs had been acting independently. The FIC indices ranged from 0.49 to 0.79, indicating synergism for farnesol/micafungin and farnesol/fluconazole and no interaction for farnesol/amphotericin B. Structural changes in the biofilm correlated well with the efficacies of these combinations. The maximum combined effect was dependent on the farnesol concentration for micafungin and amphotericin B. CONCLUSIONS: Farnesol exerts a synergistic or additive interaction with micafungin, fluconazole and amphotericin B against C. albicans biofilms, thus warranting further in vivo study.

Population pharmacokinetics and exposure-response analysis of a single dose of sotrovimab in the early treatment of patients with mild to moderate COVID-19.

Sotrovimab is a recombinant human monoclonal antibody that has been shown to prevent progression to hospitalization or death in non-hospitalized high-risk patients with mild to moderate coronavirus disease 2019 following either intravenous (i.v.) or intramuscular (i.m.) administration. Population pharmacokinetic (PopPK) and exposure-response (ER) analyses were performed to characterize single dose sotrovimab pharmacokinetics (PK) and the relationship between exposure and response (probability of progression), as well as covariates that may contribute to between-participant variability in sotrovimab PK and efficacy following i.v. or i.m. administration. Sotrovimab PK was described by a two-compartment model with linear elimination; i.m. absorption was characterized by a sigmoid absorption model. PopPK covariate analysis led to the addition of the effect of body weight on systemic clearance and peripheral volume of distribution, sex on i.m. bioavailability and first-order absorption rate (KA), and body mass index on KA. However, the magnitude of covariate effect was not pronounced and was therefore not expected to be clinically relevant based on available data to date. For ER analysis, sotrovimab exposure measures were predicted using the final PopPK model. An ER model was developed using the exposure measure of sotrovimab concentration at 168 h that described the relationship between exposure and probability of progression within the ER dataset for COMET-TAIL. The number of risk factors (≤1 vs. >1) was incorporated as an additive shift on the model-estimated placebo response but had no impact on overall drug response. Limitations in the ER model may prevent generalization of these results to describe the sotrovimab exposure-progression relationship across severe acute respiratory syndrome-coronavirus 2 variants.

Safety, Virology, Pharmacokinetics, and Clinical Experience of High-Dose Intravenous Sotrovimab for the Treatment of Mild to Moderate COVID-19: An Open-Label Clinical Trial.

Background: Five hundred milligrams of intravenous (IV) sotrovimab has been shown to be well tolerated and efficacious against pre-Omicron strains in treating patients with mild to moderate coronavirus disease 2019 (COVID-19) at high risk for disease progression. Methods: This was an open-label, single-arm substudy of phase 3 COMET-TAIL (NCT04913675) assessing the safety and tolerability of a 2000 mg IV dose of sotrovimab. Symptomatic patients (aged ≥18 years) with COVID-19 at high risk for progression were enrolled from June 30 through July 11, 2022, when Omicron BA.5, BA.2.12.1, and BA.4 were the predominant circulating variants in the United States. The primary end point was the occurrence of adverse events (AEs), serious AEs (SAEs), AEs of special interest, and COVID-19 disease-related events (DREs) through day 8. Safety, pharmacokinetics, viral load, and hospitalization >24 hours for acute management of illness or death through day 29 were assessed. Results: All participants (n = 81) were Hispanic, 58% were female, and 51% were aged ≥55 years. Through day 8, no AEs, including infusion-related reactions or hypersensitivity, were reported; 2 participants reported DREs (mild cough, n = 2). One SAE (acute myocardial infarction), which was considered unrelated to sotrovimab or COVID-19 by the investigator, occurred on day 27 and was the only hospitalization reported. Maximum serum concentration (geometric mean) was 745.9 µg/mL. Viral load decreased from baseline through day 29; only 2 (3%) participants had a persistently high viral load (≥4.1 log10 copies/mL) at day 8. Conclusions: Two thousand milligrams of IV sotrovimab was well tolerated, with no safety signals observed. Trial registration: ClinicalTrials.gov Identifier: NCT04913675.

Intramuscular vs Intravenous SARS-CoV-2 Neutralizing Antibody Sotrovimab for Treatment of COVID-19 (COMET-TAIL): A Randomized Noninferiority Clinical Trial.

Background: Convenient administration of coronavirus disease 2019 (COVID-19) treatment in community settings is desirable. Sotrovimab is a pan-sarbecovirus dual-action monoclonal antibody formulated for intravenous (IV) or intramuscular (IM) administration for early treatment of mild/moderate COVID-19. Method: This multicenter phase 3 study based on a randomized open-label design tested the noninferiority of IM to IV administration according to an absolute noninferiority margin of 3.5%. From June to August 2021, patients aged ≥12 years with COVID-19, who were neither hospitalized nor receiving supplemental oxygen but were at high risk for progression, were randomized 1:1:1 to receive sotrovimab as a single 500-mg IV infusion or a 500- or 250-mg IM injection. The primary composite endpoint was progression to (1) all-cause hospitalization for >24 hours for acute management of illness or (2) all-cause death through day 29. Results: Sotrovimab 500 mg IM was noninferior to 500 mg IV: 10 (2.7%) of 376 participants vs 5 (1.3%) of 378 met the primary endpoint, respectively (absolute adjusted risk difference, 1.06%; 95% CI, -1.15% to 3.26%). The 95% CI upper limit was lower than the prespecified noninferiority margin of 3.5%. The 250-mg IM group was discontinued early because of the greater proportion of hospitalizations vs the 500-mg groups. Serious adverse events occurred in <1% to 2% of participants across groups. Four participants experienced serious disease-related events and died (500 mg IM, 2/393, <1%; 250 mg IM, 2/195, 1%). Conclusions: Sotrovimab 500-mg IM injection was well tolerated and noninferior to IV administration. IM administration could expand outpatient treatment access for COVID-19. Clinical Trials Registration: ClinicalTrials.gov: NCT04913675.

Effect and Safety of Meropenem-Vaborbactam versus Best-Available Therapy in Patients with Carbapenem-Resistant Enterobacteriaceae Infections: The TANGO II Randomized Clinical Trial.

INTRODUCTION: Treatment options for carbapenem-resistant Enterobacteriaceae (CRE) infections are limited and CRE infections remain associated with high clinical failure and mortality rates, particularly in vulnerable patient populations. A Phase 3, multinational, open-label, randomized controlled trial (TANGO II) was conducted from 2014 to 2017 to evaluate the efficacy/safety of meropenem-vaborbactam monotherapy versus best available therapy (BAT) for CRE. METHODS: A total of 77 patients with confirmed/suspected CRE infection (bacteremia, hospital-acquired/ventilator-associated bacterial pneumonia, complicated intra-abdominal infection, complicated urinary tract infection/acute pyelonephritis) were randomized, and 47 with confirmed CRE infection formed the primary analysis population (microbiologic-CRE-modified intent-to-treat, mCRE-MITT). Eligible patients were randomized 2:1 to meropenem-vaborbactam (2 g/2 g over 3 h, q8h for 7-14 days) or BAT (mono/combination therapy with polymyxins, carbapenems, aminoglycosides, tigecycline; or ceftazidime-avibactam alone). Efficacy endpoints included clinical cure, Day-28 all-cause mortality, microbiologic cure, and overall success (clinical cure + microbiologic eradication). Safety endpoints included adverse events (AEs) and laboratory findings. RESULTS: Within the mCRE-MITT population, cure rates were 65.6% (21/32) and 33.3% (5/15) [95% confidence interval (CI) of difference, 3.3% to 61.3%; P = 0.03)] at End of Treatment and 59.4% (19/32) and 26.7% (4/15) (95% CI of difference, 4.6% to 60.8%; P = 0.02) at Test of Cure;.Day-28 all-cause mortality was 15.6% (5/32) and 33.3% (5/15) (95% CI of difference, - 44.7% to 9.3%) for meropenem-vaborbactam versus BAT, respectively. Treatment-related AEs and renal-related AEs were 24.0% (12/50) and 4.0% (2/50) for meropenem-vaborbactam versus 44.0% (11/25) and 24.0% (6/25) for BAT. Exploratory risk-benefit analyses of composite clinical failure or nephrotoxicity favored meropenem-vaborbactam versus BAT (31.3% [10/32] versus 80.0% [12/15]; 95% CI of difference, - 74.6% to - 22.9%; P < 0.001). CONCLUSIONS: Monotherapy with meropenem-vaborbactam for CRE infection was associated with increased clinical cure, decreased mortality, and reduced nephrotoxicity compared with BAT. CLINICAL TRIALS REGISTRATION: NCT02168946. FUNDING: The Medicines Company.

Carbapenem-Resistant Enterobacteriaceae Infections: Results From a Retrospective Series and Implications for the Design of Prospective Clinical Trials.

BACKGROUND: The increasing incidence of multidrug-resistant Gram negatives, such as carbapenem-resistant Enterobacteriaceae (CRE), has resulted in a critical need for new antimicrobials. Most studies of new antimicrobials have been performed in patients with nondrug-resistant pathogens. We performed a retrospective analysis of patients with CRE infections to inform the design of phase 3 clinical trials. METHODS: This was a retrospective study at 22 centers in 4 countries. Baseline data, treatment, and outcomes were collected in patients with complicated urinary tract infection (cUTI)/acute pyelonephritis (AP), hospital-acquired bacterial pneumonia (HABP), ventilator-associated bacterial pneumonia (VABP), and bacteremia due to CRE. RESULTS: Two hundred fifty-six cases of CRE infection were identified: 75 cUTI/AP, 21 HABP, 20 VABP, and 140 bacteremia. The patient population had significant comorbidities: 32.8% had chronic renal insufficiency, and 26.2% were immunocompromised. Illness severity at presentation was high: 29.3% presented with septic shock. Treatment regimens varied widely; however, a majority of patients received combination therapy. Outcomes were universally poor (28-day mortality was 28.1%) across all sites of infection, particularly in dialysis patients and those with sepsis. CONCLUSIONS: The CRE infections occured in patients with substantial comorbidities and were associated with high mortality and low rates of clinical cure with available antibiotics. Patients with these comorbidities are often excluded from enrollment in clinical trials for registration of new drugs. These results led to changes in the inclusion/exclusion criteria of a phase 3 trial to better represent the patient population with CRE infections and enable enrollment. Observational studies may become increasingly important to guide clinical trial design, inform on the existing standard of care, and provide an external control for subsequent trials.

Intermediate-type vancomycin resistance (VISA) in genetically-distinct Staphylococcus aureus isolates is linked to specific, reversible metabolic alterations.

Intermediate (VISA-type) vancomycin resistance in Staphylococcus aureus has been associated with a range of physiologic and genetic alterations. Previous work described the emergence of VISA-type resistance in two clonally-distinct series of isolates. In both series (the first belonging to MRSA clone ST8-USA300, and the second to ST5-USA100), resistance was conferred by a single mutation in yvqF (a negative regulator of the vraSR two-component system associated with vancomycin resistance). In the USA300 series, resistance was reversed by a secondary mutation in vraSR. In this study, we combined systems-level metabolomic profiling with statistical modeling techniques to discover specific, reversible metabolic alterations associated with the VISA phenotype.

Extended spectrum beta-lactamase-producing Enterobacteriaceae in international travelers and non-travelers in New York City.

BACKGROUND: We performed this study 1) to determine the prevalence of community-associated extended spectrum beta-lactamase producing Enterobacteriaceae (ESBLPE) colonization and infection in New York City (NYC); 2) to determine the prevalence of newly-acquired ESBLPE during travel; 3) to look for similarities in contemporaneous hospital-associated bloodstream ESBLPE and travel-associated ESBLPE. METHODS: Subjects were recruited from a travel medicine practice and consented to submit pre- and post-travel stools, which were assessed for the presence of ESBLPE. Pre-travel stools and stools submitted for culture were used to estimate the prevalence of community-associated ESBLPE. The prevalence of ESBLPE-associated urinary tract infections was calculated from available retrospective data. Hospital-associated ESBLPE were acquired from saved bloodstream isolates. All ESBLPE underwent multilocus sequence typing (MLST) and ESBL characterization. RESULTS: One of 60 (1.7%) pre- or non-travel associated stool was colonized with ESBLPE. Among community-associated urine specimens, 1.3% of Escherichia coli and 1.4% of Klebsiella pneumoniae were identified as ESBLPE. Seven of 28 travelers (25.0%) acquired a new ESBLPE during travel. No similarities were found between travel-associated ESBLPE and hospital-associated ESBLPE. A range of imported ESBL genes were found, including CTX-M-14 and CTX-15. CONCLUSION: ESBL colonization and infection were relatively low during the study period in NYC. A significant minority of travelers acquired new ESBLPE during travel.

Endemic Acinetobacter baumannii in a New York hospital.

BACKGROUND: Acinetobacter baumannii is an increasingly multidrug-resistant (MDR) cause of hospital-acquired infections, often associated with limited therapeutic options. We investigated A. baumannii isolates at a New York hospital to characterize genetic relatedness. METHODS: Thirty A. baumannii isolates from geographically-dispersed nursing units within the hospital were studied. Isolate relatedness was assessed by repetitive sequence polymerase chain reaction (rep-PCR). The presence and characteristics of integrons were assessed by PCR. Metabolomic profiles of a subset of a prevalent strain isolates and sporadic isolates were characterized and compared. RESULTS: We detected a hospital-wide group of closely related carbapenem resistant MDR A. baumannii isolates. Compared with sporadic isolates, the prevalent strain isolates were more likely to be MDR (p = 0.001). Isolates from the prevalent strain carried a novel Class I integron sequence. Metabolomic profiles of selected prevalent strain isolates and sporadic isolates were similar. CONCLUSION: The A. baumannii population at our hospital represents a prevalent strain of related MDR isolates that contain a novel integron cassette. Prevalent strain and sporadic isolates did not segregate by metabolomic profiles. Further study of environmental, host, and bacterial factors associated with the persistence of prevalent endemic A. baumannii strains is needed to develop effective prevention strategies.

Prevalence, persistence, and microbiology of Staphylococcus aureus nasal carriage among hemodialysis outpatients at a major New York Hospital.

The study aimed to determine the natural history of Staphylococcus aureus nasal colonization in hemodialysis outpatients. Surveillance cultures were taken from patients presenting for hemodialysis or routine care to identify S. aureus nasal carriers. A prospective cohort study was performed to identify risks for persistent colonization. Detailed microbiologic and molecular studies of colonizing isolates were performed. Only 23/145 (15.9%) dialysis patients were persistently colonized, and only HIV-positive status was associated with persistence (P = 0.05). Prior hospitalization was the only risk factor for methicillin-resistant S. aureus carriage (OR 2.5, P = 0.03). In isolates from patients with ≤ 42 days of vancomycin exposure, vancomycin minimum bactericidal concentrations (MBCs) increased with duration of exposure. Among dialysis patients, S. aureus colonization was limited and transient; only HIV status was associated with persistence. Nevertheless, duration of vancomycin exposure was associated with increasing vancomycin MBCs. Vancomycin exposure in S. aureus carriers may be involved in increasing resistance.

Clinical failure of vancomycin in a dialysis patient with methicillin-susceptible vancomycin-heteroresistant S. aureus.

We report a case of recurrent Staphylococcus aureus bacteremia in a patient who failed vancomycin due to a vancomycin-heteroresistant strain lacking methicillin resistance. Although initial isolates were susceptible, isolates obtained after vancomycin chemotherapy were vancomycin heteroresistant. This case thus illustrates the clinical emergence of vancomycin heteroresistance.