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Purpose There is variability in the pharmacokinetics (PK) of antibiotics (AB) in critically ill patients. Therapeutic drug monitoring (TDM) could overcome this variability and increase PK target attainment. The objective of this study was to analyse the effect of a dose-adaption strategy based on daily TDM on target attainment. Methods This was a prospective, partially blinded, and randomised controlled trial in patients with normal kidney function treated with meropenem (MEM) or piperacillin/tazobactam (PTZ). The intervention group underwent daily TDM, with dose adjustment when necessary. The predefined PK/pharmacodynamic (PK/PD) target was 100 % f T >4MIC [percentage of time during a dosing interval that the free ( f ) drug concentration exceeded 4 times the MIC]. The control group received conventional treatment. The primary endpoint was the proportion of patients that reached 100 % f T >4MIC and 100 % f T >MIC at 72 h. Results Forty-one patients (median age 56 years) were included in the study. Pneumonia was the primary infectious diagnosis. At baseline, 100 % f T >4MIC was achieved in 21 % of the PTZ patients and in none of the MEM patients; 100 % f T >MIC was achieved in 71 % of the PTZ patients and 46 % of the MEM patients. Of the patients in the intervention group, 76 % needed dose adaptation, and five required an additional increase. At 72 h, target attainment rates for 100 % f T >4MIC and 100 % f T >MIC were higher in the intervention group: 58 vs. 16 %, p  = 0.007 and 95 vs. 68 %, p  = 0.045, respectively. Conclusions Among critically ill patients with normal kidney function, a strategy of dose adaptation based on daily TDM led to an increase in PK/PD target attainment compared to conventional dosing.

In this study, we evaluated in situ click chemistry as a platform for discovering boronic acid-based β-lactamase inhibitors (BLIs). Unlike conventional drug discovery approaches requiring multi-step synthesis, protection strategies, and extensive screening, the in situ method can allow for the generation and identification of potent β-lactamase inhibitors in a rapid, economic, and efficient way. Using KPC-2 (class A carbapenemase) and AmpC (class C cephalosporinase) as templates, we demonstrated their ability to catalyse azide-alkyne cycloaddition, facilitating the formation of triazole-based β-lactamase inhibitors. Initial screening of various β-lactamases and boronic warheads identified compound 3 (3-azidomethylphenyl boronic acid) as the most effective scaffold for kinetic target-guided synthesis (KTGS). KTGS experiments with AmpC and KPC-2 yielded triazole inhibitors with Ki values as low as 140 nM (compound 10a, AmpC) and 730 nM (compound 5, KPC-2). Competitive inhibition studies confirmed triazole formation within the active site, while an LC–MS analysis verified that the reversible covalent interaction of boronic acids did not affect detection of the in situ-synthesised product. While KTGS successfully identified potent inhibitors, limitations in amplification coefficients and spatial constraints highlight the need for optimised warhead designs. This study validates KTGS as a promising strategy for BLI discovery and provides insights for further refinement in fighting β-lactamase-mediated antibiotic resistance.

The purpose of this study was to assess the pharmacokinetic (PK) characteristics, clinical efficiency, and pharmacoeconomic parameters of piperacillin/tazobactam administered by extended infusion (EI) or intermittent infusion (II) in the treatment of hospital-acquired pneumonia (HAP) in critically ill patients with low illness severity in China. Fifty patients completed the study, with 25 patients receiving 4/0.5 g piperacillin/tazobactam over 30 min as the II group and 25 patients receiving 4/0.5 g piperacillin/tazobactam over 3 h every 6 h as the EI group. Drug assay was performed using high-performance liquid chromatography (HPLC). The percentage of the dosing interval for which the free piperacillin concentration (% f T) exceeds the minimum inhibitory concentration (MIC) was calculated. The patients’ therapy cost, clinical efficiency, and adverse effects were also recorded. % f T>MIC was about 100, 98.73, and 93.04 % in the EI arm versus 81.48, 53.29, and 42.15 % in the II arm, respectively, when the microorganism responsible for HAP had an MIC of 4, 8, and 16 mg/L. The therapy cost in the EI group was lower than that of the II group ($1351.72 ± 120.39 vs. $1782.04 ± 164.51, p  = 0.001). However, the clinical success rate, clinical failure rate, and drug-related adverse events did not significantly differ between groups. EI treatment with piperacillin/tazobactam was a cost-effective approach to the management of HAP, being equally clinically effective to conventional II.

Carbapenems are frequently the last line of defence in serious infections due to multidrug-resistant Gram-negative bacteria, but their use is threatened by the growing prevalence of carbapenemase-producing pathogens. Ceftazidime-avibactam is a potential new agent for use in such infections. We aimed to assess the efficacy, safety, and tolerability of ceftazidime-avibactam compared with best available therapy in patients with complicated urinary tract infection or complicated intra-abdominal infection due to ceftazidime-resistant Gram-negative pathogens. REPRISE was a pathogen-directed, international, randomised, open-label, phase 3 trial that recruited patients from hospitals across 16 countries worldwide. Eligible patients were aged 18–90 years with complicated urinary tract infection or complicated intra-abdominal infection caused by ceftazidime-resistant Enterobacteriaceae or Pseudomonas aeruginosa. Patients were randomised (1:1) to 5–21 days of treatment with either ceftazidime-avibactam (a combination of 2000 mg ceftazidime plus 500 mg avibactam, administered via a 2-h intravenous infusion every 8 h) or best available therapy. The primary endpoint was clinical response at the test-of-cure visit, 7–10 days after last infusion of study therapy, analysed in all patients who had at least one ceftazidime-resistant Gram-negative pathogen, as confirmed by the central laboratory, and who received at least one dose of study drug. Safety endpoints were assessed in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT01644643. Between Jan 7, 2013, and Aug 29, 2014, 333 patients were randomly assigned, 165 to ceftazidime-avibactam and 168 to best available therapy. Of these, 154 assigned to ceftazidime-avibactam (144 with complicated urinary tract infection and ten with complicated intra-abdominal infection) and 148 assigned to best available therapy (137 with complicated urinary tract infection and 11 with complicated intra-abdominal infection) were analysed for the primary outcome. 163 (97%) of 168 patients in the best available therapy group received a carbapenem, 161 (96%) as monotherapy. The overall proportions of patients with a clinical cure at the test-of-cure visit were similar with ceftazidime-avibactam (140 [91%; 95% CI 85·6–94·7] of 154 patients) and best available therapy (135 [91%; 85·9–95·0] of 148 patients). 51 (31%) of 164 patients in the ceftazidime-avibactam group and 66 (39%) of 168 in the best available therapy group had an adverse event, most of which were mild or moderate in intensity. Gastrointestinal disorders were the most frequently reported treatment-emergent adverse events with both ceftazidime-avibactam (21 [13%] of 164 patients) and best available therapy (30 [18%] of 168 patients). No new safety concerns were identified for ceftazidime-avibactam. These results provide evidence of the efficacy of ceftazidime-avibactam as a potential alternative to carbapenems in patients with ceftazidime-resistant Enterobacteriaceae and P aeruginosa. AstraZeneca.

Carbapenem resistance is a major global health problem that seriously compromises the treatment of infections caused by nosocomial pathogens. Resistance to carbapenems mainly occurs via the production of carbapenemases, such as VIM, IMP, NDM, KPC and OXA, among others. Preclinical and clinical trials are currently underway to test a new generation of promising inhibitors, together with the recently approved avibactam, relebactam and vaborbactam. This review summarizes the main, most promising carbapenemase inhibitors synthesized to date, as well as their spectrum of activity and current stage of development. We particularly focus on β-lactam/β-lactamase inhibitor combinations that could potentially be used to treat infections caused by carbapenemase-producer pathogens of critical priority. The emergence of these new combinations represents a step forward in the fight against antimicrobial resistance, especially in regard to metallo-β-lactamases and carbapenem-hydrolysing class D β-lactamases, not currently inhibited by any clinically approved inhibitor.

The rise of carbapenem-resistant Enterobacteriaceae (CRE) has posed a major clinical challenge, with limited treatment options. Nacubactam, a novel β-lactamase inhibitor, combined with cefepime or aztreonam, effectively supports CRE infection treatment. A randomized, double-blind, placebo-controlled clinical trial was conducted for the first time in healthy male Chinese subjects, including both single and multiple doses 60 ± 5-min intravenous infusion. Twenty participants were randomly assigned to nacubactam or placebo in two dosage groups (1 g and 2 g, 10 subjects each) to evaluate pharmacokinetics, safety, and tolerability. Nacubactam demonstrated good safety and tolerability in healthy male Chinese subjects after single and multiple doses intravenous infusion with no adverse events leading to study withdrawal. Nacubactam reached peak concentration immediately after infusion, had a short half-life, and showed dose-proportional exposure. At steady state, drug accumulation was minimal. The cumulative urinary excretion rates of nacubactam were 91.8% and 87.1% in the two dose groups, indicating primary renal elimination. Exposure to metabolites M1 and M2 was minimal. Nacubactam generally exhibited good safety and tolerability in healthy Chinese male subjects after single and multiple doses of 1 g/2 g intravenous doses. It was primarily excreted renally with minimal accumulation. Carbapenem-resistant Enterobacteriaceae (CRE) have become a growing global health threat due to limited treatment options and high morbidity and mortality. Nacubactam is a novel β-lactamase inhibitor that exerts dual inhibition on β-lactamases and penicillin-binding proteins. Its combination with ceftazidime or aztreonam is promising for treating multidrug-resistant Gram-negative bacterial infections. To support clinical development and future therapeutic applications, pharmacokinetic and safety data in different populations are crucial. In this work, we conducted a phase I randomized, double-blind, placebo-controlled trial to clinically evaluate nacubactam for the first time in healthy Chinese male subjects, demonstrating its good safety profile, dose-proportional pharmacokinetics, and mainly renal excretion. These data provide insights into the clinical application of nacubactam. Trial registration This trial was registered on the Chinese Clinical Trial Registration website, registration number ChiCTR2500103582.

Multidrug-resistant (MDR) bacterial infections are a serious threat to public health. Among the most alarming resistance trends is the rapid rise in the number and diversity of β-lactamases, enzymes that inactivate β-lactams, a class of antibiotics that has been a therapeutic mainstay for decades. Although several new β-lactamase inhibitors have been approved or are in clinical trials, their spectra of activity do not address MDR pathogens such as Acinetobacter baumannii . This report describes the rational design and characterization of expanded-spectrum serine β-lactamase inhibitors that potently inhibit clinically relevant class A, C and D β-lactamases and penicillin-binding proteins, resulting in intrinsic antibacterial activity against Enterobacteriaceae and restoration of β-lactam activity in a broad range of MDR Gram-negative pathogens. One of the most promising combinations is sulbactam–ETX2514, whose potent antibacterial activity, in vivo efficacy against MDR A. baumannii infections and promising preclinical safety demonstrate its potential to address this significant unmet medical need. Development of a broad-spectrum β-lactamase inhibitor capable of combatting multidrug-resistant pathogens, including Acinetobacter baumannii .

An urgent need exists for antibiotics to treat infections caused by carbapenem-resistant Acinetobacter baumannii–calcoaceticus complex (ABC). Sulbactam–durlobactam is a β-lactam–β-lactamase inhibitor combination with activity against Acinetobacter, including multidrug-resistant strains. In a phase 3, pathogen-specific, randomised controlled trial, we compared the efficacy and safety of sulbactam–durlobactam versus colistin, both in combination with imipenem–cilastatin as background therapy, in patients with serious infections caused by carbapenem-resistant ABC. The ATTACK trial was done at 59 clinical sites in 16 countries. Adults aged 18 years or older with ABC-confirmed hospital-acquired bacterial pneumonia, ventilator-associated bacterial pneumonia, ventilated pneumonia, or bloodstream infections were randomised 1:1 using a block size of four to sulbactam–durlobactam (1·0 g of each drug in combination over 3 h every 6 h) or colistin (2·5 mg/kg over 30 min every 12 h) for 7–14 days. All patients received imipenem–cilastatin (1·0 g of each drug in combination over 1 h every 6 h) as background therapy. The primary efficacy endpoint was 28-day all-cause mortality in patients with laboratory-confirmed carbapenem-resistant ABC (the carbapenem-resistant ABC microbiologically modified intention-to-treat population). Non-inferiority was concluded if the upper bound of the 95% CI for the treatment difference was less than +20%. The primary safety endpoint was incidence of nephrotoxicity assessed using modified Risk, Injury, Failure, Loss, End-stage renal disease criteria measured by creatinine level or glomerular filtration rate through day 42. This trial is registered at ClinicalTrials.gov, NCT03894046. Between Sep 5, 2019, and July 26, 2021, 181 patients were randomly assigned to sulbactam–durlobactam or colistin (176 hospital-acquired bacterial pneumonia, ventilator-associated bacterial pneumonia, or ventilated pneumonia; and five bloodstream infections); 125 patients with laboratory-confirmed carbapenem-resistant ABC isolates were included in the primary efficacy analysis. 28-day all-cause mortality was 12 (19%) of 63 in the sulbactam–durlobactam group and 20 (32%) of 62 in the colistin group, a difference of –13·2% (95% CI –30·0 to 3·5), which met criteria for non-inferiority. Incidence of nephrotoxicity was significantly (p<0·001) lower with sulbactam–durlobactam than colistin (12 [13%] of 91 vs 32 [38%] of 85). Serious adverse events were reported in 36 (40%) of 91 patients in the sulbactam–durlobactam group and 42 (49%) of 86 patients in the colistin group. Treatment-related adverse events leading to study drug discontinuation were reported in ten (11%) of 91 patients in the sulbactam–durlobactam group and 14 (16%) of 86 patients in the colistin group. Our data show that sulbactam–durlobactam was non-inferior to colistin, both agents given in combination with imipenem–cilastatin, for the primary endpoint of 28-day all-cause mortality. Sulbactam–durlobactam was well tolerated and could be an effective intervention to reduce mortality from serious infections caused by carbapenem-resistant ABC, including multidrug-resistant strains. Entasis Therapeutics and Zai Lab.

Although amoxicillin–clavulanate is the recommended first-line empirical oral antibiotic treatment for non-severe exacerbations in children with bronchiectasis, azithromycin is also often prescribed for its convenient once-daily dosing. No randomised controlled trials involving acute exacerbations in children with bronchiectasis have been published to our knowledge. We hypothesised that azithromycin is non-inferior to amoxicillin-clavulanate for resolving exacerbations in children with bronchiectasis. We did this parallel-group, double-dummy, double-blind, non-inferiority randomised controlled trial in three Australian and one New Zealand hospital between April, 2012, and August, 2016. We enrolled children aged 1–19 years with radiographically proven bronchiectasis unrelated to cystic fibrosis. At the start of an exacerbation, children were randomly assigned to oral suspensions of either amoxicillin–clavulanate (22·5 mg/kg, twice daily) and placebo or azithromycin (5 mg/kg per day) and placebo for 21 days. We used permuted block randomisation (stratified by age, site, and cause) with concealed allocation. The primary outcome was resolution of exacerbation (defined as a return to baseline) by 21 days in the per-protocol population, with a non-inferiority margin of −20%. We assessed several secondary outcomes including duration of exacerbation, time to next exacerbation, laboratory, respiratory, and quality-of-life measurements, and microbiology. This trial was registered with the Australian/New Zealand Registry (ACTRN12612000010897). We screened 604 children and enrolled 236. 179 children had an exacerbation and were assigned to treatment: 97 to amoxicillin–clavulanate, 82 to azithromycin). By day 21, 61 (84%) of 73 exacerbations had resolved in the azithromycin group versus 73 (84%) of 87 in the amoxicillin–clavulanate group. The risk difference showed non-inferiority (−0·3%, 95% CI −11·8 to 11·1). Exacerbations were significantly shorter in the amoxicillin–clavulanate group than in the azithromycin group (median 10 days [IQR 6–15] vs 14 days [8–16]; p=0·014). Adverse events were attributed to the trial medication in 17 (21%) of 82 children in the azithromycin group versus 23 (24%) of 97 in the amoxicillin–clavulanate group (relative risk 0·9, 95% CI 0·5 to 1·5). By 21 days of treatment, azithromycin is non-inferior to amoxicillin–clavulanate for resolving exacerbations in children with non-severe bronchiectasis. In some patients, such as those with penicillin hypersensitivity or those likely to have poor adherence, azithromycin provides another option for treating exacerbations, but must be balanced with risk of treatment failure (within a 20% margin), longer exacerbation duration, and the risk of inducing macrolide resistance. Australian National Health and Medical Research Council.

Carbapenem-resistant Pseudomonas aeruginosa (CR-PA) is a major healthcare-associated pathogen worldwide. In the United States, 10-30% of P. aeruginosa isolates are carbapenem-resistant, while globally the percentage varies considerably. A subset of carbapenem-resistant P. aeruginosa isolates harbour carbapenemases, although due in part to limited screening for these enzymes in clinical laboratories, the actual percentage is unknown. Carbapenemase-mediated carbapenem resistance in P. aeruginosa is a significant concern as it greatly limits the choice of anti-infective strategies, although detecting carbapenemase-producing P. aeruginosa in the clinical laboratory can be challenging. Such organisms also have been associated with nosocomial spread requiring infection prevention interventions. The carbapenemases present in P. aeruginosa vary widely by region but include the Class A beta-lactamases, KPC and GES; metallo-beta-lactamases IMP, NDM, SPM, and VIM; and the Class D, OXA-48 enzymes. Rapid confirmation and differentiation among the various classes of carbapenemases is key to the initiation of early effective therapy. This may be accomplished using either molecular genotypic methods or phenotypic methods, although both have their limitations. Prompt evidence that rules out carbapenemases guides clinicians to more optimal therapeutic selections based on local phenotypic profiling of non-carbapenemase-producing, carbapenem-resistant P. aeruginosa. This article will review the testing strategies available for optimizing therapy of P. aeruginosa infections.