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There is a need for additional therapeutic options for serious infections caused by Gram-negative pathogens. In the phase 3, descriptive REVISIT study, we investigated the safety and efficacy of aztreonam–avibactam in the treatment of complicated intra-abdominal infections or hospital-acquired pneumonia or ventilator-associated pneumonia (HAP–VAP) caused, or suspected to be caused, by Gram-negative bacteria. This prospective, multinational, open-label, central assessor-masked study enrolled adults who were hospitalised with a complicated intra-abdominal infection or HAP–VAP. Patients were randomly allocated via block randomisation using interactive response technology stratified by infection type in a 2:1 ratio to aztreonam–avibactam (with metronidazole for complicated intra-abdominal infection) or meropenem with or without colistin for 5–14 days for complicated intra-abdominal infection or 7–14 days for HAP–VAP. The primary endpoint was clinical cure at the test-of-cure visit (within 3 days before or after day 28) in the intention-to-treat (ITT) population. Secondary endpoints included 28-day mortality in the ITT population and safety in patients in the ITT population who received study drug (safety analysis set). No formal hypothesis testing was planned. The study was registered with ClinicalTrials.gov (NCT03329092) and EudraCT (2017–002742–68) and is complete. Between April 5, 2018, and Feb 23, 2023, we screened 461 patients. 422 patients were enrolled and randomly allocated (282 in the aztreonam–avibactam group and 140 in the meropenem group, forming the ITT analysis set), of whom ten patients (seven in the aztreonam–avibactam group and three in the meropenem group) were randomly allocated but did not receive study treatment. 271 (64%) of 422 patients had at least one Gram-negative pathogen from an adequate specimen identified at baseline. The most frequent baseline pathogens were Enterobacterales (252 [93%] of 271). Overall, 19 (24%) of 80 isolates tested for carbapenemases were carbapenemase-positive (serine, metallo-β-lactamase, or both). 193 (68·4%) of 282 patients in the aztreonam–avibactam group and 92 (65·7%) of 140 in the meropenem group had clinical cure at the test-of-cure visit (treatment difference 2·7% [95% CI –6·6 to 12·4]). For patients with complicated intra-abdominal infection, the adjudicated clinical cure rate was 76·4% (159 of 208) for the aztreonam–avibactam group and 74·0% (77 of 104) for the meropenem group. Cure rates in patients with HAP–VAP were 45·9% (34 of 74) for aztreonam–avibactam and 41·7% (15 of 36) for meropenem. 28-day all-cause mortality rates were 4% (12 of 282) for aztreonam–avibactam and 7% (ten of 140) for meropenem; in patients with complicated intra-abdominal infection, mortality was 2% (four of 208) and 3% (three of 104) for aztreonam–avibactam and meropenem, respectively, and in patients with HAP–VAP, mortality was 11% (eight of 74) and 19% (seven of 36), respectively. Aztreonam–avibactam was generally well tolerated, and safety findings were consistent with the known safety profile of aztreonam monotherapy. There were no treatment-related serious adverse events in the aztreonam–avibactam group. These phase 3 efficacy and safety data provide support for aztreonam–avibactam as a potential therapeutic option for complicated intra-abdominal infection or HAP–VAP caused by Gram-negative bacteria. Pfizer.

In this trial involving 387 patients with Staphylococcus aureus bacteremia, ceftobiprole, a cephalosporin active against methicillin-sensitive and -resistant S. aureus , was noninferior to daptomycin.

Background. Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of complicated skin and skin-structure infection (cSSSI). Increasing antimicrobial resistance in cSSSI has led to a need for new safe and effective therapies. Ceftaroline was evaluated as treatment for cSSSI in 2 identical phase 3 clinical trials, the pooled analysis of which is presented here. The primary objective of each trial was to determine the noninferiority of the clinical cure rate achieved with ceftaroline monotherapy, compared with that achieved with vancomycin plus aztreonam combination therapy, in the clinically evaluable (CE) and modified intent-to-treat (MITT) patient populations. Methods. Adult patients with cSSSI requiring intravenous therapy received ceftaroline (600 mg every 12 h) or vancomycin plus aztreonam (1 g each every 12 h) for 5–14 days. Results. Of 1378 patients enrolled in both trials, 693 received ceftaroline and 685 received vancomycin plus aztreonam. Baseline characteristics of the treatment groups were comparable. Clinical cure rates were similar for ceftaroline and vancomycin plus aztreonam in the CE (91.6% vs 92.7%) and MITT (85.9% vs 85.5%) populations, respectively, as well as in patients infected with MRSA (93.4% vs 94.3%). The rates of adverse events, discontinuations because of an adverse event, serious adverse events, and death also were similar between treatment groups. Conclusions. Ceftaroline achieved high clinical cure rates, was efficacious against cSSSI caused by MRSA and other common cSSSI pathogens, and was well tolerated, with a safety profile consistent with the cephalosporin class. Ceftaroline has the potential to provide a monotherapy alternative for the treatment of cSSSI. Trial registration. ClinicalTrials.gov identifiers: NCT00424190 for CANVAS 1 and NCT00423657 for CANVAS 2.

Abstract Rationale The effectiveness and safety of aztreonam lysine for inhalation (AZLI) in patients with cystic fibrosis (CF) on maintenance treatment for Pseudomonas aeruginosa (PA) airway infection was evaluated in this randomized, double-blind, placebo-controlled study. Objectives To evaluate the safety and efficacy of inhaled aztreonam lysine in controlling PA infection in patients with CF. Methods After randomization and a 28-day course of tobramycin inhalation solution (TIS), patients (n = 211; ⩾6 yr; ⩾3 TIS courses within previous year; FEV1 ⩾ 25% and ⩽75% predicted values) were treated with 75 mg AZLI or placebo, twice or three times daily for 28 days, then monitored for 56 days. The primary efficacy endpoint was time to need for additional inhaled or intravenous antipseudomonal antibiotics. Secondary endpoints included changes in respiratory symptoms (CF Questionnaire-Revised [CFQ-R] Respiratory Scale), pulmonary function (FEV1), and sputum PA density. Adverse events and minimum inhibitory concentrations of aztreonam for PA were monitored. Measurements and Main Results AZLI treatment increased median time to need for additional antipseudomonal antibiotics for symptoms of pulmonary exacerbation by 21 days, compared with placebo (AZLI, 92 d; placebo, 71 d; P = 0.007). AZLI improved mean CFQ-R respiratory scores (5.01 points, P = 0.02), FEV1 (6.3%, P = 0.001), and sputum PA density (−0.66 log10 cfu/g, P = 0.006) compared with placebo; no AZLI dose–response was observed. Adverse events reported for AZLI and placebo were comparable and consistent with CF lung disease. Susceptibility of PA to aztreonam at baseline and end of therapy were similar. Conclusions AZLI was effective in patients with CF using frequent TIS therapy. AZLI delayed time to need for inhaled or intravenous antipseudomonal antibiotics, improved respiratory symptoms and pulmonary function, and was well tolerated. Clinical trial registered with www.clinicaltrials.gov (NCT 00104520).

Abstract Rationale The principal underlying inhaled antibiotic treatment in bronchiectasis is that airway bacterial load drives inflammation, and therefore antibiotic treatment will reduce symptoms. Objectives To determine the relationship between bacterial load and clinical outcomes, assess the stability of bacterial load over time, and test the hypothesis that response to inhaled antibiotics would be predicted by baseline bacterial load. Methods We performed three studies. Studies 1 and 2 were prospective studies including adults with bronchiectasis. Study 3 was a post hoc analysis of a randomized trial of inhaled aztreonam. A priori patients were divided into low (<105 cfu/g), moderate (105–106 cfu/g), and high bacterial load (≥107 cfu/g) using quantitative sputum culture. Measurements and Main Results Bacterial load was a stable trait associated with worse quality of life and more airway inflammation in studies 1, 2, and 3. In study 3, patients with high bacterial load showed an improvement in the primary endpoint (Quality of Life–Bronchiectasis–Respiratory Symptoms Score at Week 4) in favor of aztreonam (mean difference of 9.7 points; 95% confidence interval, 3.4–16.0; P = 0.003). The proportion of patients who achieved an increase above the minimum clinically important difference was higher in the aztreonam group at Week 4 (63% vs. 37%; P = 0.01) and at Week 12 (62% vs. 38%; P = 0.01) only in high bacterial load patients. Conclusions Improvement of quality of life with inhaled aztreonam was only evident in patients with high bacterial load. Bacterial load may be a useful biomarker of severity of disease and treatment response.

Pandrug-resistant (PDR) K. pneumoniae refractory to conventional treatment has been reported worldwide, causing a huge burden on the healthcare system, patient safety and the economy. K. pneumoniae is a prominent opportunistic pathogen causing hospital-acquired and community-acquired infections, but is rarely associated with infective endocarditis. Currently, there are sparse data guiding the optimal regimen when commonly used antibiotics fail, notably for the treatment of endocarditis infections. Here we report our experience in treating a 40-year-old female with PDR K. pneumoniae infection of cardiovascular implantable electronic device (CIED) and right-sided infective endocarditis. Initial susceptibility testing of the incriminated pathogen showed an apparent susceptibility to colistin but the prolonged course of colistin, gentamicin and meropenem did not resolve the infection. However, the synergistic combinations of aztreonam with ceftazidime-avibactam was able to overcome resistance and clear the infection rapidly. Genome sequencing showed that the PDR K. pneumoniae isolate belongs to the international high-risk clone ST14. The isolate harbored genes encoding NDM-1, OXA-48, CTX-M-14b, SHV-28 and OXA-1, explaining resistance to all β-lactams, including carbapenems. It carried the armA gene conferring resistance to all clinically important aminoglycosides and had alterations in GyrA, ParC and MgrB, explaining resistance to ciprofloxacin and colistin.

Two phase 3, double-blind studies in hospitalized adults with complicated skin and skin-structure infections (cSSSI) determined the safety and efficacy of tigecycline versus that of vancomycin-aztreonam. Patients received tigecycline (100 mg, followed by 50 mg intravenously twice daily) or vancomycin (1 g intravenously twice daily) plus aztreonam (2 g intravenously twice daily) for up to 14 days. Populations were as follows: 1116 patients (566 treated with tigecycline, and 550 treated with vancomycin-aztreonam) constituted the modified intent-to-treat (mITT) population, 1057 patients (538 treated with tigecycline, and 519 treated with vancomycin-aztreonam) constituted the clinical mITT (c-mITT) population, and 833 patients (422 treated with tigecycline, and 411 treated with vancomycin-aztreonam) constituted the clinically evaluable population. Clinical responses to tigecycline and vancomycin-aztreonam at test-of-cure were similar: c-mITT, 79.7% (95% confidence interval [CI], 76.1%–83.1%) versus 81.9% (95% CI, 78.3%–85.1%) (P = .4183); and clinically evaluable, 86.5% (95% CI, 82.9%–89.6%) versus 88.6% (95% CI, 85.1%–91.5%) (P = .4233). Adverse events were similar, with increased nausea and vomiting in the tigecycline group and increased rash and elevated hepatic aminotransferase levels in the vancomycin-aztreonam group. Tigecycline monotherapy is as safe and efficacious as the vancomycin-aztreonam combination in treating patients with cSSSI.

This phase 3 trial in acute bacterial skin and skin structure infections showed IV followed by oral delafloxacin to be noninferior to IV vancomycin/aztreonam combination therapy and well tolerated. Oral delafloxacin appears to maintain the initial response with IV delafloxacin. Abstract Background Delafloxacin is an intravenous (IV)/oral anionic fluoroquinolone with activity against gram-positive (including methicillin-resistant Staphylococcus aureus [MRSA]), gram-negative, atypical, and anaerobic organisms. It is approved in the United States for acute bacterial skin and skin structure infections (ABSSSIs) caused by designated susceptible gram-positive and gram-negative organisms, and is in development for the treatment of community-acquired bacterial pneumonia. Methods A multicenter, randomized, double-blind trial of 850 adults with ABSSSI compared delafloxacin 300 mg IV every 12 hours for 3 days with a switch to 450 mg oral delafloxacin, to vancomycin 15 mg/kg IV with aztreonam for 5-14 days. The primary endpoint was objective response at 48-72 hours. Investigator-assessed response based on resolution of signs and symptoms at follow-up (day 14 ± 1), and late follow-up (day 21-28) were secondary endpoints. Results In the intent-to-treat analysis set, the objective response was 83.7% in the delafloxacin arm and 80.6% in the comparator arm. Investigator-assessed success was similar at follow-up (87.2% vs 84.4%) and late follow-up (83.5% vs 82.2%). Delafloxacin was comparable to vancomycin + aztreonam in eradication of MRSA at 96.0% vs 97.0% at follow-up. Frequency of treatment-emergent adverse events between the groups was similar. Treatment-emergent adverse events leading to study drug discontinuation was higher in the vancomycin + aztreonam group (1.2% vs 2.4%). Conclusions In ABSSSI patients, IV/oral delafloxacin monotherapy was noninferior to IV vancomycin + aztreonam combination therapy for both the objective response and the investigator-assessed response at follow-up and late follow-up. Delafloxacin was well tolerated as monotherapy in treatment of ABSSSIs. Clinical Trials Registration NCT01984684.

Purpose A series of iterative population pharmacokinetic (PK) modeling and probability of target attainment (PTA) analyses based on emerging data supported dose selection for aztreonam-avibactam, an investigational combination antibiotic for serious Gram-negative bacterial infections. Methods Two iterations of PK models built from avibactam data in infected patients and aztreonam data in healthy subjects with “patient-like” assumptions were used in joint PTA analyses (primary target: aztreonam 60% f T > 8 mg/L, avibactam 50% f T > 2.5 mg/L) exploring patient variability, infusion durations, and adjustments for moderate (estimated creatinine clearance [CrCL] > 30 to ≤ 50 mL/min) and severe renal impairment (> 15 to ≤ 30 mL/min). Achievement of > 90% joint PTA and the impact of differential renal clearance were considerations in dose selection. Results Iteration 1 simulations for Phase I/IIa dose selection/modification demonstrated that 3-h and continuous infusions provide comparable PTA; avibactam dose drives joint PTA within clinically relevant exposure targets; and loading doses support more rapid joint target attainment. An aztreonam/avibactam 500/137 mg 30-min loading dose and 1500/410 mg 3-h maintenance infusions q6h were selected for further evaluation. Iteration 2 simulations using expanded PK models supported an alteration to the regimen (500/167 mg loading; 1500/500 mg q6h maintenance 3-h infusions for CrCL > 50 mL/min) and selection of doses for renal impairment for Phase IIa/III clinical studies. Conclusion A loading dose plus 3-h maintenance infusions of aztreonam-avibactam in a 3:1 fixed ratio q6h optimizes joint PTA. These analyses supported dose selection for the aztreonam-avibactam Phase III clinical program. Clinical trial registration : NCT01689207; NCT02655419; NCT03329092; NCT03580044.

Background The Quality of Life-Bronchiectasis (QOL-B), a self-administered, patient-reported outcome measure assessing symptoms, functioning and health-related quality of life for patients with non-cystic fibrosis (CF) bronchiectasis, contains 37 items on 8 scales (Respiratory Symptoms, Physical, Role, Emotional and Social Functioning, Vitality, Health Perceptions and Treatment Burden). Methods Psychometric analyses of QOL-B V.3.0 used data from two double-blind, multicentre, randomised, placebo-controlled, phase III trials of aztreonam for inhalation solution (AZLI) in 542 patients with non-CF bronchiectasis and Gram-negative endobronchial infection. Results Excellent internal consistency (Cronbach's α ≥0.70) and 2-week test–retest reliability (intraclass correlation coefficients ≥0.72) were demonstrated for each scale. Convergent validity with 6 min walk test was observed for Physical and Role Functioning scores. No floor or ceiling effects (baseline scores of 0 or 100) were found for the Respiratory Symptoms scale (primary endpoint of trials). Baseline Respiratory Symptoms scores discriminated between patients based on baseline FEV1% predicted in only one trial. The minimal important difference score for the Respiratory Symptoms scale was 8.0 points. AZLI did not show efficacy in the two phase III trials. QOL-B responsivity to treatment was assessed by examining changes from baseline QOL-B scores at study visits at which protocol-defined pulmonary exacerbations were reported. Mean Respiratory Symptoms scores decreased 14.0 and 14.2 points from baseline for placebo-treated and AZLI-treated patients with exacerbations, indicating that worsening respiratory symptoms were reflected in clinically meaningful changes in QOL-B scores. Conclusions Previously established content validity, reliability and responsivity of the QOL-B are confirmed by this final validation study. The QOL-B is available for use in clinical trials and routine clinical practice.