Ceftobiprole for Treatment of Complicated Staphylococcus aureus Bacteremia.

BACKGROUND: Ceftobiprole is a cephalosporin that may be effective for treating complicated Staphylococcus aureus bacteremia, including methicillin-resistant S. aureus. METHODS: In this phase 3, double-blind, double-dummy, noninferiority trial, adults with complicated S. aureus bacteremia were randomly assigned in a 1:1 ratio to receive ceftobiprole at a dose of 500 mg intravenously every 6 hours for 8 days and every 8 hours thereafter, or daptomycin at a dose of 6 to 10 mg per kilogram of body weight intravenously every 24 hours plus optional aztreonam (at the discretion of the trial-site investigators). The primary outcome, overall treatment success 70 days after randomization (defined as survival, bacteremia clearance, symptom improvement, no new S. aureus bacteremia-related complications, and no receipt of other potentially effective antibiotics), with a noninferiority margin of 15%, was adjudicated by a data review committee whose members were unaware of the trial-group assignments. Safety was also assessed. RESULTS: Of 390 patients who underwent randomization, 387 (189 in the ceftobiprole group and 198 in the daptomycin group) had confirmed S. aureus bacteremia and received ceftobiprole or daptomycin (modified intention-to-treat population). A total of 132 of 189 patients (69.8%) in the ceftobiprole group and 136 of 198 patients (68.7%) in the daptomycin group had overall treatment success (adjusted difference, 2.0 percentage points; 95% confidence interval [CI], -7.1 to 11.1). Findings appeared to be consistent between the ceftobiprole and daptomycin groups in key subgroups and with respect to secondary outcomes, including mortality (9.0% and 9.1%, respectively; 95% CI, -6.2 to 5.2) and the percentage of patients with microbiologic eradication (82.0% and 77.3%; 95% CI, -2.9 to 13.0). Adverse events were reported in 121 of 191 patients (63.4%) who received ceftobiprole and 117 of 198 patients (59.1%) who received daptomycin; serious adverse events were reported in 36 patients (18.8%) and 45 patients (22.7%), respectively. Gastrointestinal adverse events (primarily mild nausea) were more frequent with ceftobiprole. CONCLUSIONS: Ceftobiprole was noninferior to daptomycin with respect to overall treatment success in patients with complicated S. aureus bacteremia. (Funded by Basilea Pharmaceutica International and the U.S. Department of Health and Human Services; ERADICATE ClinicalTrials.gov number, NCT03138733.).

Sequential Treatment Failure With Aztreonam-Ceftazidime-Avibactam Followed by Cefiderocol Due to Preexisting and Acquired Mechanisms in a New Delhi Metallo-ß-lactamase-Producing Escherichia coli Causing Fatal Bloodstream Infection.

We report a fatal case of New Delhi metallo-ß-lactamase (NDM)-producing Escherichia coli in a bacteremic patient with sequential failure of aztreonam plus ceftazidime-avibactam followed by cefiderocol. Acquired resistance was documented phenotypically and mediated through preexisting and acquired mutations. This case highlights the need to rethink optimal treatment for NDM-producing organisms.

Difficult-to-treat (DTR) Pseudomonas aeruginosa harboring Verona-Integron metallo-ß-lactamase (blaVIM): infection management and molecular analysis.

Pseudomonas aeruginosa harboring Verona Integron-encoded metallo-ß-lactamase enzymes (VIM-CRPA) have been associated with infection outbreaks in several parts of the world. In the US, however, VIM-CRPA remain rare. Starting in December 2018, we identified a cluster of cases in our institution. Herein, we present our epidemiological investigation and strategies to control/manage these challenging infections. This study was conducted in a large academic healthcare system in Miami, FL, between December 2018 and January 2022. Patients were prospectively identified via rapid molecular diagnostics when cultures revealed carbapenem-resistant P. aeruginosa. Alerts were received in real time by the antimicrobial stewardship program and infection prevention teams. Upon alert recognition, a series of interventions were performed as a coordinated effort. A retrospective chart review was conducted to collect patient demographics, antimicrobial therapy, and clinical outcomes. Thirty-nine VIM-CRPA isolates led to infection in 21 patients. The majority were male (76.2%); the median age was 52 years. The majority were mechanically ventilated (n = 15/21; 71.4%); 47.6% (n = 10/21) received renal replacement therapy at the time of index culture. Respiratory (n = 20/39; 51.3%) or bloodstream (n = 13/39; 33.3%) were the most common sources. Most infections (n = 23/37; 62.2%) were treated with an aztreonam-avibactam regimen. Six patients (28.6%) expired within 30 days of index VIM-CRPA infection. Fourteen isolates were selected for whole genome sequencing. Most of them belonged to ST111 (12/14), and they all carried blaVIM-2 chromosomally. This report describes the clinical experience treating serious VIM-CRPA infections with either aztreonam-ceftazidime/avibactam or cefiderocol in combination with other agents. The importance of implementing infection prevention strategies to curb VIM-CRPA outbreaks is also demonstrated.

Clinical and genomic characteristics of IMP-producing Enterobacter cloacae complex and Klebsiella pneumoniae.

Carbapenemase-producing Enterobacterales (CPEs) are one of the top priority antimicrobial-resistant pathogens. Among CPEs, those producing acquired metallo-ß-lactamases (MBLs) are considered particularly problematic as few agents are active against them. Imipenemase (IMP) is the most frequently encountered acquired MBL in Japan, but comprehensive assessment of clinical and microbiological features of IMP-producing Enterobacterales infection remains scarce. Here, we retrospectively evaluated 62 patients who were hospitalized at a university hospital in Japan and had IMP-producing Enterobacterales from a clinical culture. The isolates were either Enterobacter cloacae complex or Klebsiella pneumoniae, and most of them were isolated from sputum. The majority of K. pneumoniae, but not E. cloacae complex isolates, were susceptible to aztreonam. Sequence type (ST) 78 and ST517 were prevalent for E. cloacae complex and K. pneumoniae, respectively, and all isolates carried blaIMP-1. Twenty-four of the patients were deemed infected with IMP-producing Enterobacterales. Among the infected patients, therapy varied and largely consisted of conventional ß-lactam agents, fluoroquinolones, or combinations. Three (13%), five (21%), and nine (38%) of them died by days 14, 30, and 90, respectively. While incremental mortality over 90 days was observed in association with underlying comorbidities, active conventional treatment options were available for most patients with IMP-producing Enterobacterales infections, distinguishing them from more multidrug-resistant CPE infections associated with globally common MBLs, such as New Delhi metallo-ß-lactamase (NDM) and Verona integron-encoded metallo-ß-lactamase (VIM).

Ceftazidime-avibactam alone or in combination with Aztreonam versus Polymyxins in the management of carbapenem-Resistant Klebsiella pneumoniae nosocomial Infections (CAPRI study): a retrospective cohort study from South India.

INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections commonly cause hospital-acquired infections. The study aimed to compare the outcomes of CRKP infections between patients receiving ceftazidime avibactam +/- aztreonam and polymyxins in a hospital setting with a high prevalence of New Delhi Metallo Beta Lactamase production. METHODS: We conducted a retrospective cohort study from January 2020 to September 2022 in critically ill adult patients admitted to a non-COVID-19 medical intensive care unit with CRKP infection. The patients were followed up for a total of 30 days or death, whichever was later. RESULTS: Of a total of 106 patients included in the study, 65 patients received polymyxins and 41 patients received ceftazidime-avibactam +/- aztreonam. Higher 30-day mortality was noted in the polymyxin group (56.9% vs. 29.2%, P = 0.005). The mean time to event (mortality) in ceftazidime-avibactam +/- aztreonam was 23.9 + 1.5 days which was significantly higher compared to polymyxins (17.9 + 1.2 days, p = 0.006). On Cox regression analysis, after adjusting for the covariates, the hazard ratio for time to event with the use of polymyxin was 2.02 (95% CI: 1.03-3.9). CONCLUSION: Ceftazidime-avibactam + aztreonam is possibly associated with better clinical outcomes in patients infected with CRKP.

Management strategies for severe Pseudomonas aeruginosa infections.

PURPOSE OF REVIEW: This review focuses on the management of severe Pseudomonas aeruginosa infections in critically ill patients. RECENT FINDINGS: Pseudomonas aeruginosa is the most common pathogen in intensive care; the main related infections are nosocomial pneumonias, then bloodstream infections. Antimicrobial resistance is common; despite new antibiotics, it is associated with increased mortality, and can lead to a therapeutic deadlock. SUMMARY: Carbapenem resistance in difficult-to-treat P. aeruginosa (DTR-PA) strains is primarily mediated by loss or reduction of the OprD porin, overexpression of the cephalosporinase AmpC, and/or overexpression of efflux pumps. However, the role of carbapenemases, particularly metallo-ß-lactamases, has become more important. Ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam are useful against DTR phenotypes (noncarbapenemase producers). Other new agents, such as aztreonam-ceftazidime-avibactam or cefiderocol, or colistin, might be effective for carbapenemase producers. Regarding nonantibiotic agents, only phages might be considered, pending further clinical trials. Combination therapy does not reduce mortality, but may be necessary for empirical treatment. Short-term treatment of severe P. aeruginosa infections should be preferred when it is expected that the clinical situation resolves rapidly.

Ceftazidime-Avibactam plus Aztreonam for the Treatment of Infections by VIM-Type-Producing Gram-Negative Bacteria.

This is a retrospective single-center study of 24 patients who received ceftazidime-avibactam plus aztreonam (CZA/ATM) for the treatment of VIM-type-producing Gram-negative bacillus (GNB) infections. The bacteria isolated were Enterobacterales in 22 patients and Pseudomonas aeruginosa in 2. Sixteen out of 19 isolates showed synergistic activity. Two patients presented clinical failure at day 14, and the 30-day mortality was 17% (4/24). CZA/ATM could be considered an alternative therapy for VIM-type-producing GNB infections.

Pharmacokinetics of Ceftazidime-Avibactam in Combination with Aztreonam (COMBINE) in a Phase 1, Open-Label Study of Healthy Adults.

Scant pharmacokinetic (PK) data are available on ceftazidime-avibactam (CZA) and aztreonam (ATM) in combination, and it is unknown if CZA-ATM exacerbates alanine aminotransferase (ALT)/aspartate aminotransferase (AST) elevations relative to ATM alone. This phase 1 study sought to describe the PK of CZA-ATM and assess the associations between ATM exposures and ALT/AST elevations. Subjects (n = 48) were assigned to one of six cohorts (intermittent infusion [II] CZA, continuous infusion [CI] CZA, II ATM, CI ATM [8 g/daily], II CZA with II ATM [6 g/daily], and II CZA with II ATM [8 g/daily]), and study product(s) were administered for 7 days. A total of 19 subjects (40%) had ALT/AST elevations, and most (89%) occurred in the ATM/CZA-ATM cohorts. Two subjects in the CI ATM cohort experienced severe ALT/AST elevations, which halted the study. All subjects with ALT/AST elevations were asymptomatic with no other signs of liver injury, and all ALT/AST elevations resolved without sequalae after cessation of dosing. In the population PK (PopPK) analyses, CZA-ATM administration reduced total ATM clearance by 16%, had a negligible effect on total ceftazidime clearance, and was not a covariate in the avibactam PopPK model. In the exposure-response analyses, coadministration of CZA-ATM was not found to augment ALT/AST elevations. Modest associations were observed between ATM exposure (maximum concentration of drug in serum [Cmax] and area under the concentration-time curve [AUC]) and ALT/AST elevations in the analysis of subjects in the II ATM/CZA-ATM cohorts. The findings suggest that administration of CZA-ATM reduces ATM clearance but does not exacerbate AST/ALT elevations relative to ATM alone. The results also indicate that CI ATM should be used with caution.

Mutation of PA4292 in Pseudomonas aeruginosa Increases ß-Lactam Resistance through Upregulating Pyocyanin Production.

Metallo-ß-lactamase (MBL)-producing Pseudomonas aeruginosa is increasingly reported worldwide and usually causes infections with high mortality rates. Aztreonam/avibactam is a ß-lactam/ß-lactamase inhibitor (BLBLI) combination that is under clinical trials. The advantage of aztreonam/avibactam over the currently used BLBLIs lies in its effectiveness against MBL-producing pathogens, making it one of the few drugs that can be used to treat infections caused by MBL-producing P. aeruginosa. However, the molecular mechanisms underlying aztreonam/avibactam resistance development remain unexplored. Here, in this study, we performed an in vitro evolution assay by using a previously identified MBL-producing P. aeruginosa clinical isolate, NKPa-71, and found mutations in a novel gene, PA4292, in the aztreonam/avibactam-resistant mutants. By mutation of PA4292 in the reference strain PA14, we verified the role of PA4292 in the resistance to aztreonam/avibactam and ß-lactams. Transcriptomic analyses revealed upregulation of pyocyanin biosynthesis genes among the most overexpressed in the PA4292 mutant. We further demonstrated that pyocyanin overproduction in the PA4292 mutant increased the bacterial resistance to ß-lactams by reducing drug influx. These data revealed a novel mechanism that might lead to the development of resistance to aztreonam/avibactam and ß-lactams.

Heterogeneity of treatment response in bronchiectasis clinical trials.

BACKGROUND: Recent randomised clinical trials in bronchiectasis have failed to reach their primary end-points, suggesting a need to reassess how we measure treatment response. Exacerbations, quality of life (QoL) and lung function are the most common end-points evaluated in bronchiectasis clinical trials. We aimed to determine the relationship between responses in terms of reduced exacerbations, improved symptoms and lung function in bronchiectasis. METHODS: We evaluated treatment response in three randomised clinical trials that evaluated mucoactive therapy (inhaled mannitol), an oral anti-inflammatory/antibiotic (azithromycin) and an inhaled antibiotic (aztreonam). Treatment response was defined by an absence of exacerbations during follow-up, an improvement of QoL above the minimum clinically important difference and an improvement in forced expiratory volume in 1 s (FEV1) of ≥100 mL from baseline. RESULTS: Cumulatively the three trials included 984 patients. Changes in FEV1, QoL and exacerbations were heterogeneous in all trials analysed. Improvements in QoL were not correlated to changes in FEV1 in the azithromycin and aztreonam trials (r= -0.17, p=0.1 and r=0.04, p=0.4, respectively) and weakly correlated in the mannitol trial (r=0.22, p<0.0001). An important placebo effect was observed in all trials, especially regarding improvements in QoL. Clinical meaningful lung function improvements were rare across all trials evaluated, suggesting that FEV1 is not a responsive measure in bronchiectasis. CONCLUSIONS: Improvements in lung function, symptoms and exacerbation frequency are dissociated in bronchiectasis. FEV1 is poorly responsive and poorly correlated with other key outcome measures. Clinical parameters are poorly predictive of treatment response, suggesting the need to develop biomarkers to identify responders.

Inhaled anti-pseudomonal antibiotics for long-term therapy in cystic fibrosis.

BACKGROUND: Inhaled antibiotics are commonly used to treat persistent airway infection with Pseudomonas aeruginosa that contributes to lung damage in people with cystic fibrosis. Current guidelines recommend inhaled tobramycin for individuals with cystic fibrosis and persistent Pseudomonas aeruginosa infection who are aged six years or older. The aim is to reduce bacterial load in the lungs so as to reduce inflammation and deterioration of lung function. This is an update of a previously published review. OBJECTIVES: To evaluate the effects of long-term inhaled antibiotic therapy in people with cystic fibrosis on clinical outcomes (lung function, frequency of exacerbations and nutrition), quality of life and adverse events (including drug-sensitivity reactions and survival). SEARCH METHODS: We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched ongoing trials registries. Date of last search: 28 June 2022. SELECTION CRITERIA: We selected trials where people with cystic fibrosis received inhaled anti-pseudomonal antibiotic treatment for at least three months, treatment allocation was randomised or quasi-randomised, and there was a control group (either placebo, no placebo or another inhaled antibiotic). DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, judged the risk of bias, extracted data from these trials and judged the certainty of the evidence using the GRADE system. MAIN RESULTS: The searches identified 410 citations to 125 trials; 18 trials (3042 participants aged between five and 45 years) met the inclusion criteria. Limited data were available for meta-analyses due to the variability of trial design and reporting of results. A total of 11 trials (1130 participants) compared an inhaled antibiotic to placebo or usual treatment for a duration between three and 33 months. Five trials (1255 participants) compared different antibiotics, two trials (585 participants) compared different regimens of tobramycin and one trial (90 participants) compared intermittent tobramycin with continuous tobramycin alternating with aztreonam. One trial (18 participants) compared an antibiotic to placebo and also to a different antibiotic and so fell into both groups. The most commonly studied antibiotic was tobramycin which was studied in 12 trials. Inhaled antibiotics compared to placebo We found that inhaled antibiotics may improve lung function measured in a variety of ways (4 trials, 814 participants). Compared to placebo, inhaled antibiotics may also reduce the frequency of exacerbations (risk ratio (RR) 0.66, 95% confidence interval (CI) 0.47 to 0.93; 3 trials, 946 participants; low-certainty evidence). Inhaled antibiotics may lead to fewer days off school or work (quality of life measure) (mean difference (MD) -5.30 days, 95% CI -8.59 to -2.01; 1 trial, 245 participants; low-certainty evidence). There were insufficient data for us to be able to report an effect on nutritional outcomes and there was no effect on survival. There was no effect on antibiotic resistance seen in the two trials that were included in meta-analyses. We are uncertain of the effect of the intervention on adverse events (very low-certainty evidence), but tinnitus and voice alteration were the only events occurring more often in the inhaled antibiotics group. The overall certainty of evidence was deemed to be low for most outcomes due to risk of bias within the trials and imprecision due to low event rates. Different antibiotics or regimens compared Of the eight trials comparing different inhaled antibiotics or different antibiotic regimens, there was only one trial for each unique comparison. We found no differences between groups for any outcomes except for the following. Aztreonam lysine for inhalation probably improved forced expiratory volume at one second (FEV1) % predicted compared to tobramycin (MD -3.40%, 95% CI -6.63 to -0.17; 1 trial, 273 participants; moderate-certainty evidence). However, the method of defining the endpoint was different to the remaining trials and the participants were exposed to tobramycin for a long period making interpretation of the results problematic. We found no differences in any measure of lung function in the remaining comparisons. Trials measured pulmonary exacerbations in different ways and showed no differences between groups except for aztreonam lysine probably leading to fewer people needing treatment with additional antibiotics than with tobramycin (RR 0.66, 95% CI 0.51 to 0.86; 1 trial, 273 participants; moderate-certainty evidence); and there were fewer hospitalisations due to respiratory exacerbations with levofloxacin compared to tobramycin (RR 0.62, 95% CI 0.40 to 0.98; 1 trial, 282 participants; high-certainty evidence). Important treatment-related adverse events were not very common across comparisons, but were reported less often in the tobramycin group compared to both aztreonam lysine and colistimethate. We found the certainty of evidence for these comparisons to be directly related to the risk of bias within the individual trials and varied from low to high. AUTHORS' CONCLUSIONS: Long-term treatment with inhaled anti-pseudomonal antibiotics probably improves lung function and reduces exacerbation rates, but pooled estimates of the level of benefit were very limited. The best evidence available is for inhaled tobramycin. More evidence from trials measuring similar outcomes in the same way is needed to determine a better measure of benefit. Longer-term trials are needed to look at the effect of inhaled antibiotics on quality of life, survival and nutritional outcomes.

Efficacy of Ceftazidime-avibactam Plus Aztreonam in Patients With Bloodstream Infections Caused by Metallo-ß-lactamase-Producing Enterobacterales.

BACKGROUND: In vitro data support the use of combination of aztreonam (ATM) with ceftazidime-avibactam (CAZ-AVI), but clinical studies are lacking. The aim of our study was to compare the outcome of patients with bloodstream infections (BSIs) due to metallo-ß-lactamase (MBL)-producing Enterobacterales treated either with CAZ-AVI plus ATM or other active antibiotics (OAAs). METHODS: This was a prospective observational study including patients admitted to 3 hospitals in Italy and Greece. The primary outcome measure was 30-day all-cause mortality. Secondary outcomes were clinical failure at day 14 and length of stay after BSI diagnosis. Cox regression analysis including a propensity score (PS) for receiving CAZ-AVI + ATM was performed to evaluate primary and secondary outcomes. A PS-based matched analysis was also performed. RESULTS: We enrolled 102 patients with BSI; 82 had infections caused by NDM-producing (79 Klebsiella pneumoniae and 3 Escherichia coli) and 20 by VIM-producing (14 K. pneumoniae, 5 Enterobacter species, 1 Morganella morganii) strains. The 30-day mortality rate was 19.2% in the CAZ-AVI + ATM group vs 44% in the OAA group (P = .007). The PS-adjusted analysis showed that the use of CAZ-AVI + ATM was associated with lower 30-day mortality (hazard ratio [HR], 0.37 [95% confidence interval {CI}, .13-.74]; P = .01), lower clinical failure at day 14 (HR, 0.30 [95% CI, .14-.65]; P = .002), and shorter length of stay (subdistributional HR, 0.49 [95% CI, .30-.82]; P = .007). The PS-matched analysis confirmed these findings. CONCLUSIONS: The CAZ-AVI + ATM combination offers a therapeutic advantage compared to OAAs for patients with BSI due to MBL-producing Enterobacterales. Further studies are warranted.

Ceftobiprole Compared With Vancomycin Plus Aztreonam in the Treatment of Acute Bacterial Skin and Skin Structure Infections: Results of a Phase 3, Randomized, Double-blind Trial (TARGET).

BACKGROUND: The development of novel broad-spectrum antibiotics, with efficacy against both gram-positive and gram-negative bacteria, has the potential to enhance treatment options for acute bacterial skin and skin structure infections (ABSSSIs). Ceftobiprole is an advanced-generation intravenous cephalosporin with broad in vitro activity against gram-positive (including methicillin-resistant Staphylococcus aureus) and gram-negative pathogens. METHODS: TARGET was a randomized, double-blind, active-controlled, parallel-group, multicenter, phase 3 noninferiority study that compared ceftobiprole with vancomycin plus aztreonam. The Food and Drug Administration-defined primary efficacy endpoint was early clinical response 48-72 hours after treatment initiation in the intent-to-treat (ITT) population and the European Medicines Agency-defined primary endpoint was investigator-assessed clinical success at the test-of-cure (TOC) visit. Noninferiority was defined as the lower limit of the 95% CI for the difference in success rates (ceftobiprole minus vancomycin/aztreonam) >-10%. Safety was assessed through adverse event and laboratory data collection. RESULTS: In total, 679 patients were randomized to ceftobiprole (n = 335) or vancomycin/aztreonam (n = 344). Early clinical success rates were 91.3% and 88.1% in the ceftobiprole and vancomycin/aztreonam groups, respectively, and noninferiority was demonstrated (adjusted difference: 3.3%; 95% CI: -1.2, 7.8). Investigator-assessed clinical success at the TOC visit was similar between the 2 groups, and noninferiority was demonstrated for both the ITT (90.1% vs 89.0%) and clinically evaluable (97.9% vs 95.2%) populations. Both treatment groups displayed similar microbiological success and safety profiles. CONCLUSIONS: TARGET demonstrated that ceftobiprole is noninferior to vancomycin/aztreonam in the treatment of ABSSSIs, in terms of early clinical response and investigator-assessed clinical success at the TOC visit. CLINICAL TRIALS REGISTRATION: NCT03137173.

Pseudomonas aeruginosa Susceptibility Patterns and Associated Clinical Outcomes in People with Cystic Fibrosis following Approval of Aztreonam Lysine for Inhalation.

The approval of aztreonam lysine for inhalation solution (AZLI) raised concerns that additional antibiotic exposure would potentially affect the susceptibility profiles of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients. This 5-year, prospective, observational study tracked susceptibility changes and clinical outcomes in CF patients in the United States with chronic P. aeruginosa infection. Sputum cultures were collected annually (2011 to 2016). The primary study endpoint was the proportion of subjects whose least susceptible P. aeruginosa isolate had an aztreonam MIC that was >8 µg/ml (parenteral breakpoint) and increased ≥4-fold compared with the least susceptible isolate from the previous year. Annualized data for pulmonary exacerbations, hospitalizations, and percent of predicted forced expiratory volume in 1 s (FEV1% predicted) were obtained from the CF Foundation Patient Registry and compared between subjects meeting and those not meeting the primary endpoint. A total of 510 subjects were enrolled; 334 (65%) completed the study. A consistent proportion of evaluable subjects (13 to 22%) met the primary endpoint each year, and AZLI use during the previous 12 months was not associated with meeting the primary endpoint. While the annual declines in lung function were comparable for subjects meeting and those not meeting the primary endpoint, more pulmonary exacerbations and hospitalizations were experienced by those who met it. The aztreonam susceptibility of P. aeruginosa remained consistent during the 5-year study. The relationship between P. aeruginosa isolate susceptibilities and clinical outcomes is complex; reduced susceptibility was not associated with an accelerated decline in lung function but was associated with more exacerbations and hospitalizations, likely reflecting increased overall antibiotic exposure. (This study has been registered at ClinicalTrials.gov under identifier NCT01375036.).

Optimization of Aztreonam in Combination With Ceftazidime/Avibactam in a Cystic Fibrosis Patient With Chronic Stenotrophomonas maltophilia Pneumonia Using Therapeutic Drug Monitoring: A Case Study.

ABSTRACT: In this clinician-therapeutic drug monitoring (TDM) consultant interaction, the authors describe the use of TDM in an 11-year-old female patient with cystic fibrosis receiving ceftazidime/avibactam and aztreonam for the treatment of persistent pulmonary exacerbations caused by Stenotrophomonas pneumonia. Serum drug concentrations at a steady state confirmed inadequate antimicrobial exposure, and continuous infusions of both ceftazidime/avibactam and aztreonam were required to optimize the percentage of time when free drug remained above the minimum inhibitory concentration (MIC), known as fT > MIC. After dose adjustment, this continuous infusion strategy resulted in 100% target attainment for fT > MIC. This case illustrates the importance of TDM, and the logistical issues encountered with the use of alternative dosing strategies in pediatric patients with CF.

Treatment of invasive IMP-4 Enterobacter cloacae infection in transplant recipients using ceftazidime/avibactam with aztreonam: A case series and literature review.

Infections caused by carbapenemase-producing Enterobacteriaceae (CPE) are an emerging threat in both solid organ and stem cell transplant recipients. Invasive CPE infections in transplant recipients are associated with a high mortality, often due to limited therapeutic options and antibacterial toxicities. One of the most therapeutically challenging group of CPE are the metallo-ß-lactamase (MBL)-producing Gram-negative bacteria, which are now found worldwide, and often need treatment with older, highly toxic antimicrobial regimens. Newer ß-lactamase inhibitors such as avibactam have well-established activity against certain carbapenemases such as Klebsiella pneumoniae carbapenemases (KPC), but have no activity against MBL-producing organisms. Conversely, aztreonam has activity against MBL-producing organisms but is often inactivated by other co-existing ß-lactamases. Here, we report four cases of invasive MBL-CPE infections in transplant recipients caused by IMP-4-producing Enterobacter cloacae who were successfully treated with a new, mechanism-driven antimicrobial combination of ceftazidime/avibactam with aztreonam. This novel antimicrobial combination offers a useful treatment option for high-risk patients with CPE infection, with reduced drug interactions and toxicity.

Antibiotic regimens for late-onset neonatal sepsis.

BACKGROUND: Neonatal sepsis is a major cause of morbidity and mortality. It is the third leading cause of neonatal mortality globally constituting 13% of overall neonatal mortality. Despite the high burden of neonatal sepsis, high-quality evidence in diagnosis and treatment is scarce. Due to the diagnostic challenges of sepsis and the relative immunosuppression of the newborn, many neonates receive antibiotics for suspected sepsis. Antibiotics have become the most used therapeutics in neonatal intensive care units, and observational studies in high-income countries suggest that 83% to 94% of newborns treated with antibiotics for suspected sepsis have negative blood cultures. The last Cochrane Review was updated in 2005. There is a need for an updated systematic review assessing the effects of different antibiotic regimens for late-onset neonatal sepsis. OBJECTIVES: To assess the beneficial and harmful effects of different antibiotic regimens for late-onset neonatal sepsis. SEARCH METHODS: We searched the following electronic databases: CENTRAL (2021, Issue 3); Ovid MEDLINE; Embase Ovid; CINAHL; LILACS; Science Citation Index EXPANDED and Conference Proceedings Citation Index - Science on 12 March 2021. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs. SELECTION CRITERIA: We included RCTs comparing different antibiotic regimens for late-onset neonatal sepsis. We included participants older than 72 hours of life at randomisation, suspected or diagnosed with neonatal sepsis, meningitis, osteomyelitis, endocarditis, or necrotising enterocolitis. We excluded trials that assessed treatment of fungal infections. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We used the GRADE approach to assess the certainty of evidence. Our primary outcome was all-cause mortality, and our secondary outcomes were: serious adverse events, respiratory support, circulatory support, nephrotoxicity, neurological developmental impairment, necrotising enterocolitis, and ototoxicity. Our primary time point of interest was at maximum follow-up. MAIN RESULTS: We included five RCTs (580 participants). All trials were at high risk of bias, and had very low-certainty evidence. The five included trials assessed five different comparisons of antibiotics. We did not conduct a meta-analysis due to lack of relevant data. Of the five included trials one trial compared cefazolin plus amikacin with vancomycin plus amikacin; one trial compared ticarcillin plus clavulanic acid with flucloxacillin plus gentamicin; one trial compared cloxacillin plus amikacin with cefotaxime plus gentamicin; one trial compared meropenem with standard care (ampicillin plus gentamicin or cefotaxime plus gentamicin); and one trial compared vancomycin plus gentamicin with vancomycin plus aztreonam. None of the five comparisons found any evidence of a difference when assessing all-cause mortality, serious adverse events, circulatory support, nephrotoxicity, neurological developmental impairment, or necrotising enterocolitis; however, none of the trials were near an information size that could contribute significantly to the evidence of the comparative benefits and risks of any particular antibiotic regimen. None of the trials assessed respiratory support or ototoxicity. The benefits and harms of different antibiotic regimens remain unclear due to the lack of well-powered trials and the high risk of systematic errors. AUTHORS' CONCLUSIONS: Current evidence is insufficient to support any antibiotic regimen being superior to another. RCTs assessing different antibiotic regimens in late-onset neonatal sepsis with low risks of bias are warranted.

ANTECEDENTES: La sepsis neonatal es una causa importante de morbilidad y mortalidad. Es la tercera causa de mortalidad neonatal a nivel mundial y constituye el 13% de la mortalidad neonatal total. A pesar de la elevada carga de la sepsis neonatal, la evidencia de alta calidad en el diagnóstico y el tratamiento es escasa. Debido a las dificultades de diagnóstico de la sepsis y a la relativa inmunosupresión del neonato, muchos reciben antibióticos por sospecha de sepsis. Los antibióticos se han convertido en el tratamiento más utilizado en las unidades de cuidados intensivos neonatales, y los estudios observacionales realizados en países de ingresos altos indican que entre el 83% y el 94% de los neonatos tratados con antibióticos por sospecha de sepsis tienen hemocultivos negativos. La última revisión Cochrane se actualizó en 2005. Se necesita una revisión sistemática actualizada que evalúe los efectos de los diferentes regímenes de antibióticos para la sepsis neonatal de inicio tardío. OBJETIVOS: Evaluar los efectos beneficiosos y perjudiciales de diferentes regímenes antibióticos para la sepsis neonatal de inicio tardío. MÉTODOS DE BÚSQUEDA: Se hicieron búsquedas en las siguientes bases de datos electrónicas: CENTRAL (2021, número 3); Ovid MEDLINE; Embase Ovid; CINAHL; LILACS; Science Citation Index EXPANDED y Conference Proceedings Citation Index ­ Science el 12 de marzo de 2021. También se buscaron ensayos controlados aleatorizados (ECA) y cuasialeatorizados en las bases de datos de ensayos clínicos y en las listas de referencias de artículos identificados. CRITERIOS DE SELECCIÓN: Se incluyeron ECA que compararon diferentes regímenes de antibióticos para la sepsis neonatal de inicio tardío. Se incluyeron participantes mayores de 72 horas de vida en el momento de la asignación al azar, con sospecha o diagnóstico de sepsis neonatal, meningitis, osteomielitis, endocarditis o enterocolitis necrosante. Se excluyeron los ensayos que evaluaron el tratamiento de las infecciones micóticas. OBTENCIÓN Y ANÁLISIS DE LOS DATOS: Dos autores de la revisión, de forma independiente, evaluaron los estudios para inclusión, extrajeron los datos y evaluaron el riesgo de sesgo. Se utilizó el método GRADE para evaluar la certeza de la evidencia. El desenlace principal fue la mortalidad por todas las causas, y los desenlaces secundarios fueron: eventos adversos graves, asistencia respiratoria, apoyo circulatorio, nefrotoxicidad, deterioro del desarrollo neurológico, enterocolitis necrosante y ototoxicidad. El punto temporal principal de interés fue el seguimiento máximo. RESULTADOS PRINCIPALES: Se incluyeron cinco ECA (580 participantes). Todos los ensayos tuvieron alto riesgo de sesgo y evidencia de certeza muy baja. Los cinco ensayos incluidos evaluaron cinco comparaciones diferentes de antibióticos. No se realizó un metanálisis debido a la falta de datos relevantes. De los cinco ensayos incluidos, un ensayo comparó cefazolina más amikacina con vancomicina más amikacina; un ensayo comparó ticarcilina más ácido clavulánico con flucloxacilina más gentamicina; un ensayo comparó cloxacilina más amikacina con cefotaxima más gentamicina; un ensayo comparó meropenem con atención estándar (ampicilina más gentamicina o cefotaxima más gentamicina); y un ensayo comparó vancomicina más gentamicina con vancomicina más aztreonam. Ninguna de las cinco comparaciones encontró evidencia de una diferencia al evaluar la mortalidad por todas las causas, los eventos adversos graves, el apoyo circulatorio, la nefrotoxicidad, el deterioro del desarrollo neurológico o la enterocolitis necrosante; sin embargo, ninguno de los ensayos se acercó a un tamaño de información que pudiera contribuir significativamente a la evidencia de los beneficios y los riesgos comparativos de cualquier régimen antibiótico en particular. Ninguno de los ensayos evaluó la asistencia respiratoria o la ototoxicidad. Los efectos beneficiosos y perjudiciales de los diferentes regímenes de antibióticos aún no están claros debido a la falta de ensayos con un poder estadístico adecuado y al alto riesgo de errores sistemáticos. CONCLUSIONES DE LOS AUTORES: La evidencia actual no es suficiente para apoyar que un régimen de antibióticos sea superior a otro. Se justifica la realización de ECA con bajo riesgo de sesgo que evalúen diferentes regímenes antibióticos en la sepsis neonatal de inicio tardío.

Pulmonary Outcomes Associated with Long-Term Azithromycin Therapy in Cystic Fibrosis.

Rationale: Chronic azithromycin is commonly used in cystic fibrosis based on short controlled clinical trials showing reductions in pulmonary exacerbations and improved FEV1. Long-term effects are unknown.Objectives: Examine pulmonary outcomes among chronic azithromycin users compared with matched controls over years of use and consider combined azithromycin use in cohorts using chronic inhaled tobramycin or aztreonam.Methods: This retrospective cohort study used the U.S. cystic fibrosis Foundation Patient Registry. Incident chronic azithromycin users were compared with matched controls by FEV1% predicted rate of decline and rates of intravenous antibiotic use to treat pulmonary exacerbations. Propensity score methods were utilized to address confounding by indication. Predefined sensitivity analyses based on lung function, Pseudomonas aeruginosa (PA) status, and follow-up time intervals were conducted.Measurements and Main Results: Across 3 years, FEV1% predicted per-year decline was nearly 40% less in those with PA using azithromycin compared with matched controls (slopes, -1.53 versus -2.41% predicted per yr; difference: 0.88; 95% confidence interval [CI], 0.30-1.47). This rate of decline did not differ based on azithromycin use in those without PA. Among all cohorts, use of intravenous antibiotics was no different between azithromycin users and controls. Users of inhaled tobramycin and azithromycin had FEV1% predicted per-year decline of -0.16 versus nonusers (95% CI, -0.44 to 0.13), whereas users of inhaled aztreonam lysine and azithromycin experienced a mean 0.49% predicted per year slower decline than matched controls (95% CI, -0.11 to 1.10).Conclusions: Results from this study provide additional rationale for chronic azithromycin use in PA-positive patients to reduce lung function decline.

Empiric aztreonam is associated with increased mortality compared to beta-lactams in septic shock.

PURPOSE: To determine if aztreonam as initial empiric treatment of adult septic shock is associated with increased mortality compared to the use of anti-pseudomonal beta-lactam agents. METHODS: This was a multicenter, retrospective cohort study of 582 adult emergency department patients admitted to 12 acute care facilities within a single health system from January 2014 to December 2017 with septic shock receiving either aztreonam or an anti-pseudomonal beta-lactam for empiric treatment and discharged with an infection-related ICD-9 or ICD-10 code. The primary endpoint was in-hospital mortality. RESULTS: Initial exposure to aztreonam was associated with increased hospital mortality compared to treatment with an anti-pseudomonal beta-lactam agent (22.7% vs. 12.9%, OR = 1.98, 95% CI: 1.27-3.11). When adjusted for APACHE II score, the treatment group effect on mortality remained statistically significant (OR = 1.74, 95% CI: 1.08-2.80). Aztreonam use was also associated with increased utilization of aminoglycosides (28.9% vs. 12.4%, p < 0.0001) and fluoroquinolones (50.5% vs. 25.8%, p < 0.01). There was no difference in hospital or intensive care unit length of stay in surviving patients between the two groups. CONCLUSIONS: Compared to anti-pseudomonal beta-lactams, empiric treatment with aztreonam is associated with increased mortality and greater antibiotic exposure among patients with acute septic shock. These findings suggest that treatment with anti-pseudomonal beta-lactams should be prioritized over allergy avoidance whenever feasible.

Successful Treatment of Klebsiella pneumoniae NDM Sepsis and Intestinal Decolonization with Ceftazidime/Avibactam Plus Aztreonam Combination in a Patient with TTP Complicated by SARSCoV-2 Nosocomial Infection.

Carbapenem-resistant Enterobacteriaceae (CRE) are a serious public health threat. Infections due to these organisms are associated with significant morbidity and mortality. Among them, metallo-ß-lactamases (MBLs)-producing Klebsiella pneumoniae are of global concern today. The ceftazidime/avibactam combination and the ceftazidime/avibactam + aztreonam combination currently represent the most promising antibiotic strategies to stave off these kinds of infections. We describe the case of a patient affected by thrombotic thrombocytopenic purpura (TTP) admitted in our ICU after developing a hospital-acquired SarsCoV2 interstitial pneumonia during his stay in the hematology department. His medical conditions during his ICU stay were further complicated by a K. Pneumoniae NDM sepsis. To our knowledge, the patient had no risk factors for multidrug-resistant bacteria exposure or contamination during his stay in the hematology department. During his stay in the ICU, we treated the sepsis with a combination therapy of ceftazidime/avibactam + aztreonam. The therapy solved his septic state, allowing for a progressive improvement in his general condition. Moreover, we noticed that the negativization of the hemocultures was also associated to a decontamination of his known rectal colonization. The ceftazidime/avibactam + aztreonam treatment could not only be a valid therapeutic option for these kinds of infections, but it could also be considered as a useful tool in selected patients' intestinal decolonizations.