In vitro activity of aztreonam-avibactam against Enterobacterales isolates collected in Latin America, Africa/Middle East, Asia, and Eurasia for the ATLAS Global Surveillance Program in 2019-2021

The Growing Threat of NDM-Producing Escherichia coli With Penicillin-Binding Protein 3 Mutations in the United States-Is There a Potential Role for Durlobactam?

We report identification of 5 patients with infections caused by NDM-5-producing Escherichia coli harboring PBP3 mutations that showed reduced susceptibility to aztreonam-avibactam and cefiderocol. Durlobactam, a novel diazabicyclooctane β-lactamase inhibitor, demonstrated minimum inhibitory concentrations ranging from 0.5 to 2 µg/mL supporting future investigations into a potential role in clinical management.

Aztreonam-avibactam versus meropenem for the treatment of serious infections caused by Gram-negative bacteria (REVISIT): a descriptive, multinational, open-label, phase 3, randomised trial

BACKGROUND

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.

METHODS

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.

FINDINGS

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.

INTERPRETATION

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.

FUNDING

Pfizer.

Ceftazidime-avibactam combination therapy versus monotherapy for treating carbapenem-resistant gram-negative infection: a systemic review and meta-analysis

BACKGROUND

This meta-analysis was conducted to compare the efficacy of ceftazidime-avibactam combination therapy with that of monotherapy in the treatment of carbapenem-resistant Gram-negative bacterial (CR-GNB).

METHODS

A literature search of PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov was conducted until September 1, 2023. Only studies that compared CZA combination therapy with monotherapy for CR-GNB infections were included.

RESULTS

A total of 25 studies (23 retrospective observational studies and 2 prospective studies) involving 2676 patients were included. There was no significant difference in 30-day mortality between the study group receiving combination therapy and the control group receiving monotherapy (risk ratio [RR] 0.91; 95% confidence interval [CI] 0.71-1.18). In addition, no significant differences were observed between the study and the control group in terms of in-hospital mortality (RR 1.00; 95% CI 0.79-1.27), 14-day mortality (RR 1.54; 95% CI 0.24-9.91), 90-day mortality (RR 1.18; 95% CI 0.62-2.22), and clinical cure rate (RR 0.95; 95% CI 0.84-1.08). However, the combination group had a borderline higher microbiological eradication rate than the control group (RR 1.15; 95% CI 1.00-1.32).

CONCLUSIONS

Compared to monotherapy, CZA combination therapy did not yield additional clinical benefits. However, combination therapy may be associated with favorable microbiological outcomes.

High drug-pathogen mismatch in the management of invasive carbapenem-resistant Enterobacteriaceae infections at a tertiary hospital in Nigeria

Objectives

This study aims to provide lacking data on antibiotics and treatment strategies used in the management of carbapenem-resistant Enterobacteriaceae (CRE) infections in Nigeria.

Methods

A cross-sectional study was carried out at the University College Hospital in Ibadan. CRE isolated from routine culture of specimens from hospitalized patients from December 2021 to September 2022 was identified. Treatment information and other data were collected from the patients' medical records.

Results

The hospital laboratory isolated CRE from 55 patients during the study period and 27 (49.1%) of them had data available for the study. The most frequently isolated CRE was Klebsiella spp. (13 of 27, 48.1%). Of the 24 patients who received empiric antibiotics, only two (8.3%) of their CRE isolates were susceptible. After receiving culture results, 18 (66.7%) patients were treated with at least one antibiotic, to which resistance was documented. Only three (11.1%) patients overall commenced or remained on an antibiotic, to which their CRE isolate was susceptible.

Conclusions

Despite culture data, we found a high prevalence of drug-pathogen mismatch in CRE treatment, including new or persistent use of antibiotics, to which resistance was documented. Antimicrobial stewardship efforts need to be strengthened to specifically address CRE treatment and effective antibiotics need to be made accessible.

Resistance to aztreonam-avibactam among clinical isolates of Escherichia coli is primarily mediated by altered penicillin-binding protein 3 and impermeability

This study was conducted to investigate decreased susceptibility (minimum inhibitory concentrations [MICs] 0.25-4 mg/L) and resistance (MICs > 4 mg/L) to aztreonam-avibactam (ATM-AVI). Contemporary non-replicate clinical isolates of carbapenemase-producing Escherichia coli (CP-EC) (n=90) and ESBL-producing E. coli (EP-EC) (n=12) were used. CP-EC belonged to 25 distinct sequence types (STs) and all EP-EC belonged to ST405. All strains were isolated from 2019 to 2022 at the Karolinska University Laboratory, Stockholm, Sweden. ATM-AVI MICs were determined using broth microdilution. The EUCAST epidemiological cut-off value of 0.125 mg/L was used to define the wild type (WT). Whole-genome sequences (Illumina) were analysed for detecting resistance determinants among WT vs. non-WT isolates. Among 102 isolates, 40 (39%) and 62 (61%) were WT and non-WT, respectively. Among non-WT isolates, resistance was noted for 20 and decreased susceptibility for 42. Resistance was observed among 14/47 New Delhi metallo-β-lactamase (NDM)-producers, 5/43 OXA-48 group producers, and 1/12 EP-EC. Decreased susceptibility was observed among 29/47 NDM, 13/43 OXA-48 group, and 3/12 EP-EC. Resistant isolates predominantly belonged to ST405, followed by STs 410, 361, 167, 617, and 1284. Penicillin-binding protein 3 (PBP3) inserts (YRIK/YRIN) were observed in 20/20 and CMY-42 in 5/20 resistant isolates. Several mutations in the ftsI (encoding PBP3) and regulatory genes of outer membrane proteins (OmpC and OmpF) and efflux pumps (AcrAB-TolC) were detected. A ≥ 2-fold reduction in MICs was observed among 20/20 vs. 7/20 isolates tested in the presence of the membrane permeabiliser, polymyxin B nanopeptide (PMBN) and efflux inhibitor, phenylalanine arginine β-naphthylamide (PAβN), respectively. In conclusion, resistance to ATM-AVI is a result of interplay of various determinants, including target alterations, deactivating enzymes, and decreased permeability.

Friends or foes? Novel antimicrobials tackling MDR/XDR Gram-negative bacteria: a systematic review

Gram-negative bacteria have been one of the most studied classes in the field of microbiology, especially in the context of globally alarming antimicrobial resistance levels to these pathogens over the course of the past decades. With high numbers of these microorganisms being described as multidrug-resistant (MDR), or even extended-drug-resistant (XDR) bacteria, specialists in the field have been struggling to keep up with higher prevalence of difficult-to-treat infections caused by such superbugs. The FDA approval of novel antimicrobials, such as cefiderocol (FDC), ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/relebactam (IMR), sulbactam/durlobactam (SUL-DUR) and phase 3 clinical trials' results of aztreonam/avibactam (ATM-AVI) has proven that, while all these substances provide encouraging efficacy rates, antibiotic resistance keeps up with the pace of drug development. Microorganisms have developed more extensive mechanisms of resistance in order to target the threat posed by these novel antimicrobials, thus equiring researchers to be on a constant lookout for other potential drug candidates and molecule development. However, these strategies require a proper understanding of bacterial resistance mechanisms to gain a comprehensive outlook on the issue. The present review aims to highlight these six antibiotic agents, which have brought hope to clinicians during the past decade, discussing general properties of these substances, as well as mechanisms and patterns of resistance, while also providing a short overview on further directions in the field.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#searchadvanced, Identifier CRD42024505832.

Evaluation of the MTS™ aztreonam-avibactam strip (Liofilchem) on New Delhi metallo-β-lactamase-producing Enterobacterales

The combination of ceftazidime-avibactam (CAZ-AVI) and aztreonam (ATM) is used to treat MBL-producing Enterobacterales-related infections. The new combination aztreonam-avibactam (AZA) is currently in development. We compared results obtained with the new MIC test strip (MTS) AZA (Liofilchem) with broth microdilution method (BMD) on 41 MBL-producing Enterobacterales from 41 clinical samples. The MTS AZA was also compared to combination testing method using CAZ-AVI and ATM strips. Compared to BMD, categorical agreement (CA) was 100%. Compared with combination testing method, CA was 97.6%. The MTS AZA can be used to determine MICs levels of AZA or CAZ-AVI/ATM combinations.

Clinical pharmacists' involvement in carbapenem antibiotics management at Wenzhou Integrated Hospital

BACKGROUND

Carbapenem antibiotics are a pivotal solution for severe infections, particularly in hospital settings. The emergence of carbapenem-resistant bacteria owing to the irrational and extensive use of carbapenems underscores the need for meticulous management and rational use. Clinical pharmacists, with their specialized training and extensive knowledge, play a substantial role in ensuring the judicious use of carbapenem. This study aimed to elucidate the patterns of carbapenem use and shed light on the integral role played by clinical pharmacists in managing and promoting the rational use of carbapenem antibiotics at Wenzhou Integrated Traditional Chinese and Western Medicine Hospital.

AIM

To analyze carbapenem use patterns in our hospital and role of clinical pharmacists in managing and promoting their rational use.

METHODS

We performed a retrospective analysis of carbapenem use at our hospital between January 2019 and December 2021. Several key indicators, including the drug utilization index, defined daily doses (DDDs), proportion of antimicrobial drug costs to total hospitalization expenses, antibiotic utilization density, and utilization rates in different clinical departments were comprehensively analyzed.

RESULTS

Between 2019 and 2021, there was a consistent decline in the consumption and sales of imipenem-cilastatin sodium, meropenem (0.3 g), and meropenem (0.5 g). Conversely, the DDDs of imipenem-cilastatin sodium for injection increased in 2020 and 2021 vs 2019, with a B/A value of 0.67, indicating a relatively higher drug cost. The DDDs of meropenem for injection (0.3 g) exhibited an overall upward trend, indicating an increasing clinical preference. However, the B/A values for 2020 and 2021 were both > 1, suggesting a relatively lower drug cost. The DDDs of meropenem for injection (0.5 g) demonstrated a progressive increase annually and consistently ranked first, indicating a high clinical preference with a B/A value of 1, signifying good alignment between economic and social benefits.

CONCLUSION

Carbapenem use in our hospital was generally reasonable with a downward trend in consumption and sales over time. Clinical pharmacists play a pivotal role in promoting appropriate use of carbapenems.

In Vitro Susceptibility of Aztreonam-Vaborbactam, Aztreonam-Relebactam and Aztreonam-Avibactam Associations against Metallo-β-Lactamase-Producing Gram-Negative Bacteria

BACKGROUND

Despite the availability of new options (ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam and cefiderocol), it is still very difficult to treat infections caused by metallo-β-lactamase (MBLs)-producers resistant to aztreonam. The in vitro efficacy of aztreonam in association with avibactam, vaborbactam or relebactam was evaluated on a collection of MBL-producing Enterobacterales, MBL-producing P. aeruginosa and highly drug-resistant S. maltophilia.

METHODS

A total of fifty-two non-duplicate MBL-producing Enterobacterales, five MBL-producing P. aeruginosa and five multidrug-resistant S. maltophila isolates were used in this study. The minimum inhibitory concentrations (MICs) of aztreonam, meropenem-vaborbactam and imipenem-relebactam were determined by Etest® (bioMérieux, La Balme-les-Grottes) according to EUCAST recommendations. For aztreonam-avibactam, aztreonam-vaborbactam and aztreonam-relebactam associations, the MICs were determined using Etest® on Mueller-Hinton (MH) agar supplemented with 8 mg/L of avibactam, 8 mg/L of vaborbactam and 4 mg/L of relebactam. The MICs were interpreted according to EUCAST guidelines.

RESULTS

The susceptibility rates of aztreonam-avibactam, aztreonam-vaborbactam and aztreonam-relebactam with a standard exposure of aztreonam (1g × 3, IV) were 84.6% (44/52), 55.8% and 34.6% for Enterobacterales and 0% for all combinations for P. aeruginosa and S. maltophila. The susceptibility rates of aztreonam-avibactam, aztreonam-vaborbactam and aztreonam-relebactam with a high exposure of aztreonam (2g × 4, IV) were 92.3%, 78.9% and 57.7% for Enterobacterales, 75%, 60% and 60% for P. aeruginosa and 100%, 100% and 40% for S. maltophila.

CONCLUSIONS

As previously demonstrated for an aztreonam/ceftazidime-avibactam combination, aztreonam plus imipenem-relebactam and aztreonam plus meropenem-vaborbactam might be useful options, but with potentially lower efficiency, to treat infections caused by aztreonam-non-susceptible MBL-producing Gram-negative strains.