Carbapenemase producing Gram negative bacteria: Review of resistance and detection methods

Gene expressions of clinical Pseudomonas aeruginosa harboring RND efflux pumps on chromosome and involving a novel integron on a plasmid

The clinical strain of Pseudomonas aeruginosa XM8 harbored multiple RND-type antibiotic efflux pump genes and a novel integron In4881 on its plasmid pXM8-2, rendering it resistant to nearly all conventional antibiotics except colistin. The resistance was primarily attributed to the inactivation of the oprD gene and overexpression of several efflux pump genes, including mexAB-oprM, mexCD-oprJ, oprN-mexFE, and mexXY. In this study, the XM8 strain was comprehensively characterized using various methods. Antimicrobial susceptibility testing was performed using the BioMerieux VITEK2 system and manual double dilution methods. Gene expression levels of efflux pump-related genes were analyzed via quantitative real-time PCR. The bacterial chromosome and plasmid were sequenced using both Illumina and Nanopore platforms, and bioinformatics tools were employed to analyze mobile genetic elements associated with antibiotic resistance. The pXM8-2 plasmid containsed multiple mobile genetic elements, including integrons (In4881, In334, In413) and transposons (Tn3, TnAs1, TnAs3). Notably, In4881 was reported for the first time in this study. The presence of these elements highlights the potential for horizontal gene transfer and further spread of antibiotic resistance. Given the strong resistance profile of the XM8 strain, effective measures should be implemented to prevent the dissemination and prevalence of such multidrug-resistant bacteria.

Breaking Through Resistance: A Comparative Review of New Beta-Lactamase Inhibitors (Avibactam, Vaborbactam, Relebactam) Against Multidrug-Resistant Superbugs

The introduction of new β-lactam-β-lactamase inhibitors (BLBLIs), such as ceftazidime/avibactam, meropenem/vaborbactam, and imipenem/cilastatin/relebactam, expands our therapeutic options against carbapenem-resistant Gram-negative bacteria, including those pathogens for which therapeutic options are limited. These new combinations are active against ESBL-, AmpC-, and KPC-producing Enterobacterales, with the exception of ceftazidime/avibactam, which is active in vitro against OXA-48. However, one drawback that must be taken seriously by the clinician is that they are ineffective against metallo-β-lactamases as well as Acinetobacter baumannii. The recent introduction of aztreonam/avibactam marks a significant advancement in our therapeutic armamentarium against metallo-β-lactamase-producing pathogens. The question to be answered is whether there is a preferred, newer BLBLI combination for the treatment of KPC-producing Enterobacterales infections. This review provides a thorough analysis of the similarities and differences between these new combinations to identify the most effective treatment options. The present review aims to provide clinicians with a detailed understanding of each BLBLI treatment option to guide the optimal use of these new agents for the effective treatment of difficult infections caused by carbapenemase-producing Enterobacterales infections. This review is based on literature retrieved from PubMed, Scopus, Web of Science, and the Cochrane Library.

A Review of In Silico and In Vitro Approaches in the Fight Against Carbapenem-Resistant Enterobacterales

OBJECTIVES

The rise in carbapenem-resistant Enterobacterales (CRE) has reinforced the global quest for developing effective therapeutics. Traditional drug discovery approaches have been inadequate in overcoming this challenge due to their resource and time constraints.

METHODS

English literature was searched by structured queries related to our review between January 1, 2020, and December 31, 2024.

RESULTS

The key resistance mechanisms in CRE, such as enzymatic hydrolysis, decreased permeability, and efflux pump overexpression, have been examined in this review. Computational technologies have become pivotal in discovering novel antimicrobial agents with improved accuracy and efficiency. Besides this, the review highlights the advances in structure- and ligand-based drug discovery approaches for identifying potential drugs against CRE. Recent studies demonstrating the use of such in silico techniques to develop targeted drugs against CRE have also been explored. Moreover, this review also underscores the significance of integrating both in silico and in vitro techniques to counter resistance in Enterobacterales, supported by the latest studies. However, these promising computational technologies have a few major drawbacks, such as a lack of standardized parameterization, potentially false positives, and the complexity of effective clinical translations. The drug regulatory barriers also restrict the progress of new antimicrobials for market approval.

CONCLUSION

The use of computational technologies for antimicrobial inhibitor discovery is gaining popularity, and it can be expedited by refining computational techniques and integrating them with reliable in vitro validation. The use of innovative hybrid in silico and in vitro technologies is the need of the hour to tackle CRE and mitigate the global threat of antimicrobial resistance.

[Efforts to develop therapeutic agents for bacterial infections to fight against AMR (antimicrobial resistance)]

The global spread of antimicrobial resistance (AMR) is a threat to the international community, but few new antimicrobials are in the development stage and there are few options to treat AMR infections. In light of this situation, AMR has been continuously featured on the G7 agenda since 2015, and the 2023 G7 Hiroshima Leaders' Communiqué also states that in recognition of the global and rapid spread of AMR, push and pull incentives will be explored and implemented. In addition, the World Health Assembly adopted the Global Action Plan on AMR in 2015, and Japan developed its first AMR action plan in 2016. An updated version has been released in 2023. It is hoped that the attractiveness of the antibiotic market will be improved, and the new antibiotic development will be revitalized by further expansion and enhancement of the pull incentive systems. Cefiderocol, a novel siderophore cephalosporin, demonstrates potent antibacterial activity against carbapenem-resistant Gram-negative bacteria, which are considered to be particularly high-priority pathogens by the World Health Organization (WHO) and other organizations. A partnership between the SHIONOGI, the Global Antibiotic Research and Development Partnership (GARDP) and the Clinton Health Access Initiative (CHAI) formed to improve access to cefiderocol in countries around the world, including low- and middle-income countries. In order to bring these efforts to fruition in the fight against AMR, it is important to have further understanding and cooperation from people around the world, regardless of country or field.