Discovery of 2-Sulfinyl-Diazabicyclooctane Derivatives, Potential Oral β-Lactamase Inhibitors for Infections Caused by Serine β-Lactamase-Producing Enterobacterales

Recent Developments to Cope the Antibacterial Resistance via β-Lactamase Inhibition

Antibacterial resistance towards the β-lactam (BL) drugs is now ubiquitous, and there is a major global health concern associated with the emergence of new β-lactamases (BLAs) as the primary cause of resistance. In addition to the development of new antibacterial drugs, β-lactamase inhibition is an alternative modality that can be implemented to tackle this resistance channel. This strategy has successfully revitalized the efficacy of a number of otherwise obsolete BLs since the discovery of the first β-lactamase inhibitor (BLI), clavulanic acid. Over the years, β-lactamase inhibition research has grown, leading to the introduction of new synthetic inhibitors, and a few are currently in clinical trials. Of note, the 1, 6-diazabicyclo [3,2,1]octan-7-one (DBO) scaffold gained the attention of researchers around the world, which finally culminated in the approval of two BLIs, avibactam and relebactam, which can successfully inhibit Ambler class A, C, and D β-lactamases. Boronic acids have shown promise in coping with Ambler class B β-lactamases in recent research, in addition to classes A, C, and D with the clinical use of vaborbactam. This review focuses on the further developments in the synthetic strategies using DBO as well as boronic acid derivatives. In addition, various other potential serine- and metallo- β-lactamases inhibitors that have been developed in last few years are discussed briefly as well. Furthermore, binding interactions of the representative inhibitors have been discussed based on the crystal structure data of inhibitor-enzyme complex, published in the literature.

Structure and Mechanism-Guided Design of Dual Serine/Metallo-Carbapenemase Inhibitors

Serine/metallo-carbapenemase-coproducing pathogens, often referred to as "superbugs", are a significant clinical problem. They hydrolyze nearly all available β-lactam antibiotics, especially carbapenems considered as last-resort antibiotics, seriously endangering efficacious antibacterial treatment. Despite the continuous global spread of carbapenem resistance, no dual-action inhibitors are available in therapy. This Perspective is the first systematic investigation of all chemotypes, modes of inhibition, and crystal structures of dual serine/metallo-carbapenemase inhibitors. An overview of the key strategy for designing dual serine/metallo-carbapenemase inhibitors and their mechanism of action is provided, as guiding rules for the development of clinically available dual inhibitors, coadministrated with carbapenems, to overcome the carbapenem resistance issue.

Copper-Catalyzed C–S Formation for the Synthesis of Benzyl Phenyl Sulfides from Dithiocarbamates

An odorless and efficient protocol for the synthesis of benzyl phenyl sulfides is reported. Starting from environmentally friendly phenyl dithiocarbamates and commercially available benzyl halides as starting materials, the target compounds (benzyl phenyl sulfides) could be obtained smoothly and easily by using copper salt as catalyst and Cs2CO3 as base. This method features ligand/additive-free, the use of readily available starting materials, inexpensive catalysts, and good substrate suitability, illustrating its potentially synthetic value for the convenient preparation of some biologically active molecules.

Comparison of the Performance of Phenotypic Methods for the Detection of Carbapenem-Resistant Enterobacteriaceae (CRE) in Clinical Practice

In order to investigate the diagnostic performance characteristics of four phenotypic assays in detecting carbapenem-resistant Enterobacteriaceae (CRE), we collected the CRE strains from infected patients. The results of carbapenemase gene detection, bla_KPC-2, bla_OXA-23, bla_NDM-1, bla_NDM-4, bla_NDM-5, bla_IMP-4, and bla_IMP-8, were used as a standard to evaluate the performances of combined disk test (CDT), modified carbapenem inactivation method(mCIM)/EDTA-modified carbapenem inactivation method(eCIM), NG-Test CARBA 5 (CARBA), and color developing immunoassay (CDI). The compliance of phenotype results based on CDT, mCIM/eCIM, CARBA, and CDI with genetic detection results was 94% (231/247), 95% (235/247), 98% (242/247), and 99% (246/247), respectively. CDT demonstrated a low specificity for carbapenemase detection, low negative predictive value (NPV), and low sensitivity for metallo-β-lactamase (79%, 55%, and 88%, respectively); it also failed to accurately detect IMP. The mCIM/eCIM assay had serious problems in detecting OXA-23-like carbapenemases. The sensitivity and specificity of CARBA and CDI were higher than those of the first two methods. However, CARBA did not cover the detection of OXA-23, while CDI cannot detect IMP-8, resulting in low NPVs (70% and 88%, respectively). In conclusion, CARBA and CDI assays are highly accurate except individual rare genes and allow direct genotype detections. CDT and mCIM/eCIM assays are moderately accurate and can only distinguish serine-β-lactamases from metallo-β-lactamases. Laboratories should choose the appropriate method that meets their needs based on its characteristic.