Being the second leading cause of death and the leading cause of disability-adjusted life years worldwide, infectious diseases remaincontrary to earlier predictionsa major consideration for the public health of the 21 st century. Resistance development of microbes to antimicrobial drugs constitutes a large part of this devastating problem. The most widely spread mechanism of bacterial resistance operates through the degradation of existing β-lactam antibiotics. Inhibition of metallo-βlactamases is expected to allow the continued use of existing antibiotics, whose applicability is becoming ever more limited. Herein, we describe the synthesis, the metallo-β-lactamase inhibition activity, the cytotoxicity studies, and the NMR spectroscopic determination of the protein binding site of phosphonamidate monoesters. The expression of single-and doublelabeled NDM-1 and its backbone NMR assignment are also disclosed, providing helpful information for future development of NDM-1 inhibitors. We show phosphonamidates to have the potential to become a new generation of antibiotic therapeutics to combat metallo-β-lactamase-resistant bacteria.

β-Lactam antibiotics are the first choice for the treatment of most bacterial infections. However, the increased prevalence of β-lactamases, in particular extended-spectrum β-lactamases, in pathogenic bacteria has severely limited the possibility of using β-lactam treatments.

Double-carbapenem combinations have shown synergistic potential against carbapenemase-producing Enterobacterales, but data remain inconclusive. This study evaluated the activity of double-carbapenem combinations against 51 clinical KPC-2-, OXA-48-, NDM-1, and NDM-5-producing Escherichia coli and Klebsiella pneumoniae and against constructed E. coli strains harboring genes encoding KPC-2, OXA-48, or NDM-1 in an otherwise isogenic background. Two-drug combinations of ertapenem, meropenem, and doripenem were evaluated in 24 h time-lapse microscopy experiments with a subsequent spot assay and in static time-kill experiments. An enhanced effect in time-lapse microscopy experiments at 24 h and synergy in the spot assay was detected with one or more combinations against 4/14 KPC-2-, 17/17 OXA-48-, 2/17 NDM-, and 1/3 NDM-1+OXA-48-producing clinical isolates. Synergy rates were higher against meropenem- and doripenem-susceptible isolates and against OXA-48 producers. NDM production was associated with significantly lower synergy rates in E. coli. In time-kill experiments with constructed KPC-2-, OXA-48- and NDM-1-producing E. coli, 24 h synergy was not observed; however, synergy at earlier time points was found against the KPC-2- and OXA-48-producing constructs. Our findings indicate that the benefit of double-carbapenem combinations against carbapenemase-producing E. coli and K. pneumoniae is limited, especially against isolates that are resistant to the constituent antibiotics and produce NDM.

The EPIC consortium brings together experts from a wide range of fields that include clinical, molecular and basic microbiology, infectious diseases, computational biology and chemistry, drug discovery and design, bioinformatics, biochemistry, biophysics, pharmacology, toxicology, veterinary sciences, environmental sciences, and epidemiology. The main question to be answered by the EPIC alliance is the following: “What is the best approach for data mining on carbapenemase inhibitors and how to translate this data into experiments?” From this forum, we propose that the scientific community think up new strategies to be followed for the discovery of new carbapenemase inhibitors, so that this process is efficient and capable of providing results in the shortest possible time and within acceptable time and economic costs.