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New ?-Lactamase Inhibitors Nacubactam and Zidebactam Improve the In Vitro Activity of ?-Lactam Antibiotics against Mycobacterium abscessus Complex Clinical Isolates.

ABSTRACT: The new diazabicyclooctane-based ?-lactamase inhibitors avibactam and relebactam improve the in vitro activity of ?-lactam antibiotics against bacteria of the Mycobacterium abscessus complex (MABC). Here, we evaluated the in vitro activities of two newer diazabicyclooctane-based ?-lactamase inhibitors in clinical development, nacubactam and zidebactam, with ?-lactams against clinical isolates of MABC. Both inhibitors lowered the MICs of their partner ?-lactams, meropenem (8-fold) and cefepime (2-fold), respectively, and those of other ?-lactams, similar to prior results with avibactam and relebactam.

SUBMITTER: Kaushik A

PROVIDER: S-EPMC6709484 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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New β-Lactamase Inhibitors Nacubactam and Zidebactam Improve the In Vitro Activity of β-Lactam Antibiotics against Mycobacterium abscessus Complex Clinical Isolates.

Kaushik Amit A Ammerman Nicole C NC Parrish Nicole M NM Nuermberger Eric L EL

Antimicrobial agents and chemotherapy 20190823 9

The new diazabicyclooctane-based β-lactamase inhibitors avibactam and relebactam improve the in vitro activity of β-lactam antibiotics against bacteria of the Mycobacterium abscessus complex (MABC). Here, we evaluated the in vitro activities of two newer diazabicyclooctane-based β-lactamase inhibitors in clinical development, nacubactam and zidebactam, with β-lactams against clinical isolates of MABC. Both inhibitors lowered the MICs of their partner β-lactams, meropenem (8- ...[more]

PMID: 31209013

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Project description:Metallo-?-lactamase (MBL)-producing Enterobacteriaceae are of grave clinical concern, particularly as there are no metallo-?-lactamase inhibitors approved for clinical use. The discovery and development of MBL inhibitors to restore the efficacy of available ?-lactams are thus imperative. We investigated a zinc-chelating moiety, 1,4,7-triazacyclononane (TACN), for its inhibitory activity against clinical carbapenem-resistant Enterobacteriaceae MICs, minimum bactericidal concentrations (MBCs), the serum effect, fractional inhibitory concentration indexes, and time-kill kinetics were determined using broth microdilution techniques according to Clinical and Laboratory Standards Institute (CSLI) guidelines. Enzyme kinetic parameters and the cytotoxic effects of TACN were determined using spectrophotometric assays. The interactions of the enzyme-TACN complex were investigated by computational studies. Meropenem regained its activity against carbapenemase-producing Enterobacteriaceae, with the MIC decreasing from between 8 and 64?mg/liter to 0.03?mg/liter in the presence of TACN. The TACN-meropenem combination showed bactericidal effects with an MBC/MIC ratio of ?4, and synergistic activity was observed. Human serum effects on the MICs were insignificant, and TACN was found to be noncytotoxic at concentrations above the MIC values. Computational studies predicted that TACN inhibits MBLs by targeting their catalytic active-site pockets. This was supported by its inhibition constant (Ki ), which was 0.044??M, and its inactivation constant (K inact), which was 0.0406 min-1, demonstrating that TACN inhibits MBLs efficiently and holds promise as a potential inhibitor.IMPORTANCE Carbapenem-resistant Enterobacteriaceae (CRE)-mediated infections remain a significant public health concern and have been reported to be critical in the World Health Organization's priority pathogens list for the research and development of new antibiotics. CRE produce enzymes, such as metallo-?-lactamases (MBLs), which inactivate ?-lactam antibiotics. Combination therapies involving a ?-lactam antibiotic and a ?-lactamase inhibitor remain a major treatment option for infections caused by ?-lactamase-producing organisms. Currently, no MBL inhibitor-?-lactam combination therapy is clinically available for MBL-positive bacterial infections. Hence, developing efficient molecules capable of inhibiting these enzymes could be a promising way to overcome this phenomenon. TACN played a significant role in the inhibitory activity of the tested molecules against CREs by potentiating the activity of carbapenem. This study demonstrates that TACN inhibits MBLs efficiently and holds promises as a potential MBL inhibitor to help curb the global health threat posed by MBL-producing CREs.

Project description:Mycobacterium abscessus causes serious infections that often require over 18 months of antibiotic combination therapy. There is no standard regimen for the treatment of M. abscessus infections, and the multitude of combinations that have been used clinically have had low success rates and high rates of toxicities. With β-lactam antibiotics being safe, double β-lactam and β-lactam/β-lactamase inhibitor combinations are of interest for improving the treatment of M. abscessus infections and minimizing toxicity. However, a mechanistic approach for building these combinations is lacking since little is known about which penicillin-binding protein (PBP) target receptors are inactivated by different β-lactams in M. abscessus We determined the preferred PBP targets of 13 β-lactams and 2 β-lactamase inhibitors in two M. abscessus strains and identified PBP sequences by proteomics. The Bocillin FL binding assay was used to determine the β-lactam concentrations that half-maximally inhibited Bocillin binding (50% inhibitory concentrations [IC50s]). Principal component analysis identified four clusters of PBP occupancy patterns. Carbapenems inactivated all PBPs at low concentrations (0.016 to 0.5 mg/liter) (cluster 1). Cephalosporins (cluster 2) inactivated PonA2, PonA1, and PbpA at low (0.031 to 1 mg/liter) (ceftriaxone and cefotaxime) or intermediate (0.35 to 16 mg/liter) (ceftazidime and cefoxitin) concentrations. Sulbactam, aztreonam, carumonam, mecillinam, and avibactam (cluster 3) inactivated the same PBPs as cephalosporins but required higher concentrations. Other penicillins (cluster 4) specifically targeted PbpA at 2 to 16 mg/liter. Carbapenems, ceftriaxone, and cefotaxime were the most promising β-lactams since they inactivated most or all PBPs at clinically relevant concentrations. These first PBP occupancy patterns in M. abscessus provide a mechanistic foundation for selecting and optimizing safe and effective combination therapies with β-lactams.

Dataset Information

New ?-Lactamase Inhibitors Nacubactam and Zidebactam Improve the In Vitro Activity of ?-Lactam Antibiotics against Mycobacterium abscessus Complex Clinical Isolates.

Publications

New β-Lactamase Inhibitors Nacubactam and Zidebactam Improve the <i>In Vitro</i> Activity of β-Lactam Antibiotics against Mycobacterium abscessus Complex Clinical Isolates.

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