Effects of KPC Variant and Porin Genotype on the In Vitro Activity of Meropenem-Vaborbactam against Carbapenem-Resistant Enterobacteriaceae

Abstract

Meropenem-vaborbactam is a new agent with the potential to treat carbapenem-resistant Enterobacteriaceae (CRE) infections. We describe the in vitro activity of meropenem-vaborbactam against representative CRE genotypes and laboratory-engineered Escherichia coli isolates harboring mutant blaKPC genes associated with ceftazidime-avibactam resistance. We also compared disk diffusion and gradient strip testing methods to standard broth microdilution methods. Against 120 CRE isolates, median ceftazidime-avibactam and meropenem-vaborbactam MICs were 1 and 0.03 µg/ml, respectively. Ninety-eight percent (117/120) of isolates were susceptible to meropenem-vaborbactam (MICs ≤ 4 µg/ml). Against Klebsiella pneumoniae isolates harboring mutant blaKPC, the addition of vaborbactam lowered the meropenem MICs in 78% of isolates (14/18); 100% were susceptible to meropenem-vaborbactam. Median meropenem-vaborbactam MICs were higher against K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae isolates with mutant ompK36 porin genes (n = 26) than against those with wild-type ompK36 porin genes (n = 54) (0.25 versus 0.03 µg/ml; P < 0.0001). Against E. coli TOP10 isolates with plasmid constructs containing wild-type blaKPC or mutant blaKPC, the addition of vaborbactam at 8 µg/ml lowered the meropenem MICs 2- to 512-fold, resulting in meropenem-vaborbactam MICs of 0.03 µg/ml. The rates of categorical agreement with broth microdilution for disk diffusion or gradient strips ranged from 90 to 95%. Essential agreement rates were higher for research-use-only (RUO) gradient strips manufactured by bioMérieux (82%) than for those manufactured by Liofilchem (48%) (P < 0.0001). Taken together, our data highlight the potent in vitro activity of meropenem-vaborbactam against CRE, including isolates resistant to ceftazidime-avibactam. Vaborbactam inhibited both wild-type and variant KPC enzymes. On the other hand, KPC-producing K. pneumoniae isolates with ompK36 mutations displayed higher meropenem-vaborbactam MICs than isolates with wild-type ompK36. The results of susceptibility testing with RUO bioMérieux gradient strips most closely aligned with those of broth microdilution methods.

Impact of Intrinsic Resistance Mechanisms on Potency of QPX7728, a New Ultrabroad-Spectrum Beta-Lactamase Inhibitor of Serine and Metallo-Beta-Lactamases in Enterobacteriaceae , Pseudomonas aeruginosa, and Acinetobacter baumannii

“…Even though a on September 8, 2020 by guest http://aac.asm.org/ Downloaded from combination of these mechanisms resulted in a 16-32-fold reduction of the BLI potency of QPX7728, the PV max did not exceed µg/ml; in contrast, 64 µg/ml of vaborbactam was required to completely inhibit KPC in a mutant lacking both major porins in the background of increased efflux. Since porin mutations reduce the potency of recently approved beta-lactam/BLI combinations in clinical settings (18)(19)(20)(21), the finding that QPX7728 is less affected by porin mutations to a lesser degree will be advantageous for several QPX7728 combinations.…”

“…AdeABC and AdeIJK MDR efflux pumps from A. baumannii are implicated in general defense (17). Similar to betalactams, the potency of beta-lactamase inhibitors also can be also affected by the same general resistance mechanisms (18)(19)(20)(21).…”

Multicenter Clinical Evaluation of Etest Meropenem-Vaborbactam (bioMérieux) for Susceptibility Testing of Enterobacterales ( Enterobacteriaceae ) and Pseudomonas aeruginosa

“…Prior data on the accuracy of gradient diffusion methods for MEV are limited. One previous study has reported on research-use-only (RUO) product versions of MEV gradient diffusion strips from bioMérieux and LioFilchem compared to broth microdilution for 120 isolates of carbapenem-resistant Enterobacterales (CRE), including K. pneumoniae (86 isolates), Enterobacter cloacae (17), E. coli (10) and K. aerogenes (7) (10). In that study, RUO Etest MEV displayed essential agreement of 82% and category agreement of Ն90%.…”

“…In that study, RUO Etest MEV displayed essential agreement of 82% and category agreement of Ն90%. However, the RUO Etest MEV had one very major error, two major errors, and three minor errors (10). It is important to note that these data were conducted with a prior iteration (RUO) of Etest MEV.…”

α‐Triazolylboronic Acids: A Promising Scaffold for Effective Inhibitors of KPCs

“…[7] The inhibitor is combined with meropenem for the treatment of carbapenem-resistant infections, although in vitro resistance was observed due to loss of porins expression or to the increase in the expression of bla KPC . [15][16][17] In this work, we present the inhibitory activity of 14 1,2,3triazol-1-ylmethaneboronic acids against KPC-2 carbapenemase. We demonstrate the extent these inhibitors restore susceptibility against resistant K. pneumoniae strains in combination with cefepime (FEP).…”