LN-1-255, a penicillanic acid sulfone able to inhibit the class D carbapenemase OXA-48

作者：Vallejo Juan A; Martinez Guitian Marta; Vazquez Ucha Juan C; Gonzalez Bello Concepcion; Poza Margarita; Buynak John D; Bethel Christopher R; Bonomo Robert A; Bou German; Beceiro Alejandro^*

来源：Journal of Antimicrobial Chemotherapy, 2016, 71(8): 2171-2180.

DOI：10.1093/jac/dkw105

Carbapenemases are the most important mechanism responsible for carbapenem resistance in Enterobacteriaceae. Among carbapenemases, OXA-48 presents unique challenges as it is resistant to beta-lactam inhibitors. Here, we test the capacity of the compound LN-1-255, a 6-alkylidene-2'-substituted penicillanic acid sulfone, to inhibit the activity of the carbapenemase OXA-48.
The OXA-48 gene was cloned and expressed in Klebsiella pneumoniae and Escherichia coli in order to obtain MICs in the presence of inhibitors (clavulanic acid, tazobactam and sulbactam) and LN-1-255. OXA-48 was purified and steady-state kinetics was performed with LN-1-255 and tazobactam. The covalent binding mode of LN-1-255 with OXA-48 was studied by docking assays.
Both OXA-48-producing clinical and transformant strains displayed increased susceptibility to carbapenem antibiotics in the presence of 4 mg/L LN-1-255 (2-32-fold increased susceptibility) and 16 mg/L LN-1-255 (4-64-fold increased susceptibility). Kinetic assays demonstrated that LN-1-255 is able to inhibit OXA-48 with an acylation efficiency (k(2)/K) of 10aEuroS +/- aEuroS1aEuroSxaEuroS10(4) M-1 s(-1) and a slow deacylation rate (k(off)) of 7aEuroS +/- aEuroS1aEuroSxaEuroS10(-4) s(-1). IC50 was 3 nM for LN-1-255 and 1.5 mu M for tazobactam. Lastly, k(cat)/k(inact) was 500-fold lower for LN-1-255 than for tazobactam.
In these studies, carbapenem antibiotics used in combination with LN-1-255 are effective against the carbapenemase OXA-48, an important emerging mechanism of antibiotic resistance. This provides an incentive for further investigations to maximize the efficacy of penicillin sulfone inhibition of class D plasmid-carried Enterobacteriaceae carbapenemases.

• 出版日期2016-8