Vallejo Vidal, Juan AndrésMartínez Guitián, MartaVázquez Ucha, Juan CarlosGonzález Bello, ConcepciónPoza Domínguez, MargaritaBuynak, JohnBethel, Christopher R.Bonomo, Roberto A.Bou, GermánBeceiro Casas, Alejandro2018-07-032018-07-032016-04-28Juan A. Vallejo, Marta Martínez-Guitián, Juan C. Vázquez-Ucha, Concepción González-Bello, Margarita Poza, John D. Buynak, Christopher R. Bethel, Robert A. Bonomo, German Bou, Alejandro Beceiro; LN-1-255, a penicillanic acid sulfone able to inhibit the class D carbapenemase OXA-48, Journal of Antimicrobial Chemotherapy, Volume 71, Issue 8, 1 August 2016, Pages 2171–2180, https://doi.org/10.1093/jac/dkw1050305-7453http://hdl.handle.net/10347/16935This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Antimicrobial Chemotherapy following peer review. The version of record Juan A. Vallejo, Marta Martínez-Guitián, Juan C. Vázquez-Ucha, Concepción González-Bello, Margarita Poza, John D. Buynak, Christopher R. Bethel, Robert A. Bonomo, German Bou, Alejandro Beceiro; LN-1-255, a penicillanic acid sulfone able to inhibit the class D carbapenemase OXA-48, Journal of Antimicrobial Chemotherapy, Volume 71, Issue 8, 1 August 2016, Pages 2171–2180 is available online at: https://doi.org/10.1093/jac/dkw105Objectives Carbapenemases are the most important mechanism responsible for carbapenem resistance in Enterobacteriaceae. Among carbapenemases, OXA-48 presents unique challenges as it is resistant to β-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. Methods 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. Results 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 (k2/K) of 10 ± 1 × 104 M−1 s−1 and a slow deacylation rate (koff) of 7 ± 1 × 10−4 s−1. IC50 was 3 nM for LN-1-255 and 1.5 μM for tazobactam. Lastly, kcat/kinact was 500-fold lower for LN-1-255 than for tazobactam. Conclusions 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.eng© The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reservedSteady statePlasmidsAntibiotic resistanceBacterialPenicillinCarbapenemAcylationClavulanic acidEnterobacteriaceaeGenesKlebsiella pneumoniaeLactamsMechlorethamineNew mexicoSulbactamSulfonesKineticsEscherichia coliTazobactamIncentivesMalnutrition-inflammation-cachexia syndromeCarbapenem resistancejournal article10.1093/jac/dkw1051460-2091open access