Durlobactam to boost the clinical utility of standard of care β-lactams against <i>Mycobacterium abscessus</i> lung disease

ABSTRACT β-Lactams present several desirable pharmacodynamic features leading to the rapid eradication of many bacterial pathogens. Imipenem (IPM) and cefoxitin (FOX) are injectable β-lactams recommended during the intensive treatment phase of pulmonary infections caused by Mycobacterium abscessus (Mab). However, their potency against Mab is many-fold lower than against Gram-positive and Gram-negative pathogens for which they were optimized, putting into question their clinical utility. Here, we show that adding the recently approved durlobactam-sulbactam (DUR-SUL) pair to either IPM or FOX achieves growth inhibition, bactericidal, and cytolytic activity at concentrations that are within those achieved in patients and below the clinical breakpoints established for each agent. Synergies between DUR-SUL and IPM or FOX were confirmed across a large panel of clinical isolates. Through in vitro resistant mutant selection, we also show that adding DUR-SUL abrogates acquired resistance to IPM and FOX. Since the use of β-lactam injectables is firmly grounded in clinical practice during the intensive treatment phase of Mab pulmonary disease, their potentiation by FDA-approved DUR-SUL to bring minimum inhibitory concentration distributions within achievable concentration ranges could offer significant short-term benefits to patients, while novel β-lactam combinations are optimized specifically against Mab pulmonary infections, for which no reliable cure exists.