Synergistic Efficacy of β-Lactam Combinations against <i>Mycobacterium abscessus</i> Pulmonary Infection in Mice

Abstract

<i>Mycobacterium abscessus</i> is an emerging pathogen capable of causing invasive pulmonary infections in patients with chronic lung diseases. These infections are difficult to treat, necessitating prolonged multidrug therapy, which is further complicated by extensive intrinsic and acquired resistance exhibited by clinical <i>M. abscessus</i> isolates. Therefore, development of novel treatment regimens effective against drug-resistant strains is crucial. Prior studies have demonstrated synergistic efficacy of several β-lactams against <i>M. abscessus</i><i>in vitro</i>; however, these combinations have never been tested in an animal model of <i>M. abscessus</i> pulmonary disease. We utilized a recently developed murine system of sustained <i>M. abscessus</i> lung infection delivered via an aerosol route to test the bactericidal efficacy of four novel dual β-lactam combinations and one β-lactam/β-lactamase inhibitor combination. All five of the novel combinations exhibited synergy and resulted in at least 6-log₁₀ reductions in bacterial burden in the lungs of mice at 4 weeks compared to untreated controls (<i>P</i> = 0.038).