LACTB and endocarditis: The TX0117 and TX0117c MSSA strain pair have been extensively studied in various in vitro models and in in vivo rat endocarditis models to better understand the comparative efficacy of different antibiotics against MSSA exhibiting the beta-lactamase-mediated cefazolin inoculum effect and against an isogenic MSSA that has been cured of its beta-lactamase (19, 20).