When treating an infection caused by a CPO, differentiating between resistance caused by Class A enzymes, such as the Klebsiella pneumoniae carbapenemase (KPC) and Class D enzymes, such as Oxacillinase-48 (OXA-48), versus Class B enzymes, including the New Delhi metallo-beta-lactamase (NDM), Verona Integron-encoded metallo-beta-lactamase (VIM), and Imipenemases (IMP) is critical especially when physicians consider using any of the newer beta-lactam/beta-lactamase inhibitor combinations (Falcone and Paterson, 2016; Sheu et al., 2019; Ackley et al., 2020; Johnston et al., 2020). This evidence concerns the gene LACTB and infection.