The CTX-M group 2 β-lactamases (including CTX-M-2) are extended-spectrum β-lactamases (ESBL) historically more common in South America and parts of Europe, but are rare in U.S. clinical isolates. Like other CTX-M enzymes, they hydrolyze cefotaxime/ceftazidime. Detection of a bla_CTX-M-group-2 gene would indicate an ESBL phenotype and suggest resistance to extended-spectrum cephalosporins. In practice this marker has limited U.S. prevalence, but its presence would similarly guide therapy toward carbapenems or β-lactam/β-lactamase inhibitor combinations (Bush & Bradford 2020, Tzouvelekis et al. 2012)
Bush, K., & Bradford, P. A. (2020). Epidemiology of β-Lactamase-Producing Pathogens. Clinical microbiology reviews, 33(2), e00047-19. https://doi.org/10.1128/CMR.00047-19
Tzouvelekis, L. S., Markogiannakis, A., Psichogiou, M., Tassios, P. T., & Daikos, G. L. (2012). Carbapenemases in Klebsiella pneumoniae and other Enterobacteriaceae: an evolving crisis of global dimensions. Clinical Microbiology Reviews, 25(4), 682–707.
