CTX-M group 1 β-lactamases (notably CTX-M-15) are currently the dominant extended-spectrum β-lactamases (ESBL) worldwide and in the U.S., especially in E. coli and Klebsiella isolates. These enzymes hydrolyze cefotaxime and often ceftazidime; many are carried on epidemic plasmids. Detecting a bla_CTX-M-group-1 gene indicates ESBL-mediated resistance to oxyimino-cephalosporins and typically co-resistance to other drugs. Clinically, this finding prompts use of carbapenems or new β-lactam/β-lactamase inhibitor agents and heightens infection-control precautions (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.
