A novel plasmid-mediated PAC β-lactamase (PAC-2) variant confers resistance to ceftazidime-avibactam in Klebsiella quasipneumoniae ST526, in Colombia.

Saavedra, S. Y.; Montilla-Escudero, E.; Ovalle, M. V.; Triana, J. A.; Torres, Y. S.; Vargas-Florez, N.; Gutierrez, M. A.; Barrera, A. F.; Duarte, C.

doi:10.1101/2025.05.14.654127

bioRxiv · 10.1101/2025.05.14.654127

A novel plasmid-mediated PAC β-lactamase (PAC-2) variant confers resistance to ceftazidime-avibactam in Klebsiella quasipneumoniae ST526, in Colombia.

Saavedra, S. Y.·Montilla-Escudero, E.·Ovalle, M. V.·Triana, J. A.·Torres, Y. S.·Vargas-Florez, N.·Gutierrez, M. A.·Barrera, A. F.·Duarte, C.

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Abstract

Globally, the increasing reports of resistance to ceftazidime-avibactam (CZA) in Enterobacterales are concerning. In this paper we describe an isolate of Klebsiella quasipneumoniae (GMR-RA-2034.23) highly resistant to ceftazidime-avibactam, ceftolozane-tazobactam, ceftazidime and cefotaxime in which a new variant of the PAC {beta}-lactamase, designated PAC-2 by the NCBI, was identified. The blaPAC-2 gene is encoded in a non-conjugative plasmid type IncQ (9,452 bp). The GMR-RA-2034.23 isolate did not present mutations in the OmpK35 or OmpK36 porins, associated with resistance to CZA. This is the first description of PAC-type {beta}-lactamase in Colombia. Continuous monitoring of mechanisms of resistance to CZA is crucial to prevent its spread.

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Saavedra, S. Y., Montilla-Escudero, E., Ovalle, M. V., Triana, J. A., Torres, Y. S., Vargas-Florez, N., Gutierrez, M. A., Barrera, A. F., Duarte, C.. 2025-05-14. A novel plasmid-mediated PAC β-lactamase (PAC-2) variant confers resistance to ceftazidime-avibactam in Klebsiella quasipneumoniae ST526, in Colombia.. https://doi.org/10.1101/2025.05.14.654127

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