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Levofloxacin-induced MexS mutation triggers imipenem-relebactam resistance in a KPC-producing Pseudomonas aeruginosa

Leilei Wang, Leilei Wang, Xun Zhou, Yanyan Lu, Xuefei Zhang, Jianping Jiang, Zhewei Sun, Mengyun Yin et al.

International Journal of Antimicrobial Agents, 2024

6 citations

Abstract

OBJECTIVE

Imipenem-relebactam (IMR), a novel β-lactam/β-lactamase inhibitor combination, is recommended for infections caused by difficult-to-treat Pseudomonas aeruginosa. This study aimed to investigate the evolution trajectory of IMR resistance under the selection of levofloxacin in P. aeruginosa.

METHODS

Antimicrobial susceptibility testing, complete genome sequencing and gene manipulation experiments were performed. Quantitative reverse transcription PCR for specific genes and porin levels were detected. Evolution trajectory was simulated in vitro by induction assay.

RESULTS

P. aeruginosa HS347 and HS355 were isolated from abdominal drainage of two neighboring patients (S and Z) undergoing surgery of colon carcinoma in Shanghai, China, with the latter patient having received levofloxacin. They were closely related ST16 strains, and both carried blaKPC-2 plasmids highly similar to those of P. aeruginosa endemic clones from Zhejiang province, where patient Z had received enteroscopy before this admission. Acquisition of resistance was observed for both IMR and fluoroquinolones in HS355, likely prompted by treatment with levofloxacin. The T274I substitution in MexS (putative oxidoreductase), upregulated efflux pump operon mexEF-oprN and decreased production of porin OprD leading to cross-resistance to fluoroquinolones and IMR, which was also verified by in vitro mutant selection under levofloxacin selection.

CONCLUSION

The emergence of a rare blaKPC-2-plasmid-bearing ST16…

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