Genome characteristics of an MDR Pseudomonas monteilii carrying a novel VIM-type β-lactamase, bla.

Objectives: This study aimed to determine the genetic environment and characterize plasmid carrying a novel VIM-type β-lactamase (VIM-84) in a multidrug-resistant Pseudomonas monteilii (P. monteilii) isolate obtained from the human gut through whole-genome sequencing.

Methods: DNA extraction of P. monteilii L2757hy was performed using the Genomic DNA Isolation Kit (QIAGEN, Hilden, Germany). Whole-genome sequencing was performed by Illumina NovaSeq 6000 and Oxford Nanopore platforms. The transferability of resistance genes was screened as single clonal on Mueller Hinton Agar (MHA) plates containing rifampicin and meropenem. Verification was performed using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI/TOF-MS) and polymerase chain reaction (PCR) with Pseudomonas aeruginosa PAO1Ri as the recipient strain.

Results: L2757hy was identified as P. monteilii through sequencing and average nucleotide identity (ANI) analysis. The genome was assigned as ST147 and comprised a 6, 130, 057 bp chromosome with a GC content of 61.8% and a 49, 704 bp plasmid. Several resistance genes, including bla, aac(6')-IIa and tmexCD-toprJ, as well as virulence genes, such as iroN and wzaJ, were identified on the chromosome. A novel VIM-type bla was found on the plasmid, which was previously identified in Pseudomonas aeruginosa. Plasmid harboring bla was untypable, and it could be transferred to P. aeruginosa PAO1Ri and was associated with a class I integron with the genetic environment intI1-bla-tniR-tniQ-tniB-tniA, likely derived from Tn402.

Conclusions: Our study revealed that the novel bla gene was harbored by P. monteilii rather than P. aeruginosa. We suggested that P. monteilii may serve as a reservoir for resistance genes. © 2024 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.