Detection of IMP-4 and SFO-1 co-producing ST51 clinical isolates.

PURPOSE

To explore the genetic characteristics of the IMP-4 and SFO-1 co-producing multidrug-resistant (MDR) clinical isolates, YQ13422hy and YQ13530hy.

METHODS

MALDI-TOF MS was used for species identification. Antibiotic resistance genes (ARGs) were tested by PCR and Sanger sequencing analysis. In addition to agar dilution, broth microdilution was used for antimicrobial susceptibility testing (AST). Whole-genome sequencing (WGS) analysis was conducted using the Illumina NovaSeq 6000 and Oxford Nanopore platforms. Annotation was performed by RAST on the genome. The phylogenetic tree was achieved using kSNP3.0. Plasmid characterization was conducted using S1-pulsed-field gel electrophoresis (S1-PFGE), Southern blotting, conjugation experiments, and whole genome sequencing (WGS). An in-depth study of the conjugation module was conducted using the OriTFinder website. The genetic context of and was analyzed using BLAST Ring Image Generator (BRIG) and Easyfig 2.3.

RESULTS

YQ13422hy and YQ13530hy, two MDR strains of ST51 harboring and , were identified. They were only sensitive to meropenem, amikacin and polymyxin B, and were resistant to cephalosporins, aztreonam, piperacillin/tazobactam and aminoglycosides, intermediate to imipenem. The genetic context surrounding was 5'CS--IS-In- -IS-. The integron of is In, which is the array of gene cassettes of 5'CS- . Phylogenetic analysis demonstrated that YQ13422hy and YQ13530hy belonged to the same small clusters with a high degree of homology.

CONCLUSION

This observation revealed the dissemination of the gene in in China. We found that and co-exist in MDR clinical isolates. This work showed a transferable IncN-type plasmid carrying the resistance gene in . We examined the potential resistance mechanisms of pYQ13422-IMP-4 and pYQ13422-SFO-1, along with their detailed genetic contexts.