Characterization of the novel plasmid-encoded MBL gene blaAFM-1, integrated into a blaIMP-45-bearing transposon Tn6485e in a carbapenem-resistant Pseudomonas aeruginosa clinical isolate. (17th September 2021)

• Record Type: Journal Article
• Authors: Zhang, Xuefei; Wang, Leilei; Li, Dan; Wang, Chen; Guo, Qinglan; Wang, Minggui
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 77:Number 1(2022)
• Page Start: 83
• Page End: 88
• Publication Date: 2021-09-17
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkab342
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Objectives: To characterize the novel subclass B1 MBL AFM-1, encoded by a bla IMP-45 -bearing megaplasmid from a carbapenem-resistant Pseudomonas aeruginosa (CRPA) clinical isolate. Methods: CRPA HS17-127 and its transconjugant were discovered to carry bla AFM-1 in our previous study. bla AFM-1 and bla NDM-1 were cloned and expressed in Escherichia coli TOP10 and P. aeruginosa PAO1, respectively, to test the resistance phenotype. Kinetic studies were performed to elucidate the biochemical characteristics of the AFM-1 enzyme. Comparative genomic analysis was applied to investigate the genetic context of bla AFM-1 . Results: PAO1 transconjugant TcHS17-127 exhibited carbapenem resistance with an imipenem MIC of 64 mg/L. E. coli transformants with cloned bla AFM-1 or bla NDM-1 had increased MICs of all β-lactams tested (except aztreonam) and imipenem MICs of 4–8 mg/L. Kinetic studies showed that AFM-1 had greater catalytic efficiency against cephalosporins than carbapenems. bla AFM-1 was located on a 486 963 bp IncP-2 plasmid, pHS17-127, containing a 57.3 kb MDR Tn 1403 -derivative transposon, Tn 6485e, which is genetically closest to the bla IMP-45 -bearing Tn 6485 transposon but has acquired an extra IS CR27 n3- bla AFM-1 module. Multicentre surveillance of 605 P. aeruginosa clinical isolates identified three bla AFM carriers from different STs. Two of them co-carried bla AFM-1 and bla IMP-45 . A BLAST search against the NCBI database showed six bla AFM carriers on various plasmids and the chromosomes of different Gram-negative species. Conclusions: The bla AFM-1 gene confers carbapenem resistance and has been captured in distinct species of non-fermenters. Co-carriage of bla AFM-1 and bla IMP-45 in an MDR transposon on a conjugative plasmid can be expected to promote further dissemination of bla MBL s.