Tn4661-mediated transfer of bla CTX-M-15 from Klebsiella michiganensis to an outbreak clone of Pseudomonas aeruginosa

• Published in: Microbial genomics 2024-10, Vol.10 (10)
• Main Authors: Bartlett, Katelyn V., Luo, Ting L., Ong, Ana C., Maybank, Rosslyn A., Stribling, William, Thompson, Bernadette, Powell, Aubrey, Kwak, Yoon I., Bennett, Jason W., Lebreton, Francois, Mc Gann, Patrick T.
• Format: Article
• Language: English
• ISSN: 2057-5858; 2057-5858
• DOI: 10.1099/mgen.0.001303

Carriage of CTX-M-type extended-spectrum β-lactamase (ESBL) is rare in Pseudomonas aeruginosa . During routine surveillance of an endemic ST-621 P. aeruginosa at a large hospital, isolate MRSN 100690 carrying bla CTX-M-15 was cultured from a patient (P2). This was the first detection of this ESBL in the endemic ST-621 lineage. All 1 488 bacterial isolates collected from the same facility in the 12 months prior to the incidence of 100 690 were screened for the presence of bla CTX-M-15 . A set of 183 isolates was identified, in which corresponding patient metadata was evaluated for spatiotemporal overlaps with P2. The resulting three isolates, along with 100 690, were long-read sequenced using the Oxford Nanopore MinION platform to determine a potential donor of bla CTX-M-15 . The screen revealed a single Klebsiella michiganensis isolate, MRSN 895358, which carried an IncA/C2 plasmid harbouring bla CTX-M-15 . Notably, the patient harbouring 895358, P1, occupied the same hospital room as P2 9 months prior. Genomic alignment revealed that both isolates shared an identical 80.8 kb region containing the IncA/C2 plasmid replicon and bla CTX-M-15 . This region was plasmid bound in 895 358, but chromosomally bound in 100 690 due to Tn 4661 -mediated transposition. ESBL bla CTX-M-15 was acquired and subsequently integrated into the chromosome of a ST-621 P. aeruginosa , likely initiated by plasmid transfer from a K. michiganensis strain.