Multidrug-Resistant Sequence Type 235 Pseudomonas aeruginosa Clinical Isolates Producing IMP-26 with Increased Carbapenem-Hydrolyzing Activities in Vietnam

Forty clinical isolates of multidrug-resistant Pseudomonas aeruginosa were obtained in a medical setting in Hanoi, Vietnam. Whole genomes of all 40 isolates were sequenced by MiSeq (Illumina), and phylogenic trees were constructed from the single nucleotide polymorphism concatemers. Of these 40 isolates, 24 (60.0%) harbored metallo-beta-lactamase-encoding genes, including bla(IMP-15), bla(IMP-26), bla(IMP-51), and/or bla(NDM-1). Of these 24 isolates, 12 harbored bla(IMP-26) and belonged to sequence type 235 (ST235). Escherichia coli expressing bla(IMP-26) was significantly more resistant to doripenem and meropenem than E. coli expressing bla(IMP-1) and bla(IMP-15). IMP-26 showed higher catalytic activity against doripenem and meropenem than IMP-1 and against all carbapenems tested, including doripenem, imipenem, meropenem, and panipenem, than did IMP-15. These data suggest that clinical isolates of multidrug-resistant ST235 P. aeruginosa producing IMP-26 with increased carbapenem-hydrolyzing activities are spreading in medical settings in Vietnam.