Resistance mechanisms and genetic relatedness among carbapenem-resistant Pseudomonas aeruginosa isolates from three major hospitals in Hanoi, Vietnam (2011–15)

BACKGROUND: MDR bacteria including carbapenem-resistant Pseudomonas aeruginosa are recognized as an important cause of hospital-acquired infections worldwide. This investigation seeks to determine the molecular characterization and antibiotic resistance genes associated with carbapenem-resistant P. aeruginosa. METHODS: We conducted WGS and phylogenetic analysis of 72 carbapenem-resistant P. aeruginosa isolated from hospital-acquired infection patients from August 2011 to March 2015 in three major hospitals in Hanoi, Vietnam. RESULTS: We identified three variants of IMP gene, among which bla(IMP-15) was the most frequent (n = 34) in comparison to bla(IMP-26) (n = 2) and bla(IMP-51) (n = 12). We observed two isolates with imipenem MIC >128 mg/L that co-harboured bla(IMP-15) and bla(DIM-1) genes and seven isolates (imipenem MIC > 128 mg/L) with a bla(KPC-1) gene from the same hospital. MLST data shows that these 72 isolates belong to 18 STs and phylogenetic tree analysis has divided these isolates into nine groups. CONCLUSIONS: Our results provide evidence that not only bla(IMP-26) but other IMP variants such as bla(IMP-15) and bla(IMP-51) genes and several STs (ST235, ST244, ST277, ST310, ST773 and ST3151) have been disseminating in healthcare settings in Vietnam. In addition, we report the emergence of two isolates belonging to ST1240 and ST3340 that harboured two important carbapenemase genes (bla(IMP-15) and bla(DIM-1)) and seven isolates belonging to ST3151 of P. aeruginosa that carried the bla(KPC-1) gene in Vietnam, which could potentially cause serious restricted availability of treatment options in healthcare settings.