Genomic characterisation of carbapenem-resistant Pseudomonas aeruginosa from ICU admission screening in Hanoi, Vietnam, 2023

OBJECTIVES: Vietnam is among the countries most affected by antimicrobial resistance (AMR) in the Asia-Pacific. While multidrug-resistant (MDR) Enterobacterales have been extensively studied, genomic data on MDR Pseudomonas aeruginosa in Vietnam remains scarce. To address this, we characterized 20 carbapenem-resistant P. aeruginosa (CRPA) isolates from rectal colonization of ICU patients.

METHODS: Screening for CRPA was conducted using a selective chromogenic medium (mSuperCARBA). Species identification was achieved through MALDI-TOF mass spectrometry, while antimicrobial susceptibility testing (AST) was performed using the Vitek®2 system and broth microdilution. Whole-genome sequencing (WGS) was performed using the Illumina NextSeq platform.

RESULTS: Twenty CRPA isolates were collected from rectal swabs of 691 patients admitted to the ICUs of the 108 Military Central Hospital in Hanoi, Vietnam, between July 1, 2023, and October 31, 2023. The predominant multilocus sequence type (MLST) was ST308, accounting for 50% (10/20) of the isolates. Notably, 70% (14/20) of the CRPA isolates harboured genes encoding metallo-β-lactamases (MBL), with bla NDM-1 being the most prevalent (86%, 12/14), followed by bla IMP-26 (14%, 2/14). Low susceptibility was observed for ceftazidime-avibactam (15%, 3/20) and ceftolozane-tazobactam (10%, 2/20), while cefiderocol resistance was observed in 50% (10/20) of isolates. Colistin demonstrated the most favourable susceptibility profile, with 90% (18/20) of isolates remaining susceptible.

CONCLUSION: A significant proportion of CRPA isolates in our study were MBL producers, with high levels of resistance to novel β-lactams and β-lactam/β-lactamase inhibitor combinations. These findings underscore the urgent need for effective infection prevention and control strategies to mitigate the further spread of MBL-producing CRPA.