Dissemination of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa in Serbian Hospital Settings: Expansion of ST235 and ST654 Clones.

This nationwide study aimed to investigate the molecular characteristics of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa in Serbia, underlying resistance mechanisms, the genetic context of detected MBL genes, and the clonal relationship between isolates harboring genes-encoding MBL. Overall, 320/5334 isolates collected from 2018 to 2021 were identified as P. aeruginosa . Carbapenem-resistant P. aeruginosa (CRPA) were screened for the presence of bla VIM , bla IMP , and bla NDM , genes whereas MBL-positive isolates were tested for the presence of the bla CTX-M-2 , bla PER , bla TEM , bla SHV , bla VEB , and bla GES . Multilocus sequence typing and phylogenomic analysis were performed for P. aeruginosa -producing MBL. The majority of the P. aeruginosa isolates were recovered from the lower respiratory tract (n = 120; 37.5%) and wound specimens (n = 108; 33.75%). CRPA isolates accounted for 43.1% (n = 138) of the tested isolates, 31 out of them being bla NDM-1 -positive (22.5%). The colistin resistance rate was 0.3%. MLST analysis revealed the occurrence of ST235 (n = 25) and ST654 (n = 6), mostly confined to Serbia. The distribution of beta-lactamase-encoding genes in these isolates suggested clonal dissemination and possible recombination: ST235/ bla NDM-1 , ST235/ bla NDM-1 / bla PER-1 , ST654/ bla NDM-1 , ST654/ bla NDM-1 / bla PER-1 , and ST654/ bla NDM-1 / bla GES-5 . High-risk clones ST235 and ST654 identified for the first time in Serbia, are important vectors of acquired MBL and ESBL and their associated multidrug resistance phenotypes represent a cause for considerable concern.