Whole genome sequencing of ceftolozane/tazobactam-resistant, XDR Pseudomonas aeruginosa ST773 in hospitalized critically ill infants and young children with ventilator-associated pneumonia.

All five isolates belonged to serogroup O11 and sequence type ST773.

Nevertheless, whole-genome sequencing-based phylogenetic analyses, such as core genome MLST and SNP-based phylogeny, showed that the isolates were non-clonal and had a closer genetic relationship to previously identified ST773 strains from Egypt and Germany.

Several multidrug efflux systems and a broad range of acquired antimicrobial resistance genes, such as bla NDM-1, rmtB4, tet(G) , and flor2 , carried on a conserved integrative conjugative element previously reported in ST773, were found by genomic analysis.