Emergence of blaNDM−1 in Pseudomonas aeruginosa ST308 and ST773 from bloodstream infections in Egypt

Abstract Carbapenem-resistant Pseudomonas aeruginosa (CRPA) remains a significant challenge to clinical management, particularly in critically ill hospitalized patients. The present study aimed to investigate the prevalence and molecular epidemiology of bla NDM-1 among 50 Pseudomonas aeruginosa isolates causing bloodstream infections in cancer patients in Egypt, and to characterize their antimicrobial resistance profiles, carbapenemase production, and biofilm-forming capacity. Antimicrobial susceptibility testing, minimum inhibitory concentrations, multiplex PCR for carbapenemase genes, biofilm assays, and multilocus sequence typing (MLST) were performed. Two representative isolates underwent whole-genome sequencing (WGS) to determine the genetic context of bla NDM-1 . All isolates exhibited multidrug-resistant or extensively drug-resistant phenotypes. Carbapenem resistance was detected in 80% ( n = 40) of isolates, and bla NDM-1 was identified in 64% ( n = 32), comprising 80% of carbapenem-resistant isolates. Strong biofilm formation was significantly associated with bla NDM-1 carriage ( P = 0.0115). MLST analysis of a subset of bla NDM-1 –producing isolates ( n = 10) revealed two sequence types among bla NDM-1- producing isolates: ST308 ( n = 6) and ST773 ( n = 4). These findings indicate the dissemination of high-risk Pseudomonas aeruginosa clones ST308 and ST773 carrying bla NDM-1 in Egypt. WGS showed chromosomal integration of bla NDM-1 within integrative and conjugative elements (ICEs) containing IS91-family transposases and multiple additional resistance genes. However, the relatively small sample size and the limited number of isolates subjected to WGS may restrict the generalizability of these findings. The presence of bla NDM-1 within mobile genetic platforms highlights the ongoing evolution and dissemination of CRPA in this clinical setting and calls for enhanced surveillance, as these lineages may act as reservoirs for the acquisition and dissemination of diverse antimicrobial resistance determinants via their putative ICE.