Genetic diversity of ESBL-producing Escherichia coli in ICU settings.

Extended-Spectrum β-Lactamase (ESBL) - producing Escherichia coli pose a major threat in ICU settings due to rising multidrug resistance and limited data on their genetic diversity. Therefore, it is of interest to analyze the molecular epidemiology of 186 non- duplicate ESBL-producing E. coli isolates from ICU patients over 12 months using Polymerase Chain Reaction (PCR) for ESBL genes, phylogenetic grouping, Multilocus Sequence Typing (MLST) and antimicrobial susceptibility testing. The blaCTX-M gene family was predominant (82.3%), with blaCTX-M-15 as the most common variant and 41.9% of isolates carried multiple ESBL genes. Phylogenetic group B2 and high-risk clones such as ST131, ST405 and ST648 were most prevalent, with high co-resistance to multiple antibiotic classes. Thus, we show significant genetic diversity and dominance of high-risk clones, emphasizing the need for molecular surveillance and targeted infection control strategies.