Synergistic Roles of Quorum Sensing, Biofilm Formation, and Integron-Mediated Resistance in the Infection of Children's Klebsiella Pneumoniae

The present study investigated the virulence determinants and antibiotic resistance patterns of Klebsiella pneumoniae isolates recovered from pediatric stool samples in Iraq. Out of 94 samples, 17 isolates (13.6%) were confirmed using biochemical identification and 16S rRNA gene sequencing. These isolates demonstrated high virulence potential, where 92% produced quorum-sensing N-acyl homoserine lactone (AHL) signals and 98% carried the sdiA gene. Biofilm formation was detected in all isolates, with 76% exhibiting strong biofilm production. Hemolysin activity was observed in 64% of isolates, indicating enhanced persistence and potential tissue damage. Antimicrobial susceptibility testing revealed high levels of resistance to β-lactam antibiotics, particularly ampicillin (96%), amoxicillin-clavulanate (94%), cefotaxime (92%), and ceftazidime (88%). In contrast, imipenem (14%) and tigecycline (0% resistance) retained notable effectiveness. Extended-spectrum β-lactamase (ESBL) production was detected in 18% of isolates, while metallo-β-lactamase (MBL) production was found in 46%. Integron analysis showed the presence of class 1 and class 2 integrons in 66% and 18% of isolates, respectively. Additionally, sul1 and qacEΔ1 genes were identified in 67.6% and 85.3% of integron-positive isolates, respectively. Overall, 96% of isolates were categorized as multidrug-resistant (MDR) and 20% as extensively drug-resistant (XDR). These findings highlight the coexistence of virulence and resistance determinants in pediatric Klebsiella pneumoniae, emphasizing the urgent need to strengthen infection control practices, improve molecular surveillance systems, and promote responsible antimicrobial use to limit the spread of highly resistant and virulent strains in clinical settings.