Interplay Between Virulence Genes, Antimicrobial Resistance Profiles, and Biofilm Formation in Klebsiella pneumoniae Causing Urinary Tract Infections in North Lebanon.

Klebsiella pneumoniae (K. pneumoniae) is a major cause of urinary tract infections (UTIs) and poses a growing public health concern due to multidrug resistance and virulence potential. This study aimed to characterize antimicrobial resistance, biofilm formation, and virulence gene distribution among urinary K. pneumoniae isolates from North Lebanon and to explore correlations between these factors. A total of 153 non-duplicate isolates from hospital and community settings were analyzed for antibiotic susceptibility, hypermucoviscosity, biofilm formation, and presence of key virulence (fimH, mrkD, magA, rmpA, entB, iucA, iroN, kfu) and β-lactamase (blaTEM, blaSHV, blaCTX-M) genes. Adhesion-associated genes fimH and mrkD were highly prevalent, particularly in hospital-acquired and strong biofilm-producing isolates. Capsular and regulatory genes (magA) was more frequent in putative hypervirulent and community-acquired strains, while siderophore genes entB and iucA were strongly associated with biofilm formation and hospital-acquired infections. A significantly higher resistance to cephalosporins, along with an increased frequency of multidrug-resistant phenotypes, was detected in hospital-acquired, classical, and strong biofilm-forming isolates. ESBL production was significantly more common in hospital-acquired and biofilm-forming isolates. Strong biofilm formation was largely associated with classical K. pneumoniae and hospital-acquired infections, whereas putative hypervirulent strains were primarily weak biofilm producers and community-acquired. These findings highlight the interplay between virulence determinants, biofilm formation, and antibiotic resistance, emphasizing the need for targeted infection control and treatment strategies in North Lebanon.