Biofilm-Forming Capacity and fimH Gene Prevalence Among Uropathogenic Klebsiella spp. in Gabon: Assessing the Link with Resistance to Third-Generation Cephalosporins and Aminoglycosides

Background/Objectives: Bacteria of the genus Klebsiella are opportunistic pathogens frequently responsible for severe urinary tract infections (UTIs). Biofilm formation is a critical virulence factor that facilitates bacterial persistence and promotes the dissemination of antimicrobial resistance. This study aimed to characterize the biofilm-forming capacity and the prevalence of the fimH adhesin gene among clinical Klebsiella isolates in Gabon, and to evaluate their association with resistance to third-generation cephalosporins and aminoglycosides. Methods: A total of 114 urinary isolates, including Klebsiella pneumoniae (n = 96), Klebsiella oxytoca (n = 7), and Klebsiella aerogenes (n = 11), were analyzed. Biofilm formation was assessed using the crystal violet staining method and quantified by spectrophotometry. The fimH gene was detected using conventional PCR. Susceptibility to cefotaxime, ceftazidime, gentamicin, and amikacin was determined using an automated system. Results: The study revealed that 81.58% of the clinical Klebsiella isolates were biofilm producers. Quantitative analysis showed a predominance of weak (43.86%) and moderate (26.32%) producers, while only 5.26% were categorized as strong producers. The fimH gene was detected in 95.61% of the isolates, reaching 100% prevalence in Klebsiella pneumoniae. Interestingly, non-biofilm-producing Klebsiella spp. isolates exhibited the highest resistance rates to 3GC (67.90% for both cefotaxime and ceftazidime), suggesting that resistance to this class may be independent of biofilm-forming capacity in this cohort. Conversely, the highest resistance rates to aminoglycosides were observed among strong biofilm producers, reaching 60% for gentamicin and 40% for amikacin. Conclusions: Uropathogenic Klebsiella spp. in Gabon exhibit a high capacity for biofilm formation, with resistance patterns appearing to be antibiotic-class dependent. These findings suggest that considering biofilm phenotypes could be relevant for microbiological surveillance to improve the understanding of UTI resistance dynamics.