Characterization of Klebsiella pneumoniae Virulence and Biofilm Formation Patterns in Southwestern Nigeria

Background: Klebsiella pneumoniae possesses a range of virulence factors that enable this bacterium to colonize, persist, adhere to host tissues, invade, and cause disease. The pathogen poses a significant risk to immunocompromised individuals and those with pre-existing health conditions. This research focused on assessing the virulence traits and biofilm-forming abilities of K. pneumoniae isolates in Nigeria. Methods: Clinical samples were collected from 420 patients across seven tertiary hospitals in Southwestern Nigeria between February 2018 and July 2019. Standard microbiological procedures were employed to identify Klebsiella isolates. The presence of six specific virulence genes was determined using polymerase chain reaction (PCR): fimH, kfu, rmpA, uge, wcaG, and aero_1. Additionally, PCR was utilized to identify capsular serotypes K1, K2, and K5. Results: A substantial proportion (82%) of K. pneumoniae isolates demonstrated the ability to form biofilms. Of these, 51 isolates (39.8%) were classified as strong biofilm producers, 54 (42.2%) as moderate, and 23 (17.9%) showed no biofilm production. Among the virulence genes detected, uge was the most common (68.0%), followed by fimH (65.6%), aero_1 (63.3%), kfu (29.7%), rmpA (28.1%), and wcaG (14.1%). Statistically significant correlations were found between biofilm formation and the presence of aero_1, fimH, kfu, and rmpA. In terms of capsular serotypes, the majority of isolates were non-K1/K2/K5 (84.4%), with lower frequencies observed for K2 (7.0%), K1 (5.5%), and K5 (3.1%). Conclusions: This study highlights that the aero_1, fimH, and uge genes are frequently present in K. pneumoniae isolates from this region, and that these strains often carry multiple virulence genes. The strong virulence potential and biofilm-forming capacity of these isolates underscore a significant public health threat, particularly in vulnerable populations.