Phenotypic and genotypic ınvestigation of virulence factors in Klebsiella pneumoniae strains ısolated from ventilator-associated pneumonia (VAP) cases.

Klebsiella pneumoniae is an opportunistic pathogen that normally resides in the gastrointestinal tract of humans and animals, as well as on water and plant surfaces. It can cause a variety of infections, particularly in immunocompromised individuals. K. pneumoniae possesses numerous virulence factors including capsular polysaccharides, hemolysin production, erythrocyte agglutination, hypermucoviscosity (HV), biofilm formation, fimbriae, toxins, and siderophores. This study aimed to determine the virulence factors of K. pneumoniae strains isolated from cases of ventilator-associated pneumonia (VAP). A total of 19 K. pneumoniae isolates identified using the VITEK system and obtained from tracheal aspirate cultures of patients on mechanical ventilation in the ıntensive care unit of Kırşehir Ahi Evran Training and Research Hospital between 2022 and 2023 were included in the study. The presence of capsule, hemagglutination, and biofilm formation was detected in 100%, 100%, and 52.63% of the isolates, respectively. The virulence genes uge, wabG, ycfM, fimH, mrkD, ureA, iutA, ybtA, entB, and fyuA were present in 100% of the isolates; kpn was detected in 52.63%, and kfuBC in 94.73%. In contrast, the rmpA, wcaG, iroN, iroD, alls, and cnf-1 genes were not detected in any of the isolates. The findings of this study may serve as a guide for pathogen-targeted therapy and the development of preventive strategies against VAP.