Role of Klebsiella pneumoniae virulence genes peg-344, fimH, magA, and khe in oxidative stress according to biofilm categorization of lower respiratory tract infected patients

Abstract

Abstract—Background: Klebsiella pneumoniae is a causative agent for bacteremia and pneumonia. Virulence factors encoded by genes such as peg-344, fimH, magA, and khe effectively orient the pathogenicity of K. pneumoniae. Infections lead to the formation of reactive oxygen species (ROS) by LPS-induced cell death, with glutathione (GSH) potentially alleviating this stress, as indicated by increased malondialdehyde levels in infected cells. The current study aims to assess the relationship between selected virulence genes and studied oxidative stress biomarkers in lower respiratory K. pneumoniae-infected patients, according to biofilm-forming ability. Methodology: K. pneumoniae 35 isolates were diagnosed by the VITEK system, from 90 sputum samples (positive growth) of 220 patients at Al-Najaf Teaching Hospital, Iraq. Biofilm formation was evaluated using a microtiter plate assay, genomic extraction was performed by the boiling method, and by Monoplex PCR, the genes were amplified. GSH and MDA levels were analyzed utilizing the Ellman and TBARS methods, respectively. Results: The study of 35 K. pneumoniae isolates found that 80% produced biofilms (strong: 11.5%, moderate: 37%, weak: 31.5%, non-biofilm-forming: 20%). Biofilm intensity significantly influenced glutathione (GSH) levels, with strong biofilms showing the highest levels (Welch ANOVA: 203.57, p < 0.001). Malondialdehyde levels also varied significantly (Kruskal-Wallis: H=19.940, df=3, p < 0.001), with ROC analysis indicating MDA's diagnostic potential for biofilm identification (AUC = 0.952, p < 0.001). Additionally, multiplex PCR showed peg-344 (8.5%), fimH (94.2%), and Khe (77.1%), while magA was absent. GSH and MDA levels were evaluated using TBARS and the Ellman method. Conclusion: The study reveals that K. pneumoniae isolates exhibit moderate biofilm formation, associated with increased levels of GSH and MDA. Strong biofilm producers show significantly higher MDA levels, indicating a potential link to virulence factors affecting lung epithelial linings.