Effect of nanoparticles on the expression of virulence and biofilm genes in Klebsiella pneumoniae

Nanoparticles have received significant focus due to their extensive use in several industries and most notably as antimicrobial agents. The current work was dedicated to evaluating the role of different nanoparticles on the gene expression of defense mechanism genes in Klebsiella pneumoniae. Cultural characteristics and molecular identification identified 9/150 (6%) of the isolates from urine as K. pneumoniae. The 9 isolates were tested for their resistance to 12 antibiotics and the isolate, K. pneumoniae strain alamasfe, that showed the highest rate of resistance towards antibiotics, was submitted to NCBI under the accession number PQ126166. AgNPs, SiNPs, Clay NPs, and TiO2NPs were tested for their effect on the growth of K. pneumoniae. The MIC of K. pneumoniae for AgNPs and SiNPs was 1000 µg/mL and for Clay NPs and TiO2NPs it was 2000 µg/mL. Klebsiella pneumoniae strain alamasfe was exposed to sub MIC concentrations of AgNPs, Silicon NPs, Clay NPs, and TiO2NPs to evaluate the effect of these nanoparticles on the expression of genes related to bacterial defense systems including ompC, ramA, soxS, luxS. Results showed that ramA was the most highly expressed gene among the genes studied in K. pneumoniae when exposed to AgNPs, Clay NPs, and TiO2NPs. This gene was expressed 548.75 fold when exposed to TiO2NPs followed by 319.57 fold when exposed to AgNPs, and 14.93 fold when exposed to clay NPs. The second most expressed gene tested was soxS. This gene was over expressed 76.11 fold when exposed to AgNPs and 131.6 fold when exposed to TiO2NPs. Similar effects were noticed with the effect of nanoparticles on ompC but with lower fold changes. Down-regulation of ompC, ramA, soxS, and luxS genes was noticed in response to SiNPs which highlights the importance of SiNPs as effective antimicrobial agents that can impair bacterial defenses, resistance mechanisms, and communication pathways. The down-regulating of these critical genes may render bacteria more susceptible to environmental stresses and antimicrobial treatments, thereby reducing their pathogenicity and resistance.