Investigating the effects of zinc oxide and titanium dioxide nanoparticles on the formation of biofilm and persister cells in Klebsiella pneumoniae

Abstract The biofilm formation in klebsiella pneumoniae isolates poses a significant problem as it can result in treatment failure and the development of chronic infections. These biofilms act as protective barriers, rendering the bacteria resistant to antibiotics. Additionally, persister cells, which make up a small fraction of the bacterial population, have the ability to enter a dormant state after treatment with high doses of antibiotics. These persister cells play a crucial role in the high level of biofilm‐mediated tolerance to antibiotics. The present study aimed to investigate the impact of Zinc oxide (ZnO) and titanium dioxide (TiO 2 ) nanoparticles on the formation of biofilm and persister cells in K. pneumoniae . The minimum inhibitory concentration (MIC) of colistin in K. pneumoniae ATCC 13883 was determined using the microdilution method. The formation of persister cells was evaluated by introducing sub‐MIC of colistin. Subsequently, the MIC of ZnO NPs and TiO 2 NPs in these persister cells was assessed using the microdilution method. Furthermore, the effects of nanoparticles on the expression levels of biofilm‐associated genes were analyzed using real‐time polymer chain reaction (PCR). The MIC values for colistin, ZnO, and TiO 2 were determined at 2, 12.5, and 6.25 μg/mL, respectively. In the presence of nanoparticles, biofilm formation decreased. Real‐time PCR results showed the messenger RNA (mRNA) level of mrkH and fimH were decreased and the expression of luxS and mazF were increased. Biofilm formation of K. pneumoniae ATCC 1383 was inhibited in response to nanoparticles. According to the results of the present study use of nanoparticles may help control multidrug‐resistant (MDR) infections in hospitalized patients.