Effect of Ag2O and TiO2 Nanoparticles on rsbA Gene Expression Related to Swarming Phenomena in Proteusspp.

Abstract

The rsbA gene is a regulatory gene associated with the swarming motility in Proteusspecies, which is linked to pathogenicity and survival mechanisms during urinary tract infections.The study aims to investigate the impact of silver oxide (Ag₂O) and titanium dioxide (TiO₂) nanoparticles on the rsbA gene expression associated with swarming phenomena in Proteus spp. A total of 109 urine specimens were collected from patients infected with urinary tract infections attending different hospitals in Baghdad, Iraq. Twenty-nine isolates were identified as Proteusmirabilis, while eleven bacterial isolates were identified as Proteusvulgaris. The Vitek-2 compact system was employed in order to confirm the primary bacterial identification. The bacterial ability for swarming movement was assessed using the central spot inoculation method for all Proteusspp. isolates. The minimal inhibitory concentration was determined using the agar dilution method; the results indicated that both P. vulgaris and P. mirabilis isolates were inhibited by Ag₂O nanoparticles at a MIC value of 10 mg/ml; on the other hand, TiO₂ nanoparticles inhibited the growth at 15 mg/ml. The disk diffusion assay was used to test antibiotic susceptibility. The results showed that about 60% of P. vulgaris and P. mirabilis isolates were not sensitive to ceftriaxone. Meropenem, on the other hand, was the most effective drug against P. vulgaris and P. mirabilis, with an 80% sensitivity rate. The ability of ten Proteus isolates for swarming movement in the presence of sub-inhibitory concentrations of nanoparticles (10 mg/ml and 5 mg/ml for TiO₂ and Ag₂O, respectively) was evaluated, and the results revealed that the swarming movement of all these isolates was decreased. rsbA gene expression was measured for ten Proteusspp. isolates before and after the addition of sub-inhibitory concentrations of nanoparticles using the qRT-PCR technique, and the results showed a decrease in the fold change values in most of the selected isolates, which refers to the downregulation effect on the rsbA gene related to swarming phenomena.The present study concluded that both Ag₂O and TiO₂ nanoparticles exhibit strong antibacterial activity against Proteusvulgaris and Proteusmirabilis, significantly reducing their swarming diameter.