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The Effect of Zinc Oxide Nanoparticles on The Expression of Genes Involved in the Production of Pseudomonas Aeruginosa Biofilm Isolated from Cystic Fibrosis Patients
Mona Konkuri, Yousef Erfani, Sharmin Kharrazi, Setareh Haghighat,
Volume 18, Issue 6 (2-2025)
Abstract
Background and Aim: Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that is often found in patients with cystic fibrosis, burn wounds, immunodeficiency, and chronic obstructive pulmonary disorder. In addition, P. aeruginosa is also considered one of the most important pathogens causing hospital infections, widely found in medical devices (ventilation), because they tend to grow on moist surfaces. Considering the importance of cystic fibrosis treatment and the ability of P. aeruginosa to form biofilms, this study examines the effect of nano zinc oxide particle on the expression of genes associated in biofilm formation in isolated P. aeruginosa from cystic fibrosis patients.
Materials and Methods: Sputum and throat samples from 150 patients with cystic fibrosis were cultured on MacConkey agar culture medium. After an overnight incubation, the grown colonies were determined and confirmed by biochemical tests. An antibiotic sensitivity test by disk diffusion method (Kirby –bauer) were used to determine the antibiotic susceptibility pattern. Zinc nanoparticles were synthesized following established protocols and evaluated using scanning electron microscopy (SEM). The multi-antibiotic-resistant strains were inoculated with 16 µg/ml of 2 nm ZnO nanoparticles and inhibition zone were meseared. The impact of these nanoparticles on the expression levels of gas, retS, lasR, and rhlR genes was assessed using Real-Time PCR. The relative gene expression level was determined using the gene expression method: (ΔΔCt-2).
Results: Of the total 150 samples, 73 (48.66%) isolates were identified as P. aeruginosa. All P. aeruginosa isolates were resistant to selected antibiotics. SEM evaluation indicated that the synthesized nanoparticles had an average size of approximately 4 ± 0.44 nm. The results from the Real-Time PCR tests showed a decrease in the expression of the gacA, retS, lasR, and rhlR genes in the presence of the zinc nanoparticles in P. aeruginosa strains. The most significant reduction in gene expression was observed for the rhlR gene, whereas the least reduction was noted for the retS gene.
Conclusion: The use of nano zinc oxide can eliminate Pseudomonas aeruginosa infection by preventing biofilm formation and providing better treatment results for cystic fibrosis patients with lung infection.

Studying the Frequency of Stenotrophomonas Maltophilia from Different Clinical Samples and Determining the Antimicrobial Susceptibility Pattern of Isolates
Sam Torabinejad, Mohadeseh Ostovari Deilamani, Farhad Nikkhahi, Reza Bigverdi, Fatemeh Fardsanei,
Volume 19, Issue 2 (7-2025)
Abstract
Background and Aim: Stenotrophomonas maltophilia is a non-fermentative Gram-negative bacillus and the third most common cause of hospital-acquired infections. Treatment of infections caused by this bacterium has not always been successful due to its high potential for multiple resistance to a wide range of antibiotics and the formation of biofilms. Obviously, accurate and timely diagnosis of bacterial agents causing hospital-acquired infections and determination of the microbial susceptibility pattern of isolates can make a significant contribution to infection control in hospitals. Therefore, the aim of this study was to determine the frequency of Stenotrophomonas in different clinical samples and to determine the biofilm production rate and microbial susceptibility of isolates.
Materials and Methods: In a cross-sectional descriptive study, non-fermentative Gram-negative isolates suspected of being Stenotrophomonas maltophilia isolated from different clinical samples from teaching hospitals in Qazvin province were collected and examined from April to March 2023. After phenotypic and molecular confirmation of the isolates using standard methods, the microbial susceptibility pattern of the isolates and the amount of biofilm production were examined using the microplate titer method.
Results: In this study, out of 50 isolates collected, the highest number of isolates were isolated from blood culture (33 isolates) and the lowest number of isolates were isolated from urine samples (1 isolate). Also, the highest frequency of samples was reported from the emergency department with 32 samples (63.8%) and the lowest frequency was reported from the ENT and oncology departments, each with 1 sample (0.8%). All isolates were 100% resistant to imipenem and meropenem due to the inherent resistance of this bacterium to carbapenems, which was a confirmation in the identification of this bacterium. The highest sensitivity to the antibiotics levofloxacin, minocycline and cotrimoxazole was observed with a frequency of 90%, 88% and 84%, respectively. The highest resistance to the antibiotic ceftazidime was observed, which was reported as 88%. In this study, 70% of the strains produced strong biofilms.
Conclusion: In this study, we saw an increase in hospital infections caused by Stenotrophomonas maltophilia in clinical samples of Qazvin hospitals. Knowledge of the frequency of opportunistic pathogens causing hospital infections and the microbial sensitivity of isolates leads to control of infections caused by these pathogens, proper treatment of infections and reduction of mortality in hospitalized patients. Fortunately, in this study, the isolates had high sensitivity to fluoroquinolone family antibiotics and antimetabolites.

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