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Background <p><i>Staphylococcus aureus</i> is a major bacterial pathogen responsible for a wide range of infections in humans. The emergence of antibiotic-resistant strains, such as MRSA, has created an urgent need for alternative therapeutic strategies. Silver nanoparticles (AgNPs) have emerged as promising antimicrobial agents; however, their effects on key virulence factors, such as α-hemolysin (<i>Hla</i>), have not been fully characterized.</p> Objective <p>This study aimed to isolate <i>S. aureus</i> from clinical samples, synthesize AgNPs, and evaluate their antibacterial activity and ability to inhibit the expression of <i>Hla</i> virulence genes.</p> Methodology <p>A total of 250 clinical samples (urine, burns, and sputum) were collected. <i>S. aureus</i> was confirmed by culture, biochemical reactions, the API20 system, Vitek2, and PCR. The morphology and characterization of the AgNPs were prepared using the chemical reduction method and characterized using UV-vis spectroscopy, SEM, XRD, and FT-IR.</p> Results <p>Among the 250 specimens screened, 44 (17.6%) harbored <i>S. aureus</i>, and the isolation rates were similar regardless of the sample type. The antibacterial activity of AgNPs ranged up to 14.41&#xa0;mm inhibition zone was impressive. The MIC and MBC of AgNPs were determined to be 8 and 64&#xa0;µg/mL, respectively. The expression of <i>Hla</i> gene was also downregulated in the AgNP group compared to that in the untreated control group, according to real-time PCR data.</p> Conclusion <p>Chemically synthesized AgNPs exhibited potent antibacterial and anti-virulence activities against clinical <i>S. aureus</i> isolates and significantly suppressed <i>Hla</i> gene expression. This dual action highlights their potential as therapeutic agents against <i>S. aureus</i> infections, warranting further investigation of their mechanisms of action.</p>

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Inhibitory activity of silver nanoparticles on Staphylococcus aureus growth and α-hemolysin gene expression

  • 期刊论文

  • 发表日期：

    2026年4月2日

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  • Al-Hasan Ali Yousif Al-Abayechi,
  • Meethaq Sattar Abood,
  • Zehra Can Karahan,
  • Mazin Yashkur Zaki AL-Khairo

摘要

Background

Staphylococcus aureus is a major bacterial pathogen responsible for a wide range of infections in humans. The emergence of antibiotic-resistant strains, such as MRSA, has created an urgent need for alternative therapeutic strategies. Silver nanoparticles (AgNPs) have emerged as promising antimicrobial agents; however, their effects on key virulence factors, such as α-hemolysin (Hla), have not been fully characterized.

Objective

This study aimed to isolate S. aureus from clinical samples, synthesize AgNPs, and evaluate their antibacterial activity and ability to inhibit the expression of Hla virulence genes.

Methodology

A total of 250 clinical samples (urine, burns, and sputum) were collected. S. aureus was confirmed by culture, biochemical reactions, the API20 system, Vitek2, and PCR. The morphology and characterization of the AgNPs were prepared using the chemical reduction method and characterized using UV-vis spectroscopy, SEM, XRD, and FT-IR.

Results

Among the 250 specimens screened, 44 (17.6%) harbored S. aureus, and the isolation rates were similar regardless of the sample type. The antibacterial activity of AgNPs ranged up to 14.41 mm inhibition zone was impressive. The MIC and MBC of AgNPs were determined to be 8 and 64 µg/mL, respectively. The expression of Hla gene was also downregulated in the AgNP group compared to that in the untreated control group, according to real-time PCR data.

Conclusion

Chemically synthesized AgNPs exhibited potent antibacterial and anti-virulence activities against clinical S. aureus isolates and significantly suppressed Hla gene expression. This dual action highlights their potential as therapeutic agents against S. aureus infections, warranting further investigation of their mechanisms of action.