مقالات پذیرفته شده در هفتمین کنگره بین المللی زیست پزشکی
Enhancing Photodynamic Inactivation Efficacy Against Acinetobacter baumannii Using an Efflux Pump Inhibitor
Enhancing Photodynamic Inactivation Efficacy Against Acinetobacter baumannii Using an Efflux Pump Inhibitor
Zahra Shirdel,1Zahra Fekrirad,2,*
1. Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran 2. Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran
Introduction: Acinetobacter baumannii is a Gram-negative pathogen which is resistant to multiple drugs (MDR) and often causes hospital-acquired infections, particularly in intensive care units (ICUs) and in patients with compromised immune systems. Infections caused by A. baumannii include pneumonia, meningitis, bloodstream infections, and surgical site infections. One effective approach to combat antibiotic-resistant pathogens is photodynamic inactivation. In this method, a non-toxic dye called a photosensitizer is exposed to low-intensity visible light or laser which generates cytotoxic reactive oxygen species or free radicals. During photodynamic inactivation, some of the photosensitizers are pumped out of the cell by efflux pumps, reducing the antimicrobial effect of the process. The objective of this study was to enhance the efficacy of antibiotic-resistant photodynamic inactivation using verapamil as an efflux pump inhibitor
Methods: Erythrosine B was used as the photosensitizing agent. The light source utilized was a 530 nm diode laser with a maximum output power of 25 mW. The bacterial suspensions were incubated with erythrosine B (50 μM) and verapamil (10 μg/ml) in the absence of light, at room temperature, for 20 minutes. Subsequently, the treated cells were exposed to the diode laser for a period of 30 minutes. Following laser exposure, the bacteria were enumerated through a tenfold serial dilution method. Controls included bacterial suspensions exposed to light alone, bacterial suspensions incubated with 0.9% sterile saline in the dark (untreated), bacterial suspensions incubated with EB (50 μM) alone or verapamil (10 μg/ml) alone, and EB (50 μM) + verapamil (10 μg/ml) in the dark.
Results: Simultaneous photodynamic inactivation using verapamil and erythrosine B dye was capable of reducing the number of live A. baumannii bacteria by more than 3 logs and inducing a lethal effect. Meanwhile, photodynamic inactivation using the dye alone reduced the bacterial count by less than 1 log and had only a sub-lethal effect.
Conclusion: The findings demonstrated that the efflux pump inhibitor verapamil led to an increase in the effective concentration of the dye in the bacterial cytoplasm and enhanced the bactericidal effect of photodynamic inactivation compared to using the photosensitizer alone.