Volume 17, Number 3, September 2005
| | Bactericidal Efficacy of Ultraviolet Irradiation on Staphylococcus aureus |
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Karlina Hardjawinata, Rina Setiawati, Warta Dewi
Department of Oral Biology, Faculty of Dentistry, Padjadjaran University, Bandung, Indonesia
Abstract
Objective: To determine the bactericidal effect of ultraviolet radiation on Staphylococcus aureus air contaminant for preventing airborne transmission.
Materials and Methods: The air of a dental clinic was sampled on settling plates to isolate Staphylococcus aureus. The suspension of Staphylococcus aureus was irradiated with a 6-W ultraviolet lamp after 5, 10, 15, and 30 minutes, and 1, 2, 3, 4, and 24 hours. After every exposure time, 0.1 ml suspension was taken with a pipette and cultured on a sterile nutrient agar plate. This process was repeated by culturing 0.1 ml of Staphylococcus aureus suspension without ultraviolet radiation for a control. All cultures were incubated overnight at 37ºC, and the developed colonies were counted with a Stuart electrical bacteria colony counter.
Results: Ultraviolet radiation inhibited 89.1% of the colonies after 5 minutes, and 89.6% after 10 minutes. The number of colonies undergoing division diminished with longer irradiation times, and all bacteria were destroyed after 3 to 4 hours of radiation. Staphylococcus aureus suspension without radiation showed an increase in 6.7% of the colonies after 5 minutes and an increase of 117.9% after 4 hours. A greater number of colony-forming units developed with longer exposure times.
Conclusions: Ultraviolet radiation has a bactericidal effect on Staphylococcus aureus, even after exposure for 5 minutes. Therefore, ultraviolet radiation could be used to control the airborne transmission of Staphylococcus aureus in treatment areas such as dental clinics.
Key words: Staphylococcus aureus, Ultraviolet rays
Asian J Oral Maxillofac Surg. 2005;17:157-161.
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