Effects of Different Times of Glutaraldehyde ۲% on Bacillus subtilis Spores (In Vitro)

Background: Due to the importance of disinfectant and sterilization of dental instruments, in total, ۱۴%–۲۸% of dentists, ۱۳% of assistants, and ۱۷% of healthcare workers (HCWs) have been subjected to the hepatitis B virus (HBV), and more than ۲۰۰ healthcare providers (HCPs) pass away annually in the United States from HBV infection catched from their work place. Objective: This study examined the effects of glutaraldehyde ۲% on Bacillus subtilis spores in the Surgery and Microbiology Department of the Dental Branch of Islamic Azad University. Methods: This experimental research evaluated a total of ۵۸ samples, one called first evidence (pure glutaraldehyde not exposed to spore suspension), one called second evidence (spore suspension not exposed to glutaraldehyde), and ۴۰ samples including a suspension with a normal turbidity of ۱×۱۰۸ CFU/mL according to ۰.۵ McFarland with exposure to glutaraldehyde ۲%. Experiments were done in time intervals of ۱۰, ۱۵, ۲۰, ۲۵, ۳۰, ۴۰, and ۶۰ minutes with ۸ repeats. In all times, a B. subtilis spore suspension was used as evidence and also as a case. Results: This research was done on ۵۸ samples. The results showed that in the ۱۰th minute there were ۱۰۲ colonies, ۱۸.۶ ± ۳.۴ in the ۱۵th minute, ۶.۲ ± ۱.۴ in the ۲۰th minute, ۲.۱ ± ۰.۸ in the ۲۵th minute, and no colonies after ۳۰ minutes. In an overall observation, it was seen that there were more colonies in the first ۱۰ minutes, and from ۱۵ to ۲۰ minutes, this amount significantly decreased; after ۳۰ minutes in each ۸ repeats, the growth of colonies had stopped completely, while in the evidence samples, B. subtilis spores grew. Conclusion: It seems that the density of ۲% glutaraldehyde in ۳۰ minutes time was enough to destroy the spores of B. subtilis.

Keywords:

Glutaraldehyde , Bacillus Subtilis Spores , Disinfection