[Comparison of the bactericidal effects of acid glutaraldehyde and alkaline glutaraldehyde]

Two glutaraldehydes, acid glutaraldehyde (sonacide) and alkaline glutaraldehyde (cidex) were evaluated for their bactericidal effect under different conditions. Two percent acid and alkaline glutaraldehyde could destroy vegetative bacteria and spores in twenty minutes. Less than 2.9 percent residual contamination rate could be achieved after immersing equipment in 0.1 percent acid glutaraldehyde or 0.5 percent alkaline glutaraldehyde for 30 minutes. Complete sterilization could be obtained by using two percent acid glutaraldehyde, while 0.5 percent residual contamination was noted after equipment had been immersed in two percent alkaline glutaraldehyde for one month. Acid glutaraldehyde could destroy bacteria completely in 30 minutes even after the solution had been standing for one month, but alkaline glutaraldehyde had an 11.4 to 26.9 percent residual rate. There were no deleterious effects on metal equipment after immersing for 14 days, but yellowish discoloration and hardening were observed on plastic and rubber equipment. It is concluded that both of these two glutaraldehydes are effective bactericides, but acid glutaraldehyde is more effective even after standing for one month or after dilution.