Ultrasonic Synergistic Effects in Liquid-Phase Chemical Sterilization

Abstract

New methods of sterilization employing a chemical with moderate heat and ultrasonic energy have been devised. Inactivation of high-density bacterial spore suspensions is achieved by treatment with low concentration aqueous acid glutaraldehyde solutions at temperatures above or about 54 C. Low (20 kHz) or high (250 kHz) frequency ultrasonic energy is synergistic with glutaraldehyde. Rapid inactivation may also be achieved by using ultrasonic energy and aqueous alkalinized glutaraldehyde solutions at low (25 C) or moderate (55 C) temperatures. If compared to present room temperature techniques, "surface sterilization" time for contaminated objects can be reduced from hours to minutes.

Synergism between Ultrasonic Waves and Hydrogen Peroxide in the Killing of Micro‐organisms

“…In general, our results agree with those reported by Shaner (1964), Perkulis et al (1970) and Sierra & Boucher (1971) who found that the combination of ultrasonic waves and disinfectants was able to kill various vegetative organisms, spores and yeasts in a very short time compared with the effect of the disinfectant alone. These workers found that ultrasonic waves increased the permeability of the cell membrane to disinfectants, increased the potency of the disinfectant solution and accelerated the rate of chemical reaction between the disinfectant and the cell components.…”

“…aureus, Bacillus subtilis, Aspergillus niger or Saccharoniyces cerevisiae could be sterilized by sonication for 2 rnin in benzalkonium chloride solution (1 : 1000). Further, Sierra & Boucher (1971) reported that suspensions of B. subtilis spores were non-viable after sonication in 1 % (w/v) glutaraldehyde solution for 5 min whereas sterilization with the germicide alone required treatment for 60 min. Accordingly, it was decided to investigate the synergistic effect of ultrasonic waves and H202 on different micro-organisms.…”

Antimicrobial Activity, Uses and Mechanism of Action of Glutaraldehyde

“…Using the Association of Official Analytical Chemists (AOAC) sporicidal test and vacuum-dried spores, he found that 10 h was necessary for complete kill. Other work, however, using similar time-survivor measurements and aqueous suspensions of B.subtilis spores, indicated that a 3 h contact period gave approximately a six log drop in viable count (Sierra & Boucher 1971;Kelsey et al 1974;Forsyth 1975;Miner et al 1977). Vegetative bacteria are readily susceptible to the action of glutaraldehyde.…”

Inactivation ofBacillus subtilisspores by combining ultrasonic waves under pressure and mild heat treatment

“…The use of ultrasound has been suggested for disinfection and food preservation but its limited lethal effect on bacterial spores (Berger and Marr 1960) has discouraged any attempt at using it as a sterilization procedure. The combination of ultrasound with, for example, chemical treatment (Sierra and Boucher 1971;Ahmed and Russell 1975;Lillard 1993), heat treatment (Burgos et al 1972;García et al 1989) or ionizing radiation (Dharkar 1964), increased the lethal effect of ultrasound on vegetative cells, but the inactivation of bacterial spores was still low.…”