A New Synergized Glutaraldehyde-Phenate Sterilizing Solution and Concentrated Disinfectant

Research leading to the development of Sporicidin, a new (synergized glutaraldehyde-phenate) sterilant and concentrated disinfectant, is reported. Microbial evalua tion and shelf life testing of the new formulation was done using AO AC tests?Use-Dilution, Sporicidal, Tuberculo cidal?and the E.P.A. Virucidal Test. Full-strength Sporicidin sterilizes (is sporicidal) in 6Yi hours at both 20C and 25C, and disinfects in 1-2 minutes. When diluted with 15 parts of tap water, Sporicidin is tuberculocidal, virucidal, and germicidal in 10 minutes, qualifying as a hospital disinfectant that will not "yellow" the hands or skin. The shelf life of activated Sporidicin, full strength or diluted 1 in 16, is 30 days. According to the data pre sented, which were the basis of E.P.A. registrations, Sporicidin is: (a) the fastest glutaraldehyde sterilant at room temperature, and (b) the only glutaraldehyde product that can be diluted below 2% and still qualify as a hospital disinfectant. (Infect Control 1981; 2(l):26-30.) INTRODUCTION AND DEFINITION OF TERMS There is always a need for efficient chemosterilization methods for dental office, hospital, and industrial applications. Instruments and equipment in repeated use require sterilizing and disinfecting procedures that are safe, effective, and rapid. Chemicals that sterilize and disinfect at room temperature ("cold" solutions) have obvious significant advantages over methods that require heat. These advantages include convenience of use, ability to sterilize and disinfect instruments thatcannot withstand high temperatures, safety to users, relative noncorrosive ness, and the fact that they do not require cumbersome equipment or a large investment of capital. Sterilizing and disinfecting solutions are used in virtually every medical and dental facility in the world. The terms sterilization and disinfection are sometimes confused. Sterilization is the highest form of disinfection. From: Milligan College, Milligan College, Tennessee. Reprint requests: Eddie D. Leach, Ph.D., Professor of Biology, Milligan College, Milligan College, TN 37682. Sterilization is defined as the destruction of all forms of microbial life, including bacteria, fungi, viruses, and spores. Disinfection, which is the destruction of all disease-causing organisms except spores, may be accom plished with numerous chemical solutions. But, to assure sterilization, only a sporicidal agent may be used. Spores represent the form of microbial life most highly resistant to present methods of sterilization, including heat, steam under pressure, gas, irradiation, and chemicals.1'2 TYPES OF CHEMICAL STERILANTS AND DISINFECTANTS There are many antimicrobial agents, but few are sporicidal and usable as chemosterilizers.3'4 Health facilities have been using quaternary ammonium salts ("quats"). These are relatively inexpensive, but are not fully effective against some types of organisms, such as Pseudomonas,5 other gram-negative bacteria,6 and the tubercle bacillus.7 Also, soap and other anionic agents inactivate the "quats."8 For many years formaldehyde solutions were used in hospitals to sterilize instruments and equipment. This agent had several disadvantages. Most important of these were its toxicity and the time required for sterilization. Up to 24 hours of immersion was necessary, much too long for convenient use.9 Too large an inventory of instruments was needed to cover the sterilization period. Formaldehyde vapors caused eye and upper respiratory tract irritation and the solution was painful to the user.10 For these reasons formaldehyde was undesirable as a hospital disinfectant and sterilant. During the early 1960s alkaline glutaraldehyde was introduced, and became popular as a sterilizing/disinfect ing solution.11'12 It was found to be less toxic and more effective than formaldehyde as a disinfectant.13'14 Gluta raldehyde, with an acid pH, had long been known as a disinfectant. However, its sporicidal properties were not demonstrated until the solution was made alkaline.15 Glutaraldehyde is relatively stable when at an acid pH (approximately 3.7 ? 4.5). In this form, it has an indefinite shelf life, but it is not rapidly sporicidal at room temperature. When buffering agents raise the pH of glutaraldehyde from acid to alkaline its sporicidal quality appears, but 26 Sterilant/Concentrated Disinfectant/Leach This content downloaded from 157.55.39.162 on Thu, 11 Aug 2016 06:29:25 UTC All use subject to http://about.jstor.org/terms there is a reduction in the shelf life of the solution because of the polymerization of the glutaraldehyde molecules at these higher (alkaline) pH levels. This polymerization blocks the active sites of the glutaraldehyde molecule that are responsible for its biocidal activity. The rate of polymerization increases as the pH is raised.16 For example, at a pH of 8.5, 2% glutaraldehyde maintains its sporicidal activity for only two weeks.12 Attempts to increase the shelf life of the buffered glutaraldehyde solution were successful when the pH of the alkaline glutaraldehyde was lowered from 8.5 into the range of 7.5?8.0.17 In addition, there were attempts to improve the antimicrobial efficacy and to increase the sporicidal activity at elevated temperatures (60C) for the sterilization procedure,18'19 but these removed it from the category of "cold" sterilization. Glutaraldehyde is almost universally recognized as the most effective disinfectant and room temperature sterilizing solution in its alkaline form, i.e., when it is buffered to an alkaline pH. The original glutaraldehyde product that existed ten years ago was an improvement over the formaldehyde solutions used previously, but it had certain dis advantages: 1. Short shelflife (two weeks at pH 8.5) 2. Long contact time required for sterilization (10 hours) 5. Need to use gloves to prevent "yellowing" of the hands 4. Vapors irritated the nasal passages and eyes 5. Relatively expensive when used as a disinfectant.