Disinfection was first introduced by Lister who introduced "carbolic acid" (phenol), the first disinfectant. Today disinfectants are widely used in the health care, food and pharmaceutical sectors to prevent unwanted microorganisms from causing disease.
Disinfectant chemicals act to disrupt significant cellular structures or processes in order to kill or eliminate microorganisms. A number of different chemicals have been commercialized as disinfectants, as shown in Table 1.
Table 1. Classes of Disinfectant Chemicals
Sterilization & Disinfection
Sterilization is defined as the elimination of all microbial life.
Generally, a commercially available disinfectant will exhibit the ability to reduce microbial contamination by several orders of magnitude in a standard test method in order to be approved for use. In use however, mot all disinfectants exhibit the activity that one would expect based on standardized tests. There are many reasons for this but one of the main points to consider is the carefully controlled conditions of the standard test methods are simply mot the Same as the real world. One well known is the failure of quaternary ammonium compounds in the presence of anionic detergents and, in the case of some formulations, hard water. These conditions disrupt the binding of the quaternary ammonium compounds to the microbial cell membrane.
Figure 1. Microbes from least to most susceptible to disinfection.
With the growth in concern over antibiotic resistance there have been a number of studies attempting to demonstrate a similar resistance to disinfectants in multi-drug resistant bacteria. Studies have shown that in some cases adaptations can occur that provide resistance to low levels of disinfectants however, the levels of disinfectant that these bacteria can "resist" are many times lower than the recommended use levels. Antibiotic resistant bacteria have shown similar levels of reduction in side by Side standard tests as nonresistant bacteria when disinfectants were used at the manufacturer's recommended dilutions. Generally, the resistance of microorganisms to disinfection is due to the existing cellular structures and life cycle adaptations. It is important to read the label carefully and follow the manufacturer's directions to achieve the best results.
Disinfectant rotations are an idea that originated in the Health Care and Pharmaceutical Sectors to deal with the wide variety of microbial challenges that must be prevented from gaining a foot hold in very clean environments. The theory behind disinfectant rotation is that no one disinfectant will be effective against all microbes So rotating between a series of powerful disinfectants will prevent any particular microbe from establishing itself in the facility. They may be of Some benefit in facilities that disinfect on a regular basis but there is no publicly available data to support any particular scheme.
The first step in successful disinfection is to choose a disinfectant that will act on the types of microorganism that is to be eliminated. For example, a quaternary ammonium formulation will not be effective against bacterial spores while a formaldehyde based product would. The next step is to confirm that the disinfectant is compatible with the planned application: it is difficult to disinfect bare wood Structures such as bank barns.
Recently, there concern has been a great deal of concern regarding the effects of "persistent organic chemicals" in the environment. The chemicals in Bio Agri Mix disinfectants are not persistent in the environment.