Disinfectants antimicrobial activity

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

Povidone—iodine is a brown, water-soluble powder containing approximately 10% iodine. However, the amount of free iodine, which is responsible for the antimicrobial activity, is low in a concentrated solution, but is released as the solution is diluted (41). Concentrated solutions have actually been contaminated with bacteria (42). For use as an antiseptic, povidine—iodine is diluted with water or alcohol to a concentration of 1% iodine. Detergents are added if it is used as a surgical scmb. lodophors are important as broad-spectmm antiseptics for the skin, although they do not have the persistent action of some other antiseptics. They are also used as disinfectants for clinical thermometers that have been used by tuberculous patients, for surface disinfection of tables, etc, and for clean equipment in hospitals, food plants, and dairies, much as chlorine disinfectants are used. 

Alcohols, particularly ethanol [64-17-5] and 2-propanol [67-63-9] are important disinfectants and antiseptics. In the aUphatic series of straight-chain alcohols, the antimicrobial activity increases with increasing molecular weight up to a maximum, depending on the organism tested. For Staphylococcus aureus the maximum activity occurs using amyl alcohol [71-41-0], for Salmonella typhosa, octyl alcohol [111-87-5], CgH gO (43) ioT Mycobacterium tuberculosis... 

Because of lower toxicity and high antimicrobial activity, the phenols having the greatest use in disinfections are o-phenylphenol (Dowicide 1) [90-43-7J, C 2H qO i9-benzyl-/)-chlorophenol (Santophen 1) [120-32-1J, C H CIO and -Z fZ-amylphenol [80-46-6] They possess similar general... 

Inorganic Acids. Strong inorganic acids have little antimicrobial activity in themselves but inhibit microorganism growth by lowering the pH. Disinfectant toilet bowl cleaners that contain 9.5% HCl or more are antimicrobial. Carbonic acid [463-79-6] in soft drinks provides some antibacterial preservation. Sulfurous acid [7782-99-2] is an effective preservative used to preserve wines (see Wine), fmit juices (qv), and dried fmits. 

Whereas tests (186) indicated that ampholytes were effective in skin cleansing for preoperative use, for wound cleansing, and as an antiseptic in the oral cavity (187), as well as other medical appHcations, the food and beverage industries have proved to be the principal employers of these compounds. Ampholytes are used as sanitizers and disinfectants, not as food preservatives. Low toxicity, absence of skin irritation, and noncorrosiveness, along with antimicrobial activity, has given ampholytes acceptance in dairies, meat plants, and the brewing and soft drink industries. These disinfectants have been manufactured and distributed in Europe and Japan, but not in the United States. 

Of the other peroxygen compounds with antimicrobial activity, potassium monoperoxysulphate is the main product marketed for disinfectant use. It is used for body fluid spillages and equipment contaminated with body fluids, but its activity against mycobacteria and some viruses is limited. 

The phenols from the higher boiling point fractions have greater antimicrobial activity but must be formulated so as to overcome their poor solubility. A range of solubilized and emulsified phenolic disinfectants are available including the clear soluble fluids,... 

Many derivatives of phenol are now made by a synthetic process. Homologous series of substituted derivatives have been prepared and tested for antimicrobial activity. A combination of alkyl substitution and halogenation has produced useful derivatives including clorinated phenols which are constituents of a number of proprietary disinfectants. Two ofthe most widely used derivatives are/ -chloro-m-cresol (4-chloro-3-methylphenol, chlorocresol, Fig. 10.7C) which is mostly employed as a preservative at a concentration of 0.1%, and / -chloro-m-xylenol (4-chloro-3,5-dimethylphenol, chloroxylenol. Fig. 10.7C) which is used for skin disinfection, although less than formerly. Chloroxylenol is sparingly soluble in water and must be solubihzed, for example in a suitable soap solution in conjunction with terpineol or pine oil. Its antimicrobial capacity is weak and is reduced by the presence of organic matter. 

As is apparent from the above information, there is no ideal disinfectant, antiseptic or preservative. All chemical agents have their limitations either in terms of their antimicrobial activity, resistance to organic matter, stability, incompatibility, irritancy, toxicity or corrosivity. To overcome the limitations of an individual agent, formulations consisting of combinations of agents are available. For example, ethanol has been combined with chlorhexidine and iodine to produce more active preparations. The combination of chlorhexidine and cetrimide is also considered to improve activity. QACs and phenols have been combined with glutaraldehyde so that the same effect can be achieved with lower, less irritant concentrations of glutaraldehyde. Some... 

Method for determination of the antimicrobial activity ofQAC disinfectant formulations. BS 6471 1984 [1994]. 

Reybrouck G. (1992) The evaluation of the antimicrobial activity of disinfectants. In Principles and Practice of Disinfection, Preservation and Sterilization (eds A.D. Russell, W.B. Hugo G.A.J. Ayliffe), 2nd edn, pp. 114-133. Oxford Blackwell Scientific Publications. 

The most widely used and effective disinfectant solutions are based on iodine (iodophor) with concentrations ranging between 0.05% and 0.1%, but sometimes higher concentrations are recommended. Other agents such as chlorhexidine or chlorine dioxide, peroxide, sodium chloride and lactic acid may also be effective (Wilson et al., 1997) but are not common. Recent trials show positive effects of aloe vera-based dipping agents (Leon et al., 2004). One problem of iodine containing products is their low pH value (<4.0), which is necessary for their antimicrobial activity (Hansen and Hamann, 2003). 

The purpose is to assure that the recommended disinfectant has the acceptable relative standard of the antimicrobial activity using the membrane filtration technique and surface testing technique. 

The follow information (italics) is from Russell, A. D., Chapter 3. Principles of Antimicrobial Activity and Resistance, Disinfection, Sterilization, and Preservation, Block, S. S., editor., 5th ed., Lippincott, Williams and Wilkins, New York, 2001 ... 

Isopropyl alcohol has some antimicrobial activity (see Section 10) and a 70% v/v aqueous solution is used as a topical disinfectant. Therapeutically, isopropyl alcohol has been investigated for the treatment of postoperative nausea or vomiting,... 

Key terms such as disinfection, sterilization and preservation are defined in Chapter 17 but other terms are often employed to describe the antimicrobial activity of agents. Hence, terms such as biocidal, bactericidal, virucidal and fungicidal describe a killing activity, whereas bacteriostatic and fungistatic refer to inhibition of growth of the organism... 

Kampf, G., Rudolf, M., Labadie, J-C. Barrett, S. P. (2002) Spectrum of antimicrobial activity and user acceptability of the hand disinfectant agent Sterillium Gel. J ELosp Infect, 52,141—147. 

Phenols (Fig. 17.7) are widely used as disinfectants and preservatives. They have good antimicrobial activity and are rapidly bactericidal but generally are not sporicidal. Their activity is markedly diminished by dilution and is also reduced by organic matter. They are more active at acid pH. The main disadvantages of phenols are their caustic effect on skin and tissues and their systemic toxicity. The... 

---