Sporicidal agents

Russell A.D. (1990) Bacterial spores and chemical sporicidal agents. Clin Microbiol Rev, 3, 99-119. Russell A.D. (1996) Activity of biocides ogidn X mycoh CtQno.. JApplBacteriol Symp Suppl, 81, 87S-lOlS. 

Other Standard Precautions After an invasive procedure or autopsy, all instruments used and locations need to be disinfected with a sporicidal agent. Recommended for use is... 

Selenium sulfide is a cytostatic and sporicidal agent available without prescription in a variety of shampoos and lotions for treatment of scalp seborrheic dermatitis. Higher concentrations are available by prescription for the treatment of pityriasis versicolor, which is caused by the yeast M. furfur, and tinea capitis. 

Rutala (1996) prepared a comprehensive set of guidelines for sporicidal agents to combat bacterial spores and in 1996 provided guidelines for the selection of topical and other antimicrobial agents. 

The product contact surfaces in this environment are typically removed for cleaning however, in some installations, the sterilization, transfer, and reinstallation of the component feed hoppers present such difficulty that these systems are decontaminated in situ with a sporicidal agent, rather than removed after each use. These units should still be removed for cleaning and sterilization on a validated periodic basis to prevent the buildup of residues that might impact their in-situ decontamination or create particle control problems. All other product contact surfaces should be sterilized prior to each use. Nonsterilized items should not be allowed to enter the ISO 5 portion of the fill zone, and sanitization is essential for all nonproduct surfaces in the fill zone, as well as the surrounding background environment. 

Russell, A. D. (1990) Bacterial sporesand chemical sporicidal agents. Clin Microbiol Rev, 3,99-119. 

Relatively few antibacterial agents are actively sporicidal [108-110]. Many agents may be inhibitory to germination or outgrowth of bacterial spores, yet not necessarily kill them [108]. Actively sporicidal agents include the aldehydes [111], although it must be noted that much higher concentrations are required than for bactericidal activity [49]. 

Glutaraldehyde has a mode of action similar to formaldehyde but is less volatile and less toxic to people. It is a relatively powerfixl sporicidal agent and a virucidal agent effective against both lipophilic and hydrophilic viruses. It is frequently used in applications where the object to be disinfected will be used clinically, such as for sterilization of endoscopic equipment or for preparation of heart valves for surgical implants. Its effectiveness... 

Germicide destroys microorganisms, with emphasis on pathogenic agents, called germs. It maybe a disinfectant or an antiseptic. It does not claim to be a sporicide. 

Bacterial spores are the most resistant of all microbial forms to chemical treatment. The majority of antimicrobial agents have no useful sporicidal action, with the exception of the aldehydes, halogens and peroxygen compounds. Such chemicals are sometimes used as an alternative to physical methods for sterilization ofheat sensitive equipment. In these circumstances, correct usage of the agent is of paramount importance since safety margins are lower in comparison with physical methods of sterilization (Chapter 20). 

Iodophors are complexes of iodine with a surface-active agent such as polyvinyl pyrrolidone (PVP povidone-iodine). Iodophors retain the activity of iodine. They kill vegetative bacteria, mycobacteria, fungi, and lipid-containing viruses. They may be sporicidal upon prolonged exposure. Iodophors can be used as antiseptics or disinfectants, the latter containing more iodine. The amount of free iodine is low, but it is released as the solution is diluted. An iodophor solution must be diluted according to the manufacturer s directions to obtain full activity. 

Antibacterial agent Bactericidal Sporicidal (%wt/vol) Bacteriostatic Sporostatic... 

Yeasts (including Candida albicans) and dermatophytes are usually sensitive, although chlorhexidine fungicidal action is subject to species variation, as are other agents. The effective concentrations of chlorhexidine agents for bactericidal, bacteriostatic, sporicidal, and sporostatic organisms are listed in Table 2.13. 

Russell (1990) reported the outer cellular membrane of the bacteria cell, which is understood as well as the more complex structure of the spore membrane -agents that are bacteriostatic and bacteriocide as well as sporostatic and sporicidal. 

A very commonly used disinfectant is ethanol-water in neutral or, preferably, in acidic conditions. Aqueous ethanol displays its best germicidal efficiency at a concentration of 60 to 70%. However, the most commonly used concentration in industry is about 20%, because higher concentrations require specific explosion-proof facilities. At 20%, ethanol has no sporicidal effect, its effect on viral inactivation is only partial and it does not destroy pyrogens (it only tends to destabilize large molecular aggregates of lipopolysaccharide molecules). For these reasons, 20% ethanol can only be considered as a bacteriostatic agent. Mixtures of ethanol with bases or acids are somewhat more sporicidal, but are not sufficient to provide sterilization at short incubation times and low temperatures. 

The degree of ionization of acidic and basic antimicrobial agents depends on pH. Some compounds are active only in the unionized state (e.g., phenolics) whereas others are preferentially active as either the anion or cation. It therefore follows that the activity of a particular concentration of an agent will be enhanced at a pH that favors the formation of the active species. Thus, cationic antibacterials such as acridines and quaternary ammonium compounds are more active under alkaline conditions. Conversely, phenols and benzoic acid are more active in an acid medium. Chlorbutol is less active above pH 5 and unstable above pH 6. Phenylmercuric nitrate is only active at above pH 6 whereas thiomersal is more active under acid conditions. The sporicidal activity of glutaraldehyde is considerably enhanced under alkaline conditions whereas hypochlorites are virtually ineffective at above pH 8. 

Formaldehyde is well established as a bactericidal agent [13], although most of the research has focused on its sporicidal effects [24, 74] which are therefore considered in more detail in the following section. 

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