ANTISEPTICS AND DISINFECTANTS Anca Dana Buzoianu, Corina BocșMaria Neag Educational Objectives What you need to know Define the terms "antiseptic" and "disinfectant" Know the main classes of antiseptics and disinfectants List the representatives of each class Specify the main clinical uses Definition Germicides (antiseptics, disinfectants and preservatives) are biocidal agents that have the property of inactivating / destroying microorganisms. Antiseptics represent the class of antimicrobial substances that, applied to the skin or mucosa, reduce the microbial flora. Disinfectants are substances which, applied to the surfaces of various objects, destroy microorganisms but do not have an effect on bacterial spores. Antiseptics and disinfectants may have bactericidal or bacteriostatic action. This action depends not only on the substance but also on the concentration used. Classification From a chemical point of view, antiseptics and disinfectants are classified in: Alcohols (ethanol, isopropanol) Aldehydes (glutaraldehyde, formaldehyde) Peroxides (hydrogen peroxide, peracetic acid) Biguanides (chlorhexidine) Halogenated compounds: with chlorine (hypochlorous acid, chloramine), with iodine (iodine povidone) Mercury compounds (mercury chloride, thiomersal) Silver compounds (silver nitrate) Zinc compounds (zinc sulphate, zinc oxide) Colorants (ethacridine lactate, methylene blue, gentian violet) Quaternary ammonium compounds (benzalkonium chloride). Alcohols Ethanol, isopropanol and n-propanol are the most commonly used alcohols, both as antiseptics and as disinfectants. Their antimicrobial spectrum is wide, they act on bacteria, viruses, fungi, but their activity on spores is limited. Alcohols inhibit sporulation, but the effect is reversible. For this reason, they are not used for sterilization. In small concentrations, they associate and enhance the activity of other biocides. Alcohols are commonly used for disinfection of surfaces / small objects, in well-ventilated areas as they are flammable. Repeated and prolonged use causes discoloration and degradation of areas where they have been applied. The antimicrobial activity of alcohols decreases significantly when using solutions with a concentration below 50%. The effect is optimal at concentrations between 60% and 90%. The destruction of microorganisms occurs due primarily to membrane proteins and then cellular damage. Ethanol 70% has higher activity compared to isopropyl alcohol. Many preparations used as antiseptics and containing alcohols exist on the market: Official preparations - Solutio iodii spirituosa 2%, Solutio camphorae spirtuosa 10% (ethyl alcohol) Typical preparations - Sanitary alcohol (70% ethyl alcohol), Aseptoderm (2-propanol) etc. Aldehydes Glutaraldehyde is a 5-carbon atoms dialdehyde. It is in the form of a clear, oily liquid, miscible with water, alcohol and other organic solvents. It is available as an aqueous solution of acid ph (3-4). Solutions are used in varying concentrations, from 2% to 70%. Glutaraldehyde is not active against bacterial cells in acidic aqueous solution. Changing the ph of the solution to 7.5 - 8.5 turns it into a biocide solution because at a higher ph several reactive groups are formed at the cell surface (hydroxyl, carbonyl, amino), resulting in a rapid bactericidal effect. The major drawback of alkaline glutaraldehyde solutions is that they only retain their activity for about 14 days, after which they begin to polymerize. Polymerization causes blocking of active sites and biocidal activity decreases. Formaldehyde is an aldehyde used in solution in combination with methanol. It is added to delay the polymerization. It is used as a disinfectant, acting on bacteria, viruses, and spores. Compared to glutaraldehyde, it has slower action. Peroxides Hydrogen Peroxide (H2O2) was discovered by the French chemist Louis J. Thenard in 1818, but it was only after a century that it was able to be produced in pure state and used for medical purposes. Pure hydrogen peroxide is extremely unstable, which is why the 30% concentration (Perhydrol) solution is produced and delivered to the recipients (hospitals, pharmacies) by the pharmaceutical industry. The cytotoxic activity of H2O2 is based on the production of hydroxyl radicals, radicals with increased reactivity. In vitro, these radicals and other oxygenated compounds act as oxidizing agents by reacting with lipids, proteins or nucleic acids. All these reactions can contribute to the antimicrobial effect of hydrogen peroxide. Unlike other biocidal agents, hydrogen peroxide has several advantages: It naturally exists in tissues It produces effervescence (helps clean the wound) Non-toxic compounds result following the decomposition It is cheap. It can be used as: An antiseptic - 3% solution for wounds, 1-3% solution for mouthwash, and more concentrated solutions are used in dermatology, surgery A disinfecting of the surfaces A bleaching agent (pigment spots, teeth, hair). Biguanide Chlorhexidine has been used as an antiseptic since the 1950s. In practice, there it is present under 3 forms: chlorhexidine digluconate, acetate or hydrochloride. As a positively charged molecule, it has the ability to bind to negatively charged cell-site locus. This affects cellular integrity. Depending on the concentration used, chlorhexidine has a bacteriostatic or bactericidal effect. The spectrum of action is broad (aerobic, anaerobic bacteria, virus), but it does not have an effect on spores. The antimicrobial activity should be maintained for at least 48 hours after application to the skin. Unlike the action of povidone- iodine, the action of chlorhexidine is faster and is not influenced by the presence of biological fluids (e.g. Blood). Chlorhexidine is marketed as solutions in different concentrations (0.5% - 4%), with or without the addition of isopropyl alcohol or ethanol. Numerous chlorhexidine preparations are available as otcs. 2% chlorhexidine is recommended by the CDC (Centers for Disease Control and Prevention) as the first line for catheter insertion care. This is more effective than other compounds in preventing colonization at this level. It is also more effective in reducing the rate of systemic infections, a target purpose during patient care. Sometimes allergic reactions to chlorhexidine may be severe, even anaphylactic shock or cardiac arrest. However, these serious reactions are preceded by mild allergic reactions (pruritus, oedema). Therefore, any reaction occurring after the administration of chlorhexidine should not be neglected. In Denmark, it was reported that 9.6% of perioperative allergic reactions are caused by chlorhexidine. Preparations: Dermanios Scrub Clorhexidine 4% - antiseptic soap Maxilsept TA (chlorhexidine digluconate, ethanol) - disinfectant for medical devices and any type of surfaces. Halogenated Compounds Iodine compounds are currently among the most used antiseptics. Iodine has been used to prevent infections and treat injuries for over 150 years. Prior to the discovery of iodine as an element, some plants were used to treat wounds, which subsequently were shown to have increased iodine content. Iodine as an element was discovered in 1811, its bactericidal activity in 1880, but only after 1900 surgeons began to use the compound as a preoperative antiseptic. The iodine is readily dissolved in ethanol or ether to form a dark brown solution, or in chloroform or benzene, to form a violet solution. One of the first antiseptic solutions based on iodine was the Lugol solution (iodurated iodine solution). This solution is prepared from 1% iodine, 2% potassium iodide and distilled water. The bactericidal effect of iodine-povidone is due to free iodine. It acts on the -SH or -OH groups in the structure of the enzymes or proteins of the microorganisms, causing their destruction. Iodine-povidone is a free iodine deposit which determines its constant release. Povidone has the role of binding iodine, thus reducing its irritant potential. Thus, tolerability increases in the skin and mucous membranes. Numerous studies, both clinical and experimental, have demonstrated the superior efficacy of iodine as an antiseptic compared to other biotic agents. Iodine also has action on Gram+, Gram- germs, spores, fungi, protozoa and even MRSA (Methicillin-resistant Staphylococcus aureus), as opposed to other antiseptics that do not have such a broad spectrum of action. At present, the most used antiseptic in the class of iodine- halogenated compounds is iodine-povidone. Its clinical use began in 1956 and is currently being conditional in many pharmaceutical forms: solution, spray, cream, ointment, etc. The concentration varies between 9% and 12%. Iodine solutions are mainly used to treat wounds, but also to reduce microbial flora both before and after surgery. Semisolid pharmaceutical forms (creams, ointments) are used to prevent the spread of pathogens to the wound or to limit the spread of a localized infection. Uses: For hygienic and pre-operative, cutaneous and hand disinfection Disinfection of the skin before procedures (injections, puncture, biopsies) Asepsis of wounds, including skin burns Adjuvant in cutaneous infections. Preparations: Betadine surgical soap, 75mg / ml cutaneous solution Betadine 100 mg / ml cutaneous solution Betadine ointment 100 mg / g. Compounds with Chlorine Following a survey conducted by the American Water Works Association, chlorine is considered the most widely used disinfectant for secondary drinking water disinfection. Chlorine