STERILISATION 4 DR SATHYA ANANDAM PHENOLS Carbolic General

STERILISATION - 4 DR SATHYA ANANDAM

PHENOLS � Carbolic � General acid. Broad spectrum of activity purpose environmental disinfectant. � Distillation of Coal tar between temperatures of 1700 C and 2700 C. � Joseph Lister (Father of antiseptic surgery)introduced their use in surgery in 1865. � Cell membrane damage. � Phenol in 1% solution is having bactericidal action.

Available as : � not 1. Phenol. 2. Lysol. 3. Cresol. inactivated by organic matter. Toxic to humans Disinfection of Floor Work benches Sharp instruments used in minor procedures.

2. Other phenolic formulations in wide use are : 1. Chlorophenols. 2. Chloroxyphenols (Dettol). Relatively inactive against pseudomonas. Dettol which is inactivated even by hard water. 3. Chlohexidine (Hibitane ) : Alcohol based compound. non toxic skin antiseptics. Most active against gram + ve organisms. 4. Hexachlorophane : Bacteriostatic against Staphylococcal infections. 5. Triclosan: To control the out breaks of Methicillin Resistant Staphylococcus aureus (MRSA) strains.

Uses : 1. Preoperative preparation of skin (Good antiseptics). 2. To control pyogenic cocci in surgical and neonatal units

GASES Ethylene Oxide: � Colorless liquid with sweety smell. � It is highly penetrable, non corrosive but skin irritant. � Explosive , if > 3% in the air. This property can be eliminated by mixing with CO 2 or Nitrogen. � Requires � Most exposure of 4 to 18 hours. hospitals have ethylene oxide chambers to sterilize mattresses and large equipment

Mode of Action : � Damage DNA or RNA. � Materials should be exposed to gas at the concentration of 70 - 100 mg/L at 450 C - 600 C with humidity > 70% for about 2 hours to ensure sterility.

Uses : Respirators. Suture material. Dental equipment. Plastics. Food stuffs Heart-lung machines. Disadvantages: Mutagenicity and Carcinogenicity. Unsuitable for fumigating the rooms.

Formaldehyde gas � Used � Gas for fumigation of operation theaters. is generated by adding 150 gm of K Mn. O 4 to 280 ml formalin for 1000 cubic feet (28. 3 Cu. m) room. � Doors should be sealed and unopened for 48 hrs.

Betapropiolactone Used as 0. 2 % gas. Condensation product of Ketane and formaldehyde. Advantages: 1. More effective than formaldehyde. Unsuitable for fumigation. 2. Rapid biocidal 3. Used for preparation of vaccines. Disadvantages: Carcinogenicity, Poor penetrating power.

SURFACE ACTIVE AGENTS � Synonyms: � Alters Cleaning agents, Surfactants. energy relationship at interfaces and reduces the interfacial tension. � These are widely used as : � Wetting agents. � Detergents. � Emulsifiers.

Classified into 4 groups: 1. Cationic (Most important antibacterial agents ) 2. Anionic 3. Nonionic. 4. Amphoteric.

Cationic surface active agents Acts on the phosphate groups present on the cell membranes and cause loss of semi permeability, protein denaturation. Bactericidal effect except on spores , tubercle bacilli. Active in alkaline p. H. Ex : Cetavlon, Cetrimide, Benzalkomium chloride.

Anionic Compounds � Effective � Ex: in acid p. H. Common soap. � Saturated fatty acids (coconut oil): Gram negative bacteria. � Unsaturated fatty acids (oleic acid ) : Gram positive bacilli and Neisseria group of organisms.

Amphoteric compounds Tego compounds. � Possess detergent property of anionic and antimicrobial activity of cationic compounds. � Active in the wide range of p. H

METALLIC SALTS : � These are not in general use. � Active against Gram negative and Gram positive bacteria and viruses. � Salts of heavy metals (Copper, Silver and Mercury)are used Mode of action : Protein coagulants. Disrupt the cell enzymes.

Uses: Antiseptic agent. Bacteriostatic agent. Low bactericidal effect. Limited fungicidal effect.

Salts of Mercury: Thiomersal, Phenyl mercury nitrate, Mercurochrome, Merthiolate: Highly toxic used as preservative for sera. Copper salts: Mainly as fungicides. Silver salts (Aqueous solution): Abrasions, wounds and burns

Peroxygens (Oxidizing Agents) Oxidize cellular components of treated microbes. Disrupt membranes and proteins. A. Ozone: u Used along with chlorine to disinfect water. u Helps neutralize unpleasant tastes and odors. u More effective killing agent than chlorine, but less stable more expensive. u Highly reactive form of oxygen. u Made by exposing oxygen to electricity or UV light.

B. Benzoyl Peroxide: u Used in acne medications C. Hydrogen Peroxide: u Used as an antiseptic. Effective in disinfection of inanimate objects. u Sporicidal at higher temperatures. u Used by food industry and to disinfect contact lenses

D. Peracetic Acid: � One of the most effective liquid sporicides available. � Kills bacteria and fungi in less than 5 minutes. � Kills endospores and viruses within 30 minutes. � Used widely in disinfection of food and medical instruments because it does not leave toxic residues

EVALUATION OF EFFICACY OF DISINFECTANT Phenol co- efficiency test : (Rideal Walker Test) similar quantities of organisms are added to rising dilutions of phenol and the disinfectant to be tested Dilution of a test disinfectant ____________ = > 1 Same dilutions of phenol.

Phenol coeff : value 1 same effectiveness as phenol. <1 –less effective. >1—more effective Chick Martin test : Modified Rideal Walker Test. In the presence of organic matter.

Minimum inhibitory concentration � Measures the lowest concentration of disinfectant that inhibit the growth of salmonella typhi in a nutrient medium

In-Use test � Disinfectant solution commonly used in Hospital practice � Quantitative estimation of viable microbes � Efficacy of a new disinfectant : Ability to inactivate known number of standard strains of pathogenic Staphylococci on a specified surface within a given time. � These results are more useful than phenol coefficient test.

Standard precautions � Wash hands before and after all patient or specimen contact. � Handle the blood of all patient as potentially infectious. � Wear gloves for potential contact with blood and body fluids. � Place used syringes immediately in nearby impermeable container, DO NOT recap or manipulate needle in any way.

Standard precautions � Wear protective eye-wear and mask if splatter with blood or body fluids is anticipated. � Handle all linen soiled with blood and /or body secretions as partially infectious. � Process all laboratory specimens as potentially infectious. � Wear mask for TB and other respiratory organisms (HIV is not air borne).

Spill management � Cover with paper towel/blotting paper /newspaper. � Pour 1% sodium hypochlorite solution on & around the spill. � Keep it covered for 10 minutes. � Remove paper with gloved hand & discard in infectious waste for incineration.