Antiseptics & Disinfectants

Question 1

Who was Ignaz Semmelweis?

Answer 1

demonstrated as early as 1840s the efficacy of handwashing following Pasteur’s identification of infective agents as causes of disease

Question 2

Who was Joseph Lister? In what 2 ways did he use antiseptics and disinfectants? What was his principle?

Answer 2

pioneer of antiseptic surgery and preventative medicine that suggested the use of antiseptics during surgery

1. treatment of hands with 1:20 carbolic lotion
2. used methods for chemical sterilization of bandages, dressings, and surgical instruments

bacteria must never gain entry into an operation wound

Question 3

What are cleansers, antiseptics, and disinfectants?

Answer 3

CLEANSER = aids in the physical removal of foreign material, NOT NECESSARILY a germicide

ANTISEPTICS = biocide applied to living tissue

DISINFECTANTS = biocide applied to inanimate objects

Question 4

Why are antiseptics and disinfectants not used interchangeably?

Answer 4

antiseptics may be inactivated on inanimate surfaces and disinfectants are hazardous to living tissue

• antiseptics: registered with FDA
• disinfectants (sanitizer, sterilants): regulated by EPA

Question 5

What do cleansers typically contain? What are the 3 types?

Answer 5

surfactants or detergents that remove dirt and contaminating organisms by solubilization and physical means

1. anionic
2. cationic
3. nonionic

Question 6

What is an example of an anionic cleanser? How do they work? How are they commonly inactivated?

Answer 6

SOAPS (surfactants) - dissociation in water to R-COO liberates a molecule with both hydrophilic and hydrophobic portions that can emulsify and solubilize hydrophobic dirt, fat, and protoplasmic membranes

cationic detergents or positive ions (free Ca in hard water)

Question 7

What is an example of cationic cleansers? How do they work? What are they commonly inactivated by?

Answer 7

quaternary ammonium compounds (QACs) with germicidal activity —> combine readily with proteins, fats, and phosphates

soaps —> forms a precipitate, which terminates activity of both compounds

Question 8

What is the mechanism of action of antiseptics? What are 5 parts of an ideal antiseptic?

Answer 8

nonspecific disruption of cellular membranes or enzymes

1. broad spectrum of activity
2. low toxicity
3. high penetrability
4. maintain activity in the presence of pus and necrotic tissue
5. little skin irritation or interference with normal healing process

Question 9

When is the use of antiseptics indicated?

Answer 9

situations that require maximal reduction of bacterial contamination

• after surgery
• during catherterization
• insertion of invasive implants

Question 10

What is disinfection? Sterilization?

Answer 10

DISINFECTION = process of eliminating most, if not all, pathogenic organisms, excluding spores, from inanimate objects

STERILIZATION - elimination of ALL microbial forms, including fungal and bacterial spores, by physical or chemical (EPA-registered agent) means

Question 11

What is the difference between surface and immersion disinfection?

Answer 11

SURFACE = treatment of objects that are too large to soak in disinfectant (cabinets, exam tables, chairs, lights, cages)

IMMERSION = immersion of small objects in disinfectants for sufficient time to kill the majority of contaminating pathogenic organisms

Question 12

What are the ideal characteristics of a disinfectant?

Answer 12

• broad spectrum
• fast action
• activity in the presence of organic material, like blood, sputum, and feces
• compatibility with detergents
• low toxicity
• odorless
• economical
• should not corrode instruments or metallic surfaces or disintegrate rubber, plastic, or other materials

Question 13

What are the 3 groups of disinfectants?

Answer 13

1. HIGH-LEVEL: destroys all microorganisms except high concentrations of bacterial spores
2. INTERMEDIATE-LEVEL: inactivates acid-fast microorganisms (Mycobacterium tuberculosis, viruses, fungi)
3. LOW-LEVEL: kills most bacteria, some viruses, and some fungi, but not tubercle bacilli or bacterial spores, in less than 10 mins

Question 14

How are instruments classified based on risk of infection involved in their use?

Answer 14

CRITICAL - enter or penetrate skin or mucous membranes, usually at a sterile site —> should be sterilized

SEMICRITICAL - touch intact mucous membranes —> require high-level disinfection

NONCRITICAL: do not touch mucous membranes, but may touch intact skin —> low to intermediate disinfection

Question 15

What are the most commonly used alcohols for antiseptic and disinfecting action? How do they work? When are they most effective?

Answer 15

ethyl and isopropyl alcohol —> lipid solvents and protein denaturants that kill organisms by solubilizing lipid cell membranes and denaturing membrane proteins

when diluted with water - 70% ethyl alcohol, 50% isopropyl alcohol

Question 16

How do alcohols act on microorganisms?

Answer 16

highly effective against most vegetative Gram-positive, Gram-negative, and tubercle bacilli, fungi, and enveloped viruses

DO NOT inactivate bacterial spores

Question 17

What are 2 reasons that alcohols are not recommended for high-level disinfection or sterilization?

Answer 17

1. inactivity against bacterial spores
2. reduced efficacy in presence of protein or bioburden (denatures blood proteins, allowing it to adhere to instruments)

Question 18

What 3 major adverse effects associated with repeated or prolonged alcohol use?

Answer 18

1. damage shellac mounting of lensed instruments
2. swell or harden rubber and plastic tubing
3. corrosive to metal surfaces

Question 19

What causes the drastic reduction in alcohol effectiveness as an antiseptic or disinfectant? On what surface does it work best?

Answer 19

organic matter, like feces, mucus, and blood

clean skin —> rapidly reduces bacterial counts, but rapid evaporation limits contact time

Question 20

What toxic reaction has been reported with alcohol usage as antiseptics?

Answer 20

skin drying, local irritation

Question 21

What halogens are commonly used as antiseptics and disinfectants?

Answer 21

• iodine
• chloride

Question 22

What does iodine have germicidal activity against? How does it work?

Answer 22

• Gram-positive and Gram-negative bacteria
• bacterial spores
• fungi
• most viruses

diffuses into the cell and interferes with metabolic reactions and disrupts protein/nucleic acid structure

Question 23

How is iodine prepared? Why? What is the best way of preparing it?

Answer 23

in alcohol (tincture) - insoluble in water

1-2% iodine solution + 70% ethyl alcohol = kills bacteria within 3 mins of application, making it more effective than alcohol alone

Question 24

What are 3 disadvantages to using tincture of iodine?

Answer 24

1. irritating and allergenic
2. corrodes metals
3. stains skin and clothing

Question 25

How has iodine been prepared to try and reduce undesirable aspects? How does this work?

Answer 25

prepared with solubilizing surfactants, like iodophors = povidone-iodine

iodophors have similar spectrum spectrum of activity to aqueous solutions, making them less irritating, allergenic, staining, and corrosive, while having prolonged activity

Question 26

Why are iodophors especially excellent cleansing agents, disinfectants, and antiseptics? What is the best preparation? Why?

Answer 26

retain their activity in the presence of organic matter

1% iodine = more concentrations are less efficacious

Question 27

How do iodophors act on microorganisms? Why must they be used carefully?

Answer 27

• quickly bactericidal
• prolonged contact time kills fungi and bacterial spores

can be systematically absorbed through skin and mucous membranes

Question 28

What microbicidal activity does chlorine have? Which 2 chemical formes are used today?

Answer 28

bactericidal, fungicidal, virucidal, protozoacidal

1. hypochlorites: sodium and calcium
2. organic: chloramine-T

Question 29

What is the mechanism of action of chlorine?

Answer 29

inhibits cellular enzymatic reaction, causes protein denaturation, and inactivates nucleic acids

Question 30

Why is the use of hypochlorite disinfectants limited? How are they used?

Answer 30

chloride solutions are corrosive and destroy fabrics —> very irritating to skin and delay healing (NOT RECOMMENDED AS AN ANTISEPTIC)

low-level disinfectant on dairy equipment, animals housing, hospital floors, and other noncritical items