Sterilization, Disinfections and Antisepsis

Question 1

Results in the complete destruction of all forms of microbial
life, including bacterial and fungal spores.

Answer 1

Sterilization

Question 2

Results in the destruction of specific pathogenic

microorganisms - does not necessarily result in sterilization

Answer 2

Disinfection

Question 3

An agent is one that has been formulated for use on skin or
mucous membranes to prevent or inhibit the growth of
microorganisms. (Should not be used to
decontaminate inanimate objects.)

Answer 3

Antisepsis

Question 4

Removal of debris, blood, and proteins – and most
microorganisms – not necessarily rendering the device “safe
to handle” by HCW’s who are not wearing protective attire.

Answer 4

Decontamination

Question 5

Instruments or objects that are introduced directly into
the bloodstream or into other normally sterile areas of
the body

Answer 5

Critical items

Question 6

Noninvasive flexible and rigid fiber optic endoscopes,
endotracheal tubes, anesthesia breathing circuits, and
cystoscopes.

Answer 6

Semicritical items

Question 7

Those that either do not ordinarily touch the patient or

touch only intact skin.

Answer 7

Noncritical items

Question 8

Killing of microorganism
Germicides
Substances that kill microbes (pathogens and
nonpathogens) but not necessarily their
endospores.
– Bactericide
– Fungicide
– Virucide
– Amoebicide

Answer 8

-cide or cidal

Question 9

Inhibit growth or multiplication of microoganism

Answer 9

-static or stasis

Question 10

steam under pressure
121C/15 psi for 15-90 mins
132C/27 psi for 4-20 mins
minimal time required
loading and packing critical to performance

Answer 10

Autoclaving

Question 11

 The process of sterilizing unwrapped instruments
using steam for three minutes, at 270 °F at 27-28
pounds of pressure.
 Not used for routine sterilization – used in OR settings

Answer 11

Immediate Use (Flash) Sterilization

Question 12

Does not achieve sterility but kill pathogens that might be present in milk, dairy products and beer: Mycobacterium, Salmonella
 Classic 63 C 30 min
 Flash High-temperature short-time (HTST)
l 72 C 15 sec, then rapid cooling
 Ultra-high temperature (UHT) treatments
l 140 C

Answer 12

Pasteurization

Question 13

Sterilize solution of heat-sensitive
materials.
 Membrane filters (~0.1 mm thickness) Cellulose acetate, Cellulose nitrate, Polycarbonate, Polyvinylidene difluoride, other synthetic materials.
 Pore size:
 0.45 mm or 0.22 mm : for bacteria
 0.01 mm : for spirochetes, mycoplasma, viruses and large proteins

Answer 13

Sterilization by Filtration

Question 14

A mask is a physical barrier between your mouth and nose and your environment.
-N95 masks are 95 per cent efficient at filtering out particles that are greater than 3 micrometers in diameter.
-N99 masks are 99 per cent efficient and N100, 100 per cent
efficient.
-Droplets emitted by sneezing, coughing or talking are 5 micrometers or bigger, so these masks will work well for influenza or tuberculosis infection control.

Answer 14

What is a Mask?

Question 15

Ex: gamma rays, x-rays, high-energy electron beams
-Ionization of water forms highly reactive hydroxyl
radicals
-Uses: pharmaceuticals, disposable dental and medical supplies (syringes, gloves, sutures)

Answer 15

Ionizing radiation: shorter wavelength

Question 16

Ultraviolet rays: thymine dimers inhibit replication of DNA

• Not penetrating
• Damage human eyes, skin cancer, burns

Answer 16

-Nonionizing radiation

Question 17

GVHD is a disorder in which the grafted tissue
attacks the host tissue, i.e. by the proliferation
of the T-cells. Exposure to this
prevents the proliferation of leukocytes,
especially T-cells.

Answer 17

 Irradiated (gamma radiation exposure) RBCs help to prevent graft-versus-host
disease (GVHD).

Question 18

-Prolongs the shelf-life of the food in
cases where microbial spoilage is the
limiting factor.
-The treatment of hamburger eliminates
the residual risk of a contamination by E.
coli.

Answer 18

Use of irradiation for food in the form of ionizing radiation destroys bacteria by damaging bacterial DNA.

Question 19

 Exert antimicrobial activity by injuring plasma
membranes, inactivate enzymes and denaturing proteins.
 irritates skin disagreeable odor is now rarely used.
 Used for intermediate and low level disinfection

Answer 19

Phenol and Phenolics

Question 20

Only good for gingivitis. All the antibiotic soap with this is not shown to be effective.

Answer 20

Triclosan

Question 21

 Most active against gram positive
bacteria
 Toxic in newborns
 Now used for staphylococcal skin
decolonization in patients undergoing
prosthetic or cardiac valve implant
surgery

Answer 21

Hexachlorophene (pHisoHex)

Question 22

Is not a phenol derivative.
Frequently used for disinfection of skin and mucous membranes.
Used for surgical hand scrubs and preoperative skin preparation of patients.
Low toxicity. Strong affinity to skin or mucous membranes.
Killing effect by damaging plasma membrane.
Effective against most vegetative bacteria but not
sporicidal.

Answer 22

Chlorohexidine

Question 23

 Work by forming covalent crosslinks with a number of organic functional groups on proteins.
 Formalin: 37% aqueous solution of formaldehyde gas.
 Glutaraldehyde: used to sterilize hospital instruments
 Less irritating more effective than formaldehyde
 CidexTM (2% soln): bactericidal, tuberculocidal, virucidal in 10 min; sporicidal in 3 to 10 hr
 Is the only liquid chemical disinfectant that can be considered a sterilant

Answer 23

Aldehydes

Question 24

 Denaturation of proteins by alkylation
 Sterilize without heat
 Sterilization of medical supplies and equipment:
disposable plastic syringes, lensed instruments, artificial heart valves, heart-lung machine, and mattresses
 Note: formaldehyde gas rarely used - flammable

Answer 24

Ethylene oxide, Propylene oxide gaseous chemosterilizers

Question 25

 Advantages: combined detergent and
germicidal activity; stable and working
dilutions have low toxicity
 Disadvantages: non sporicidal, limited
activity against viruses, mycobacteria; may support growth of bacteria
 Uses:
surface decontamination -floors and walls; equipment wipe down; antiseptic formulations
available
Topical uses:
 Benzalkonium chloride: ZephiranTM (Antisepsis of skin and mucous membranes and as a disinfectant)
 Cetylpyridinium chloride: Cepacol® /
Colgate Total

Answer 25

Quaternary Ammonium Compounds

Question 26

 dehydrate cells, disrupt membranes and cause coagulation of protein.
 May be used for hard surface disinfection or skin antisepsis.
 A 70% aqueous solution is more effective at killing microbes than absolute alcohols.
 Uses:
 skin disinfectant (antiseptic)
 surface decontamination
 benchtop, cabinet wipedown

Answer 26

Alcohols

Question 27

Single most important procedure for preventing nosocomial infections. Can be classified simply by whether plain soap or detergents (soap breaks oily film on skin [emulsification]) or antimicrobial- containing products are used.

Answer 27

Handwashing

Question 28

 They are oxidizing agents and cause damage by oxidation of essential sulfydryl groups of enzymes.
 Reacts with water to form hypochlorous acid,
which is microbicidal.
 used to bleach water.
 Household bleach can be used at a dilution of 1:10 in decontamination of spillage of infectious material.
 Disadvantage: unstable when diluted – needs to be made daily.

Answer 28

Halogens : Iodine (I2) Chlorine (Cl2)

Question 29

Tincture of iodine (2% iodine in 70% alcohol)
is an antiseptic.
 Iodophores: Iodine can be combined with
neutral carrier polymers such as polyvinylpyrrolidone to prepare iodophores
such as povidone-iodine.
 Iodophores permit slow release and
reduce the irritation of the antiseptic.
 Betadine(R), Isodine(R)

Answer 29

Iodine Preparations

Question 30

Metals ions combine with -SH groups on proteins
-Heavy Metals: Silver nitrate (1% for
ophthalmic preparations); Mercurochrome (mercury); Copper Sulfate; Zinc chloride; Zinc oxide
-Organic Acids and Derivatives: Sorbic acid; Benzoic acid; Methylparaben; Propylparaben

Answer 30

Heavy Metals and Organic Acids

Question 31

 Acts on the microorganisms through its release of nascent oxygen. Produces hydroxyl-free radical that damages proteins and DNA.
 Used at 6% concentration to decontaminate instruments and equipment such as ventilators.
 3% solution is used for skin disinfection and cleaning of wounds and ulcers.
 Strong solutions are sporicidal.
 Disadvantages: Decomposes in light, broken down by catalase, proteinaceous organic matter drastically reduces its activity.

Answer 31

Hydrogen Peroxide

Question 32

Mixture of acetic acid and hydrogen
peroxide in an aqueous solution.
Disinfects by oxidizing of the outer cell membrane of vegetative bacterial cells, endospores, yeast, and mold spores.
 Used as a cooling tower water disinfect where it prevents bio film formation and effectively controls
Legionella bacteria.
 Extremely effective for sanitizing fowl carcasses
without affecting the skin or the flesh of the bird carcass by applying direct to the meat.
 Plasma (gas phase) sterilization

Answer 32

Peracetic Acid (PAA)

Question 33

Beneficial for sterilizing temperature sensitive polymeric material – such as endoscopes.
 Provides safe non-toxic, dry, low temperature
sterilization in about 1 hour.
 Gas plasma is generated in an enclosed chamber under deep vacuum using UV or microwaves to create free radicals in a gaseous phase.
 The gas permeates the chamber and its contents.

Answer 33

Plasma Sterilization

Question 34

Uses low-temperature, hydrogen peroxide gas plasma technology to sterilize instruments and medical devices.
 Quick instrument reprocessing (OR)
endoscopes and other devices without lumens
 Processes a wide range of instruments
including multiple single-channel
flexible endoscopes, cameras, rigid
scopes, light cords, batteries, and power
drills.

Answer 34

STERRAD Sterilization System