Chapter 10

As a result of successfully completing this chapter, readers will be able to:

Define the term, “disinfection,” and explain how disinfection differs from sterilization

Review factors that impact the effectiveness of a disinfectant

Discuss the relationship between the risk level (intended use) of the device to be disinfected and the selection of a disinfectant

Explain disinfectant activity levels as they relate to the resistance of microorganisms to germicidal agents:◦ high-level disinfection◦ intermediate-level disinfection◦ low-level disinfection

Review factors which affect the chemical action of and other important selection considerations for disinfections

Provide basic information about the types of disinfectants commonly used in healthcare facilities: quaternary ammonium compounds, phenolics, alcohol, halogens, glutaraldehyde, ortho-phthalaldehyde, and formaldehyde

Review safety requirements that should be followed when using chemical disinfectants

Define the term, “thermal disinfection,” and note key points to ensure that it is occurring

Disinfectant - A chemical used on inanimate objects such as medical instruments to kill all microorganisms , except spores

Antiseptic – A chemical used on living tissue such as skin, to slow the growth of microorganisms

Sterile – Free from all living organisms

Disinfection – The destruction of nearly all pathogenic microorganisms on an inanimate surface. Disinfection is accomplished using chemical or heat processes

Reduces the number of microorganisms on an object

Disinfectants are designed to be used at a specific strength

Excessive Moisture – Excessive moisture can cause disinfectant solutions to become diluted. Lowering the concentration of the chemical disinfectant can reduce its ability to kill microorganisms

Type and number of microorganisms present

Direct Contact with the Item In order to be effective, disinfectants

must make direct contact with all surfaces being disinfected

Time Disinfectants must be allowed time to

work Check manufacturer’s instructions for

the correct exposure time required to achieve the desired biocidal effect

Temperature of the Disinfectant

pH

Hardness of the Water

Material Compatibility

Positioning of the Device(s) being disinfected

Should be based on:◦ The intended use of the

device

◦ The degree of disinfection required for the device

◦ Risk levels are based on the Spaulding Classification System

Items introduced directly into the bloodstream or other normally sterile areas of the body

Surgical Instruments, Implants, etc.

Items which come in contact with intact mucous membranes

Fiberoptic Endoscopes, Cystoscopes, etc.

Come in direct contact with the patient’s unbroken skin

Crutches, Blood Pressure Cuffs, equipment, etc.

Table Modified from Favero and Bond, 1991

Classification of Patient Care Items

CriticalSterilizationSterile body cavity

Semi-criticalHigh-levelMucous membranes

Non-criticalLow levelIntact skin

Item ClassDestruction Method

Body Contact

High-level

Intermediate-level

Low-level

Process that uses a sterilant for a shorter contact time that needed for sterilization

High-level disinfection kills all microorganisms, except bacterial spores

Process that utilizes a agent that kills viruses, mycobacteria, fungi, and vegetative bacteria, but not bacterial spores

Process that utilizes a agent that kills vegetative forms of bacteria some fungi and lipid viruses

Lipid Virus – A virus whose core is surrounded by a coat of lipoprotein. Viruses included in this structural category are generally easily inactivated by many types of disinfectants, including low-level disinfectants

Non-lipid Virus – A virus whose core is not surrounded by a lipid envelope. These viruses are generally more resistant to inactivation by disinfectants

Table Modified from Favero and Bond, 1991

Hierarchy of Disease Producing Agents

Low-Level DisinfectionLipid or medium sized viruses (Hantavirus, Herpes Simplex Virus)

Low-level DisinfectionGram Positive & Negative Vegetative Bacteria

Intermediate-level DisinfectionFungi

Intermediate-level DisinfectionNonlipid and small viruses (Poliovirus)

High Level DisinfectionMycobacteria

SterilizationBacterial spores

Extended Sterilization TimesPrions

Destruction MethodOrganism Producing Disease

Types of devices being disinfected

Whether items can be disassembled

Manufacturer’s recommendations

Positioning of the device

Process Quality Assurance Tests

Shelf Life and Use Life

Preparation required (mixing, etc.)

Reuse factors

Additional inspections required by the manufacturer

A detailed overview of common chemical disinfectant characteristics can be found on pages 161 – 169 in the text.

Low-Level Disinfectant

Advantages:◦Bactericidal, fungicidal and virucidal against lipophilic viruses

◦Built-in Detergent Properties

Disadvantages:◦Not sporicidal◦Generally not tuberculocidal or virucidal

against hydrophilic viruses◦Not Compatible with Soap◦Absorbed or Neutralized by Cotton or Charcoal◦Not effective against some gram-negative

organisms commonly found in hospitals

Advantages:◦ Broad Spectrum of

use; bactericidal for gram-negative and gram-positive bacteria, fungi, and tuberculocidal against lipophilic viruses.

◦ Residual Activity* (can also be a disadvantage)

Disadvantages:◦Not sporicidal◦ Inactivated by

organic material◦Corrosive to Rubber

and some Plastics

Advantages:◦ Rapid bactericidal

agent against vegetative microorganisms, tuberculocidal, fungicidal, and virucidal

◦ Fast-Acting◦ Non-Staining◦ Leaves No Residue

Disadvantages:◦ Requires a minimum 5

minute wet contact.◦ No residual activity◦ Volatile, flammable◦ Inactivated by Organic

Soil◦ Can dissolve lens

mountings on certain optical instruments

◦ Tends to harden and swell plastic tubing

◦ Not sporicidal

Chlorine

Iodophors

Advantages:◦ Effective against

Gram-Positive and Gram-Negative Microorganisms, Tuberculocidal, Fungicidal, and Virucidal

◦ Rapid-Acting

Disadvantages:◦Inactivated by

Organic Matter◦Corrosive to Metals◦Not Sporicidal◦Stains fabrics,

plastics and other synthetic materials

◦Relatively Unstable

Advantages:◦ Bactericidal,

Tuberculocidal, and Virucidal

◦ Rapid-Action against vegetative bacteria

Disadvantages:◦Corrosive to Metals◦Detrimental to

Rubber and some Plastics

◦May burn tissue◦Stains fabrics and

other materials◦May require long

contact time to kill some fungi

Advantages:◦ Kills vegetative bacteria

(within 2 minutes)

◦ Bactericidal (gram-positive and gram-negative), tuberculocidal, fungicidal, virucidal, sporicidal (For sterilization (killing spores) the soak time ranges 6-10 hours).

Disadvantages:◦ Noxious odors, good

ventilation required◦ Unstable (14-28

product life)◦ Dilution of product

reduces activity◦ Vaporizes◦ No cleaning ability◦ Rinsing Required◦ Employee Health

Concerns

Advantages:◦ Fast-acting◦ User-friendly◦ Compatible with a wide

range of endoscopes and medical devices

◦ Requires no activation or mixing

Disadvantages:◦ Does not have sterilant

label claim◦ Improper rinsing can

cause staining of patient tissues

◦ Patient with a history of bladder cancer should not be exposed to items processed by OPA

Advantages:◦ Bactericidal,

tuberculocidal, fungicidal, and virucidal

◦ Sporicidal (as 8% Formaldehyde/70% alcohol)

Disadvantages:◦ Inactivated by organic

material◦ May stain fabrics,

plastics, and other synthetic materials

◦ Not sporicidal◦ Carcinogen (1PPM, 8

hour TWA)◦ Irritating fumes

Follow manufacturers’ instructions Use appropriate containers Cover the containers Wear gloves Reuse only those products labeled for

reuse Watch expiration dates Test as necessary Rinse thoroughly Dispose of according to established

guidelines

A Log Book should be maintained for high-level disinfectants

(See page 171 of the text for a sample log book page)

Wear PPE Use an exhaust hood when necessary Develop a spill plan Provide an eyewash/shower and other first

aid supplies Provide easy access to a phone and phone

numbers for emergencies Provide yearly staff training Monitor disinfectants (including air quality)

Thermal Disinfection – Disinfection accomplished by heat

Check spray arms and nozzles of mechanical washer/disinfectors daily to insure they are working correctly

Medical washers and washer/disinfectors are regulated by the FDA