Transcript Disinfection

DR. MOHAMMED AL-FATTANI
CONSULTANT OF MEDICAL MICRO BIOLOGY
M&CH JEDDAH
2016
1st day
CLEANING AND STERILIZATION TRAINING
COURSE
OUTLINE OF THE COURSE
 Introduction to cleaning, disinfection and sterilization
 Microbial control: Principles of Disinfection
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(Nosocomial Infection)
Handling & transport of soiled items
Handling, inspection, storing and transporting of
sterile items
Process chemicals in automated cleaning and
disinfection
Environmental Cleaning
Definition of Cleaning:
Cleaning is always the first step in reprocessing and is
defined by the FDA as removal of soil residues and is a necessary
step prior to reuse of any medical device.
To validate the cleaning process, the device is inoculated
with soil, cleaned using the recommended cleaning procedure,
and then residuals (any soil remaining on the device) are
recovered and measured.
The acceptance criteria to validate the procedure are: a
visually clean device; 3-log reduction in microorganisms; protein
levels <6.4 ug/cm2; hemoglobin <2.2 ug/cm2; carbohydrate <1.8
ug/cm2; endotoxin <2.2 ug/cm2.
Definition of Disinfection:
Disinfection is defined as using physical or chemical
means to kill microorganisms.
Disinfection frequently accomplished through the use of
chemical disinfectants, or via thermal disinfection (the
application of high temperature water).
A disinfection process is considered to be validated if the
device is visually clean and a 6-log reduction in microorganisms
can be shown.
Definition of Sterilization:
Sterilization is a process that renders a device free from
viable microorganisms.
The level of sterilization is defined by Sterility Assurance
Level (SAL), which is the probability that a device is not sterile.
For example, an SAL of 10-6 indicates a 1 in 1 million possibility
that the device is non-sterile.
Sterilization can be achieved in a number of ways, but
the most common methods of sterilization are steam, dry heat,
hydrogen peroxide, ethylene oxide, and radiation.
The acceptance criteria for sterilization of non-critical
devices (those that do not penetrate the body) is 10-3, and the
acceptance criteria for critical devices is an SAL of 10-6.
Other Definition / Introduction of Sterilization and
disinfection:
For protection of both the medical staff and patient.
sterilization techniques are the most importance in
preventing the spread of infectious disease.
This is of special significance in most of medical fields
such as dentistry because more microorganisms are found in the
oral cavity than in any other part of the body.
With the increasing number of adult patients and diverse
life-styles, the orthodontist is more at risk than ever to exposure
to serious pathogens and must take precautions to guard against
their transfer.
 STERILIZATION: Sterilization is a process by which articles
are freed of all microorganisms both in vegetative or spore
state.
 DISINFECTION: Disinfection is a process of destruction of
pathogenic organisms capable of giving rise to infection.
 ANTISEPTIC: It means prevention of infection by inhibiting
growth of bacteria.
Microbial Control : Principles Of Disinfection
Nosocomial Infection
What is the definition of microbial control?
Microbial control is the process that controls or prevents the growth of
dangerous microorganisms through sterilization, disinfection, antisepsis,
sanitization or degerming.
Sterilization is the complete elimination of all forms of microbial life.
Disinfection is the destruction of pathogenic organisms on inanimate
objects, while antisepsis refers to the elimination of bacteria on a living tissue.
Sanitization refers to the reduction in the number of pathogens to a level
deemed safe by public health guidelines.
Degerming is the physical removal of microorganisms through the use of soaps or
detergents.
How does microbial control work?
Microbial control uses antimicrobial products and technologies to reduce
or prevent the growth of harmful microorganisms (viruses, bacteria and molds)
that threaten human health or the environment.
Antimicrobial substances or agents use various different mechanisms to
eliminate microbes.
Controlling microbial growth is important in the medical field,
pharmaceutical and biotechnology industries, academic research and food
industry.
Microbial Control : Principles Of Disinfection
Heat - Related Methods:
1. Heat is frequently used to eliminate microorganisms.
2. Moist heat kills microbes by denaturing enzymes.
3. Heat works better at low pH.
4. Thermal death point (TDP) is the lowest temperature at which all the
microbes in a liquid culture will be killed in 10 minutes.
5. Thermal death time (TDT) is the length of time required to kill all bacteria
in a liquid culture at a given temperature.
6. Decimal reduction time (DRT) is the length of time in which 90% of a
bacterial population will be killed at a given temperature.
7. Boiling (100º C) kills many vegetative cells and viruses within ten minutes.
8. Autoclaving (steam under pressure) is the most effective method of moist
heat sterilization. The steam must directly contact the material to be sterilized.
9. Fifteen psi, 121° C for fifteen minutes kills all vegetative bacteria and
endospores.
 Filtration:
 Filtration is the passage of a liquid or gas through a filter with pores small
enough to remain microbes.
 Microbes can be removed from air by high -efficiency particulate air filters.
 HEPA – 0.3 um pore size
 Decreases numbers
 Membrane filters composed of nitrocellulose or cellulose acetate are
commonly used to filter out bacteria, viruses, and even large proteins.
(Figure 1.1)
 Range from 0.22 um – 0.45 um for bacteria but sometimes mycoplasma or spirochetes
can pass through.
 Sizes can go as low as 0.01 um to filter viruses and proteins.
Low Temperatures:
 The effectiveness of low temperatures depends on the particular microorganism
and the intensity of the application.
 Most microorganisms do not reproduce at ordinary refrigerator temperatures
(0-7º C).
 Many microbes survive (but do not grow) at subzero temperatures used to store
foods.
High Pressure:
 High pressure denatures proteins in vegetative cells.
 Endospores aren’t usually harmed, but can be allowed
to grow out and the vegetative form killed with high
pressure.
 Used in Japan and the U.S. to preserve fruit juices –
preserves the flavor, color, and nutrient values.
Desiccation :
 In the absence of water, microorganisms can grow but cannot remain
viable.
 Viruses and endospores can resist desiccation.
 Mycobacterium tuberculosis is fairly resistant to desiccation but the
gonorrhea bacterium is very sensitive.
 Environmental conditions effect efficiency of desiccation – pus,
feces, and mucus are protective.
Osmotic Pressure :
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Microorganisms in high concentrations of salts and sugars undergo
plasmolysis.
 Molds and yeasts are more capable than bacteria of growing in materials
with low moisture or high osmotic pressure.
Radiation :
 The effects of radiation depend on its wavelength, intensity and duration.
 Ionizing radiation (gamma rays, X-rays and high-energy electron beams)
has a high degree of penetration and exerts its effect primarily by ionizing
water and forming highly reactive hydroxyl radicals.
 Destroys DNA.
 Non-ionizing radiation causes damage to DNA.
 Ultraviolet causes formation of thymine dimers.
 Microwaves heat water but it is possible to isolate vegetative
forms from microwave ovens after usage and uneven heating in
solid foods may leave live organisms in the food after
microwave cooking.
Chemical Methods of Microbial Control :
Definition:
- Chemical agents are used on living tissue (as antiseptics) and on inanimate
objects (as disinfectants).
- Few chemical agents achieve sterility.
Principles of Effective Disinfection :
- Properties of the disinfectant – how it works determines what it will be
effective against.
- Concentration of the disinfectant - requires proper hydration.
- The presence of organic matter can act as a buffer.
- The degree of contact with microorganisms – if the surface needs cleaning or
is porous microorganisms can escape contact with the disinfectant.
- Temperature should also be considered, since increased temperatures usually
enhance the efficacy of disinfectants.
- Time left in contact is also an important consideration.
Evaluating a Disinfectant :
 Phenol coefficient – compares activity of a disinfectant
to phenol, was once the standard to evaluate the
effectiveness of a disinfectant.
 In the disk-diffusion method, a disk of filter paper is
soaked with a chemical and placed on an inoculated
agar plate; a clear zone of inhibition indicates
effectiveness (Fig. 2).
Types of Disinfectants:
1) Phenol and Phenolics
2) Hexachlorphene is used in pHisoHex
3) Chlorhexidine
4) Halogens (iodine and chlorine)
5) Alcohols
 Phenol and Phenolics :
 Phenolics are derivatives of phenol that have been altered to reduce
irritating qualities or increase antimicrobial activity when combined with
detergents.
 Phenolics exert their action by injuring plasma membranes.
 Can also denature proteins – enzyme inactivation
 Bisphenols have two phenolic groups and include triclosan (over the
counter) and hexachlorophene (prescription).
 Hexachlorphene is used in pHisoHex :
1. Particularly good against gram-positive strep and staph (cause skin infections
in infants).
2. Can cause neurological damage if exposure is high (bathing several times per
day)
3. Triclosan is used in soaps, toothpaste, and incorporated into plastic
kitchenware.
4. Broad spectrum, especially against gram-positive bacteria and fungi
5. Resistant strains of bacteria have arisen and triclosan may contribute to
antibiotic resistance as well.
 Chlorhexidine :
 Binds well to skin and mucus membranes, low toxicity ,surgical hand
scrubs and pre-op skin prep.
 Can damage eyes.
 Not sporocidal.
 Some halogens (iodine and chlorine) are used alone or as components of
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inorganic or organic solutions.
Iodine may combine with certain amino acids to inactivate enzymes and
other cellular proteins.
Betadine, Isodine (povidone-iodines)
Povidone is surface active – improves wetting actions.
The germicidal action of chlorine is based on the formation of hypochlorous
acid (HOCl) when chlorine is added to water.
Used to disinfect drinking water and swimming pools.
Two drops Clorox per liter (four if cloudy) and let sit 30 minutes.
 Alcohols :
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Alcohols exert their action by denaturing proteins and dissolving
lipids.
 Not good for wound disinfection because proteins coagulate and form a
protective coat around bacteria.
Nosocomial Infection
Handling and transport of
soiled items
 Bloodborne Pathogens are biological agents, which may be
present in human blood and can cause disease. Examples of
bloodborne pathogens include the hepatitis B virus, human
immunodeficiency virus (HIV) and the organisms, which cause
malaria.
Handling – inspection – storing
and transporting of sterile items
Environmental Cleaning
Definition:
 Environmental cleaning is a fundamental principle of infection
prevention in healthcare settings.
 Contaminated hospital surfaces play an important role in the
transmission of dangerous pathogens, including Clostridium
difficile, and antibiotic-resistant organisms such as methicillinresistant Staphylococcus aureus (MRSA) and vancomycinresistant enterococci (VRE).
 Environmental cleaning: processes associated with cleaning and
disinfection of surfaces and substances that can pose a risk of harm to
patients
 Environmental services: an operational unit within a hospital or health
care facility that is responsible for cleaning, housekeeping, laundry,
and related duties
 HAIs: healthcare associated infections; infections transmitted to
patients while in a healthcare facility or during medical treatment
 Colonization: the presence of bacteria or bacterial infection on a
patient's body without signs or symptoms of infection-related illness;
or bacteria present on a surface that may come into contact with a
patient
Examples of environmental items that have been shown to harbour
microorganisms such as MRSA, VRE, C.difficile, A. baumannii,
RSV, influenza virus and others :
 Bed - Bed frame - Bed linen - Bedside table - Blood pressure cuff - Call bell
Chair - Clean gloves that have touched room surfaces only Computer
keyboard.
 Door handle - Electronic thermometer - Floor around bed - Hemodialysis
machine - Patient bathroom - Phlebotomy tourniquet etc…
Environmental Cleaning
Top 10 Best Practices
 The environment plays a role in transmission of infections.
 Cleaning is an essential part of reducing healthcare-acquired
infections.
1. Proper hand hygiene
• Use alcohol-based hand rub
• Use soap and water if hands visibly soiled
• Always clean hands after glove removal
2. Proper use of gloves
 Change gloves between dirty and clean procedures
 Always clean hands after glove removal
 Do not leave the room wearing soiled gloves
 Do not wear gloves in common areas of the facility
3. Focus on frequently touched surfaces
4. Work from clean-to-dirty and from high-to-low areas
• Avoid contaminating already cleaned areas and surfaces
5. Avoid generating aerosols
• Roll up soiled linen carefully and away from your clothing
• Place soiled items in bins – do not throw
• Tie up waste bags without compressing air
6. Change cleaning cloths
• Do not re-dip in to cleaning solution ~ Double-dipping
• It will be necessary to use multiple cloths for each space
7. Ensure cleaning equipment and supplies are clean
• All used cloths and mop heads are stored separately when soiled and sent for
laundry at end of each day
• Mops and cloths are dried thoroughly and stored in clean area
• Clean the cleaning cart daily
8. Proper use of cleaning and disinfecting products
• Follow instructions for dilution and calibrate automated dilution
systems regularly
9. Ensure surface or item is cleaned before disinfected
• Presence of organic soil will alter activity of disinfectant
• 1-step or 2-step products
10. Communicate issues to your supervisor
• Presence of pests
• Improper disposal of sharps