التعقيم والتنظيف والتطهير .......بالانجليزية

Disinfection and sterilization
-A basic knowledge is crucial for biosafety in the laboratory and also fundamentals of precleaning
-specific requirements ,type of experimental and nature of the infectious agent

Definitions
Antimicrobial : kills microorganisms or suppresses their growth and multiplication
Antiseptic : inhibits the growth and development microorganismswithout necessarily killing them. Body surface
Decontamination : removing and/or killing microorganisms. &removing or neutralizing hazardous chemicals and radioactive
materials.

Disinfection :A physical or chemical means of killing microorganisms, but not necessarily their spores
Sterilization : destroys and/or removes all classes of microorganisms and their spores
Precleaning and cleaning laboratory materials
removal of visible dirt and stains, achieved either by
a- brushing, vacuuming or dry dusting; or
b-washing or damp mopping with water containing a soap or detergent.
Steps of cleaning
1. Sorting (separation )
2. Soaking usually water (cold or warm)
3. Washing use of detergents
4. Rinsing
5.Drying and / or Drainage
Types of cleaning
- Manual
- Mechanical:
-washer – sterilizer.
- ultrasonic cleaner
Detergent :
A cleaning agent composed of
Wetting agent and builder agent
Choosing detergent :
manufacturers recommendations
hardness of water
cleaning
surfaces and furnishing
effective procedures
trained personnel
walls: no spills, no splashes.
Floors:
No dusting , dry vacuum
Wet mopping : triple bucket.
Flooding then wet vacuum( surgery)
Scrubbing machines for corrido
Disinfection
A process that destroys disease- producing microorganisms with exceptions.
- high level disinfection: kills vegetative bacteria , all viruses, fungi and tubercle bacilli but not ( necessarily high numbers) and bacterial spores.
Low level disinfetion: kills most vegetative bacteria , some viruses , some fungi but definitely not tubercle bacilli and bacterial spores
Disinfection
Factors affecting activity :
-Concentration: the more concentrated the greater the killing ( not simple arithmetic )
-Number and type of microbes: difficulty increases with number ( not simple arithmetic ) ,consideration to type of organisms.
- Contact time: ( not simple arithmetic )
-cleanliness of surfaces :soil interferes, organic matter includes organisms & inactivates disinfectant and detergent may counteract .
_water hardness , temperature .pH and biofilm

Disinfection
Types of microbial contamination in ascending order of difficulty to be inactivated (destroyed – killed)
Group A: vegetative bacteria ( gram positive and negative ), fungi, and lipophilic (enveloped )viruses (HBV)

Disinfection methods
Pasteurization
- for anesthesia equipment (not sporicidal and equipment must be dried and handled aseptically )
Ultra violet irradiation in burn units, Ors and Tb isolation rooms
- (not cost-effective: poor penetration ,high maintenance , short lived and hazardous )
Chemical

Disinfection
Group B : Tubercle bacilli ,mycobacteria and hydrophilic (non enveloped)) (HAV) More resistant =higher concentration or longer exposure ( contact time)
Group C: bacterial spores , most resistant (except for prions )=even higher concentration or longer exposure
Most disinfectants are not sporicidal


Descending order of Resistance
- Prions
- Coccidian
- Spores
- Mycobacteria
- Small non- enveloped viruses
- Cysts
- Trophozoites
- Gram negative bacteria
- Fungi
- Large non-enveloped viruses
- Gram positive bacteria
- Lipid enveloped viruses

 Chemicals: 
- Alcohols
- Halogens
- Phenols, bisphenols and biguanides
- Quaternary ammonium compounds
- Aldehydes
Peroxygens and ozone
Alcohols
Ethanol or isopropanol
-Fast acting , require 5 minutes and H2o)
-Non staining
-Used for :thermometers, skin and external
surfaces.
-Effective against fungi, bacteria ,mycobacterium and viruses. isopropyl not effective in enteroviruses
iodine and iodophores ( free iodine)
rapidly active
many uses, thermometers, as antiseptic
has detergent effect
staining , corrosive and irritant
also not sporicidal
phenolics:
phenols and cresol
disinfectant leaving a film
irritant and corrosive
inactivated by organic material
for food preservation and cleaning floors.
Bactericidal, fungicidal, mycobactericidal, not enterovirucidal and non sporicidal

Formaldehyde
· a gas that kills all microorganisms and their spores, at temperatures above 20 °C.
· is not active against prions. It is relatively slow-acting and needs a relative humidity level of about 70%.
· marketed as the solid polymer, paraformaldehyde, in flakes or tablets, or as formalin, a solution of the gas in water of about 370 g/l (37%), containing methanol (100 ml/l) as a
stabilizer.
Gluteraldehyde
- concentration
- pH acidic less effective than alkaline, but still toxic and irritant
- minimum effective concentration ( disinfectant / sterilant)
- biomaterial : protein ,,,,,,,,, denaturation
- Resistance : high level and sterilant
- Mycobacteria ( tuberculosis and Atypical)

Gluteraldehyde

- Activity check or pH check
- Reuse
- Shortest sporicidal report (not confirmed) ;3 hours with renewel totally impractical
- High level disinfection with mycobacteria ; Up to 30 min

Peroxygens
Hydrogen peroxide : widely and rapidly effective –environmentally friendly –harmful to glue –should be rinsed –unstable.
Disinfection of soft contact lenses and endoscopes
Antiseptic for open wounds
Bactericidal , virucidal , fungicidal , mycobacterial and sporicidal (6-25%)

Peroxygens
Paracetic acid
Widely and rapidly effective in presence of organic material – may be corrosive – unstable
High level disinfection and sterilization of instruments and endosoopes
Food industry
Bactericidal , virucidal , fungicidal , mycobacterial and sporicidal ( sterilant in low temperature and concenterations)

Ozone
-O3
- effective as gas and in water (unstable)
Disinfection and sterilization of instruments ( medical and dental)
-Bactericidal , virucidal and sporicidal (spores 15 times resistant)

شكراً الموضوع حلو قوى. جزاك الله كل خير.