1. Lab.2- Types of Chemical Methods Sterilization

2.  Chemical Agent 
A chemical agent that kill pathogenic and non pathogenic m.o. but not spores ( not necessary all microbial life ), it either kill or stop the growing of microorganism. It act on lipid contents of the cell membrane ,denaturation of protein, and on nucleic acid.

3. Types of Chemical Methods Sterilization:-
Chemical Agent
Mild (Antiseptics)
Potent (disinfectant)
Dettol
Chlorhexidine (Hibitane)
Iodine
Hydrogen peroxide
Soap and detergent
Alcohol
Phenol group
Strong alkaline and acids
Chlorine

4. Type of Chemical Sterilization:-
a) Potent: disinfectant:
It is toxic for living tissue, it’s used for nonliving(inanimate).
1)Phenol group: contain benzene ring, Used for bathrooms, hospital, floor ……ect.
Mechanism of action::Disruption of plasma membrane.
2)Strong alkaline and acids e.g. NaOH
Used for treating sputum for detecting TB and decrease viscosity.
Mechanism of action::Hydrolysis and protein denaturation.

5. Type of Chemical Sterilization:-
3) Chlorine is most often used in form of sodium hypochloride (household bleach) in dilution (1:10) treatment of swimming pools etc.
Mechanism of action:: Strong oxidizing agent which alters celluler components.

6. A disinfectant in addition should be-
1. Non-corrosive.
2. Good penetrating agent.
3.Compatible with other organic compounds like soap.

7. Type of Chemical Sterilization:-
b) Mild: Antiseptics: which can be safely applied to skin or mucous membrane and are used to prevent infection by inhibiting growth of bacteria.
1- Dettol Mechanism of action::Disruption of cell membrane
2- Chlorhexidine (Hibitane): very good as skin antiseptics used to treat surgical wounds because it work on both gram-positive and gram-negative bacteria
Mechanism of action::Disruption of plasma membrane.

8. Type of Chemical Sterilization:-
3- Iodine: used in surgery to sterile skin pre-operation. Mechanism of action: Protein denaturation. 4-H2O2(hydrogen peroxide ) can be used for sterilization of deep wound or gangrene infected by anaerobic bacteria Mechanism of action: Oxidation

9. Type of Chemical Sterilization:-
5- Soap and detergent
Mechanical removal of microbes through scrubbing.
Detergent:- is a surfactant or a mixture of surfactants with cleaning properties in dilute solutions, is similar to soap but is more soluble in hard water.
6- Alcohol at conc.70% because it can penetrate tissue easily at this concentration better than 99%(absolute).
Mechanism of action: Protein denaturation and lipid dissolution

10. An antiseptic in addition should be:-
1. Rapid in action and practice sustained lethal action.
2. Non-irritating to tissues when applied.
3. Non-allergic.
4. No systemic toxicity (Non-absorbable).
5.Active even in the presence of body fluids e.g.- blood, pus.

11. Procedures : Activity of some Disinfectants
The purpose of this method is to study the activity of some disinfectants and to learn the importance of time, germicidal, concentration and microbial species in disinfection.
Select one of the chemical agents provided. Add 5ml of the solution in to sterile test tube.
To 5ml of disinfectant, add 0.5ml of Esch . coli culture Gently shake the tube. Not the time.
Divide Nutrient agar plate in to 4 sections with a marking pen. (1,2,3 ) minutes.
Transfer one loop ful of the disinfectant culture mixture to a section of the N.A. plate. Lable each plate with the name of m.o., the disinfectant, concentration ex. ( Esch.col : 1% phenol ) .
Incubate at 37o for 48 hours.
Result : Observe all plate. Section from growth ( + ) or absence of growth (- ) .