Disinfectant - Pharmaceutical microbiology (Second year b.pharm) (3rd semester)

Disinfectant - Pharmaceutical microbiology (Second year b.pharm) (3rd semester)

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  DISINFECTANT • Introduction • Classification& mode of action of disinfectant • Factors affecting disinfectant, antiseptics & their evaluation • Evaluation of bacteriostatic & bactericidal Prepared by, Prof. Shinde Kiran (M.Pharm) Assistant Professor (VNIPRC) Pharmaceutical Microbiology-I Second Year B.Pharm IIIrd Semester Vidya Niketan Institute Of Pharmacy & Research Centre, Bota
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  Introduction  Disinfection: Itis the process of destruction or removal of micro-organisms and reducing them to a level not harmful to health.  Disinfection generally kills the sensitive vegetative cells but not the heat – resistance endospores.  Disinfectants are usually bactericidal but occasionally they may be bacteriostatic.  It plays an important role in control of microbial contamination and prevention of infection.  If the object is lifeless like the areas, dishes, floor, etc the chemical agent is used and called is disinfectant.
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   Ideal disinfectantshould have following properties: 1. Broad spectrum 2. Non toxic 3. Odourless 4. Fast acting 5. Economical 6. Surface compatibility 7. Easy to use 8. Solubility and miscibility 9. Stable on storage 10.Not affected by physical factors
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  1. Acids &Alkalis 2. Halogens 3. Heavy metals 4. Phenol & its derivatives 5. Alcohols 6. Aldehydes 7. Dyes 8. Detergents & Soaps 9. Quaternary ammonium compounds Classification & Mode of Disinfection
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  Factors affecting disinfectantaction 1. Concentration of disinfectants 2. Temperature 3. Time of contact 4. pH of the environment 5. Surface tension 6. Formulation of the disinfectant 7. Chemical structure of disinfectant 8. Type & number of micro-organisms present 9. Interacting substances in the environment 10. Potentiation synergism & antagonism of disinfectants
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  1. Concentration ofdisinfectant: The rate of killing of micro-organisms varies directly with the concentration of the disinfectant. Concentration exponent or dilution coefficient is an important characteristic of each disinfectant and is useful in determining the effect of dilution on the disinfectant. Where, n is conc. Exponent / dilution coefficient for disinfectant t1 is death time with conc. C1 t2 is death time with conc. C2 2. Temperature: The rate of disinfection normally increases with the temperature. This bactericidal activity may be expressed by temperature coefficient .the rise in temperature is denoted by q where, 10 ‘C per rise in temp. is q 10 or Q 10 Where, t1 & t2 are two temperature differing 10 ‘C
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  3. Time ofcontact: Sufficient time of contact must be allowed for the disinfectant 4. pH of environment: A change of pH during the disinfection process can affect the rate of growth of inoculum 5. Surface tension: The contact between aqueous solutions of disinfectant is facilitated if they have surfactant properties. This helps in adsorption of surface active disinfectants on the surfaces of cells 6. Formulation of the disinfectant: This may be important for the effective use of disinfectants. 7. Type & no. of micro-organisms present: The efficiency of disinfection greatly depends on the nature & no. of containing microorganisms & specially on the presence or absence of bacterial spores.
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  8. Chemical structureof disinfectant: Chemical structure of compounds affects the disinfectant activity. 9. Interfering substances in the environment: Material such as blood, body fluids, pus, milk, food residues or colloidal proteins may reduce the effectiveness of disinfectant. This may be due to adsorption or chemical interaction from adequate contact with germicide. 10. Potentiation, synergism & antagonism of disinfectant: Potentiation of a disinfectant leads to enhanced antimicrobial activity. Synergistic effects are often shown by 2 antimicrobial agents which is giving an increased activity. Antagonism leads to decreased antimicrobial activity and use is made of antagonism in the elimination of antimicrobial properties of materials.
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  Factors affecting AntimicrobialAgent 1. Properties of chemical agents 2. Environment 3. Types of micro-organisms 4. Intended application 5. Toxicity of agents 6. Cultural state
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  Evaluation of Antimicrobialagents & Disinfectants [Bacteriostatic & Bactericidal] Methods or Techniques used in evaluation of disinfectant 2. Filter paper and cup plate method 1. Tube Dilution and agar plate method 5. Kelsey Sykes method 3. Ditch – plate method 4. Phenol coefficient method Bacteriostatic: Kills the organism It includes Serial fluid & solid media method Cup plate method Ditch plate method, etc. Bactericidal: Inhibits the growth It includes Phenol Co-efficient method, etc.
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  Advantages Disadvantages 1. Theyare inexpensive can be performed easily 2. They supply standards for crude properties. 3. they give reproducible results in the hands of experienced workers. 1. These tests do not give any information related to tissue toxicity 2. Sampling errors are large in phenol coefficient tests. 3. Phenols coefficient test do not give any indication of the effects of dilution on the activity of disinfectant
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  Thank-you