Factor affect the Efficacy of disinfection and sterilization?

    (1)Type of microbiology
         Sterilization is a process that eliminates all forms of microorganisms, including bacterial spores. And disinfection is a process that eliminates many kind of microorganisms, but except bacterial spores. In addition, some type of  bacteria may resistance some sterilization process or disinfection process. For example, spore-forming organisms are most resistant to sterilization.
   (2)Number of microbiology
        It is an exponential relationship between the number of microorganisms and the time taken to eliminate them. It means that the larger number of microorganisms need the more time to destroy all of them.
   (3)Location of microbiology
       If the microorganisms are in a place that the germicide cannot attend then the efficacy of the disinfection and sterilization will be compromised.
   (4) Innate resistance of microorganisms
        For example some bacterial can secrete beta-lactamase to inhibit  beta-lactam and break the  beta-lactam ring, it cause bacterial resistant  beta-lactam of antibiotic such as penicillin.
 

Fig 1 .Penicillinase:

 Beta-lactamase break the  beta-lactam ring and inhibit pencillin active.

  
(5)Biofilm
        Biofilm accumulation reduces efficacy of sterilization by impairing exposure of the sterilant to the microbial cell.

Fig 2 Biofilm resistance to antibacterial agents

   (6)Organic and inorganic matter
        Organic matter includes serum, blood, fecal and pus. Those can interfere with antimicrobial activity.  The organic matter have chemical reaction between germicide, forming a non-germicidal complex. And the organic matter protect the microorganism from germicide, acting as a physical barrier.

More information:
More information:
1. Healthcare Infection Control Practices Advisory Committee (HICPAC)
2.WHO - Infection Control Guidelines for Transmissible Spongiform Encephalopathies



                                                              Writte by Chang,yi-chu (Blythe)

Approach to Disinfection and Sterilization

1. why is this important?
Early civilizations practiced salting, smoking, pickling, drying, and exposure of food and clothing to sunlight to control microbial growth.And use of spices in cooking was to mask taste of spoiled food.  Some spices prevented spoilage.In 1804,the first steps toward sterilization was made by Nicolas Appertaining who placed the food in glass jars, sealed them with cork and sealing wax and placed them in boiling water. It has helped to reduce food borne illness and prevent food decay. In mid 1800s Semmelweiss and Lister helped developed aseptic techniques to prevent contamination of surgical wounds.Before then nosocomial infections caused death in 10% of surgeries.And up to 25% mothers delivering in hospitals died due to infection.

 Food cans use method of preserving food using heat-processing to remove microorgaisms in glass jars.

 

2. Difinition:

    (1)Sterilization: Killing or removing all forms of microbial life including endospores  in a material or an object by physical or chemical methods.
    (2)Disinfection: Decreasing the number of pathogenic microorganisms ,except bacterial spores, to the point where they no longer cause diseases. Applied to inanimate objects.
    (3)Germicide: it is an agent that kills certain microorganisms,usually pathogenic organisms. The term germicide includes both antiseptics and disinfectants.
    (4)Antiseptics: "sepsis" comes from Greek for decay or putrid,indicates bacterial contamination. Antiseptics are a type of germicide, usually  applied to living tissue.
    (5) Disinfectants: it similar antiseptics. But disinfectants are not used for skin antisepsis because they can injure skin and other tissues.

More information:
More information:
1. Healthcare Infection Control Practices Advisory Committee (HICPAC)
2.WHO - Infection Control Guidelines for Transmissible Spongiform Encephalopathies




                                                                      write by Chang,yi-chu (Blythe)