A discussion on the inhibiting the growth of microorganisms in vitro. Different processes of sterilization and disinfection.

2. Sterilization
 Is the complete destruction of all microorganisms,
including cells, spores, and viruses. When something
is sterile, it is devoid of microbial life. Sterilization of
objects can be accomplished by dry heat, autoclaving,
gas, various chemicals and certain types of radiation.

3. Disinfection
 Is the destruction or removal of pathogens from
nonliving objects by physical or chemical methods.
Pasteurization is a method of disinfecting liquids.
 Disinfectants-are chemical agents used to eliminate
pathogens
 Antiseptics are solutions to disinfect skin and other
living tissues.
 Sanitation-is the reduction of microbial populations to
levels considered safe by public health standards.

4. Microbicidal agents
 Microbicidal agents-are disinfectants to kill microbes
 Bactericidal agents are disinfectants that kill bacteria
but not necessarily bacterial endospores
 Sporicidal agents- to kill bacterial endospores
 Algicidal agents-are used to kill algai in swimming
pools and hot tubs.
 Viricidal agents to destroy viruses
 Pseudomonicidal agents kill pseudomonas species
 Tuberculocidal agents- kill M.tuberculosis

5. Microbistatic agent
 Is a drug or chemical that inhibit the growth and
reproduction of microorganisms.
 A bacteriostatic agent is one that specifically inhibits
the metabolism and reproduction of bacteria.

6.  Sepsis-refers to the presence of pathogens in blood or
tissues
 Asepsis means the absence of pathogens
 Antisepsis-is the prevention of infection
 Antiseptic technique- developed by Joseph Lister in
1867,refers to the use of antiseptics.
 Sterile technique-is practice to exclude all
microorganisms from a particular area, so that the area
will be sterile.

7. Using physical methods to inhibit
microbial growth
 The physical methods commonly used in hospitals,
clinics and laboratories include heat, the combination
of heat and pressure, desiccation, radiation, sonic
disruption, and filtration.

8. Heat
 Is the most practical, efficient and inexpensive method
of sterilization of those inanimate objects and
materials that can withstand high temperatures
 2 factors:
A. Temperature
B. Time
-determine the effectiveness of heat for sterilization

9.  There is a considerable variation fro organism to
organism in their susceptibility to heat; pathogens
usually are more susceptible than nonpathogens .

10. Dry Heat
 Dry heat baking in a thermostatically controlled oven
provides effective sterilization of metals, glasswares,
some powders, oils and waxes.

11. Moist heat
 Heat applied in the presence of moisture , as in boiling
or steaming, is faster and more effective than dry heat
and can be accomplished at a lower temperature; thus
it is less destructive to many materials that would
damaged at higher temperatures.

12. Cold
 Refrigeration merely slows the growth of most
microorganisms; it does not completely inhibit the
growth.

13. Desiccation
 The process of being thoroughly dried

14. Radiation
 The UV rays, which do not penetrate glass and
building materials, are effective only on surfaces. They
penetrate cells and thus can damage DNA .

15. Filtration
 Filters of various pore sizes are used to filter or
separate cells, large viruses, bacteria and certain other
microorganisms from the liquids or gases in which
they are suspended.

16. Gaseous atmosphere
 It is possible to inhibit growth of microorganisms by
altering the atmosphere in which they are located

17. Using chemical agents to inhibit
microbial growth
 Chemical disinfection refers to the use of chemical
agents to inhibit the growth of pathogens, either
temporarily or permanently.

18. Various factors affect the efficiency
or effectiveness of a disinfectant
 Prior cleaning of the object or surface to be disinfected
 The organic load that is present, meaning the presence of
organic matter on the materials being treated
 The bioburden, meaning the type and level of microbial
contamination
 The concentration of the disinfectant
 The contact time, meaning the amount of time that the
disinfectant must remain in contact with the organisms in
order to kill them. The physical nature of object being
disinfected
 Temperature and ph

19. Characteristics of an ideal chemical
antimicrobial agent
 It should kill a wide variety of microorganisms
 It should be fast acting, contact time should be short
 Should not be affected by the presence of organic material
 Must be nontoxic to human tissues and noncorrosive and
nondestructive to materials
 It must be soluble in water and easy to apply
 Should be inexpensive and easy to prepare
 Should be odorless
 It must be stable both as a concentrate and as a working
dilution.