This chapter discusses methods for controlling microbial growth through sterilization, degerming, and antisepsis. It explains that sterilization kills all microbes including endospores using heat or other methods. Bacteria typically die at a constant rate depending on factors like number, environment, and exposure time. Physical methods for control include moist heat like autoclaving, dry heat, filtration, radiation, and low temperatures. Chemical methods use agents to control growth on living tissues and inanimate objects by changing the pH environment, with antiseptics used on living tissues and disinfectants on inanimate objects.

1. CHAPTER 7: CONTROL OF
MICROBIAL GROWTH
August 20, 2013

2. TERMINOLOGY
 Sterilization is the removal of destruction of all forms of
microbial life
 Heating is the most common form
 Other sterilization methods may not kill organisms, especially
with endospores
 Degerming is the removal of microbes from a limited area
 (skin on injection site)
 Antisepsis is the destruction of vegetative pathogens on living
tissue

4. RATE OF MICROBIAL DEATH
 Bacteria populations typically die at a constant rate
Several factors influence the rate of death
 Number of microbes
 more = longer
 Environmental influences
 Temperature, available nutrients
 Time of exposure to antimicrobials
 Microbial characteristics

5. PHYSICAL METHODS OF CONTROL
 Moist Heat
 Autoclaving is the preferred
method of sterilization
 Conditions inside an autoclave:
100 degrees C under 1 atm OR 15
psi
 All organisms will be killed under
15 psi (except prions)
 Filter
 Pasteurization
 Radiation
 Dry Heat
 direct flaming
 Low Temperatures
 Desiccation
 Drying out the
organism, remains viable
 Osmotic Pressures

6. CHEMICAL METHODS OF CONTROL
 Chemical agents can control
growth on living tissue and
inanimate objects
 Chemical agents chance the
pH environment
 Antiseptics are used on living
tissue
 Disinfectants are used on
inanimate object
Page 206

7. REVIEW CHAPTER 7
Page 212
Review #’s: 13
Multiple Choice #’s: 4, 9, 10
Critical thinking #’s 1, 3