Controlling Microbe Growth

What does microorganisms control

• Controlling exposure controls disease

What do we seek outside the body

• Sterilization

• Disinfection

• Antisepsis

What is Sterilization

• Any process that eliminates or kills/deactivates all forms or life and other biological agents (such as prions and viruses)

What are the methods are sterilization

• Autoclaving

• Radiation

• Filtration

• Hydrogen peroxide vapor

What is disinfection

• Using specialized cleansing techniques that destroy or prevent growth of most organisms

• Some survive (spores,cysts)

• ex: alcohol, bleach,ammonia,chlorine,heat

What is antisepsis

• Applying antimicrobial substances to living tissue/skin to reduce the possibility of infection,sepsis, or putrefaction

What does -cidal mean

KILLS its target

What does bactericide kil

Bacteria

What does fungicide kill

fungi

What does virucide kill

• It inactivates viruses

What is does sporicide do

• Capable of destroying endospores

What does germicide/microicde do

• Chemical agents that kill microorganisms

What does -static mean

• Prevents further growth of microbes

What does bacteriostatic prevent

• The growth of bacteria

What does fungistatic prevent

• inhibit fungal growth

What are the modes of action for antimicrobial

• Proteins

• Nulceic acids

• Cell wall (gram +)

• Cell membrane (gram-enveloped viruses)

What do proteins target

• Heat

• acids/bases

• Chlorine

What does nucleic acids produce

• Hydrogen peroxide

• Radiation

What does cell wall target

• Alcohols

What does cell membrane target

• Detergents

• Alcohols

How does heat effected microorganisms

• Elevated temperatures are microbicidal

• Lower temperatures are microbistatic

What does moist heat do

• Hot water, boiling water, or steam between 60C and 135C

• Denatures proteins

What does dry heat do

• Hot air or an open flame 160C+

• Dehydrates cells

• Chars cells

What are autoclaves

• High heat, steam

• Enormous pressure

What is cold and heat

Physical control

How does cold affect microorganisms

• Slow things down, doesn’t kill

• -70C to 135C can preserve cultures of bacteria, viruses, and fungi

What does desiccation do to microorganism

• Drying of cells

• Kills some; no effect on others

What is radiation mechanism

• Very effective BUT

• you have to overcome repair mechanisms

What is Filtration

• Used to prepare liquids/gasses that cannot withstand heat (serum,blood products, vaccines, drugs, iv fluids)

• Important step in water purification

• Unable to remove toxins that can cause disease

• High efficiency particulate air (HEPA) filters are used in hospital rooms and sterile rooms

What is osmotic pressure

• Adding large amounts of salt/sugar to create a hypertonic environment for bacteria

  • causes plasmolysis

• Pickling, smoking, and drying

  • used for centuries to preserve foods

• Osmotic pressure is never a sterilizing technique

What are the chemical agents in microbial control

• Liquid, gaseous, or solid

• Range of actions

What is an aqueous solution

• Chemicals dissolved in pure water

What are tinctures

• Chemicals dissolved in pure alcohol or water alcohol mixtures