MODULE 3: Microbial Growth and Safety

• Controls microbial growth and particulate contamination within acceptable levels.

  Antiseptic Technique
• Refers to microbial contamination.

  Sepsis
• Absence of significant contamination

  Asepsis
• Removal of all microbial life.

  Sterilization
• Removal of pathogens, except bacterial spores from nonliving objects.

  Disinfection
• Removal of pathogens from living tissue.

  Antisepsis
• Lower microbial counts on eating utensils

  Sanitization
• Use of heat to kill pathogens and reduce the number of spoilage bacteria in food and beverages

  Pasteurization
• An antimicrobial that INHIBITS bacterial growth but DOES NOT KILL the bacteria.

  Bacteriostasis
• An antimicrobial that kills a microorganism

  Bactericidal
• 4 Physical Methods of Sterilization

  Moist Heat

  Dry Heat

  Filtration

  Ionizing Radiation/Cold Sterilization
• Chemical Method of Sterilization

  Ethylene Oxide

  Formaldehyde vapor & vapor phase H2O

  2% Glutaraldehyde

  Peracetic acid
• Physical Method of Sterilization: Destroys microorganism by COAGULATION OF ENZYME and STRUCTURAL PROTEINS and DEGRADATION OF NUCLEIC ACID

  Moist Heat
• Principle of AUTOCLAVE

  Steam under pressure
• sterilizing unused and used media

  121degC, 15 psi, 30 minutes
• medical waste

  132 degC, 15 psi, 30-60 minutes
• used to raise temperature, not to kill the organisms

  Pressure
• indicator of Autoclave

  Bacillus stearothermophilus
• bacillus stearothermophilus is incubated at what temperature?

  56 degC
• an infectious protein particle that causes neurologic disease in animals and humans and not killed by autoclave

  Prions
• Physical Method of Sterilization: Discontinuous/intermittent method/fractional

  tyndalization and inspissation
• uses flowing stem and equipment used is arnold sterilizer

  tyndalization
• Thickening through evaporation/dehydration

  Inspissation
• Used to sterilized media containing milk or serum


  Tyndalization
• Used for sterilization of culture media that are EGG-BASED AND OF HIGH PROTEIN content

  Inspissation
• Sterilization temperature of Tyndalization

  100degC for 30 minutes for 3 consecutive days
• Sterilization temperature of Inspissation

  75-80 degC for 2 hours for 3 consecutive days
• Physical method of sterilization: It kills microorganism by DENATURATION of proteins; sterilization WITHOUT WATER.

  Dry heat
• Physical Method of Sterilization: it is utilized for the sterilization of GLASSWARES, OIL PRODUCTS and POWDERS.

  Dry Heat
• Used to sterilize glasswares, metal instruments, oils and certain fatty substances which are not permeable to water

  Oven
• Sterilization Temperature and time for Oven 


  160-180 degC for 1-2 hours
• Biological indicator for Oven

  Bacillus subtilis var niger
• Bacillus subtilis var niger is incubated at what temperature?

  35-37 degC
• Most common method of treating infectious waste

  Incineration
• Burning to ashes, temperature of

  870-980 degC
• disadvantages of incineration


  production of toxic emission and presence of metals in ash
• Physical Method for Sterilization: For loops and needles


  direct flaming
• Physical Method for Sterilization: to control disease

  cremation
• These are porous membranes 0.1mm thick to sterilize culture media, antibiotics.

  Membrane Filter/Circular Filter
• Membrane filters are composed of?

  Cellulose Acetate and Polycarbonate