Chapter 5 & 20 Flashcards
Sterilization
Process of destroying all microorganisms or viruses within or on a product (including endospores and fungal spores); no varying degrees
Disinfection
A process that reduces the number of microorganisms or viruses within or on a product until they no longer represent a hazard
Disinfectant
A chemical agent used to disinfect inanimate objects
Antiseptic
A disinfectant that is nontoxic enough to use on human cells
Types of Disinfectants
- cide: treatments that kill
- static: treatments that inhibit rather than kill
- e.g., germicide, fungicide, viricide, bacteriostatic/fungistatic agents
Bacteriocide
Used to kill vegetative forms of bacteria, but not usually endospores
Bacteriostatic or Fungistatic Agents
A chemical or conditions that prevent the growth of these organisms, but does not kill them
Decontamination
Involves the inactivation and removal of both microbes and any toxins that may be present within or on the product
Sanitation
In the food industry, decontamination on an area or product to meet public health standards
Factors Affection Disinfectant Action
- Time of contact: death is not always instantaneous (may take hours)
- Temperature; usually work better at high temps but most are designed to work near room temp
- pH: work best at certain value (will vary)
- Number of microorganisms: greater number of cells, greater amount of time needed
- Presence of Extraneous Matter: organic matter may react and cause them to be less effective (soil, blood, pus, etc.)
- Concentration: in most cases, the more concentrated the shorter the killing time
Decimal Reduction Time (D time)
The time it takes to kill 90% of bacteria present; usually constant over time - if it takes two minutes to kill 90% of a bacteria population, then a population of 100 would be reduced to 10 in two minutes and one in four
Types of Microorganisms
- Least resistance: vegetative forms of most bacteria and viruses with membranes
- Moderate resistance: Mycobacterium tuberculosis, Staphylococcus aureus, and Pseudononas species, viruses with no membranes
- Highest resistance: bacterial endospores
Cells in the stationary growth phase are more resistant than cells that are actively growing.
Effectiveness of Destroying Microbes
- High: Kill all organisms, including endospores; surface will be sterilized
- Intermediate: Kill resistant pathogens (mycobacterium tuberculosis) and non-enveloped viruses
- Low: Kill vegetative bacteria and enveloped viruses
Antimicrobial Chemotherapy
The use of drugs to destroy or inhibit the growth of microorganisms that are causing disease
Antibiotics
A chemical produced naturally by a microorganism (usually other bacteria or molds) that have antimicrobial effects; e.g., Streptomyces griseus (soil bacteria) are used to create streptomycin
Synthetic Agents
Chemicals that have antimicrobial effects, but are produced in a laboratory (e.g., sulfa)
Antimicrobic
A word that incorporates all types of antimicrobial drugs, regardless of origin
High Selective Toxicity
An ideal characteristic of chemotherapeutic agents; the chemical is toxic to the microbe causing the disease, but much less so to the cells of the host (all chemicals are at least slightly toxic to a host - therapeutic index is used)
Therapeutic Index
Ratio of the minimum dosage that is toxic to the host to the minimum dosage that is toxic to the microbe (MIC); e.g., 500mg/hr is toxic to humans while only 50mg/hr is toxic to bacteria - the ratio is 500/50 10:1
MIC (Minimum Inhibitory Concentration)
The lowest dose that prevents the growth of a microbe