chapter 7 power point Flashcards
What factors need to be considered for microbial control?
Site to be treated, environmental conditions, susceptibility of microorganisms
Examples include the nature of the site determining the treatment method and the efficacy of warm disinfectants.
Differentiate among sterilization, disinfection, antisepsis, degermination, sanitization, and pasteurization.
- Sterilization: Eliminates all forms of microbial life
- Disinfection: Destroys vegetative microbes on inert substances
- Antisepsis: Disinfection of living tissues
- Degermination: Mechanical removal of most microbes in a limited area
- Sanitization: Reduces microbes to prevent transmission
- Pasteurization: Kills vegetative bacteria to reduce spoilage
Each method has practical uses in different contexts.
Define microbial death.
Permanent loss of reproductive ability and vital activities of microbes
Lethal agents may not always change the appearance of microbial cells.
What is the difference between microbicidal and microbiostatic?
- Microbicidal: Designed to destroy microbes
- Microbiostatic: Inhibits microbial growth
Examples include bacteriocidal and fungicidal for microbicidal, and bacteriostatic and fungistatic for microbiostatic.
What are the least resistant organisms?
- Most bacterial vegetative cells
- Most fungal spores and hyphae
- Yeast
- Enveloped viruses
- Protozoan trophozoites
These organisms are generally more susceptible to control methods.
What are the highest resistance organisms?
- Bacterial endospores
- Prions
Endospores are considered the most resistant microbial form; their destruction leads to the elimination of all other organisms.
What is the thermal death point (TDP)?
Lowest temperature at which all microbes in a particular liquid will be killed in 10 minutes
This is a key measure in determining the effectiveness of heat sterilization.
What is the purpose of an autoclave?
Sterilization using wet heat at 121ºC under pressure of 15 psi
Autoclaves are widely used for heat-resistant materials such as glass and media.
What is tyndallization?
Intermittent sterilization using free-flowing steam for 30 to 60 minutes
This method is designed to reduce sporulating bacteria.
What is the effectiveness of boiling water for microbial control?
Kills most vegetative bacteria and viruses in 10 to 15 minutes but ineffective against spores and prions
Boiling is useful for decontamination and disinfecting unsafe drinking water.
What is desiccation?
Drying that inhibits microbial growth
It is used for food preservation in many cultures.
What is the effect of ionizing radiation?
Penetrates deeply and requires long exposure for sterilization
Examples include gamma rays and electron beams.
What are phenols and phenolics used for?
Disinfectants that denature proteins and disrupt cell membranes
They remain effective even in the presence of organic contaminants.
What is the primary use of alcohols in microbial control?
Bacteriocidal, fungicidal, and virucidal
Most effective at a 70% solution.
What is the purpose of food preservation?
To slow down spoilage, prevent food-borne illnesses, and maintain nutritional value
Techniques include pasteurization, freezing, and drying.
What is pasteurization?
A method applying heat to kill potential pathogens and reduce spoilage microbes
It does not change the flavor or food value.
Fill in the blank: The _______ coefficient test was used in the past to evaluate disinfectants.
Phenol
This test compares the efficacy of disinfectants.
What are quaternary compounds (quats)?
Popular detergents for microbial control that are colorless, tasteless, and harmless to humans at low concentrations
They are ineffective against naked viruses and mycobacteria.
