Microbiology Ch11: Physical & Chemical Agents for Microbial Control
Examples of Disinfection
- A 5% solution of bleach to clean a lab table - Immersing thermometers in an iodine solution - Boiling eating utensils
__________ and __________ are limited in their application by their corrosive and hazardous nature.
- Acids and Alkalis
Decontamination methods employ either __________ or physical agents to destroy microorganisms.
- Chemical
As UV radiation passes through a cell, it is initially absorbed by __________.
- DNA
__________ is the process of reducing microbes in or on living tissues.
- Degermination
The antimicrobial properties of some agents arise from their capacity to disrupt the structure of, or __________, proteins.
- Denature Denaturation: occurs when the bonds that maintain the secondary and tertiary structure of the protein are broken. This will cause the protein to unfold or create random, irregular loops and coils.
The primary targets of microbial control are microorganisms that cause which of the following (there are 2)
- Disease - Food Spoilage
__________ is the removal or inactivation of harmful products or microbes, like toxins.
- Disinfection
Radiation is characterized by a range of wavelengths known as the __________ __________.
- Electromagnetic Spectrum
How are many cultures of microbes routinely preserved?
- Freezing
__________ is an agent that inhibits fungal growth.
- Fungistatic (static: inhibits growth)
Categories of Chemical Agents include (there are 8 groups)
- Halogens - Phenolic comounds - Alcohols - Oxidizers - Aldehydes - Gases - Detergents - Heavy Metals
Ionizing Radiation: Gamma Rays & X-rays
- Has become safer and more economical to use - Great alternative for sterilizing materials that are sensitive to heat or chemicals - Sterilizes in the absence of heat - Irradiation is a type of Cold (low-tmp) Sterilization
What is the most prominent among antimicrobial physical agents?
- Heat
Examples of Physical agents or mechanical means used to control microbes:
- Heat - Radiation - Filtration
Acids and Alkalis are commonly used for what? (name 2)
- Household cleaners - Food preservation
What types of surfaces are Disinfectants used on?
- Inanimate Objects
__________ radiation destroys bacterial pathogens in foods.
- Ionizing
__________ is the process of bombardment w/ radiation at the cellular level to control microbes.
- Irradiation
__________ acid is the organic acid added to sauerkraut to prevent the growth of anaerobic bacteria, especially clostridia.
- Lactic acid
When microbes are treated with temps. that exceed their maximum growth temp., the condition is described as:
- Microbicidal
Halogens are microbistatic or microbicidal?
- Microbicidal, they can be sporicidal with longer exposure times
An antimicrobial agent's adverse effect on cells is knows as its __________ of __________.
- Mode of Action Agents affect one or more cellular targets, inflicting damage progressively until the cell is no longer viable
The Heat treatment of perishable liquids to destroy heat-sensitive vegetative cells & prevent infection & spoilage is called __________.
- Pasteurization
__________ acid is the organic acid that is commonly used in breads to retard molds.
- Propionic acid
Specific molecular damage occurs on the Pyrimidine bases (Thymine & Cytosine), which form abnormal linkages with each other called __________ __________.
- Pyrimidine Dimers
_________ is used for microbial control that includes electromagnetic waves with shorter wavelengths.
- Radiation
Pyrimidine Dimers in cells result in the lack of __________ and __________.
- Replication and Transcription
Two goals of Pasteurization
- Retention of liquid qualities - Reduction of microbial load
Effects of Ionizing radiation on food products
- Small decreases in Thiamine - Killing of Bacterial pathogens - Changes in texture of some foods
Example of a Surfactant
- Soap
Antimicrobial chemicals can exist in what physical state?
- Solids - Gas - Liquids
What are Desirable qualities in a Germicide?
- Solubility in a solvent - Broad-spectrum action - Rapid action - Penetrating ability
__________ are chemical agents that can destroy all forms of life, including endospores.
- Sterilants
What process completely removes or destroys all viable microorganisms, including viruses, from an object or habitat?
- Sterilization
Chemicals called _________ work as microbial agents because they lower the surface tension of cell membranes.
- Surfactants * Are polar molecules ex) detergents with hydrophilic and hydrophobic regions
Sepsis
- The state of putrefaction - The presence of pathogenic organisms or their toxins in tissue or blood
Why aren't Bromine and Fluorine routinely used in germicidal preparations?
- They are too dangerous!!!
What are the three Pyrimidine nitrogenous bases that are found in DNA or RNA?
- Thymine - Cytosine - Uracil
__________ radiation is most lethal from 240nm to 280nm.
- Ultraviolet or UV
__________ radiation is non-ionizing radiation that readily induces mutations
- Ultraviolet or UV
Microbial forms that are relatively resistant to heat:
- Viruses - Prions - Endospores
Which root(s) indicates the ability to prevent the growth of microorganisms?
- stasis - static
Microbicidal = __________ temperatures Microbistatic = __________ temperatures
... cidal = High temps (kills) ...static = Low temps (stops growth)
The Halogen Antimicrobial Chemicals:
Fluorine, Bromine, Chlorine, Iodine -a group of nonmetallic elements with similar chemical properties - Can exist as ionic (halide) or nonionic, most halogens exert their antimicrobial effect on nonionic (chloride, iodide)
What is Lyophilization
Freeze-drying - Preserving the viability of cultures - Separating dissolved solid from solvent by freezing the solution and evacuating the solvent under vacuum
What does Disinfection destroy?
Only Vegetative Cells
Microbial Death
Permanent loss of reproductive ability under ideal environmental conditions
Quats
Quaternary Ammonium Compounds These detergents are weakly microbial and are used as disinfectants, sanitizers, and preservatives
What is meant by Aqueous Solution?
Solutions containing pure water as the solvent are termed Aqueous
What is meant by Tinctures?
Solutions dissolved in Pure Alcohol or Water-Alcohol mixtures
True or False: Microbistatic antiseptics & drugs are used to control microorganisms in the body because Microbicidal compounds can be toxic to the human body.
TRUE - Microbicidal can be toxic
True of False: Catheters, endoscopes, and implants are not heat-sterilizable
TRUE They need to be sterilized using Sterilants
Example of Denaturation
ex) Agents that Alter Protein Function
Example of Surfactants
ex) How agents affect the Cell Membrane