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